Checking Compression on a 1971 LT-1 With Transistor Ignition

[Les G.]

I would like to check compression on my 1971 with TI but I want to make sure not to damage the TI unit. Is there a special procedure to do this? You would normaaly just remove the coil wire, would this damage the TI?

[Clem Z.]

Re: Checking Compression on a 1971 LT-1 With Transistor Ignition

I would like to check compression on my 1971 with TI but I want to make sure not to damage the TI unit. Is there a special procedure to do this? You would normaaly just remove the coil wire, would this damage the TI?

unplug the black box(AMP) or you could do damage to the electronics

[Patrick B.]

Re: Checking Compression on a 1971 LT-1 With Transistor Ignition

I have a 70 LT-1 still running on the original TI unit. I just put a jumper from the coil output to ground when I want to turn the engine over without starting it.

[Clem Z.]

Re: Checking Compression on a 1971 LT-1 With Transistor Ignition

just make sure the high voltage from the tower does not jump to either side terminal on the coil

[Patrick B.]

Re: Checking Compression on a 1971 LT-1 With Transistor Ignition

just make sure the high voltage from the tower does not jump to either side terminal on the coil

Pulling the coil wire at the distributor to attach the jumper to ground avoids the possibility of a spark from the tower to either side terminal. Sorry I forgot to mention that detail.

[Les G.]

Re: Checking Compression on a 1971 LT-1 With Transistor Ignition

When you say coil output do you mean the ignition wire that goes from the top of the coil to the center of the distributor cap. Do you place an alligator clip inside the coil to ground??????

[Patrick B.]

Re: Checking Compression on a 1971 LT-1 With Transistor Ignition

When you say coil output do you mean the ignition wire that goes from the top of the coil to the center of the distributor cap. Do you place an alligator clip inside the coil to ground??????

I remove coil wire from the distributor. The terminal at the distributor end of the coil wire is shorted to ground with a clip lead. That way it is not necessary to attach the clip lead directly to the coil tower. Clem pointed out that attaching the clip lead directly to the coil tower would risk sparking to the coil side terminals if the alligator clip got too close to one of the side terminals.

[Clem Z.]

Re: Checking Compression on a 1971 LT-1 With Transistor Ignition

if you unplug the amp you don't even have to remove the ignition shielding

[Edward J.]

Re: Checking Compression on a 1971 LT-1 With Transistor Ignition

if you unplug the amp you don't even have to remove the ignition shielding

Clem, sometimes those wire connectors don't like being tampered with after 40+ years, can create problems, top shied is not a big deal and remove of the neg. wire on coil.