Strange timing issue

ponyracer1 · Apr 28, 2009

Cars a 92 GT, aod car with a tko swap. All stock longblock with new MSD cap/rotor/wires, good plugs. Runs great, going to the strip friday so I started looking for some free HP and ran into a strange issue.

Pulled the spout, checked the timing, it was at 14 degrees on the balancer at idle. Advanced it to 16 and took it for a ride looking for detonation, there wasn't any. I continued doing this and now I'm at 24 degrees???? Still no detonation, I'm running 93 octane. I figured the balancer slipped (stock with 100K+) so I did the TDC check with your finger on the #1 plug until your on the comp stroke. Checked the balancer and the dizzy, everything lines up.

Any ideas?? Engine appears stock but I don't believe it's original, 40-60 psi oil pressure at idle, checked the cyls from the bottom when I swapped the pan gasket and there was no vertical scoring and the cross hatch looks very thick still.

Sorry for the book, thanks in advance!!

matts90lxhatch · Apr 28, 2009

I have ran up to 17 degrees of timing with the spout out on a n/a engine without hearing any detonation. But I never chanced taking it any higher. Especially if your making more power than stock using a power adder. It doesn't take much detonation with a power adder and you'll pop a head gasket or worse.

I would back the timing back down to 14-15 degrees initial and leave it alone personally.

ponyracer1 · Apr 28, 2009

I wish I had a power adder. She's bone stock H/C/I with longtubes and an offroad h pipe. I'm thinking there's no way this thing can run like this so there's a problem somewhere and I'd like to find it. I'd also like to know I'm getting the most out of my motor, (finding detonation and dropping it back a little) but I'm a little scared to push it any farther. Can anything be damaged with to much timing if theres no detonation?

FastDriver · Apr 28, 2009

Forgive the dumb question, but did you replace the spout connector? If you did reconnect it, have you checked to ensure that the ignition is actually advancing at higher rpm? If it's still on the stock tune, the computer will advance the timing 16* total. So, if your base timing is 24*, you should see it at 40* at high rpm.

If it isn't that, then your balancer is inaccurate. You aren't running 40* total without detonation on iron heads, and you'd probably still see detonation even with good aluminum heads. Try a friend's balancer or get a new one. You could also test it by using a stopper and turning the motor one way until it stopped and then turning the motor the other way until it stops. The timing should be above and below TDC by the same amount. i.e. if you turn it one way and it stops at 10* BTDC, then when you turn it the other way, it should stop at 10* ATDC.

Chris

ponyracer1 · Apr 28, 2009

I only have a basic timing light but tomorrow I'll be picking up my buddy's good one that will show the all in timing at higher RPM's. So at this point should I just keep going 2 deg at a time until I get detonation and back it off a couple? I'm thinking the balancer must have slipped, I just don't understand how it could line up when I tested it.

Oh yea, set it with the spout unhooked every time, and hooked it back up prior to test driving.

Thanks!!

FastDriver · Apr 28, 2009

Oh wow, I just realized you live in the town where I grew up. Based on your "for now" comment in your Location, I'm guessing that you're in the Air Force? My brother lives on Eglin and can help you out if you like. He's got a magical timing light that even he hasn't figured out yet, and I'm sure he'd be willing to lend a hand. Plus, you could go take a look at his twin-turbo POS he's rollin' around in.

I personally think you should back the timing off just to play it safe until you figure out what's wrong. Either, 1. the balancer is off, 2. something is preventing the computer from advancing the timing, or 3. detonation is occurring but is unrecognized.

The "thumb over spark plug hole" test is good for determining the compression stroke, but is no where near accurate enough to give you any idea if your balancer is off by 10-15 degrees.

Chris

ponyracer1 · Apr 29, 2009

Thanks for the reply, I'm going to hit it with an "all in" light today and see what she says. I'm betting your right and the balancer has slipped a bit so my 24 degrees is more like 14 degrees.

Strange timing issue

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