1974 Firebird Trans Am 455


alright where to start, good battery, good wires, good plugs, butt no spark at plugs. its a big headache bc its really not all that complicated. we have power from the battery going to the coil. 12 volts coming in and 12 leaving the coil. brand new coil to distributer wire. we have good spark plug wires, but no spark! we are 99% sure its a good coil.
one thing we noticed is like i said, 12 volts leaving the coil. however, when you hold the end of the coil wire (the end that connects to the distributer) with one hand and ground your other hand. when you turn the motor over you should get shocked the hell out of. we held the wire and turned the motor but no shock. Im open for any comments or suggestions.

thx, John

 

I presume it's points type coil from your description? If so, there should not be 12v present on the ground side (goes to distributor) all the time. It should go to zero when the points close. If it is a constant 12v on that side, there is an open in the ground side. You said it had a new wire from the coil to distributor... is this the one that goes to the points?

12vdc is not enough to shock the hell out of you, but you will feel mild pulses if it's an interrupted 12vdc.

I thought some GMs were HEI by 74, and some Pontiacs had a weird HEI distributor, from 72ish for a couple of years. The size of a points distributor vs the much larger regular HEI, but it was HEI with a cap having integral plug wires. If you have one of these oddballs, it might have a dead module.

Can you take a pic?

 

If the wire is good you will not neccesarily get shocked as the insulation will protect you. If it is HEI I have seen a lot of cases where the rotor button burns through in the center and the spark goes into the distributor shaft. Something else to check. I have also seen people put a new coil in an HEI cap and put the carbon button in with the rubber insulator on the wrong side. No start there too.

 

I've had some ignition problems with some of my Pontiacs before. I once had a perfectly running system that mysteriously quit running. I just replaced the distributer and it fired right up.

+1 on checking the cap and rotor. Does your system use a resistor block?

 

thx to everyone for the help. i got it running this afternoon. It has not ran in 7 years! I took apart the distributer and noticed corrosion build up on the rotore and distributer contacts. Too much to allow a good contact. I cleaned it using a file and put it back together and now had spark. To my surprise, it started up. I ran it for about 30 minutes with no problems. thanks again to everyone for your help.

John

 

Glad to hear it bud.

 

[QUOTE=yep,350L_S_1;4244654]1974 Firebird Trans Am 455


alright where to start, good battery, good wires, good plugs, butt no spark at plugs. its a big headache bc its really not all that complicated. we have power from the battery going to the coil. 12 volts coming in and 12 leaving the coil. brand new coil to distributer wire. we have good spark plug wires, but no spark! we are 99% sure its a good coil.
one thing we noticed is like i said, 12 volts leaving the coil. however, when you hold the end of the coil wire (the end that connects to the distributer) with one hand and ground your other hand. when you turn the motor over you should get shocked the hell out of. we held the wire and turned the motor but no shock. Im open for any comments or suggestions.

pull the distributor cap off check to see if the rotor is in working condition
making sure that the rotor is seated down

also check under the distributor car look at contact points to see if they are no worn out -- these things can stop fire also

intell tech

 

i just read that you got it running that great

sorry i'm too late