slight firecracker pops out exhaust

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340wedge1971

340wedge1971

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Timed my 318 today,still getting a slight firecracker pop through exhaust at high rpms....It is bored .030,360 heads,.464 cam with .292 duration,600 eddy with a performer manifold,stock mech fuel pump.My buddy stopped by and suggested that it is starving for fuel and too much air is getting into the cylinder which is causing the slight pop...any thoughts?Its not consistant like a stuck valve and no back fire out the carb...
 
I wonder about the valve springs are they stock? I see 360 heads and a cam with .464 lift. stock springs in good condition are said to be good for about . 450 lift or so but not for high rpms just a thought.
 
They are new performance springs,locks,& retainers...supposed to be good up to .500 lift with 1.5 rockers...
 
Too much total timing can cause that. When you said you timed it did you mean initial......like 10,12,14 BTC? Or did you check it at 3000 rpms or so when all the advance is in? If your total is up around 40 or more i would suspect that is your issue.
 
If it is running lean that is easy to determine. Close the choke plate slightly while you rev the motor, if the miss clears up you know your heading in the right direction. Also check for a vaccum leak, that will cause a lean condition also.
 
OldmanRick said:
Too much total timing can cause that. When you said you timed it did you mean initial......like 10,12,14 BTC? Or did you check it at 3000 rpms or so when all the advance is in? If your total is up around 40 or more i would suspect that is your issue.
Click to expand...

Also a good place to start.
 
Guess i should have asked at what "high" rpm is this occuring, Hopefully not 7k........:).
 
Just did the initial timing,i need to get a timing light on it to check the upper rpm range,i will check for vaccuum leaks as well.It has been accuring around 3000-3500.Should the eddy 600 be enough for this motor?
 
340wedge1971 said:
Just did the initial timing,i need to get a timing light on it to check the upper rpm range,i will check for vaccuum leaks as well.It has been accuring around 3000-3500.Should the eddy 600 be enough for this motor?
Click to expand...

Operating properly the 600 carb should be fine for that application. That rpm range is corresponding with the area of full total advance so there may be some validity to my too much advance thoery. Let us know when you check it out.
 
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