Never a straight line

[jbcollier]

Put it in fifth using the shifter and note the linkage position.  Disconnect the linkage and put it in fifth manually, different or the same?  Moves further engaged?  Linkage issue.  No difference? Internal issue.

[BDA]

I saw where John mentioned that 5th gear in a 365 was the first thing to go if the tranny had run too low of oil. Figuring the issue would likely be repeated for on an NG3, I went about trying to find a spare NG3 and replace all the guts or whatever parts I needed to get the thing going again. While I was at it, I might replace all the synchros and seals.

I thought I'd call Richard at Banks to see what he thought and he told me that NG3s will run without oil (for a little while). He had some where the customer didn't put oil in theirs, he drove it for 200 miles and it was seizing up. He unseized or replaced the bearings and it has been running fine ever since!

When I told him of my plans to replace the synchros he said he didn't recommend that because unless you had the serial number for the car, you couldn't determine the correct synchro. Everything might be the same on the old and new one but the face might be a couple of degrees different and it wouldn't shift!

Always an education talking to Richard! I wish I could just hang around his shop and see what goes on there!

[BDA]

They aren’t going to adjust themselves

In which our hero (maybe I’m somebody’s hero!) adjusts the valves of his engine and hilarity ensues…

The Introduction

I realize that this post will probably not relate to anybody since I am very likely the only one here with a BDA motor but some might find this interesting, instructive, and/or even humorous so I will press on regardless (ok, I stole that from the name of the famous rally).
For those who are not familiar with the BDA motor, it is sort of the next iteration of the Lotus TC motor using the same block (actually, the main and maybe only difference is that the BDA block is taller). Its development in 1968 coincided with the Formula 1 Ford V-8 DFV built for Colin Chapman and in some ways the BDA is half a DFV. The BD stands for Belt Driven and in that way it is not like the DFV which is gear driven. The other way is that the BDA is different is because it was carbureted while the DFV was fuel injected. The BDA is a twin cam, four valve motor and for a street motor of its time, it was pretty advanced. Twin Cam Escorts were having a harder time in rallies and so were phased out as the BDA powered Escort RS1600 went into production in 1970. The RS1600 was very successful in rallies. There are nearly an alphabet’s worth of BD variants differing in displacement, valve sizes, induction (carburetors or fuel injection) and block material (e.g. BDB – BDH, BDJ and on and on. If you’re curious, take a look at this: https://historicmotorsportcentral.com/2014/04/16/the-cosworth-bd-engine/ for more information). These motors were very successful in many racing classes, most interesting to me was SCCA’s Formula B (later called Formula Atlantic) in the mid ‘70s to early ‘80s. The motors used for those cars were generally designated BDD or BDN (though they were often called BDAs) and they produced upwards of 240 bhp at 9500 rpm.

[BDA]

Part the First – A Quick and Easy Job

Getting back to the subject at hand, I basically have a detuned Formula Atlantic motor. Dave Bean (RIP) built my motor in 1980 from a street BDA head (racing heads had bigger valves) I had acquired. I’ve been trying to learn how to tune the carbs properly and in online conversations, the fact that the valve clearances should be right for an accurate tune came up. My motor has at most 20,000 miles and given the outward appearance and attention to detail, not to mention Dave’s reputation, my valves should be in good shape, but I thought it was useful to at least know what the valve clearances were so I measured them. Well, what I found was a bit disconcerting. All the intake valves were tight. Where the correct clearance was 0.008”, they ranged from 0.006” to 0.003”! Thankfully, the exhaust valves were all good. The correct clearance for them was 0.010” and all were either 0.009” or 0.010”. I have no explanation for the tight intake valves.

It was obvious to me that I needed to adjust my valves whether that helps me in the carb tuning area or not. A bit of description of how this part of the engine goes together might be in order. The head is in three pieces [exploded view of head.jpg]. On the top is the cam cover. Next is the cam carrier. This houses the cams and provides bores in which the cam followers run.  The followers are similar to TC followers in that they are a steel “cup” but mine have a post in the middle of the cup [follower.jpg][underside of follower.jpg]. The bottom of the cup (or looked at from another way, the face of the follower) is what the cam rides on. The post inside the cup pushes against the shim that sits on the valve stem. Lastly, is the head itself which has the valves, springs, etc. The valve spring retainers have a built-in “cup” that contains a shim for each valve [spring retainer.jpg]. Those shims [shim.jpg] are what provide the adjustment and are either to be swapped out with the correct thickness shim or the shim is to be ground to the proper size.

The general procedure is to measure the valve lash, take off the cam carrier, measure the shims for each valve, and from that, decide the thickness of the new shims to give the proper clearance. Order them and receive them, put everything back together and drive off into the sunset. How hard can it be? I’ve never worked on a Twin Cam but I thought it could be easier than for a Twin Cam motor because I thought the cam carrier and belt would simplify things. Well, let’s just see how that worked out. This will be good! Consider stopping to pop popcorn here!

To take the cam carrier off the head, you must first take the belt off the cams. For me this means taking off the steering wheel, taking out the seats, and the carpet board on the firewall and opening the door I made in the middle of the firewall for access to the front of the engine. Loosen the adjusting idler and slip the belt off. [cam carrier.jpg] Next, you position magnets on the followers (the best you can since some of the cam lobes will be in the way). I thought the idea was that when you took the cam carrier off, the shims and the followers would all come with it. When I took my cam carrier off, most of the shims stayed in the valve spring retainers but not all. Some of them fell off their follower or dislodged from their spring retainer. In this picture, you can see the head with the shims in the spring retainers [head.jpg] and in this picture, you can see the followers in the cam carrier looking at it from the bottom. [underside of cam carrier with followers.jpg]

Ok! That was fun! Since I didn’t know the thickness of the shims that every valve started with and I might have replaced some of them on the wrong valve, it meant that I had to mark all the shims with their position and thickness, make a note of where I put them, then put everything back together and re-measure the valve clearance to make sure I calculated the proper thickness of the new shims. First I had to at least clean off the bottom of the cam carrier. Then I labeled each shim with which valve I thought it went to and how thick it was and recorded that in my notebook. I also noticed that the face of one of my followers was scarfed up. [scarfed up follower.jpg] The best I could tell is the follower might have gotten stuck in the bore such that it wouldn’t rotate and the edge of the cam dug a feathered pattern toward the edge of the face but that’s just a guess. Regardless what happened, it had to be replaced (are we having fun yet?). I called up Ken Gray at Dave Bean and ordered the shims I needed and a new follower. Well I tried to. The thinnest shim Ken had was way too thick for what I needed. I guess I’ll be sanding or grinding some shims!

Edit: Elsewhere I noted that John Muir had passed but neglected to note that Dave Bean had also.

[BDA]

Part Deux - New parts and proceeding with the plan

I figured the next valve clearance measurement would be easy. I didn’t have to worry about the position of the cams with respect to anything. Finally, something that should go quickly! Wait a minute, Hoss! The valves and the pistons will at some point interfere with each other if they aren’t in sync. I’m going to have to put the timing belt back on and at least get the cam/crank orientation close. [note: After I put it all back together, I realized I could have put the crankshaft at 90° before or after TDC and all the pistons would be half way up in their cylinders which would give me plenty of room for opening any valves so I could have turned the cams independently of the crank… The things you think of when you don’t need to worry about it anymore!]

I placed the shims where I thought they belonged, lightly greased the followers, as recommended by the manual (I believe this is to ensure good initial lubrication as well as to aid in keeping the follower in the bore of the cam carrier so it doesn’t fall out when putting the cam carrier back on the head). I snugged up the fifteen bolts that hold the cam carrier to the head and then went in the car to put the belt back on. That’s when I realized that with the engine in the car, it is definitely a two man job. From inside the car, it is very difficult to ensure that the timing belt has the proper wrap on all the lower pulleys and impossible to turn the crank when needed. I called my buddy, Dennis T. to help me. He crawled underneath the car to turn the crank when needed and to hold the belt tight against both sides of the crank pulley, and I stayed up top making sure the motor was at TDC for #1 cylinder and the cams were properly aligned and to put the belt on and snug up the idler/adjuster [cam pulleys aligned.jpg].

After measuring a few valves, they seemed to have a wider gap than before. I guess we had to torque the bolts holding the cam carrier to the head (8 – 10 ft-lbs.)! After that we got clearances that were predictably similar to the original clearances. As a matter of fact though, they didn’t measure exactly the same as before (even the valves I was sure had their original shims). The follower is shrouded by the “tube” for the spark plug and a ridge in the casting that helps collect oil around the cam and follower. [cam carrier.jpg] It was peculiar that one feeler gauge would feel loose but the next size up would not go in at all. I took my new measurements as accurate since I felt like I was getting a better feel for it and I had a second set of eyes and hands to back me up. That’s my story and I’m sticking to it!

A couple of days after I ordered the shims and follower from Dave Bean, I received them! Amazingly quick service and delivery! Thank you Ken! The first thing I noticed is that instead of the flat shims that fit in the valve spring retainer, I got what Ken called lash caps. [lash cap.jpg] They are cups with different thickness “bottoms” that provide the adjustment. They sit on top of the valve stem but unfortunately, the cup is deeper than the distance from the valve keeper to the top of the valve so those didn’t look like what I wanted. Then I took the follower DBE sent me and tried to put it in the bore where the scarfed up follower went and it wouldn’t fit! Hmmm… This freaked me out a little so I decided to order shims and a follower from Burton Power in England. They have a complete line of BDA, TC, and more modern Ford engine parts and go fast racing parts. I figured that Burton being closer to the source, as it were, that their parts might be more accurate. (yeah, it doesn’t make sense to me now either, but I was grasping!) The next day, I ordered some shims and a follower. The shipping cost about what the parts cost but I figured I’d certainly have what I needed. Is a simple valve adjustment starting to sound more complicated and expensive than it should? Yeah, that’s what I thought too!

[BDA]

The Third Part - Not boring! Or How many Dennises are there?

While I waited for those parts to come, I sanded down the shims I had for my intake valves which were too tight. It wasn’t fun but I think I got them all pretty good. I was also able to swap valve shims around to get the expected gap much closer. Then I talked to Dennis Shaw, my machinist. I should mention that he is a successful race engine builder (he used to build the motors for Team Highball, the Mazda factory IMSA team back in the ‘70s and ‘80s which won the 24 Hours of Daytona four times in a row.  https://www.youtube.com/watch?v=MuSvVK6n1V8). He figured he could do something with either the bore or the follower. If he’s going to be machining on the cam carrier, I might as well take the cams out since that would require a proper cleaning job and I didn’t need to pay him for taking the cams out if I could do that myself. Does it sound like adjusting valves has turned into a fur ball yet?

According to the manual, in order to take the cams out of the carrier, you have to take the pulleys off first. I pulled the pulley off the exhaust cam. I saw the keyway in the pulley and the key slot in the cam but I didn’t see a key! In fact, they used a lot of RTV silicon to make sure the oil wouldn’t leak out the front and there was RTV in the key slot in the cam. Now I’m scared! Without some positive way of setting the position of the pulley, I didn’t know how to get the cam timing back where it was! The cam timing spec was specified in terms of the position of full lift – 102° ATDC. Well, with the engine and tranny in the car (and not a convenient way of fixing a degree wheel on the crank, I wasn’t sure I could tell where 102° ATDC was. I thought my only hope was if Dave marked the flywheel for that when he built the motor. That seemed possible but not likely. At this point, I sure as hell didn’t want to take the pulley off the intake cam! I figured I was in enough trouble already! As it turned out, you can take the cams out of the carrier with the pulleys on them. I sure wish I had known that!

In the next day or so, I received the order from Burton Power. I got the shims I wanted so I tried the follower I ordered in the bore and it was too big too! Now, it should be said that oversized followers are available so that if your bore was trashed you could rebore it bigger and use the bigger follower. That’s not what I had. The original bore was 1.200” and the oversized followers are 1.250”. The new ones I had were only several thousandths bigger than 1.200”. I figured that Dennis should be able to enlarge the bore a little for one of my new followers. All this for a valve adjustment?!

I met Dennis a day or so later. I felt confident that he’d be able to do something about the follower and bore and I was hopeful that he’d be able to come up with some way of making sure my cam timing was good. I was a little heartened when talked with him on the phone and he said when he changes the cam timing on motors he builds, he starts with a 4° change since 2° probably wouldn’t make a difference. So if he could help me get in the ballpark, that would be good enough. Maybe using a key would put the cam in that 2° window…

He first worked on the follower bore. After talking about it and measuring things he decided it didn’t make any sense to try to cut a few thousandths from the bore with his mill so he worked on it with a ScotchBrite buffer on an air grinder and a brake cylinder hone on a drill. He got it close and then polished the follower with his crank journal polisher. (A fun fact is that his crank journal polishers are like a big band sander but the abrasive is actually cork!) After a while he got it to feel really nice.

Then, on to degreeing the cams. I told him that at TDC, the cam lobs were essentially 180° opposed to each other. He didn’t believe me. Well, I couldn’t explain it. All I could do was tell him that that’s the way it was and the TC motor was alike in that way. We tried to think of some way of degreeing the cam without taking the tranny off. He noticed that there was a stain (probably caused by the RTV in the key slot of the cam) on the inside of the pulley bore that likely indicated where the key slot on the cam had been. Given the diameter of the bore in the pulley there and the thickness of the stain, we calculated that it was not just a couple of degrees different from using a key but eight or ten degrees different so just putting a key in the cam and mating the pulley to the cam was not going to work. At this point, it was looking like unless Dave marked the cam timing degree (102° ATDC) on the flywheel, I would have to take the tranny out of the car and mark it myself. Marking the flywheel wouldn’t be that difficult (measure the circumference of the flywheel, divide by 360 multiply by 102 and measure that distance from TDC and Bob’s your uncle!) but while I’ve taken the tranny out several times, it is a huge pain! When you’re up to your ass in alligators, it’s difficult to remember that the initial objective was to drain the swamp! It seemed like there was a new alligator every time I turned around!

While I was trying to figure out my next move, Dennis was looking at my cam and cam carrier. He had suggested there should be some witness marks on the cam and carrier from the build but so far we hadn’t seen them. Then he saw them! There was a scribe mark on the cam that lined up with a scribe mark on inside of the cam carrier. [cam TDC scribe mark.jpg] There are painted marks on the front and back of the pulleys for external reference to TDC and when those scribe marks were lined up on the intake cam (which still had its pulley), that pulley was oriented to TDC (as noted by the paint marks). Also the lobes of the cam were about 180° degrees opposed to each other as I remembered! The mystery was solved! Finally things are starting to work out!

I’m working on documentation for my car and made a note to include a mention of those witness marks in it. When I got home, I looked at what I had already put in my document:

“Cam timing
From front, the yellow lines (on the pulleys) should fall onto the line formed by the cam axes at TDC. From the rear, the yellow lines (on the pulleys) align with the cam box top surface on the outside. Inside, there are scribe lines on rear of #1 cam bearing (top) and corresponding marks on cams. All at TDC.”

That was a quote from the letter Dave Bean sent me with the motor. I guess I could have saved myself a lot of worrying if I had thought to read my own documentation but what fun would that have been? So now, I just need to clean up the cam carrier really well and assemble it on the motor.

[BDA]

The Fourth – But not of July

After Dennis’ fooling around with the cam carrier, it was important to give it a good cleaning. Since I don’t have a good parts washer (that might be rectified sooner rather than later), I took the cam carrier and cams to my buddy, Dennis T.’s,  house and washed it all down really well, bagged it up and brought it home. Dennis was anxious to help me with it (he really had no idea what he was getting involved with but I wasn’t going to tell him!) so the next day, he came over to help me with everything. Before we got started, I retorqued the head. This is something that I would normally do after a thousand or so miles but because the head bolts were under the cam carrier, it was never done. Then I mic’ed all the shims one more time to make double dog sure what shims I had and where they were. [head.jpg]

The plan was to assemble the head, then install the timing belt and the exhaust pulley in preparation for a final check of valve clearances. Since one of the followers was new, it was likely that that valve may need further adjustment. Since the exhaust cam pulley was off, we locked both cams at TDC (from the scribe marks on the cams and cam carrier) with lock pliers (the crank was already at TDC). The idea was to put the exhaust cam pulley on the cam, but loose, then put the belt around all the pulleys, adjusting the exhaust cam pulley so that the TDC marks were relatively accurate and tighten bolt on the pulley to the cam. My main concern was that the two pulleys not only be as close to their TDC position as possible but also that the two cam pulley’s be “in sync” so the cogs in the belt would mesh properly with both pulleys. Conceivably, their marks could line up pretty closely but the cogs in the belt might not mesh properly on both pulleys putting stress on the cogs on the belt (thinking about it after the fact, that is a silly worry but without sufficient experience, paranoia can set in). In the two previous times I fooled with the timing belt, if the belt was wrapped properly on the crank and jackshaft pulleys, there was enough slack to slip the belt on without trouble. Not this time! Seemingly, no matter what we did to ensure there was no slack in the belt, we couldn’t get it over all the pulleys. Finally I took pulley all the way off the exhaust cam, wrapped the belt around all the pulleys and then by tightening the bolt holding the pulley on. That did work and was close enough to be sure there would be no meeting of any valves and pistons and we could measure the valve clearances again. Thankfully, measuring the valve lash happens pretty quickly when you have a friend under the car turning the engine! There were only about seven valves that were off at all. Two of them were off 0.001” and five were off 0.002”. We took the cam carrier off again and the two of us sanded shims to get them the proper thickness. I wouldn’t have bothered with the ones that were only 0.001” off but since they were all exposed anyway, I took care of them. The two of us made pretty quick work of the shim sanding and we went back, put the shims over the proper valves and reassembled the cam carrier to the head. We finally put some gasket goo on the joint between the cam carrier and the head and torqued it down on the head. We made sure the crank, the distributor, and the cams were all at TDC and then went to put the belt on. It was not cooperating again. We finally got it on by moving the exhaust cam a little. I should note that this was all made a bit more difficult because we had to be careful when turning a cam counter clockwise. Because the best way to turn the cam is by the bolt at the pulley and that bolt would loosen if you turned it counter clockwise. Sometimes we had to turn the cam with lock pliers. We spun the engine once and the belt seemed to settle in properly. All our marks were in the right place and the distributor was off only a little but I was going to time the engine anyway so close was good enough. The saying, “close enough for government work” comes to mind.

The next day I couldn’t shake the fear that a pulley might actually being a tiny bit off so that when the engine ran for a bit, it would shred the cogs off the belt (the paranoia of inexperience!). I got under the car, turned crank around one more time again and monitored the pulleys and tested the belt tension one more time. Everything looked good so I continued putting the rest of the motor together. As a mental check it might be useful to remind you in case you forgot that the original objective was just to adjust the valves!

I finally collected all the tools I had out and put the car on the floor of the garage. I cranked it a few times and it didn’t seem to want to start. A couple of times it popped out of the #1 carb. I thought it should at least try to start but I wasn’t concerned because I figured the timing must have moved than I thought when I was monkeying with the belt. I had intentionally left the seats, carpet board, and door to the engine compartment out in case I saw something that needed my attention. The truth is that I wished that I had a second pair of eyes but I was alone. While I cranked the engine, I turned around to make sure everything was where it was supposed to be but the belts looked like they were trying to walk off of the cam pulleys! I rechecked all the belt runs I could see from inside the car and everything looked good. I slackened the belt and pushed it further back on the pulleys and tried it again… The same thing! I slackened the belt again and monkeyed with it some more… The same thing! I took the adjustment idler off again and noticed there was a spacer behind it. I took the spacer off and noticed that there was a relief in the spacer that even though it looked like it should fit on a shoulder on a bearing of the idler, it didn’t. It HAD to fit in there. There was no other reason for those two parts to be made like that. Besides, if they didn’t fit correctly, the adjustment idler would get a little cocked on the spacer and that must be what was causing the belt to walk off the pulleys. In fact, it was probably what was causing the problems putting the belt on before, too! I cleaned both spacer relief and the shoulder on the idler, filed and sanded any rough spots but it was as though they were both the same diameter. I finally chucked a small grinding wheel in my Dremel tool, set it for the slowest speed and opened up the relief in the spacer till it slid in. I put the belt back on and adjusted it and the belt seemed to stay where it belonged! I learned that it was possible for me to pretty much change the belt by myself! I also learned that sometimes turning the motor 360° by hand doesn’t necessarily tell you everything you want to know. And finally I learned that this is a hell of a way to adjust valve clearances!

[BDA]

The Fifth Chapter – A Compleat Idiot Shouldn’t Rely on the Past

Now I had to statically time the ignition since the ignition was apparently off more than I thought. Dave Bean also included instructions for setting the ignition timing starting setting it statically with a spark plug and then setting it dynamically at 6000 rpm (You TC owners should note that the manual recommends you time your motor statically). Actually, looking at the RS1600 manual, the advance isn’t finished coming in till 6500 rpm! [distributor curve.jpg] It is impossible to put a wrench on the distributor locking bolt with air filters on the carbs and after I took them off, it still wasn’t easy! I guess that’s what happens when you take a pushrod motor and turn it into a twin cam cross flow motor. The distributor that was easily accessible when it was a pushrod motor is now buried under the carbs and I had the added complication of fuel , oil pressure, and dry sump oil plumbing.

An age ago, when I first started wrenching, I learned how to statically time the engine of my VW bug from reading How to Keep Your Volkswagen Alive: A manual of Step-by-Step Procedures for the Compleat Idiot (“Compleat” is not misspelled! Look it up.). The author, John Muir (RIP), explains how to statically time your motor with a test light: With the ignition on, you set the motor a little before TDC on cylinder #1, hook up the test light between a low tension terminal of the coil and ground, back up the distributor (turned it counter clockwise), and slowly turned it clockwise till the light comes on. So that’s what I did. There, it should at least start.

It didn’t. It didn’t even try! As before, it popped a time or two out of the #1 carburetor but that was all. I rechecked everything. I put a long screwdriver in #1 cylinder, I took off the cam cover, all the marks were right. Could it be that my test light was lighting because one of the other plugs were firing and not #1? I pulled out all the spark plugs and grounded a plug in the connector for #4 and retested the timing and the plug sparked! It was 180° off! It turns out that using a spark plug rather than a test light is a better idea.

I took off the carbs to get good access to the distributor and pulled the distributor out and re-aligned it (I had a picture of the orientation of the distributor and the rotor that I took at the beginning of this adventure!). After putting the carbs back on, I was able to get the motor to run after a fashion.  The next day, I was able to get it timed dynamically with the help of my buddy, Dennis T. It still needed some work but it will make noise on its own now. The valve adjustment is finally over! My goodness that was a huge ordeal! I’m glad I won’t have to worry about that for a long time!

I took a short drive over to Dennis T.’s house to give him a ride. It sounded like there was at least one very loose valve. Loose is better than tight but I didn’t spend all that time to have it sound worse. Dennis is an MG guy and he wasn’t too worried about the clattering but I just couldn’t get used to it. I was WAY too annoying (which also meant loud) to me! This was REALLY bewildering! I don’t know what could be the problem since I had taken the cam carrier off, measured valve clearances, and reassembled it multiple times before the final assembly so there was nothing new about any of it. It all seemed to go together as it should.  We last measured it before we did the final adjustments – when we sanded the shims the 0.001” and 0.002” I described above. We didn’t measure after that because we had just finished measuring and what could change? When I got back I took off the cam carrier to see what was going on.

[BDA]

Lap Six – Once More With Feeling!

One of the valve spring retainers looked like it had been sprayed with metal flakes and the rim of the opening where the shim goes was chewed up a bit. The only reason for that was that the shim must have gotten dislodged in the retainer and it chewed the “mouth” of the retainer “cup”. [where it all started again.jpg] There was also a little distress on the follower. [possibly damaged follower.jpg] It didn’t look bad but I didn’t know of any way to be sure. I called up Dennis Shaw to see what he thought. The pictures I sent him and my descriptions weren’t enough for him to make an accurate assessment. I REALLY didn’t want to take the head off but in the end, he thought it made sense to make sure that the keepers and the valve were in good shape. Taking the head off would be nothing compared to what I’d have to do if I dropped a valve! (Ok, so adjusting valves could possibly end up in a possible dropped valve?! That sounds so wrong!)

My main concern with taking the head off was the mess involved with draining the water. That actually went well. After that, it was a pretty simple job taking it off. Thank God something in this process was easier than I thought! [headless.jpg]

Since I had gone this far and I had a spare, I thought it made sense to replace the follower that had gotten beat up. The follower was oversized from the stock dimensions by about 0.008” in diameter so the bore would have to be enlarged. Boring out that follower bore really required that the cam carrier be disassembled, and now that I knew about the cam timing scribe marks, I was much more comfortable taking both cams out so there was no worry about metal shavings lodging themselves in the cam carrier. Ok, I was more comfortable than if I had never done it but I really didn’t intend to be so comfortable with it!

[BDA]

Book Seven – There Is at Least one First Time for Everything!   

I took the head, the cam carrier, and the spare follower to Dennis Shaw’s shop. I am super impressed with Dennis. The first thing he did when he looked at my head was ensure that it was flat. I had no reason to expect it not to be but I still held my breath throughout that! Then he took the head over to the spring compressor stand he has. He had a little trouble getting the valve spring retainer off the keepers and spring. That was troubling to him. The valve did not fall freely out the guide but was stuck a little. That was troubling to him too.  He chucked the valve in his valve grinding machine at different points on the stem to see if he could determine if it was bent. He thought he detected a very slight bend. He took another valve out. It fell freely. When he compared the two valves, they really weren’t that different. He polished the valve stem a little and honed the valve guide and in a little while he was satisfied the valve fit with the guide was good. He inspected the keepers and how their fit in the groove of the valve felt. There was no perceptible difference between a known good valve and the one that was in question. He lightly ground the end of the valve stem of the valve in question to make sure that the end was flat and perpendicular to the axis of the stem and then lightly lapped the valve.

Next he machined the spring retainer that had gotten chewed up to clean it up – a simple operation – and he reassembled the head. I didn’t need any new parts! Good news and I was ready for some good news!

Then, on to boring the cam carrier for the new follower… This was really interesting! I figured he would chuck the cam carrier in a tilting fixture that had a graduated angle adjustment. Adjust the angle to the proper angle and bore the follower bore to the proper diameter and voilà, we’d be done. Well, not so fast!

After he adjusted the tilting fixture to the “proper” angle, he chucked a dial indicator in his mill and ran the probe up and down the wall of the bore first on the “outside” and “inside” wall (the outside wall is the furthest from vertex of the angle of the carrier and the inside is closest to the vertex). He adjusted the tilt of his fixture and rechecked the walls with the dial indicator till there was minimal variation the length of the bore. The bore turned out not to be completely round or exactly the right angle. Not only was there some wear (I probably put 15,000 miles or a bit more on it but I had no idea how many miles were on it when I got it) and I figure the machining tolerances in the late ‘60s and early ‘70s weren’t that good so Dennis probably got it closer to spec than the factory.

Then he chucked a boring bar in the mill head. This is where he volunteered that he had never done this before!  Well, I suppose there’s a first time for everything. As unsettling as that admission was, I felt I was in good hands given all the race engines Dennis had built over many years.  There have certainly been a lot of things I’ve done for the first time in this adventure and even though he didn’t have any experience with a BDA, I didn’t know a better person to get me through them.

Dennis continued to be extremely careful and precise. Each pass of the boring bar took off only a couple of thousandths of material and as he got closer to the size he wanted (0.0015” larger in diameter than the follower) he test fit the follower after each pass. Finally the follower almost fit. Then he announced he was going to take a second cut at the same diameter. I thought that maybe the aluminum might have some spring to it but he said there was the flex in the boring bar that would likely open the bore a minute amount (It was about ½” of steel that was about four inches long. It would take a lot to bend that even a little!)! Keep in mind that he was making very small cuts in relatively soft aluminum! He took the cut and the follower fit perfectly!

[BDA]

Crazy Eights – A Coming Together

With all that taken care of, I went home to put the cam carrier together. During this process, I finally broke down and bought a parts washer so I was able to clean the head, cam carrier, and all the other parts at home before assembling them on the engine.

I got a new head gasket and before I cleaned off the top of the block, I sucked all the oil I could out of the holes for the head bolts. I didn’t want to tighten them up against any hydraulic pressure. I carefully cleaned off the top of the block so junk doesn’t fall into any part of the engine. I positioned that gasket and lowered the head on it as straightly as I could. There were no aligning pins and the head is fixed to the block with bolts so I tried to make sure the gasket was lined up properly by peering down the head bolt holes in the head, putting an aligning punch down some of the bolt holes and twirling it around. Even at all that, some of the head bolts had to be screwed through the gasket. I found out later that using aligning studs were the preferred method! I’ll remember that for next time! 

When torqueing the head bolts, some of them did not tighten smoothly so I retorqued them all several times. I put the appropriate shims on valves. I estimated the shim for the valve that initiated this latest chapter of this saga. Since Dennis had to work on that valve including grinding the end of stem and there was a new follower for that valve, it was unlikely to take the same shim that I calculated the first time. I felt pretty confident that I was on the home stretch of this project but I still couldn’t help but wonder if this was a light at the end of the tunnel or the light from a train coming at me?

I called my buddy Dennis T. to come to help me with the rest of assembly. When he came over, we tried to think of what had caused that shim to become dislodged. We didn’t come up with any answers but we thought using grease on the followers was enough to hold the followers in the cam carrier. In all the stuff we did the last time we bolted the carrier on the head, I wasn’t sure if we also used magnets but we figured that if we had, they may have contributed to some movement of that shim. We decided we would rely on the grease to hold the followers in the cam carrier. The other thing we were going to is check the valve gaps after the final assembly to make sure that if something did happen, we would find it before we started the motor.

I won’t bore you with our next steps any more than I feel necessary. Dennis and I basically ran through the procedure I described at the beginning of this story (bolting the carrier on, measuring the valve gaps, calculating the required shim thicknesses, inserting the proper shims, reassembly, measure gaps again.). Then we checked the adjustment again after we fitted the cam carrier for the last time with gasket goo. They were all within two thousandths and only a couple was off that far. After static timing the distributor, we fired it up and set the timing dynamically at about 6000 rpm. The motor sounded a noticeably better than I remember it sounding before.  Besides sounding better, I found that I was able to balance the carbs a lot closer than before. After all that work, at least there were some tangible benefits!

[BDA]

Epilogue

The valve adjustment saga is over! It took a lot longer than I expected and I tried to over-estimate the time required. In the middle of this adventure, I checked into how similar modern motors handle valve adjustment. Since the Toyota 4AGE motor took over for the BDA in Formula Atlantic racing, I thought that might be an interesting comparison. It turns out that in the Toyota motor, the shim sits in a pocket on the top of the follower and the cam rides on the shim. All that is required is to compress the valve spring a bit pushing the follower lower, take out the wrong sized shim that is sitting between the cam and the follower and exchange it with the proper sized shim. This seems like an obvious way of doing it but it's really not that obvious. Usually valve tappets or followers actually have a slightly convex surface that the cam rides on. Along with that, the cam is ground with a slight taper. Those two things cause the tappet or follower to rotate reducing the wear on both the tappet or follower and the cam. If the cam rides on a flat shim, that situation is no longer present (unless the shim has both a flat and a convex side which seems highly unlikely) so it would appear that the cam would ride on the same part of the shim continually. It is apparently not a problem but I'm not sure why. Possibly the hardness of the shim and cam is enough to keep wear in line and maybe modern oils contribute to that too. I asked Dennis Shaw about that. He said that the 4AGE's method of valve adjustment was not uncommon for street engines but for racing engines, the BDA method was preferred. He explained that if you floated a valve, the cam could spit the shim out of the pocket of the follower and you'd be in a world of hurt.
 
It took me months and the help of a friend and a machinist to adjust my valves and I'm trying to figure out just what is so bad about rocker arms!! My BDA is certainly much more race bred than many motors. Its relationship to the DFV is a bit closer than I previously thought and while that has its advantages, it also has its disadvantages (changing valve clearances being primary!). It's tempting to compare it to modern motors, but that's unfair; just as it's unfair to compare the TC to modern motors. I think it's even unfair to compare my motor to the TC, thought that is a more apt comparison. Those motors were designed in the' 60s. That was a long time ago and things have changed a lot since then! For example, my old 2005 Mercedes Benz C230 has a supercharged 1.8 liter four valve DOHC engine. It has about 120,000 miles on it and I've never even thought of adjusting the valves! That's what hydraulic lifters will do for you! But as much of a hassle this has been, I think it's something to embrace. Most of us want to have a bit more familiarity with our cars than the average person. Ok, I may have more familiarity than I had bargained for but for me, it's all part of owning a classic car that is a continual project. I'm retired and there's no other project I'd prefer to work on! Maybe one day I'll be the  "Compleat Idiot" John Muir inspired me to be so long ago!

Acknowledgements

EuropaTC and literarymadness for their support and insights for this faux tome

Dennis Shaw for his advice and machining skill

Dennis T. for his advice, support, and touch with the 3/8" torque wrench

Edit: fixed literarymadness's name

[jbcollier]

And lots of fun was had by all :-)  Glad it ended well.

- Thank you for supporting my maxim that every carb adjust starts with checking the valve clearances first!

- Putting the pistons at 90° and turning the cams is still not a good idea.  Yes the valves won't hit a piston but the valves may hit each other.  You can only do it if you remove one cam while working on the other.  Not practical in a BDA.  Works in a TC though.  I still prefer the method you followed.

- Don't use magnets to hold things in place.  Aside of the troubles you encountered, it can permanently magnetize the part which will then attract filings and increase wear.

-  Good point about the larger shims getting spit out at high rpms.  Believe me, it happens.  They are also heavier and add unwanted valve train weight.

- In the "aw-heck-that's-nothing" category, on an Aston Martin 6, you adjust the valves by trimming the valve end or swapping in a larger follower.  That means most valve adjusts require head removal!  Many shops now modify them to take Jag shims pretty much like your BDA set-up.

- Finally, if you don't make a mistake, you never learn anything.

[BDA]

Thanks, JB!

Good point about the valves possibly hitting each other. I hadn’t considered that! I’m even gladder that I decided not to try it!

Magnets are essential when pulling the cam carrier off otherwise the followers are likely to fall out. That would likely be a mess. At least, the RS1600 manual says to use them and I figure that’s the reason. As I found out, that’s the only time magnets should be used. An old racing buddy who owns a few Formula B and Atlantic cars told me he uses a spring contraption he thought Cosworth designed for holding the followers up. I have no idea how it would work. He never sent me a picture of it.

“Finally, if you don’t make a mistake, you never learn anything.”

I totally agree! We rarely examine our successes like we do our failures. I learned a lot throughout this whole adventure!

[EuropaTC]

 

time for a  ?

Brian