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TR6 72 tr6 stumble question

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sparks4540

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Hey everyone. I'm new here to this site and also to British cars. I bought my first Triumph tr6 2 months ago, price was cheap and I also like the car, and just finished doing a 90% resto on it. The previous owner had it modified somewhat, header, Weber DGV carbs...
I have done nothing but musclecar restoration before and mechanical and engine rebuilding and tuning. I'm having some issues with this one though so bare with me..
To begin, the car has Weber DGV carbs, dual exhaust pipes with the stock muffler and electronic ignition. Recent tune up and plugs yesterday. So here come my two questions.
First off, the car has 170-180psi of cylinder pressure. This is a 72 TR6 and the prior owner told me that the block was rebuilt. On a 350 chevy, 130 psi translates to about 9.75:1 compression. I thought these motors ran about 8:1 or so stock. Does this compression check sound like the pistons may have been changed or is this accurate?? I know that camshaft duration affects compression and I didn't find anything in the shop manual, but then again I really was looking for specs on compression...
Secondly, the car stumbles at about 10% throttle in any gear. When the throttle is cracked open it stumbles and once you get about 1/4 of the way into the gas it goes just fine. I have done a lot of synchronizing with these carbs and adjusting the mixture screws and it has improved tremendously. I have also tried moving the timing up and down just a couple degrees. I should add that spark plug coloration looks good, however cylinders 1 and 6 were richer than the others. This was with the Bosch platinums that came in the car and I just installed Autolite standards yesterday and have not pulled them. Any other suggestions to get rid of this stumble would be appreciated.
Thanks for your help.
Chris
 
Sure sounds like an accelerator pump sticking, plugged or maladjusted. I know, because they claim I'm maladjusted as well.
 
Thanks for the input. The car does hesitate when the throttle is quickly popped open so that made me take a peek at the accelerator pump. However, By the looks of it, there is not an adjustment for the accelerator pump on the Weber DGV carb...correct or not??
 
Chris,
Weber DGV's on a TR6, although sold alot, are not an ideal setup for this car. They inherently have a tendency to stumble from start, perhaps because of the "unatural" amount of distance and the path of the fuel to the chamber. They are adjustable by changing parts and sometimes can work well, usually by someone adroit at working on these babies. I went through two sets on two different TR6's and was never satisfied. Returning to the original Stomberg carbs is ideal, a setup for which the car was designed. I run triple Strombergs on my 73 TR6 and have far fewer problems than I did with the Webers. Others out there will argue that DGV's work well, but it is usually the people that sell them.

Bill
 
Yeah Shannon, Richard Good is the source for the triple intake. Very satisfied, surprisingly easy to keep balanced. Richard can recommend someone for the triple ZS carbs, they have to be modified, at least the middle one, with a longer shaft to connect to each other. Really a snap to install and get running. And bitchen looking!
Gary Martin (at Richard's suggestion) from South Dakota sold me the 3 rebuilt (gorgeous!) carbs, and cheap, although I have forgotten how much and can't find his phone #. Again, Richard has all that. Go for it!

Bill
 
I have always wondered why it wouldn't be simpler to use a pair of 2inch SUs, the inlet manifold is alloy so could be reamed out 1/8 inch (making the diameter 1/4 inch bigger)
and the linkage would surely be simpler.
I suppose the lengths of the intake tracts are more equal with 3 carbs and a custom inlet manifold, but it seems a complex solution to a simple question.
Anyone tried this alternative?
Simon.
 
Sounds like a good idea, Simon. I checked out my old intake manifold and see that there is enough metal to port this thing out bigger, assuming that the bolt pattern is the same. Too, the inside of the factory intake is really ragged. Bet porting and polishing the carb side would greatly increase the efficiency of the mist flow, especially the immediate flat wall it hits before resuming the path down the tubes to the chamber. Unless, of course, the engineers figured this flat surface contributes to the required turbulence. Bet Piman would know.

Bill
 
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