holley help please 750 vac.

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two_70darts

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ok car not running for a while 750 on 340 satrted car runs back fires up through carb at quik exl.1 took out old gas no change 2.cahanged out power valve no change 3. changed out exclr. valve under bowl 4.shooter is a 31 6. checked timing 5 6.pulled plugs there good little rich but ok checked wires there correct place it seems to suck back air under some what smoth but fast exl. then kinda studders thatn may back fire through carb any help please any one pleaseee...:read2:
 
Acellerator pump shot?

crossed, disconnected, bad plug wire?

broke, broken, cracked plug?

stuck valve(s)?
 
acellarator pump replaced all wires landed correct and new a while abck 100 miles on them all plugs checked and good car revs well slowlley with no problums just under quik snaps it sucks back air and stumbles or back fires
 
heads a fresh rebuilds cam and lifters are old 200,000 plus timing chain same pistons are 10.5 heads have minor surface decking comp. check 7 at 190 200 psi 1 at 175psi
 
Have you hooked up a vacuum gauge? Sounds to me like you may have a leaking intake valve. A compression/leakdown check would also be in order.
 
The chief has it. Get out the best tool in the box. Check the vacuum
 
What kinda distributor do you have? Is this a points style ignition? If it is, do I really need to keep askin questions? Also, you said the accelerator pump was replaced. Have you LOOKED down the carburetor throat and SEEN then thing pumpin fuel? check the plug wire and coil wire boots. If they've dried out and cracked over time, leakin voltage will cause mayhem to ensue. Start up the engine at night and raise the hood. See a fireworks show? There's your problem.
 
Change your spark plugs. If your plugs read slightly rich then they are most likely fouled out enough. I had the same exact problem on my 340.
 
i shall proceed with all the above rec. and get back here thanks for all and any insight really need any help possible
 
I go with accelerator pump, if ran good last time it was running that's were I would look. You can start it with the air cleaner removed and give it a few quick stabs while looking to see how the shot comes out of the shooters, should be nice straight steady stream.
 
Purple Haze said:
I go with accelerator pump, if ran good last time it was running that's were I would look. You can start it with the air cleaner removed and give it a few quick stabs while looking to see how the shot comes out of the shooters, should be nice straight steady stream.
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haze thankz i did replace the pump will re verify fuel apouring in my carb though thanks through the shooters that is
 
think next im gonna do the vacumm test, what am i lookin for cheif any help would be fantastic i need it,and also how to do leak down test please help any one
 
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