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the engine did run before the rebuild, but it was basically stock and therefore a gas guzzling dog. i went through all the standard tuning practicing procedures for the carb, and no love. i was thinking about setting the idle, which was at first difficult and i could only get it to ‘idle’ at about 1600 rpm. i realize that this is technically running, but i did eventually see some old school videos that got the idle @ 600rpm, lopey, but steady. combined with the fact that i had someone follow me when i tested and they said no smoke at all when i got into the secondaries, but plenty when i was in the primaries. so i put a 50cc accelerator pump, power valve and 84 jets (73 jets in the primaries) in it. Basically throwing a bunch of gas at, knowing it was way outside the parameters i should be tuning. during the test, fuel pressure dropped to 4psi, indicating the real problem, the stock 5/16 fuel line was inadequate for the engine and carb. i’ve got to say, thanks for all the suggestions and help. Stay dirty!
i’m with evil on this one, if the air/fuel mixture is off, ie; vaporlock then the O2 sensor will give you an error code even if the O2 sensor is still good.
in the old days vapor lock was caused by higher than usual under hood temperatures. cures were wrapping the fuel line like you already did and wrapping the hedders on modified cars.
so this is my first BBC project, rebuilt and installed the engine this spring, so ever since the rebuild i’ve had this problem.
this car runs 11.3 seconds in the quarter, 112 mph even with the problem. 3.70 gearsand yes, i did write holley an email 6 weeks ago, still no response from them.
just reading through the forum and came across this
it may or may not be related, let us know if it helpsi want to see more, lol. it looks like the head is upside down on a bench(?) and all of the valves should be closed. in which case i doubt if changing the valves would help. the valve guides normally have to be replaces as well.
thanks for the input guys.
so almost stalls when i get into the secondaries, recovers to a point, but much less performance than on the primaries. performance on the primaries is very good.i have tried both 30cc and 50cc accelerator pumps, with and without power valve, and gone through the procedure for jetting and tried several cams.
right now it’s at 30cc accelerator pump, no power valve, #84 jets, and orange cam #2 position, which gives almost no gas from the pump. this is the best performance that i have gotten.
i have gotten many opinions that suggested and agreed that it’s too rich, but i had someone follow me on a test drive and no black smoke when i get into the secondaries or after, where there is smoke on the primaries. makes me think it’s too lean.
my first thought was accelerator pump leak, but that would be unusual in a reman carb.
next idea is vacuum leakhttp://www.lmctruck.com/features/cst/cst341.htm
have a lookjust a guess, sounds like the catalytic converter is plugged.
the problem is, cats don’t plug up unless something else is wrong.
another question, does this happen when the car is cold, or hot, or both?i’m with nightflyr here except i check the linkage first. it’s location under the vehicle traps moisture and debris and the linkage gets packed with dirt (most common) or rusts, especially if it’s not used.
electrical, i love it, not.
i’d check the relay first. 2 parts, the solenoid which seems to be working and the switch. disconnect power from the switch, and an ohmmeter should show infinite resistance, activate the solenoid and the switch should show a very low resistance.next there should be a temperature sensor in the circuit, when the engine gets hot enough it sends a signal to the relay which turns on the fan. probably only one sensor in the car and it operates the light or gauge as well.
hi eric,
i’m working on ’79 TRANS AM with 454 cid chevy and aggressive cam, holly 700cfm double pumper, 4 corner idle. the car idles and runs well on the primaries but falters and runs sluggish when the secondaries open. there is no power valve, 50cc accelerator pump and i have got the jets (86s) at best performance. with a new fuel pressure gauge the after market, Holley (blue) fuel pump, is only producing 3.6 to 3.7 lbs of pressure as secondaries come in. i think the pump should do better and i’m wondering if the stock 1/4′ fuel line is the problem. any thoughts? thanks and stay dirty.
charlie