I went from a really crappy homemade 2" Y pipe and dented pipes to much freer flowing 2 1/2" setup.

I started to get popping out my mufflers. It never did it prior to swapping out my exaust. I'm useing a 600 holley. When I played around with the idle mixture, that seemed to help some, but it still pops occasionaly while my car sits idleing. I have'nt had time to mess with it much since I put it away for winter

Does it sound like it's time to try jetting up?

IMHO, any change in exhaust backpressure will require the carb to be retuned, both idle mixture and jetting have to be checked.

Also forgot to mention, check your vaccuum lines a vaccuum leak can cause the same problem.

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70 Camaro Z/28 with 461cu.in. BBC & OD Auto, 3.31 12 bolt posi.

[This message has been edited by wayner (edited January 05, 2005).]

The other thread added to my suspicion that it may be a running too lean now, but I wanted some opinions.

I put new vac. lines on last spring, but I did'nt clamp the one on the distributors vaccum can. It seemed pretty snug. Should I try clamping it?

The popping did'nt start until I changed the exaust, right after firing my car back up for the first time.

Can someone reccomend a good book on holleys?I have a spare 650 I can use for a ginny pig. I want to learn how to change out jets and eventually be able to rebuild one.

Thanks.



[This message has been edited by sikzdrivr (edited January 05, 2005).]

Changing the exhaust may also affect how your timing needs to be (re)set. Also- it's always possible that you knocked loose or otherwise damaged an ignition wire while doing the install, right? Check to be sure.

As you start to change things, just do ONE thing at a time, so you don't get further away from your baseline. You have to figure, you just gave your car a huge advantage in breathing from the previous configuration, so take it slow and get it right.

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"Say your prayers, tonight you're mine, you're the victim, I'm the crime!"

If the car sits there idling and its poping sounds like its missing?
if you have headers when the car is cold start it wait 20 seconds wet your finger and touch each header tube to see if you have a cold one just to make sure all 8 are firing if you have a cold one check the plug and wire on that cyclinder
You havent touched anything since the poping started other than exhaust?
no valve adjustments?

Double check your plug wires, and also take off the distributor cap and check your rotot, it might be burnt.

Much of my ignition (cap, rotor, coil, wires and plugs) is fairly new.

And all 8 primaries passed the "spit on the finger" test. They were all getting nice and hot.

I have'nt tried re-setting the timing. Or touched any of the valve train.

It did'nt sound like it was missing when I listened up front with the hood open. My engine used to do a weird "jump" when it used to have a miss. Not from the cam either. I could also hear it miss each it "jumped". It's not doing that now when it pops out the mufflers, it just pops.



[This message has been edited by sikzdrivr (edited January 06, 2005).]