No Spark When Cranking '72 LT-1

[Scott S.]

Hi guys,

I have a '72 LT-1 that has a TI system installed by a previous owner. It's giving me some grief and I am hoping that someone can give me some idea(s) of what to check.

Here's the scenario:

There is no spark when cranking but as I turn the key toward the start position from the run position or release it from start to run there is a spark, most of the time. We were able to confirm this tonight with a timing light as well as by placing a volt meter on the wire on the starter that is supposed to feed 12V to the ignition during cranking....0 volts.

When I originally purchased this car in '06 I would turn the key and go, no problem. But during the cold winter months (I'm in Toronto) I would start it occasionally and this is when I first noticed that I could crank it for an unusually long time only to have it fire as I released the key.

I just had the engine rebuilt and while I was at it I put in a new TI amplifier board thinking it was likely the weak link. I got it from Corvette Central and it appears to be the unit that's advertised in the Driveline...(K+B electronics or something) That certainly hasn't solved the problem as now I can't start the darn thing at all. In fact, I'm thinking it may have made it worse.

Any thoughts on what I should check?
Thanks.

[Dave F.]

Re: No Spark When Cranking '72 LT-1

Do you know if the car originally had the K66 option or did the previous owner convert it to an aftermarket TI??

[Scott S.]

Re: No Spark When Cranking '72 LT-1

Is the TI system an aftermarket unit or the original GM K66 option?

I believe it's original...but from a different car. Is there a way to tell for sure?

[Dave F.]

Re: No Spark When Cranking '72 LT-1

I can't speak to the amplifier you purchased - no experience with it. I can recommend T.I. Specialty when it comes to the K66 (www.tispecialty.com) or 765-962-4265. Dave Fiedler seems to be the K66 guru and proved it by me. If you go to his website you will find a fairly comprehensive article on the system and you may get some idea of tracking down your problem.

As for the system itself, you really only have two main things to worry about - the amplifier or the distributor pickup coil, and that's the sum of my knowledge on the K66.

[Philip C.]

Re: No Spark When Cranking '72 LT-1

Hi guys,

I have a '72 LT-1 that has a TI system installed by a previous owner. It's giving me some grief and I am hoping that someone can give me some idea(s) of what to check.

Here's the scenario:

There is no spark when cranking but as I turn the key toward the start position from the run position or release it from start to run there is a spark, most of the time. We were able to confirm this tonight with a timing light as well as by placing a volt meter on the wire on the starter that is supposed to feed 12V to the ignition during cranking....0 volts.

When I originally purchased this car in '06 I would turn the key and go, no problem. But during the cold winter months (I'm in Toronto) I would start it occasionally and this is when I first noticed that I could crank it for an unusually long time only to have it fire as I released the key.

I just had the engine rebuilt and while I was at it I put in a new TI amplifier board thinking it was likely the weak link. I got it from Corvette Central and it appears to be the unit that's advertised in the Driveline...(K+B electronics or something) That certainly hasn't solved the problem as now I can't start the darn thing at all. In fact, I'm thinking it may have made it worse.

Any thoughts on what I should check?
Thanks.

I would check the ignition switch, then the ground on the amp box, make sure you have star washer between the grounds on radiator support and on the amp. Check power at the coil with a test light, TI ignition some times wont light a timing light on cranking or even at idleing Phil 8063

[Timothy B.]

Re: No Spark When Cranking '72 LT-1

Scott,
I don't think TI was available in 72 but may be wrong. Check solenoid wiring, when cranking the engine the solenoid should allow power back up to where the distributor plugs in. Same thing when key is released, power from ignition switch to white resistance wire that comes out of TI harness where the distributor plug is located. You should be able to test with test light.

The only other wires are coil and amplifer plug and ground.
I agree to check grounds at amplifer box and also make sure engine grounds are in place. I don't know but earlier corvettes used ground straps and they can easily be removed with engine overhaul.