Back fire and power loss

ignition coil under rotor inside distributor.

Fishbreath wrote:
How many miles and do you know the maintenance history?
I do agree that getting it on an scope will help to determine the problems. The 454 with high mileage (over 100k) had some issues with the timing chain jumping a tooth.

Its not just the 454, its all SB/BB chevys, fords, and Mopars. Its the funky timing chains that strength and wear the gears. We use to recommend changing the timing sets at about 75K to prevent failure and bending valves/pushrods.

How many miles and do you know the maintenance history?
I do agree that getting it on an scope will help to determine the problems. The 454 with high mileage (over 100k) had some issues with the timing chain jumping a tooth.

if the engine has a vacuum advance on the dist. disconnect the hose and drive it .it may seem a little lazy but if it doesn't backfire anymore its the pick-up coil in the dist.

I would start by removing the doghouse cover and starting the engine at night, do you see any arcing from the wires to the engine block? The next thing I would do is check to see if that vintage engine has a plastic timing gear, then check the timing. Base timing is 4*BTDC it will run better between 9-12* BTDC. Let us no what you find and you will get get better help rather than a bunch of possible solutions.

I had the same thing with a 1983 Winnie 7.4 that I used to have (sold in 2001) and I can't remember what the problem was. ???
But I do remember it was associated with the distributor.
Could have been with the advance or ignition trigger or trigger wiring.
Should still be HEI distributor, BEST non-computer ignition system ever made!

If it was a point and condenser setup I'd say definitely the condenser but I think that was way past gone in 87. I then would put a timing light to the distributor and check to see if the vacuum advance and /or the mechanical advance is working. It's a very common problem with the older distributors to have a gummed up mechanical advance.

Plugged converter?

Yes it does have egr and it works fine

Suspect a vacuum leak somewhere in the intake. If it runs fine when somewhat cold and falters when warmed up, its usually a fuel supply issue. (or too much air) Does this engine have EGR?

Chum lee