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mcgrsr 01-21-2005 06:53 AM

please help timing a ZZ383
how do you set the timing if you don't have a timing tab on the cover i don't think there is one available. This is a brand new crate from gm is there a different way to put it in time without the tab

the manual that came with the motor says set spark timing at 32 degrees before top dead center at 4000 rpm with the vacuum advance line to the distributor disconnected and plugged . this setting will produce 32 degrees of total advance at wide open throttle. The HEI vacuum advance canister should remain disconnected

can someone please help the motor is running pretty good it's just is pinging when i get on the throttle. when cruising it does not happen and Iam running high test fuel. Just seems so close to be running perfect HELP PLEASE 01-21-2005 07:59 AM

I had the same problem with my 235 straight 6. The stock timing mark is on the flywheel and you see it through a hole in the bell-housing. I converted my drive train to a 200R4 tranny so lost the bell housing and the flywheel thus have no timing marks anywhere. I also tossed the stock single groove front crank pulley in favor of a late model two groove one from the 230-250 series straight 6 (direct replacement), but it has no markings on it either.

To get my timing mark back, I first set the #1 piston at exact TDC on the ignition stroke (both valves closed). Then I got a Mr. Gasket timing tab and bent it and drilled mounting holes until I got it to lay properly next to the new crank pulley. They sell a couple variations, this and this and this. You should be able to get one of them to fit even if you need to bend and braze an ear or two on the mounting flange. If none of these can be made to fit, you can simply braze a hunk of small steel rod onto the front timing cover for a zero pointer. Once the tab was firmly in place, held down by two front timing cover bolts, I used a chisel and hammer to cut a groove in the front pulley rim exactly in line with the "0" on the tab. Now I can use my Harbor Freight dial back timing light to accurately set my timing.

johnsongrass1 01-21-2005 08:01 AM

Find TDC on the piston, make a mark 2 1/4" from the mark on the balancer to your left as you are standing in front of the vehicle. Then make a mark on the cover. Set timing there. This only works with a 8" balancer. OR rotate the distributor a small amount clockwise till the ping goes away. 01-21-2005 08:06 AM

Good point Johnson; timing wants to be set @ max advance that doesn't ping. The best way I have found for modified engines where factory specs don't apply is to set initial advance using a manifold vacuum gauge. Find the advance at idle (w/ distributor vacuum advance line removed and plugged of course) that give maximum vacuum then back it down about 1 vacuum unit. Road test and advance or retard until you find the sweet spot of max advance w/o ping.

edge 01-21-2005 08:12 AM

Re: please help timing a ZZ383

Originally posted by mcgrsr
how do you set the timing if you don't have a timing tab on the cover i don't think there is one available. This is a brand new crate from gm ...
EDIT: Is this the crate engine you have? If it is new, it would seem the dealer that you purchased it from should make good on getting you a timimng cover with a tab included.

It seems odd that a new GM crate engine would come without a timing tab. If this is your engine, it has an 8" balancer. Perhaps a simple bolt-on timing tab is available for that particular balancer, that would work with the composite timing cover.

EDIT: Now that I think about it more, since the engine is in the car, changing the timing cover, even if provided at no cost by GM, will be a royal pain. If a bolt on timing tab is not available, I would do as Johnsongrass suggested and JB Weld a makeshift tab to the timing cover.

Best of luck!


mcgrsr 01-21-2005 09:27 AM

I have a couple things to try thanks alot

302 Z28 01-21-2005 10:08 AM

Old trick we used to use back in the sixties is to power time it. Loosen the distributor hold down so the distributor can be moved, but not too easy. Crank the engine and rev it past the mechanical advance limit. Hold the revs and advance the timing by moving the distributor until the engine starts banging. Back the distributor off a tad and lock it down. Take it for a test drive to see if you have any valve clatter, if so back the dist down a bit more.


mcgrsr 01-21-2005 10:40 AM

thanks vince i'll give that atry

Tech @ BG 01-21-2005 10:52 AM

Timing Pointer
Another option would be to get one of the pointer bases that bolts to the distributor, that has a base bolted to the intake. Since the "actual number" doesn't make a difference and you're just looking for the best performance you can use that as an easy way to change higher or lower.

johnsongrass1 01-21-2005 11:12 AM

We also use a dist. with a dial knob where the vacuum can resides. It makes tuning timing as easy as it get's.

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