Timing an engine/ Help ??

[SouthernExposure]

Hello,

Could anyone out there give me a little hint on the proper location of the timing tab/indicator to time a 1989 5.7L with OMC outdrive?

I know it sounds like a silly question but I have run into a strange arrangement. Only me!

Thanks,

Tony
SE

[mikev]

it should be the same place as any other small block chevy if you are facing the front of the motor it will be on the righthand side a little metal tab sticking out of the timing chain cover right next to the harmonic balancer.

[Jamesbon]

What Mikev said.

If you want to "make a new one," rotate your engine to #1 top dead center in the firing position, both intake and exhaust valves will be fully closed, then install your new pointer and confirm the zero degree mark on the balancer is lined up with the zero degree mark on your new pointer.

I've been known to use a coat hanger as a pointer in a pinch :D

That's it in a nutshell...

[BUIZILLA]

Perhaps, if you elaborate a little on your *strange arrangement*, it would help us help you better..

Does your engine have the OMC electronic ignition box, by the left valve cover on a bracket?

There is a SPECIFIC base reference if it does.

J

[SouthernExposure]

Here goes,

(Only owned the boat for 1 month or so)

Murphy's Law is now Tony's Law

The engine is a 1989 Chevy 5.7L w/OMC Cobra. The problem that started all this is the boat would not idle at low speed...docking. So I decided to tune her up...plugs, wires, etc. Also I had to install an aftermarket timing tab because the original one was not there. That's why I have asked where is the proper location of the timing tab..I thought it would be like a normal 350 Chevy...above the harmonic balancer on the port side attached to the timing cover. I was going to check the timing prior to changing the parts out but did not due to working between rain drops.
Big mistake, although I did not take the distributor out or loosen it to replace the parts. So the timing really should not of changed too much. Anyway, once the parts were replaced I hooked up the old timing light and the timing mark was up around the 12 o'clock position. So when I tried to set it at 8 degrees for the fuel I'm using (according to the book) it would run rough and quit. I have a new carb on her now and a new timing chain and sprocket set. The timing indicators on the sprockets were correct, the chain had a little slack but I don't think enough to make that much of a difference. I'm tired of working on this thing. The only thing left to replace is the distributor. Once a finish putting her back together will see what happens. There is more but I'm tired of typing.

Thanks,

Tony

[mikev]

first question why didnt you replace the timing chain cover while you had it off this would have solved the problem and they are cheap. that said if the tab is missing i would just time it by ear some of the old timers are real good at this and can get it dead on. get the lowest idle it will run good at then take it for a trial run and just make sure it doesnt ping. be careful though too much advance and you get a hole in the tops of your pistons.

[BUIZILLA]

Did you use the front plug on the port side, or starboard side, for the timing light?

Do you, in fact, have the OMC electronic ignition?

J

[SouthernExposure]

Hi again,

I did not need to replace the cover it was fine and the new cover does not come with the timing tab. I have checked with a company that someone recommended on this forum for something else..Doug Russell Marine. The timing tab is sold separately according to the exploded view. That's why I picked up an aftermarket indicator tab.

The ignition system is points and condenser no electronics. I used plug wire # 1 located on the port side. The intake is also marked # 1 on the port side. I double checked in the book..same location.

[BUIZILLA]

Okay, the aftermarket pointer is your problem. You have a non-Vortec pointer on a Vortec engine...

Bring the engine to ABSOLUTE TDC on #1. Check for TDC using a pencil in the plug hole for movement while someone SLOWLY rocks the engine with a breaker bar procedure.

The TDC mark on the damper will be at about 1:30 clock position looking at the front of the engine. If the mark on the balancer is at 12 o'clock, with the piston at TDC...BINGO, you found your problem.

This is really an easy fix to overcome.

J

[Jamesbon]

I'd also take a stab at those points and condensor. I've had them work great in the past, but when they go, strange things start happening...

[mikev]

i did not know there was a difference in the vortec engines vs. the non vortec i guess it is true you learn something new every day.

[Rootsy]

Vortec motor uses an 8 inch harmonic balancer.. pre-vortec uses a 6 3/4.... timing marks should be in the same spot on the balancer. on the vortec motors they utilize a plastic timing cover and the timing numbers are stamped on the balancer.. pre-vortec uses a timing tab with a single scribe on balancer.. UNLESS you hve an aftermarket or some kinda non production gm setup.

case in point. MY 97 350 from merc uses the vortec setup on a 6 3/4 balancer... i thought it was a vortec motor until i took a look at the cylinder heads... other than this i have not encountered any other cases of differing unless you have an aftermarket balancer with the timing marks on them.

The Vortec motor came out in roughly 1996 in passenger vehicles and trucks.. and mercury began using them in the 350 mag motors in roughly 97... and around 98 went to vortec for the lesser 350's and 305's.