QuestionI've rebuilt my carburetors and replaced the deceleration bypass valves with new diaphragms. I've been trying to tune it according to my copy of the BL manual. No matter what I do I still get the same results. After a slow acceleration and release of the throttle, the idle drops slowly and rests at over 1000 rpms. This of course is not normal operation. If I do a quick tap of the throttle, the rpms shoot up and then quickly drop down below 500 rpms and then slowly rise to 800, which is what I expect to be normal operation. I've tried seating both of the valves, but this doesn't seem to make a difference. I'm not entirely sure the valve on the rear carb is seated. I have a hard time adjusting that with the FASD in the way. Is there a specific tool I can use to get a better grip on the screw? I can sometimes get it to turn a little bit before the screwdriver slips off.
I'm also having a hard time diagnosing my clutch. Problems started occurring a couple weeks ago. Shifting into 1st or 2nd is pretty hard and sometimes I can't get into reverse. The gears clash. I replaced my slave cylinder and bled the air out, several times. I'm beginning to think it's my master cylinder. When I can shift it, I have to keep the pedal all the way to the floor to keep the clutch disc from gripping, similar symptom to a brake master cylinder failure.
One last thing. I've had the head rebuilt. After reinstalling it, I added a set of Pace Setter long tube headers. The headers were not a perfect fit to the exhaust pipe, causing a leak. I replaced the header with the original exhaust and I now have a valve tap. I'll be checking my valve lifter clearances soon, but I want to know if the exhaust leak could have caused the valve tap.
AnswerThe decel valves can be tested by adjusting the screw so as to hold the valves closed all the way. Once you do that if the slow idle return is still there, you know they are not the cause. Throttle linkage adjustment and worn throttle shafts are the more likely cause anyway.
As far as the clutch goes, when you need to replace or overhaul a slave cylinder, the master cylinder is also needing work. I would never do one by itself.
No, a leaking exhaust can not make a valve lifter change in any way. You do need to check all valve clearances and torque the head nuts and bolts. (Be careful to follow the book instructions as the TR-7 is very different than other engines) Be sure to torque stone cold. If when adjusting the valve clearance if you have a size range problem look to Saab 99 shims as they had a broader range of sizes.
Howard
