Tune up help
Thread Starter
Intermediate
Joined: Jun 2001
Posts: 33
Likes: 1
From: adams run, SC
Tune up help
Just bought a 71 with 454. Replaced aftermarket intake and carb with original setup(qjet and intake) car has new hei distributor. Car did not run well with the old junk either. Anyway, I have been trying to tune it up, but have become increasingly frustrated. I tried to set timing by the Lars paper(36 degrees) I have also set timing by the book(8-12 degrees). Either way car hesitates on acceleration. I have some white smoke out the exhaust and after test driving, I can hear a tapping noise from the valves. I did a leak down test that revealed all cylinders at about 15% with audible hissing from the oil dipstick. Compression test showed 115lbs on cyl 1357 and about 120 on cyls 2468. I don't know what to do next. Suggestions please.
Team Owner
Joined: Jan 2006
Posts: 37,637
Likes: 3,118
From: Crossville TN
Before you can effectively set up the carb@ idle, you must seal up all vacuum leak paths. Any such leaks will cause an increase in airflow into the intake charge. For a hesitation [bog] at WOT with low rpms, check the action of the accelerator pump in carb. An improperly set secondary airvalve can also cause a "bog": either because it is set to open too early, or because it is set to open tool late.
Le Mans Master
Joined: Oct 2000
Posts: 6,362
Likes: 30
From: Oak Harbor WA
White smoke out the exhaust can be a sign that coolant is being introduced from a blown head gasket or a crack and those compression numbers seem really low. I hope I am wrong on both accounts.
Have you researched the factory cylinder pressure numbers range?
Personally, if the basic engine isn't sound then you are wasting time trying to get timing and fuel sorted out.
Have you researched the factory cylinder pressure numbers range?
Personally, if the basic engine isn't sound then you are wasting time trying to get timing and fuel sorted out.
