Engine help! New HEI Distributor, intermittent spark.

[mrjordann]

Hey guys. Old distributor went out so I ordered a new one. I set it to fire on TDC compression stroke. According to my timing light, it's getting inconsistent spark. Why could this be? I believe power to the distributor is constant.

Thanks for any help!

 

[Steamer]

I take you meant to say distributor and not alternator.

“Set to fire at TDC” is wrong. (Too retarded) Timing should be at least 7 degrees before TDC which is marked on the flywheel by the raised bb. The line that appears in the timing window just after the bb is TDC.

It could be your timing light is intermittent and not the spark. Which HEI distributor did you get? Did you install new ignition wires also? How bout a pic or two?

 

[mrjordann]

I take you meant to say distributor and not alternator.

“Set to fire at TDC” is wrong. (Too retarded) Timing should be at least 7 degrees before TDC which is marked on the flywheel by the raised bb. The line that appears in the timing window just after the bb is TDC.

It could be your timing light is intermittent and not the spark. Which HEI distributor did you get? Did you install new ignition wires also? How bout a pic or two?

Yessir, thanks for the info. Ignition wires less than a year old. Distributor is "A-team" brand... Identical to my old one. When said it fires at TDC, what I meant was the spinning unit under the cap was before the cylinder #1 plug at TDC.

I can't get it to idle at any position.

 

[Solace in Solitude]

I’m on an iPhone, and could be wrong...

your plug wires don’t look like the proper firing order to me. Should be 153624

Looks like you have them in 152635 order

 

[mrjordann]

I’m on an iPhone, and could be wrong...

your plug wires don’t look like the proper firing order to me. Should be 153624

Looks like you have them in 152635 order

I believe they are correct... they are exactly how the old one was set up when it ran fine...

 

[too tall]

I have had issues with the magnetic pickup inside gm HEI distributors being the incorrect one, or at least wired backwards. IIRC Pontiac OEM pickup coils were wired opposite of the GM ones. Maybe because of the module? I could get it to run if I advanced the timing to 35ish degrees roughly. You could try to switch the two wires and see if that makes any difference. I have also had different modules react differently . The best module as far as performance was concerned I ever used was the performance distributors one. If the distributor is new , It shouldn't be a concern but I had many failures occur at the base of the reluctor chewing into the plastic covered magnetic pickup. I think it was mostly cause by the distributor shaft drive ( Flat part at the end that drives the oil pump) being too short and the gear on the cam pulling the shaft down into the reluctor. At the point when I had issues it acted like intermittent spark and just inconsistent timing ,backfiring and causing all sorts of running issues.
BTW your wires are on correctly .