Head assembly question

[Bryan Boyle]

I started pulling my spare head apart to make sure all was assembled properly (doesn't everyone have a spare head?).  Glad I did, because, while the valve seats were redone (the engineer's blue to check valve seating is still apparent around the seats on the casting), it seems that the cam bearings were not changed (there is evidence of them being 'experienced'; the journals on the cam are fine, no marks, but there was no evidence of assembly lube when they were put back together.

This also leads me to think I should pop the valves and make sure the stems were lubed before assembly, too. 

But one question: the seal on the input cam (they're D cams, for what it's worth) needs replacing...but I'm pretty sure the tool that's called out in the manual to put the new seal on has been many years lost to history, and I note that there is a split ring on the cam in between where the alternator pulley would sit (maybe a locating fitting?) and the seal. 

For those who've done this...is that ring (easily?) removable so I can slide the new seal on?  Or...is there some other method that's been used in the past.

(I've ordered a new set of bearing shells and have a tube of Graphogen to put it all back together...btw).  Just want to get it right (without bunging up the new seal, which I have in hand).

Plan is to just swap heads (this one has been surfaced lightly and I checked with a straightedge; it's flat) when I pull the lump, but want to get it right so I'm not doing it a second time...

BB
3291R

[jbcollier]

If the shop thought the head was going to be used, it would not be unusual to just lube everything with engine oil.  As long as it doesn't sit too long, under a year, it works just fine.

Myself, I wouldn't be too concerned about the valve stems.  If you are worried, just place the head upside down and use an oiler to put a drop or two of oil on each stem through its port and let it sit for a few hours.

The ring locates the cam pulley -- which is why you need to be careful not to over tighten its nut.

If you just push the seal on, the groove for the ring may damage the seal.  You just need something "soft" for the seal to slide over this sharp spot.  You could use electrical tape, heat shrink, thin plastic tube, etc.  lube things up generously and fit it carefully.

[Bryan Boyle]

If the shop thought the head was going to be used, it would not be unusual to just lube everything with engine oil.  As long as it doesn't sit too long, under a year, it works just fine.

Myself, I wouldn't be too concerned about the valve stems.  If you are worried, just place the head upside down and use an oiler to put a drop or two of oil on each stem through its port and let it sit for a few hours.

The ring locates the cam pulley -- which is why you need to be careful not to over tighten its nut.

If you just push the seal on, the groove for the ring may damage the seal.  You just need something "soft" for the seal to slide over this sharp spot.  You could use electrical tape, heat shrink, thin plastic tube, etc.  lube things up generously and fit it carefully.

This head obviously sat for a while in the shop.  I disassembled the cams from the head and clipped off the old crumbling seal.  A couple of the long studs are bent a little; the shorter ones are ok, so, will replace the 8 long studs, and use new nylocs all around when I go to put it all together.  Not replacing hardware and consumables is false economy in my book.

The woodruff key is in the cam real tight...will pop it out later and remove the ring and use your idea of taping the shaft to slide the new seal on with generous lubing...and then put all back together.   Like your idea about oiling valve stems though their ports, and will reassemble with graphogen or the ZDDP Paste (I've a tube of both) when I get to that stage.  But, there were obvious wear marks on the shells, no scuffs or marks on the cam journals, so, thinking 'it's apart, just replace the shells" to forestall any issues down the road.

[EuropaTC]

Hi Bryan,

I've nothing really to add to what John's said, the cam seal is an easy fit and commonly available. I didn't need any special tools and from my notes the dimensions are ID 22mm, OD 34.5mm, 6mm wide if you have a local bearing supplier.

From your comments on worn cam shells & bent studs then I would be suspicious on the rebuild and want to check valve clearances before it goes back together. As the cams are off I'd also pop the followers out and make a note of the shims in there so if the clearances are wrong then you'll know what shims to get. It's much easier to do whilst the head is on the bench than leaning over into the engine bay.

If you don't already have a copy, one thing I would get is Miles Wilkin's book on the Twin Cam engine. It's been revised in the last few years for newer sealants but the main benefit is the number of photos as he takes you through a complete strip/rebuild and the comments along the way about the best way to do things. It's a bit like Brian Buckland's book on the Elan, written with the average DIYer in mind.

Brian

[Bryan Boyle]

Hi Bryan,

I've nothing really to add to what John's said, the cam seal is an easy fit and commonly available. I didn't need any special tools and from my notes the dimensions are ID 22mm, OD 34.5mm, 6mm wide if you have a local bearing supplier.

From your comments on worn cam shells & bent studs then I would be suspicious on the rebuild and want to check valve clearances before it goes back together. As the cams are off I'd also pop the followers out and make a note of the shims in there so if the clearances are wrong then you'll know what shims to get. It's much easier to do whilst the head is on the bench than leaning over into the engine bay.

If you don't already have a copy, one thing I would get is Miles Wilkin's book on the Twin Cam engine. It's been revised in the last few years for newer sealants but the main benefit is the number of photos as he takes you through a complete strip/rebuild and the comments along the way about the best way to do things. It's a bit like Brian Buckland's book on the Elan, written with the average DIYer in mind.

Brian

I have a new seal in my stock of parts along with all the top end gaskets (head,  timing case, d plugs, valve cover, carb o-rings, secondary throttle (though it's been stripped of the throttles) bases, exhaust, thermostat).  Examining the head I have on my bench now, I'm wondering if that plug next to the hole for the head/block breather tube in the existing head is not the source of the leaking.  Will be interesting to check when I pull the existing head off.
 
You make a good point about checking the clearances...will add to the list.  Agree it's easier on the bench...really don't want to be fiddling around with it in situ.  Spending an hour of bench time checking clearances and figuring out if everything is copacetic is a lot easier than pulling the darn thing apart with the lump mounted in the frame.

I have wilkins' book and have been memorizing it...like I do with most tech manuals.  What's that old saying "Trust, but verify"?  Trying to line up everything I can (within reason...there is always the 'by the way' things that get you.

[jbcollier]

As you are changing the valve seals, you’ll be removing the valves regardless and smear the stems with oil on reassembly.

[Fotog]

The ring locates the cam pulley -- which is why you need to be careful not to over tighten its nut.

I know that to be true since I did it.  The result was that unbeknownst to me, the split ring was rotating, or not, I guess, caught on the cam cover, and damaged the groove in the camshaft.  I did see little flakes of aluminum in the air and shut it down, but not before the camshaft damage.

It looks to me that the design is such that the ring should be held captive by the sleeve that protrudes from the backside of the pulley.  I think mine is ever-so-slightly bell-shaped and doesn't prevent the ring from popping off when the screw is over-tightened.

I accomplished a fix by having a washer welded to the pulley so that I didn't need the split ring any longer.

The initial idea was to change the oil seal to prevent oil from spraying about.  I got to do that twice!  But I also adjusted valves and re-torqued the head while I was at it.

[fotsyr]

When setting the valve clerances the head should be attached to the block. Use an old head gasket and torque the head. If not the clearances will change.
 

[EuropaTC]

I'll admit that I've heard that statement before, usually that they tighten up but they really shouldn't change significantly.

The critical dimension is between the valve stem/shim/follower assembly and the cam lobes and I just can't see how that's going to change when the head is bolted down. I agree it's important to torque the cam holders/bearings correctly before measuring and wonder if that's the reason folks have found the clearances altering ? Not correctly tightened on the bench ?

Anyway, we know clearances tighten up in use so all I do is to set them at the high end. Then if they do close up by one or even two thou then you'll still be within spec.

I did see a change last time I did the job on the Europa, most were exactly the same as on the bench but I think one (memory hazy) was a thou different.  I put that down to user error with the feeler gauges, it's not logical for a single valve to change when the other 3 stay the same is it ?

Brian

[Bryan Boyle]

Just finished cleaning up the head and removing the old bearing shells, and mic'd all the existing shims, so, I'll know what I need to change, if anything. (everything is marked as to which cylinder it came from..and the bearing caps are stamped with a number (as is the gasket flange) and arrow so everything should be ok when it goes back together). 

Noted that the set of existing shells were all the same width; according to Ray (and Ken), the #1 and #10 shells should be a bit narrower and the new set coming in has the proper widths.  There are no marks on the cam bearing surfaces (or lobes), so, should be good to go there.

Made up a stand so that the head is off the bench top so I won't bend anything when checking the clearances.  Wilkins describes doing the clearance check before the head is mounted; I get why you might do it with the head bolted on, a couple folks I've talked to who've done more than one said the difference in a street engine with stock components is nothing to loose sleep over (but also agree that erring on the high side of the tolerance is better than the low side to account for minor bedding in).

Replacing the woodruff key (which was buggered to begin with) and the input shaft was missing the oil galley plug in the back end; pulled one out of my spares stock and put that in. 

My plan is to build up this head, with copious amount of assembly lube, and when the lump gets pulled (next month), put the engine up on a stand, and just swap out with the existing head.  Also get the clutch done (the output seals on the tranny aren't leaking (yet), and, since the lower link bushings are roached, putting in adjustable lower links.

Debating whether to pull the front cover and rebuild water pump and new cam chain...while it's out...the water pump is not weeping, and have 3/4" of thread showing on the chain adjuster...thinking (along with replacing the transfer tubes) that the hard part (pulling the lump) will be done, so get everything out of the way while it's accessible...

[EuropaTC]

Hi Bryan,

Personally, if the engine is out, the head off, then I'd do the water pump as well unless you are very, very sure it's only just been done and perfect. The overhaul kits are (were ?) cheaper than the head gasket sets and it's a very simple job to press in the bearing/impellor in a bench vice.  The cost of gaskets alone is reason enough to make sure it's 100% before putting the head back on..

One thing that's cropped up on the Elan forums is that pumps fail more often these days because they spend most of the year sitting and not moving every day like they used to do. The anecdotal evidence is around the mechanical seal sticking slightly and wearing more than it should on those infrequent starts.  I don't know if that's true or not but I suspect there may be some merit to it.

Timing chain, unless it's definitely worn on the sprockets, I'd leave alone. The Europa still has the original chain from 1972, the Elan I replaced in the 80s IIRC simply because it'd been there since 1968, but to me they just don't seem to wear. I wonder if keeping the right adjustment is the reason and a loose, floppy chain will wear quicker ?

Brian

[Bryan Boyle]

Hi Bryan,

Personally, if the engine is out, the head off, then I'd do the water pump as well unless you are very, very sure it's only just been done and perfect. The overhaul kits are (were ?) cheaper than the head gasket sets and it's a very simple job to press in the bearing/impellor in a bench vice.  The cost of gaskets alone is reason enough to make sure it's 100% before putting the head back on..

I have a new kit (in the bag) that came in the 2 packing cases of both replaced and new parts when I bought the car.  I'm of the opinion that if it's accessible (and would be if the engine is out), it would probably be false economy to bypass it.  Just another afternoon worth of work (and a couple o-rings and such, especially if the rear plate doesn't come undone)

One thing that's cropped up on the Elan forums is that pumps fail more often these days because they spend most of the year sitting and not moving every day like they used to do. The anecdotal evidence is around the mechanical seal sticking slightly and wearing more than it should on those infrequent starts.  I don't know if that's true or not but I suspect there may be some merit to it.

There is something to that.  Though, I think over the last few months, she's probably had more miles put on her than in the previous few years; when I was underneath doing the oil pan seals, I took a look up there and didn't see any rust stain or weeping coolant out of the weep hole.  But, again, if I'm in the area, right?

Timing chain, unless it's definitely worn on the sprockets, I'd leave alone. The Europa still has the original chain from 1972, the Elan I replaced in the 80s IIRC simply because it'd been there since 1968, but to me they just don't seem to wear. I wonder if keeping the right adjustment is the reason and a loose, floppy chain will wear quicker ?

Brian

Well, when I had the cover off last spring, it had the proper tension (as measured between the two sprockets) and didn't look like the sprockets were excessively worn; I don't have any chain noise or whining...so, it may be just a case of backing off the tensioner when I go to pull the head (to give me some slack to remove the sprockets) and putting it back together properly.

FWIW, I did take my straightedge and front to rear, side to side, and diagonally on the head I have on the bench right now, and it appears to have been at least dressed flat.  Couldn't get my thinnest feeler in there, and shining a light through from the backside of the straightedge, didn't see any light through the machined surface.  Thinking, all things being equal, if the block is the same, a fresh gasket and front case seal, new D plugs, new input cam seal, and new valve cover gasket will work properly.  At least, that's my hope.

[Bryan Boyle]

Also assuming, looking at the exploded diagram, that when I pull the head off, the chain tensioner (red arrow/box, including the sprocket) comes out at the same time with it (or do I release it first and pull out the top, then insert after the head is back on)?  Which means I have to back off the threaded adjusting assembly (green arrow/box) down in the block.  I understand, from Wilkins, there are special washers involved...another thing to put on a future list, right?

Also thinking out loud that the dizzy has to come out since when I release the cam sprockets and the chain is limp, it will probably drop off the jackshaft sprocket, loosing the timing relationship between the cams and the distributor setting.  Not an issue, I'm thinking, since if I line up the crank to TDC as specified to the front cover and the marks on the cam sprockets (or the #4 lobes rocking to the center as in Wilkins, I can reset the dizzy to #1 and get it back to where it belongs (probably easier when the lump is out of the car than reaching over the rear and under the intake...).  Am I on the right track?

[EuropaTC]

Hi Bryan,

Easy answer first - yes, I tend to set the engine to TDC but as you say, once the chain moves independently of the cams/crank you have no assurance that the jackshaft/distributor has stayed put. So the re-assembly means starting from scratch to set the timing. You'll be doing that with the cams anyway and arguably the cam timing is more important than the ignition; duff ignition won't go, duff cam timing could be expensive !

For the next one, I can only tell you what I do, whether that's right or the easiest way I don't know, it's just what I'm comfortable with. 

I'll cable tie the cam sprockets to the chain in a couple of places. Slacken off the adjuster bolt/screw and then remove the cam sprockets from the cams. With a bit of fiddling, they'll slip out of the way. This means you don't have to split the chain or remove the cams. If you decide to do the water pump/front cover as well that's optional but it would retain the relative timing of the cams to each other if not the crank, you won't (potentially) be a tooth out on relative cam timing.  If you're retaining the chain I'd also retain the sprockets it's been running with.

Mark up a diagram with the bolts to remove. Head bolts are easy, it's the timing cover ones you overlook and then wonder why it won't come apart !

I'm pretty sure I've left the brass tension arm/sprocket in place. It gets in the way when you want to set the head down afterwards but otherwise no problem.

The awkward part is lifting the head with the wear strip/chain guide that's part of the front cover and goes into the head space. It's at an angle so you can't do a straight vertical lift until you're clear - more jiggling about !

General rambling - thinking aloud.

As you're intending to remove the engine block then I think in that position I'd invest in a timing disc and use that for timing. If nothing else you will know if the marks on the cam sprockets are right or not and it's something Wilkins does in his book IIRC ? (I tried a disc but had the engine in the car and gave up as "too hard", going with the sprocket marks instead)

Do you have a sump gasket set to replace as well ? In theory removing the front cover should be possible without the sump but I've never managed it. With the engine out I'd consider replacing every potential leaky gasket/oil seal as a good investment.

[Bryan Boyle]

All good points, though it makes me wonder how to slide the head on (maybe I'm getting ahead of myself) if the slipper on the left side is proud of the block but the block has 2 studs as locators....maybe I'm just overthinking...the TC is a new experience (tearing apart 821s and doing jug seals is easy compared to this...), so just running through the potential issues. 

wire tie the sprockets to the chain are something we do when working on the AJ27 4 litre engines in the early aught Jag XJ series when we do the tensioners (the originals were plastic...and crack...and the chain jumps a tooth...any more than one, and you bend valves in the interference engine design).  Great thought!

OTOH, some parts came in to day: new long studs (a couple of them are bent) for the cam cover, zddp paste to put it together, NEW proper size bearing shells, woodruff key, and oil galley plug for the intake camshaft (it is missing).   Back to the shop to pull the old long studs out and put the new ones in...