Alrighty put on your thinking caps.

I start the car and it idles fine (or at least as close as I can tell--2 chamber Flowmasters make the car sound a bit rough), but if I bring it up over 1500 is gurgles, at 2000 it coughs, then at 2500 it backfires hard and drops. It's not constant. It only does this about every 2 engine cycles (at least that's what it sounds like).

Any ideas? Timing seems to be fine, plugs and wires are clean, the gas is good (92 octane on a 9:1 motor) but she just won't breathe for me! TIA--Amanda

sounds like coil gone bad to me.

Let us know how it goes.
Shannon

Have you done any recent work on the engine? Any carb work? A bad coil could cause this but there are other things as well.

I knew I should have put that in my original response......yes, of course there are other possibilities.......the situation described MY past experiences however.
I threw the coil possibility out there because I myself along w/ a couple of other people I know have chased this exact same problem for days.....replacing fuel lines, fuel pumps, rebuilding carbs, checking timing, replacing distributor caps/rotors, etc., etc, etc....all because of a faulty coil. For some reason the coil seems to be the last thing people think of.

BTW Amanda......a broken valve spring will also give similar results and will be cheaper to check and fix than a coil. Of course if you have access to a known to be good coil from another vehicle it would be worth trying too.

Shannon

I think Amanda mentioned a cam change and distributor work recently. Did you check your timing with the engine at 2500 rpm to verify your advance is working? Also, I am not sure if valves adjusted a little too tight would do this--but it may be worth checking. Last, an overly lean condition may cause this. Good luck.
Greg

[This message has been edited by corvgreg (edited 04-03-99).]

If it is a points type distributor, it is possible that the points are bad or need the dwell set.
Valve springs are a good possibility also.

If you are using an MSD billet distributor with magnetic pickups, you may want to test your MSD ignition system and coil first (per MSD instructions). I had a similiar problem 6 months ago on a 1 year old MSD distributor...the coil and box checked out fine so I narrowed it down to the magnetic pickup. It was toast! MSD said it was a rare problem but one that can occur. Hope this helps.

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Over tight valves can cause this to happen. Over tightining a valve causes the valve to remain open slightly and we all know what happens when a spark fires and a valve is open! I went through this the otherday took forever to figure out.

JT
71 L65 SS soon to be 454
>>looking for a 64 or 65 2door<<

its the valves!
had the same problem on my 69 396 a couple months ago;
however i replaced my cam and lifters while i was at it.

runs great now.