Cascade Crew

Xophertony · Posted: Sat Jan 06, 2007 5:37 pm Post subject: Timing Question

so it seems as though i need to adjust the timing on the six about once a tank. i am sure i am getting it realy tight etc... i was telling my tale of woe to chris yesterday and he was saying that a failing ignition module can be the casue of this on an HEI system. the car does have 162K on it with what i assume is the original distributer, so this would not surprise me. this brings us to my questions:

1. is there a way to test my ignition module.

2. are v8 and v6 IMs compatable (chris and i both think not). if they are compatable i'll put the "new" ignition module the GTA has in the six and buy the GTA a new distributer. which is what i should have done when i fried the GTAs ignition module in the first place.

3. could the timing chain be jumping teeth? i have not heard any strange noises or anything but i don't realy know what a timing chain jumping sounds like.

thanks in advance for the help guys. Smile

Dewey316 · Posted: Sat Jan 06, 2007 5:49 pm Post subject:

How much are you having to adjust the timing? are we talking 1 or 2 degree's or lots of time?

If the timing chain jumps, you would notice, it would change the CAM timing too.

Al Hasse · Posted: Sat Jan 06, 2007 6:14 pm Post subject:

Had a timing chain go at about 190K in the V6 before the new motor went in. The chain didn't snap, the gears (sprockets) are tipped with a nylon material to reduce noise, and this stuff wore down enough for the chain to slip off. Never could keep it running very well when it was slipping.

Xophertony · Posted: Sun Jan 07, 2007 2:36 am Post subject:

meh, it varries. usualy 8-12* off.

Twilightoptics · Posted: Sun Jan 07, 2007 4:24 pm Post subject:

Don't think the module would cause this. A bad cap might.

It's possible you're bottoming the clamping screw out when you tighten it, and it's not getting full pressure to the dizzy.

8-12º in 300miles is alot.

Like the other said, if the timing chain jumped, you'd know it.

Could be really sloppy though.

izcain · Posted: Sun Jan 07, 2007 8:32 pm Post subject:

I think I would be taking a look at the dis. first and pull it out and see what it all looks like. But sounds like you might have more then just that though. I think with that many miles I would be checking into the timing chain.

Xophertony · Posted: Thu Feb 01, 2007 3:06 pm Post subject:

allright. update on this issue. as of yet i ahve done NO diagnosis on this. here is what happened today. i started the car and the timing did it's "suprise, you have no power" thing (immediatly jumped off by about 8-12*) all of the sudden the car had no go. i drove a few blocks and stoped, turned the car off, went inside and got some food, came out re-started the car and the car had fixed itself. the timing seemed fine, i had good pull all the way through the RPM range and all seemed fine.
this seems like an electronic thing to me, but could this still be casused by the distributor itself? as my valve timing has not changed i have ruled out the timing chain. two suspects remain.

SUSPECT: ignition module.
is there a way to test the ignition module without replacing it and seeing if the problem goes away (in other words: without commiting any money).

SUSPECT:distributor itself.
when/if i remove the dizzy what am i looking for besides the obvious "it's cracked in half" kind of stuff? could this be casued by too much endplay? how do i test endplay?

do you all have any other dignostic tips for me?

Quasi-Traction · Posted: Thu Feb 01, 2007 3:34 pm Post subject:

Was the car cold when it did the timing jump?

Maybe you're having timing problems when the ECM transitions it from open to closed loop?

Xophertony · Posted: Thu Feb 01, 2007 3:59 pm Post subject:

huh......... you may be on to somthing there. but it only does it every so often.

Xophertony · Posted: Fri Feb 16, 2007 2:42 pm Post subject:

well, found ou that 2.8L and 5.7L cars do in fact have the same ignition module. the napa guy showed me the list of applicable engines and it looks like most of GMs lineup uses the same one. everything from I4 cavaliers to 5.7L GTAs.

i still need to know how to check to see if my distributor is the casuse before i dump $71 into an ignition module that may or may not be the issue. do i need to pull the dizzy or is there some other way to chack it for problems. also am i just looking for endplay or what? I know too little about distributors.

alloy · Posted: Fri Feb 16, 2007 4:17 pm Post subject:

Just thinking out loud here..........this article says that for every .013 of end play the timing moves 1 degree. My dizzy had .138 of end play, so lots of timing change. I'm just thinking that maybe........maybe the shaft is moving up and down and sticking in either the up or down position. That could possibly account for a 10-12 deg. timing variance.

I've not looked at a six banger dizzy and not sure if you can shim the end play like a V8 or not, but it's worth checking.

Anyway..........just an idea.

http://home.att.net/~rustynuts/HEI.htm

Xophertony · Posted: Fri Feb 16, 2007 4:34 pm Post subject:

thanks alot alloy. that was what i was looking for. somthing about checking endplay. looks like i do indeed have to remove the distributor to chack that. no time today and the rest of my weekend is looking prety busey, but come monday i'll dive into this.

after I do the sixs distributor i'll do the v8s too. i'll bet it has some endplay after 142000 miles.

alloy · Posted: Fri Feb 16, 2007 6:26 pm Post subject:

Awhile back I had to pull my dizzy in my car, and had wife bump the starter to get the rotor point towards #1 so I'd not have to do the finger in the #1 plug hole thing to make sure I was on the compression stroke, and when she did that I saw the distributor shaft walk up and down. I was totally shocked at how much it moved. Got that fixed immediately. Made a difference in how it ran too. Cost me about $6-$8 back then. But I'm not sure if a V6 uses the same type of shims, but it's worth checking I think.

You should be able to grab the top of the dist. shaft and work it up and down, or try turning it. It's a helical cut gear and if there is play it should easily work up and down with hand pressure. Can't really measure it this way unless you have a dial indicator, but can give you some idea of how much play it has.

Funny...........I had a guy come in with a new Accell billet distributor and it had .070 end play. When I pointed that out he was pissed..........sold him an intake for $171, and shims for $7.99!!! I spoke "small block cheby" and he liked that. Told me he'd been to many parts stores and I'm the only one he ran into that knew something other than 4 banger imports. Guess there aren't may of us dinasaurs left out there Wink

Twilightoptics · Posted: Fri Feb 16, 2007 10:22 pm Post subject:

Talking with my professor who races... he and I think that the only timing change will be in transition of load. If it's a constant load, the cam is constantly giving close to the same force on the dizzy gear so it shouldn't move. Only when slack is in the chain form load change could it push the dizzy the other way.

alloy · Posted: Fri Feb 16, 2007 11:09 pm Post subject:

Well when I had my wife was bumping my engine over, the shaft moved up and down then. I'd think it could possibly happen on accell/decell also.

Xophertony · Posted: Fri Feb 16, 2007 11:52 pm Post subject:

well, taking play out could not possably cause any harm. and since it is cheap (shims + feeler guages) i will do it first. I also allready have a few dizzy o-rings from the v6 gasket sets.

is there anything special I need to know before doing this?

alloy · Posted: Sat Feb 17, 2007 7:15 am Post subject:

Just pay attention to exactly where you took the gear off the shaft and put it back on in the same place (not 180 out)

Xophertony · Posted: Sat Feb 17, 2007 11:35 am Post subject:

i should probably take a picture of which way the rotor is pointing.

Quasi-Traction · Posted: Sun Feb 18, 2007 9:35 am Post subject:

Another solution is to take a paint marker or a sharpie and mark the distributor shaft or housing and the tooth on the gear.

Twilightoptics · Posted: Sun Feb 18, 2007 9:37 am Post subject:

Just remember which way it's pointing and get it to close to that spot again.

You can also take note of which spark plug wire it's pointing at when you pull the cap... and just make sure where ever the rotor is pointing, you put that plug wire there. This will get you close everytime.