Engine Popping after Simple Points Replacement went really bad

[Jay (59 Impala)]

I took my perfectly fine running 59 Impala with a 348 to a shop to have a simple magnetic pickup installed to replace failing points. I was told that the firing order was 180 out so they messed with that for a while. They ended up telling me that I needed a whole new electronic distributer with an electronic control module (all Pertronix). The car has not run well since. It "pops" constantly. I had it timed and tuned by another shop and they again changed the firing order which I believe was messed up by the first shop. I've personally confirmed is now correct... but it still pops. They thought it may be carbon buildup on the number 8 piston because compression was 150 when all others were 140-145. I've been adding cleaner to fuel but no improvement... Any help would be appreciated!

 

[La Hot Rods]

Pop out the tailpipe or carburetor?

 

[Jay (59 Impala)]

carb

 

[bobs409]

Moving to the correct forum.

 

[Jay (59 Impala)]

The first shop thought it may be rust in the fuel, so I even repaced the original tank. It has a tri-power that is the only thing not original to the car. Original was 4 barrel. The carbs were re-built a few years ago.

 

[La Hot Rods]

If it seems to be one cylinder, I would pull a valve cover and check for a problem there. Maybe a cam lobe has gone flat.

 

[La Hot Rods]

Firing order is
18463572

 

[wristpin]

The problem is the first shop. Electronic pickup gap set incorrectly (perhaps set gap with metall feeler gage damaging unit), dwell incorrect, maybe advance weight springs screwed up.
Avoid the rabbit hole....start looking at what they screwed with. BTW how could they believe you even drove car in with failing points then adding electronic pickup caused rust in fuel? Is there a shop around who can statically set the distributor with it removed from car?

 

[Jay (59 Impala)]

Thanks guys... great ideas. One other detail... if I pull the plug wire from #8 is doesn't pop. Does that narrow it down?
Wristpin... my feelings exactly!!

 

[La Hot Rods]

Pull the valve cover on that side, then crank the engine over and watch the rocker arms on that cylinder for movement.

 

[nana1962409]

Firing order is
18463572

Might want to edit that. Correct firing order is 18436572

 

[La Hot Rods]

Da, sorry

 

[63 dream'n]

The problem is the first shop. Electronic pickup gap set incorrectly (perhaps set gap with metall feeler gage damaging unit), dwell incorrect, maybe advance weight springs screwed up.
Avoid the rabbit hole....start looking at what they screwed with. BTW how could they believe you even drove car in with failing points then adding electronic pickup caused rust in fuel? Is there a shop around who can statically set the distributor with it removed from car?

Not only that...... how could you have driven it there if the distributor was 180 out.....it would not of been popping if it were correct......

 

[bobs409]

Was car left unattended with first shop?? Did they drive it? Can they be trusted? I would never let any of my antiques alone with any mechanic unless I fully trusted them. I've seen what "test drives" can be like!

Just tossing it out there. TRUST NO ONE!

 

[DonSSDD]

Maybe the new electronic distributor they installed is Chinese junk? Did the second shop seem to know what they were doing?

If it was running fine on points, maybe nothing wrong with cam or valves, just a crappy distributor setup?

 

[DonSSDD]

Put old distributor and points back in and see how it works?

 

[dm62409]

Just a thought here, if engine was rebuilt with a aftermarket cam, it may have the 4-7 lobe swap and would need the 4-7 spark plug wires swapped from the original firing order.

 

[1964SuperStocker]

I have an even easier test.
So long as you know its the number 8 giving you fits then pull the spark plug and put your finger down there while turning it over to find the compression stroke. As soon as you get the air to push your finger away then stop. Pull the distributor cap off and find out whether your #8 plug would be firing at that moment. If that rotor is facing any direction but the #8 on the cap then you have a clear and quick indication of where to start. If that rotor and cap line up with the #8 wire then I would pull the valve cover. May be a flat lobe because the higher compression in that cylinder may indicate that any over lap in the cam timing has been eliminated due to a flat lobe, bent push rod, lifting rocker stud................ Good luck!

Keep in mind you may have to check a couple of the cylinders vs the rotor/cap to ensure it is in fact the #8.

 

[64ss409]

If you have that valve cover off, check for a broken spring on no. 8 intake.

 

[Don Jacks]

Hook up a vacuum gauge,start engine and note readings with the number 8 wire off.Hook up number 8 wire and if the gauge goes crazy[needle dances wildly].Remove the rt.side valve cover and inspect the valve train on number 8.As Ron stated intake spring ,also bent exhaust push rod,failed cam shaft/lifter.If the exhaust isn't opening and the intake is,the result will a pop up through the intake the next time the intake opens.Unlike