Surfer69

I cant figure out if this could be caused be restricted fuel or is it strictly a timing issue? Just showed up all of a sudden. Secondary airvalve is opening for sure. Using Pertx II which shouldnt be messing up. I've never changed the GF-432 filter so I suspect it might be that. The popping isnt full-on backfires, just kind of sputtering, light popping with a reduction in power. The tweeking never stops.:confused:

As a daily driver, I have to get my fix of WOT at least every other day. :D

Jvette73

Try changing the plugs. If just one of them is misfiring it will cause crossfire under the cap which will fire another cylinder out of time and cause popping from either intake or exhaust. Even if the plugs are new or look good, one of them could still be bad. Whats your gap setting on the plugs? Dont wanna go to large on the gap as it will make it more difficult for the spark to bridge. That too will lead to misfires with the ame symptoms.

Surfer69

I have rapid fires with hot coil so they are gapped a bit wide at .045 .


[Modified by Surfer69, 10:18 AM 1/10/2004]

Jvette73

You could try narrowing the gap to .040 and see what happens.. It might cure the poping and it wouldnt cost a dime.

Master Ho

I experienced the same/similar situation with my Boss 302, after I modded the air intake and caused a lean spot/range at higher RPMs. The solution (for me) was to dyno the engine and rejet.

Surfer69

It does feel like a lean spot which would mean fuel starvation. I am going to order a new filter and will try regapping. If that doesnt fix then maybe switch back to points to determine if Pertx is causing problem. It use to run WOT perfect just a few weeks ago so I dont think its jetting.

Sigforty

:iagree:

I had the problem with my zz4 part of it was plug gap. The other part was the car was running rich at idle so long periods of idling fouled the plugs.

Smokehouse69

I'd almost be willing to bet the ranch that it is your fuel filter, I think you have diagnosed it correctly. If the car has been running perfectly and is in good tune, then the popping is probably caused by a lean condition. :thumbs:

dogboy

It sounds fuel related but check your pick up coil in the base of the HEI. I had a loose wire in mine that caused a similar condition. I couldn't rev past 4,500 rpm's. It finally broke off after a few months & left me dead in the road. $15. part ,now all is well.

Vetterodder

Another possibility is valve float. A weak spring (springs do wear out) or a broken spring isn't closing the valves. Valve float is usually rpm related rather than load but will be more noticeable at wot. End result is popping and power drop off.

Surfer69

Its not valve float cause I have new heavier springs now with fresh rebuild. I'll look at distributor and check wires but I'm still betting its fuel filter. I'll post back with final answer when I get it figured.

72ls5fla

Sounds very familiar ....

For me turned out being the following:

The fuel line running from the tank to the steel line in rear of car was collapsing.
Fuel line in front of car to fuel pump (s hose) was doing the same.

replaced both and ...

no more sputtering loss of power over 4K rpms ..

hope this help ....

Bill

1FUNVET

Is the popping coming thru the exhaust or the intake. If it's thru the exhaust it's probobly an ignition or fuel related problem. If it's popping thru the intake you could have a worn lobe or 2 on the camshaft. Is the engine a high miler?
Hope this helps.

cardo0

:cool: Nice shark Surfer dude.
That poping sound could be a lot of things. I know mine did it when the MSD 6AL hit the rev limiter. But it looked like only 4200 rpm because my mechanical tach reads low. Just a heads up.
Now a poping sounds more like a studder/stumble and I do that to when I drink too much. Maybe drunk with fuel here. Can you have some one follow you to watch for black smoke?
As I remembers this the engine stumbles when drunk with fuel and bogs or surges when to lean. Surging could be ignition or too lean. Did you get the distributor curved for the new cam? You can have a shop recurve the distributor for your combo or do it the hard way yourself. Book by Dr. Jacobs tells you how and too much to describe here. PAW sells his books for $15 (and Jacobs ignitions too). :rolleyes:

454Can-Am

Another thing you can check is your spark plug wires. My big-block (w/headers) kept frying the #3 boot and arc across to the header !
It didn't act up much until the motor got revved up. Good luck, Rick

Surfer69

UPDATE: As I should of known, it was the Pertronix II. :mad Slapped some points in and smooth up to 5500. :D

This unit was only 6 mo old. Suppose to go to 7000 rpm. :bs

I'll try and get my money back.