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Discussion Starter #1
Hey guys, in trying to figure out why my exhaust Is popping when I'm in high rpm ranges. It's starts at around 2500 and gets worse as it climbs. Timing is set at 14 BTDC. Any ideas? The engine is a brand new roller 331.

Thank you!
 

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Discussion Starter #4
Thank na for replies guys, plugs are brand new. Could it be that the rockers aren't adjusted correctly? I did them half then past hand snug
 

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Discussion Starter #6
heres my build.

331 stroker short block
TFS 170 heads
trick flow 1.6 roller rockers on 6.7 pushrods
comp cam .512/.512
MSD ready to run distributor
Brand new never before run Edelbrock 1406 carb
edelbrock performer intake
longtube headers/flowmasters

the carb is completely new, so maybe i should try richening it? And also, I'm not sure if the timing is right at 14 BTDC
 

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Do you know your total timing? 14* could be right for your initial timing, but you don't want your total timing past 38* on most sbf. Sorry can't help with the eddy, but a 600 should work for your set up. You most likely have to play with the carb setting.
 

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Discussion Starter #10
i do have a tiny exhaust leak i can hear, but I don't think thats it, its just a very minor tick. the spark plugs and wires are new, and the spark plugs are rubbing each other pretty firmly on the cap, not sure that matters? As far as lifter preload goes, i have them half turn past snug with fingers and polylocked. The PCV is connected to the passenger side valve cover and runs to the front of the carb. Maybe it is the carb?
 

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Edelbrock 1406 is pre calibrated for economy. You need to rich mixture. There's calibration chart on instruction manual and you need to buy Edelbrock Calibration kit. Best way to tune your new engine is in Dyno with oxygen censor in header collector.
 

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Discussion Starter #12
okay, ill try working with the carb. I'm also running regular gas, didn't even think if i need premium or not with 10 to 1 compression?
 

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Timing is set at 14 BTDC.

Thank you!
That is your initial timing. What is your timing curve over RPM? That is important.

Are you running mechanical and vacuum advance?

Paul
 

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Discussion Starter #14
I am running a mechanical vacuum advance, I'm not sure what my timing up the rpm range is, how do I determine this?
 

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Discussion Starter #15
I've tried playing with the carb, and running three different initial timings. 8 BTDC, 14 BTDC, and 18. I think it likes 18 more than the other two but it's still popping
 

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I am running a mechanical vacuum advance, I'm not sure what my timing up the rpm range is, how do I determine this?
You are running mechanical advance, vacuum advance or both?

To check your mechanical advance you need a timing light and an accurate tachometer. Check the mechanical advance from idle to some high RPM - say 4000 RPM - with the car in park/neutral. You can check as many points as you want but Id recommend checking at least every 500 RPM - ie 1000, 1500, 2000, 2500, etc. Vacuum advance is much more difficult to check as it must be done under load - ie on a chassis dynamometer. You can monitor engine vacuum (manifold or ported) with a vacuum gauge as you drive the vehicle then run the engine in park and externally apply the same vacuum with a hand vacuum pump, etc, and see what the timing is but its a real PITA to do. Keep in mind that your actual ignition timing is a combination of mechanical and vacuum advance. Incorrect ignition timing can cause the issues you are having - so can other things - but its worth checking.

Paul
 

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Discussion Starter #19
Thanks for all the replies guys! Bartl I don't think I could narrow it down to a cylinder, but I did notice that the driver side exhaust is making a different sound than the passenger side. It's almost like its coughing and doesn't sound as clean as the passenger side? I did also notice a hesitation when going 3/4 throttle in second gear
 
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