• We have upgraded our forum software! See here for details.

Engine Problem

S

Smokinn

Member
Joined
Mar 17, 2002
Messages
5
Reaction score
0
Location
omaha
HI
I'm new to the list so this is my first time posting anything but i'm sure you guys can help. I have a 76 chevy 4x4 short box with a 400sb auto trans. My problem is the engine spits and sputters when u romp on the gas to open the 4 barrel. I've did a complete tune up even rebuilt the carb. It's a quadjet carb. I've even went as far as replaceing the timeing gears and chain. I put in a new distruber car rotor even a whole new disdruber. But it still runs like crap. Spits gas up the carb and back fires. Any ideas will help alot.

Jason
 
First thing to do it make sure the timing is right on.Set the initial timing and then the vacuum advance. Then set the float,adjust the idle mixture.After all this if it still backfires you have a lean condition.That would mean that the carb has a blocked passage way internally.Also check the egr valve and make sure its not block.They usually are after several years.Also check all vacuum lines.Usually when I have problems I just replace all the vacuum lines.Their cheap enough to do that.Let me know what happens.
 
thanks for replying

I did set the timming manualy. I will try the other things you said to try. I hope something works im at my wits end but i will let you no what happens.

Thanks
Jaosn
 
HI
Well heres the update. I took the carb hat off and found the flots needed to be adjusted. Also replaced the retire distrubeter system and even replaced the timming gears and chain. I set the timming at factory specs and still ran like crap. I gave up and called a friend of mine thats a wiz with old carbs and he came out did a few test on it and could tell just by liesting to it that the cam was replaced with a bigger cam at one time. So he adjusted the timming to 12 b and this sucker runs like a top i couldnt believe what a difference its like night and day. So when i got home that night i looked up and found the past few owners and made a few phone calls. Found out that the cam was replaced back in 96 because the old one had a flat lobe. I want to thank every one for the ideas and help.

Thanks
Jason
 
hi,i have the same problem with my truck.350 60 over,488 lift cam,intake/exhaust,600 carb.checked timing and it was off(way off)i think carb needs to be tunned/adjusted. help would be appriciated thanks.
 
:) howziit guy!

JMO, buy an edelbrock rebuild kit and rebuild the carb. it is so simple, it took me 45 minutes to re-assemble and adjust the floats, and i'm not a great mechanic!

do a quick fast idle/IMS adjustments, adjust initial advance, check vacuum and mechanical advances, re-adjust carb.

i had the EXACT SAME problem you guys had, with THE PINK LADY. it turned out to be a defective vacuum advance diaphragm, and improperly-installed distributor advance weights, leaving me with 12* initial, no vacuum advance and 4*mechanical advance.

NOWWW, i run 16* initial, 12* vacuum and 20*mechanical. it's like i found 75 HP.

i run 87 octane, with no pinging or detonation.

still experimenting, to find optimum ignition timing.
 
You must log in or register to reply here.
Back
Top