TR6 Valve Adjust, What clearance?

[gbtr6]

Continuing my saga in getting my TR up and running again. The engine is rebuilt. I got the engine running, but it sounds like a miss, or valves not adjusted properly. What cold clearance do most of you use? How about a hot clearance? How about timing? I have the Good Parts SP2 cam. I seem to be chasing the carbs, timing, valve clearance. It has a little of a 'dead cylinder' shuffling sound to it. It's not real crisp yet.

Any other suggestions would be helpful.

Perry

 

[TR3driver]

Check with Richard, different cams are designed for different amounts of lash. I don't know anything about the SP2 cam, but an aggressive cam will definitely cause poor idle and affect mixture. Since options are very limited with the ZS carbs, you may need to switch to something else (SU or Weber).

 

[gbtr6]

Randall, Thanks I'll get in touch with Richard. I forgot to mention I have SU HS 6's, and TW needles. I set them back to base specs, mixture nuts all the way up, then 2 turns down. May need to rich them up more. . I didn't rebuild them and that could also be an issue. Richard may also have a good handle on the timing as well.

Thanks,
Perry

 

[kayjh]

I have a stock 1976 TR6 with 45,000 miles

An old South African auto mechanic staying with us for a couple of weeks tackled that job last night (with me learning). I'll check the book when I get home but I believe the clearance is 0.014. You have to set the clearance when the engine is cold (we waited 24 hours).

I'm not sure how others tackle this job, but my visitor (he has been fixing cars all his life and is now 80) and I did the following: (1) removed the spark plugs; (2) removed the distributor cover and rotor; (3) using a screw driver inserted in the alternator fan (ouch) and leaning on the fan belt rotated clockwise (viewed from the front of the engine) until the No. 6 cylinder was at TDC. We confirmed the position by looking at the points "lever" location on the distributor rotor. When it was perfectly on the high point and we replaced the rotor to verify it was pointing at No. 6, confirming the No. 6 piston was at TDC. (4) With TDC on 6, both rockers are at their highest point on both inlet and exhaust valves (i.e. tension off the valve springs) and we loosened the nut and adjusted the gap to 0.010 . (5) We worked through the remaining cylinders in order of firing until all were done, then we rotated through them again to make sure each had the correct clearance. A few had to be adjusted. (6) Replaced the spark plugs.

After completion, we double checked the gap on the points and then proceeded to use a test light to set the timing. With all of that done, we started the engine. What had been a very loud valve train and a lumpy idle with "popping" at the exhaust was about 90% smoothed out and the valve train was considerably quieter. It got even quieter as the engine warmed up.

I've read several articles that comment on the carbs on our cars. Many people (including me) complain about the carbs needing constant adjustment due to poor running. The articles point out that very often poor running problems are a result of clearance, points and ignition timing as opposed to problems with the carbs. In my case that is about 75% true. The engine idle is much improved and I expect the test drive on the road will yield improved power. Having said that, I still have some problems with the carbs but that will be a repair for another day.

 

[poolboy]

No comment on his technique...but for a stock cam the valve lash is .010" for both intake and exhaust when the engine is cold..cold as ambient temperature.
BTW, the idea that the ZS carbs need constant adjustment for ANY reason is foolishness.
If a person has problems that can actually be traced to what were once properly adjusted carbs, it's not because there are more adjustments required, it's because there are certain components within the carb that need replacement...Periodically they will and no amount of adjustment will compensate for the need to replace those components.

 

[kayjh]

No comment on his technique...but for a stock cam the valve lash is .010" for both intake and exhaust when the engine is cold..cold as ambient temperature.
BTW, the idea that the ZS carbs need constant adjustment for ANY reason is foolishness.
If a person has problems that can actually be traced to what were once properly adjusted carbs, it's not because there are more adjustments required, it's because there are certain components within the carb that need replacement...Periodically they will and no amount of adjustment will compensate for the need to replace those components.

Thanks Poolboy. Checked the book, you are correct @ 0.10 in