ok you guys I have one for you I ready to give up! I have a 1970 SS 396/350hp with a 4 speed I have completely rebuilt the engine valves,new valve springs,pistons,cam,crank ground, bearings, rings, lifters, push rods, etc.the carb. was sent out to be rebuilt recolored flow tested,stock dist.completely rebuilt and dialed in on a sun dist. machine the entire rebuilding has been a stock resto. the timming is set at the stock setting all new wires, plugs, rotor, cap, etc.everything has been rebuilt or replaced the carb. has been flow tested by a second person every time I stomp on the gas it coughs pops back thru the carb multiple times then finally it will take off also the vac. lines have all been conected as stock I have disconected the T.C.S,I advanced the timming it runs worse? where do I go next?

Would the coughing & poping be a real bad bog when the peddle is put to the floor? If so you may have the secondaries (4-barrel) opening too soon. If you have a vac. secondary try a heavier secondary spring, this will open the secondaries later. Any smoke from the exhaust when coughing & poping? and if so what colour? black smoke is too much fuel. Dave

I would classafiy a bog as a long hesitation without the poping or coughing this is while this worse when the engine is cold ( choke is off but not up to operating temp.) but it always does it but less severe when warmed up I will check the secondary, but I did have this carb. flow tested twice buy two different people that should be part of the flow test the carb. was my first thought, no smoke <BLOCKQUOTE>quote:</font><HR>Originally posted by dsr:
Would the coughing & poping be a real bad bog when the peddle is put to the floor? If so you may have the secondaries (4-barrel) opening too soon. If you have a vac. secondary try a heavier secondary spring, this will open the secondaries later. Any smoke from the exhaust when coughing & poping? and if so what colour? black smoke is too much fuel. Dave<HR></BLOCKQUOTE>



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I just put a new rpm performer intake on my 67 4-speed and I'm having trouble with sputtering and backfire through the 750 holley. I have checked a lot of things but I still need to check for more leaks through the intake...Car ran great before I put new intake on.

well thats my next step I thought it might be a vac. leak or carb. problem if you find your problem please let me know thanks, Marty <BLOCKQUOTE>quote:</font><HR>Originally posted by TJB:
I just put a new rpm performer intake on my 67 4-speed and I'm having trouble with sputtering and backfire through the 750 holley. I have checked a lot of things but I still need to check for more leaks through the intake...Car ran great before I put new intake on.<HR></BLOCKQUOTE>

Make sure you are getting gas when you "wing" the throttle. The reason I say this, is sometimes you can get the impression that the carb is pushing TOO much fuel, when in reality it is not pushing enough. Make sure there is no play at the accelerator pump on the carb. If it has ALOT of play...you are getting an off idle stumble until the pump catches up. If this confuses you.. http://64.207.13.28/mysmilies/contrib/dvv/sconf.gif .......let me know. I'll help ya through it!!

Brian
72 Elky
71 Chevelle