440 backfires thru Exhaust and won’t stay running

[jdsgtx]

440 71 Plymouth satellite when I crank key in car it crank but not firing. If I jump it on the relay it fires, backfires thru exhaust immediately and dies. I put distributor in 10 degrees before top dead center. I have advanced and retarded the timing and same thing. I had it running before but the more I started it the hard to start. It would puff white smoke out the top of carb and spit. I took carb out and cleaned it. But I wanted to check everything bc a buddy checked the timing and it was 30 btdc but might have been misread. I took valve covers off and everything was moving looked good. What should I check lol? Can’t keep running a sec or two…so I’m unable to check timing .

Hey it’s jdsgtx here! Sounds like you need to start toRetime it from the beginning and check everything

 

[Road Grabber]

Bad gas is a problem for sure.

After all your distributor You may want to consider checking the distributor drive gear and make sure it is in the correct position. Many people and engine builders don’t know this.

Make sure you get your crank on the compression stone and timing mark on TDC.

remove the cap and confirm your rotor position.

Pull the distributor and look down into the block and make sure the groove for the distributor on the drive gear is facing front to back. This position allows adequate timing adjustment and proper timing.

The rest sounds like a combination of issues.

Glad it’s running.

 

[kinghs95]

Ok so I did compression test and hear are the results.
Cylinder 1-170
Cylinder 2-170
Cylinder 3-170
Cylinder 4-149
Cylinder 5-185
Cylinder 6-155
Cylinder 7-185
Cylinder 8-180

 

[Road Grabber]

Those numbers are all over the place. You shouldn’t have more than 10 percent variance.

Is this a high mileage engine? Personally I would look into a valve job. Pull the heads and inspect the valves and gasket seal. If you had a burnt exhaust valve it would pop all the time.

Taking out the plugs would help. Keep them in order, take pictures and post them. Plugs tell you everything going on inside the cylinder. The 180 compression cylinder plugs most likely look better. If you have carbon buildup on the high compression cylinder pistons that would explain it as well.

Either way if you have miles on the engine I would think it’s time for a valve job.

My opinion of course. The others can weigh in.

 

[kinghs95]

Those numbers are all over the place. You shouldn’t have more than 10 percent variance.

Is this a high mileage engine? Personally I would look into a valve job. Pull the heads and inspect the valves and gasket seal. If you had a burnt exhaust valve it would pop all the time.

Taking out the plugs would help. Keep them in order, take pictures and post them. Plugs tell you everything going on inside the cylinder. The 180 compression cylinder plugs most likely look better. If you have carbon buildup on the high compression cylinder pistons that would explain it as well.

Either way if you have miles on the engine I would think it’s time for a valve job.

My opinion of course. The others can weigh in.

It’s got maybe a 1-2 hrs of run time. It’s a fresh rebuild with 30 over. It does not pop at all now that I timed it a little better but less power than the last time I started it.

 

[Road Grabber]

While you are at it take the time to replace the timing chain. Those two things really freshen up a motor. Double roller is all I use.

It’s a good time to inspect everything like push rods, rocker arm wear, rocker arm shaft wear, lifter wear etc. You might even decide at that time if you want a different valve train or cam.

 

[Road Grabber]

It’s got maybe a 1-2 hrs of run time. It’s a fresh rebuild with 30 over. It does not pop at all now that I timed it a little better but less power than the last time I started it.

Ok missed that part. That doesn’t explain the difference in compression. You may have head gasket problems or your rings haven’t seated yet.
Drive the car, power up under load and let off the gas over and over. Keep an eye on your engine temperature.

 

[kinghs95]

Ok missed that part. That doesn’t explain the difference in compression. You may have head gasket problems or your rings haven’t seated yet.
Drive the car, power up under load and let off the gas over and over. Keep an eye on your engine temperature.

Ok will do.

 

[oldbee]

You may have a bad head gskt, leaking between cyl 4&6. Do as above first to get the rings seated.(moly rings?).
My moly rings,years ago took about 5 cycles up&down to start seating in.

 

[toolmanmike]

Ok so I did compression test and hear are the results.
Cylinder 1-170
Cylinder 2-170
Cylinder 3-170
Cylinder 4-149
Cylinder 5-185
Cylinder 6-155
Cylinder 7-185
Cylinder 8-180

You have a couple low(er) cylinders compared to the rest but I wouldn't worry too much. They are still 150+ and a blown head gasket between the 2 is highly unlikely. So, now that you have the timing figured out what is your initial timing set at?

 

[Road Grabber]

Your exhaust pop could have been a tight exhaust valve guide which could be wearing in. Exhaust valves run much hotter.

Just make sure you don’t overdue it running the engine. Don’t let it overheat. If you do have one or more tight valve guides you don’t want a piston to smack valve(s).

Take it easy on the engine and let it wear in. Some people go nuts and that can end up badly with a spun bearing.

Are you using break-in oil? Careful with using thick viscosity oil breaking in an engine. You should have seen smoke diminishing as you ran the engine for the first time but you still have to help break the rings in like mentioned before.

I’m sure many people on the forum have advice for new engines. Don’t let a lead foot and anticipation get the best of you.

 

[cosgig]

Broken or cracked spark plug insulator maybe? I’ve had that happen before, and it popped through the exhaust.

 

[oldbee]

Less power than before??? What timing are you running now? You said running a little better after resetting the timing.

 

[kinghs95]

I’m at 12 degrees.

 

[Road Grabber]

You have 30 psi difference between cylinders. That’s a mechanical problem not electrical. Just sayin
The engine will not run smoothly with such a difference in compression.

 

[kinghs95]

Ok so I put everything back in and double checked I connected each spark plug wire onto each spark plug and I only adjusted the carb accelerator pump lever from the middle hole to the top hole like it was before and it fired up. I had to still jump the relay bc still something wrong there (haven’t tried to find out yet). But it ran like it did before smooth and strong. It’s actually 10 btdc so I could improve that. All I need to do is dial in the fuel/air mixture screws and should be on the road. I think the compression test wasn’t that accurate bc it’s still fresh and not broke in. I feel like the issue was a fuel/air issue and maybe spark plug wires. I’m planning on changing the distributor soon to the summit kit, spark plugs, and wires bc some maybe faulty from all the rewiring and rerouting and etc. I will say best thing to tell tdc was putting a wad of paper in spark plug hole and letting it blow out then lined my 0 marks and check Piston. Thanks guys.

 

[AR67GTX]

If you ran the compression check on a cold engine you might want to try it later on a warmed up engine where all the parts are warmed up, expanded and in operating mode.