No Start '55 Chevy

[ac delco]

UPDATE: Passenger side coil harness was backwards, jumbling up the firing order. I found TDC and retarded the spark 84° to line up. I put the 15° of crank advance in and it tried to run, but would not stay running. Cranks like it wants to idle. Very close.

[wompa]

You hooked up the coil harness backwards, or it was pinned incorrectly from Holley?

[ac delco]

Holley was correct. The GM sub-harness was upside down. Does not explain my 84° offset. Still won't start. Verified spark, fuel & timing. Cam LED goes red after two revolutions of crank.

[ac delco]

Changed cam sensor to NONE and ran it Bank-To-Bank. It ran, would not stay running, but it ran. I sent my DL file off to tech. I'm curious what the next step is to get my cam timing working. I know the sensor is OK and the harness too. I'd attach my DL file, but the site won't let me. At least I'm inching forward!

[Chuck L.]

What's new?

[ac delco]

Unfortunately, not much. We verified all coil/injectors. Checks out. Next put into Digital Falling for cam profile and it runs real rough and still backfires. ECU is me that my timing should be retarded by 84° to line up properly. We're going to take a long hard look at the reluctor on the crank to make sure it’s clocked properly, even though it was never taken off. If we spin the engine by hand slowly key-on, I can see cam & crank signals, and they look correct. Telling me that my timing should be retarded by 84° to line up properly. We're going to take a long hard look at the reluctor on the crank to make sure it’s clocked properly, even though it was never taken off. If we spin the engine by hand slowly key-on, I can see cam & crank signals, and they look correct. TDC #1 rise TDC #6 fall. This was on the ECU LEDs. I took a datalog of the engine running poorly and sent it off to Holley Tech.

[ac delco]

Holley Tech is having me send the ECU back. In the DL I sent to them, there were five crank errors stacked up. Unusual. I'll keep you posted when I get it back.

[Chuck L.]

OK. What's the current status?

[ac delco]

Saddening. ECU Checks out and ran a test engine just fine. It's being shipped back to me as we speak and I'll receive it a week from today. I have five plans of Attack:
Compression test: Yields 210-240 psi per cylinder. This tells me that the cam is clocked OK and we can see the cam change its LED status at TDC from low to high and back again.
Pin-out Holley harness to ECU connector. This is my next big suspect.
Replace cam and crank sensors again.
Drop pan and visual crank reluctor clocking. I used a piece of spring steel to feel 8mm reluctor hole at TDC, but could not see it.
Pull timing cover, last resort as it looks like cam is in correctly.

[Romansroad828]

Ugh! I’m having the same problem here. Any updates?

[ac delco]

Not yet! Harness pins out fine with continuity test. My reluctor on crank is A-OK. Just bought new sensors for cam and crank. Something is telling me my timing is off by 84°, but that figure seems to be very wrong. I'll try new sensors tomorrow. Do you have similar timing issues? Does anybody know the correct air gap between the reluctor wheel on the crank and the crank sensor? Currently I’m at .042".

[Danny Cabral]

The sensor gap is .030" or slightly less.
https://forums.holley.com/showthread...0283#post90283 (Related Forum Post)

[Gaz64]

You have a black crank sensor? Or Gray? Gary

[ac delco]

Black crank sensor.
It's a 24x /1x setup.
I need to move it .018" closer.
Thanks for the specification, Danny.

[Danny Cabral]

I need to move it .018" closer.
Thanks for the specification, Danny.

You're welcome, but isn't it a non-adjustable mounting point?