Alright... I can't seem to find what I'm searching for.

My '84 stock 305 idles great.
Give it some gas, and it runs like you would want it too. Sounds good, good immediate torque. Normal.

But get on the pedal a bit and you get what sounds like a rapid series of backfires. It's a "pop pop pop pop" that seems to be directly in sync with the engine. (Quiet normally, unless you go WOT. THen it gets real loud!)

I pulled off the air cleaner at night and looked to see if I could see some backfiring, and I didn't see anything strange. Nothing in the exhaust. (Lucky for my eyebrows) And if you're "flooring" it like this, once you hit about 3500 rpm (or just under 40mph) , it stops revving, and only 'backfires.' If you let off the pedal a bit, it will then shift and continue to rev up.

Now granted I'm not too worried about this problem because I have a new engine to throw in when I get some cash to finish it. But it's just annoying, and I can't seem to find anything about it.

I really just want to know what's going on.

Any insight?

Thanks,
-Chris

 

Sounds like leaking intake valves. A compression test will verify.

Either that or a very weak ignition for some reason.

Doubt it's carb related.

 

My apologies for the incorrect post location. Thank you for the reply.

I highly doubt ignition is the problem because I've just replaced all of it. (Turned out to be the ICM, but I replaced everything else trying to find out) But I won't rule it out.

I can run a compression test, but if it has anything to do with all of that, I'll just leave it, I don't plan to use this engine for anything else when the new one goes in.

Thank you again for the reply.