A moment of apprehension

[jbcollier]

We use Dexron 2 or 3 automatic transmission fluid in the dampers.  It's lighter and does not affect the diaphragms.

Pull off the dashpots and clean everything out thoroughly.  Before filling the dampers, the dashpot should rise and fall easily with just light finger pressure.

[BDA]

I didn't know you could use ATF for damper oil. I had heard that 20wt would work and I suspect there is Zenith-Stromberg damper oil in a small container for a ridiculous price also.

I would add that it might be a good exercise to drain the current oil and check how it works to make sure there is no binding anywhere. I might also check your throttles. IIRC, there are two - a main throttle and a secondary one for the crossover pipes. If your pipes were taken off, the secondaries might be taken out and the holes plugged (I don't remember exactly what was done for that). Anyway, it might be a good idea that you're getting WOT and there's nothing that would "get in the way" like a butterfly closing when it's not supposed to. Having said that, it sounds like your problem is probably the wrong oil in the dampers.

Just an FYI: it may be useless information but for some reason, I feel compelled to say that you don't NEED oil in the dampers for the carbs to work. I never used any in the SUs for my MG Midget race car. That is surely less appropriate for a street car that is not usually wide open most of the time, but who knows, it might be an interesting thing to try.

[jbcollier]

For those who don't know, the damper oil delays the rise of the piston giving a momentary richer mixture when the throttle opens.  It fulfills the same function as an accelerator pump in a non-CV carb.

[Grumblebuns]

I did more poking around this morning with the TCS. I remember using Marvel Mystery Oil back when I had my running TCS for the dashpot oil. Not being able to find the long forgotten bottle, I had some Dexron III available so I changed out the original oil and replaced it with the ATF.

I also decided to re-read the service manual on overhauling the Stromberg and came upon this interesting tidbit of info. The two depression sensing holes for the diaphragm are suppose to be behind the air valve piston. It appears that the mechanic that the PO used to rehab the TCS did not read the manual. Both holes were blocked on one piston and one on the second, no wonder the pistons wouldn't rise under a vacuum. In the second picture, the mechanic did not make sure that the tab on the diaphragm fit in the slot in the valve body for proper alignment.

I'm pretty sure that I've found and fixed the problem but won't know for sure until I do another road test.

[Bainford]

Congrats on the successful run, Joji. Exciting stuff. Hopefully your new found carb assembly issues solve the problem.

Regarding the problem of hitting reverse when down shifting into 2nd, mine is the same way. Shifting from 3rd to 2nd will easily find reverse if I am not diligent. Same goes for shifting from 5th to 4th. When pulling it out of 5th I pull the stick towards the left then push it all the way to the right before pulling it down to 4th. Otherwise, when I pull it down it will hit reverse.

And speaking of 5th, I find getting it into 5th takes a very firm shove through the detent. I very rarely ever use 5th so it's not as big an inconvenience as it sounds, but I find diligence and an acquired technique is required to effectively shift the Europa (or at least the 365 trans). Double clutching the down shifts makes a big difference too. I think it will soon be time to give Peter the nod for one of his reverse lock-out devices, and perhaps try BDA's suggestion of trimming the 5th gear detent.

Anyway, well done on the road test, and looking forward to hearing more. Cheers

[EuropaTC]

Good find ! I'd never have guessed that one as the cause, not in a million years. Amazing what the Mk1 eyeball can suss out......

Brian

[pboedker]

Interesting discovery, that could explain why the pistons don't move sufficiently. Now, careful with the gas pedal when you get to try the car again.   

Trevor, what you're describing with the gear change is exactly my experience with the original Lotus detent mechanism: The constant slamming of the gearstick wears out the linkage, until it gets sloppy and one has to align the stick to either side to hopefully select the wanted gear.
Maybe you don't know it, but I now ALSO have the 5th gear internal detent plunger ready, so that one can get rid off the Lotus detent housing completely. See the following message:
http://www.lotuseuropa.org/LotusForum/index.php?topic=127.msg5746#msg5746
(I hope it's OK, inserting this personal ad in the thread) 

[jbcollier]

The piston and carb body both have alignment notches, the diaphragm has inner and outer nubs, all to make sure the piston is properly positioned.

[Grumblebuns]

I just got back from another short test run this morning, the same route as yesterday. It appears that the carburation problem has been fixed. Going up the same hill, no need to downshift and I could even accelerate a bit in third.

Regarding the shifting the 365 gearbox, I can live with the sloppiness. I just have to adapt to the idiosyncrasy of the gearbox, like downshifting using just your fingertips. There is absolutely no slop in the linkage so besides fitting Peter's reverse lockout kit, I have to live with it. This gearbox operation is very similar to what Trevor described with his.

The other issues that I have to look into is the cold start or lack of. The car won't start when it's stone cold without starting fluid even with full choke. I'm wondering if the same mechanic mess up the choke feature when he rebuilt the Strombergs. I'll fix the problems as they crop up and I appreciate all of the tips.     

[EuropaTC]

and the results were ?    are you polishing it lovingly or kicking the tyres and using lots of foreign sounding words ?   

[BDA]

Congratulations on your find, Joji! Given your attention to detail, I was sure you'd figure it out. 

Now tell us how your latest test drive went!

[Grumblebuns]

Obviously I  wasn't going to push the motor this early the first time out but my seat of the pants feeling was that motor wise it was very comparable to my S2 wedge head with the 45 DCOE side draught. I want to put on a few hundred more miles before I start pushing the motor. I expected a bit more but then I was only shifting at 4k rpm.

I'll do a longer 20 mile trip into town tomorrow and really push it a bit more.

[BDA]

For those who don't know, the damper oil delays the rise of the piston giving a momentary richer mixture when the throttle opens.  It fulfills the same function as an accelerator pump in a non-CV carb.

Hmm... Interesting.  Unless there is a difference in theory of operation between the SU and Stromberg or I'm missing something (never to be discounted), that seems counter intuitive. Assuming they operate under similar principles, that would imply that oil would be required or at least beneficial in a race car since I would think you would certainly want a richer mixture on acceleration otherwise you might get detonation which would be extra bad for a race car. I had always assumed the oil was to dampen out the fluctuations in the motion of the piston rather than adjust the mixture. I also assumed (or maybe someone all those years ago told me) that it also enhanced throttle response. What am I missing, John?

[BDA]

Great news, Joji!  (I didn't see your post when I posted).

Is your shift linkage sloppy everywhere or is it just a problem with R & 5th? As you know, there are several places up and down the linkage that can cause general sloppiness (the nylon "hat" bushings at the shift lever, the pivot at the bell housing, the U-joint, the roll pin at the selector shaft).

[Grumblebuns]

and the results were ?    are you polishing it lovingly or kicking the tyres and using lots of foreign sounding words ?   

Went back down to the garage after my last post with a cup of coffee and did a visual inspection. Amazing, nothing leaked or is leaking. Yeah, I'm starting to feel a bit more confident with the car now.

BDA, I also did a comparison with my other TCS (non running) shifting through its gears. Although the reverse spring appears to have the same effort (very little) as the this TCS, shift action however has a lot more resistance (think walking through molasses) which I prefer and I know that the linkage is worn on that car. I went through the entire shift linkage before re-installing in the car and the PO had replaced everything so it's tight except for the sloppy action.