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Discussion Starter #1
Folks, I was setting the timing on my 1980 NA standard and the mark was so far off on the retard side that it's off the tab.I try to advance it to the 10 degree mark and I run out of travel right at the '0' end of the tab. No more travel in the distributor.
The car starts and runs fine, I've had it for a number of years and never even checked the timing until today. Yeah, I know...shameful...
Question is, do these cars have something like a two piece balancer where it could have slipped? I realize that I can put the #1 at TDC and make a new mark or at least get a clue about where it's actually set but just wondering if I'm overlooking something.
 

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Folks, I was setting the timing on my 1980 NA standard and the mark was so far off on the retard side that it's off the tab.I try to advance it to the 10 degree mark and I run out of travel right at the '0' end of the tab. No more travel in the distributor.
The car starts and runs fine, I've had it for a number of years and never even checked the timing until today. Yeah, I know...shameful...
Question is, do these cars have something like a two piece balancer where it could have slipped? I realize that I can put the #1 at TDC and make a new mark or at least get a clue about where it's actually set but just wondering if I'm overlooking something.
I think I’m in the same boat.


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Discussion Starter #3
Yeah, I'm not sure what's going on with it. I put the #1 at TDC and marked the balancer at the zero mark. Using that mark, it appears to be at about 9~10 degrees BTDC. I guess that's why it runs ok but it's not right for it to be at the end of it's travel. I wanted to try it at 12 degrees BTDC but can't do it.
Making me think that the timing chain may have stretched or someone installed it a tooth off or....?
 

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Or is the oil pump shaft off a tooth. That is my worry.


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Discussion Starter #5
Didn't even know that was possible. You made me crack the manual open but yeah, I see what you mean
 

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Discussion Starter #6
I went to check timing chain 'stretch' and was looking through the FSM. It's rather confusing to me at this point as I don't see the marks that they are necessarily referencing. The cam gear appears to be aftermarket and has the '1' '2' and '3' marks but I don't see what they are lining up with. I'm still studying it but if someone could guide me to a video or something of that nature, it would clear it up for me a little quicker than reading and looking at the drawings.
I'm much more familiar with doing things at this level on older domestics.
It is definitely having a valve timing problem though so I'm thinking chain rather than distributor.... Vacuum is pretty low and after unplugging the vacuum advance I have to run the idle all the way to it's limit to get 700 rpm.
 

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Discussion Starter #7
I'm sure this has been addressed here at some point so I'll do a search for loose timing chain subjects.
 

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Discussion Starter #8
After researching this, making adjustments, etc.....It appears to me that I need a new timing set. 🤣
I wouldn't mind so much but having to take the oil pan off to do a timing chain? Holy crap...
 

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Can you see the location notch in or outside the edge of the oblong hole of the sprocket, per the FSM?
 

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Discussion Starter #10
Yeah, that's what I just learned about as a result of my searches. The oblong mark and the v-notch. I was not familiar with that at all. At any rate, I moved it to the two mark and then to the three mark and still not enough advance. The chain is very loose.
 

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Discussion Starter #11 (Edited)
Before I go nuclear on it though...since this is the first time I've done the 1,2,3 adjustment...is it possible that I didn't move it to the correct link? I noticed a difference in the mark location when I went to the '2' mark but it didn't seem to move when I put it at the '3' mark. Being that it's so much easier to do than the chain, I'm going to try it once more just to be sure...I have to think about that. Not sure if it's possible to get it a link off considering the locating pins and all...hmmmm. Definitely going to take another look at it though.
 

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Discussion Starter #12 (Edited)
Ok, I definitely screwed that up.
I just popped the cover off and looked again. It is off way too far to be correct. Initially, when I started this the notch was 'behind' the groove by about the width of the groove when it was on the number one position...it's about a QUARTER INCH behind the groove now on the number THREE position...and the number three is not even straight up at TDC, it's at nearly 11 o'clock.... My eyes were playing tricks when I did it the other night I guess. I probably was having a hard time seeing that faint groove in the low light..plus doing it a midnight after a long day didn't help. I'm sure I turned the cam to get the pin aligned and I didn't notice that I'd retarded it by however many degrees each notch is.
Fingers crossed that I can dodge the chain replacement..
 

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Greg, first of all if your timing chain has stretched it won't affect the distributor timing one bit. The chain only runs the camshaft. All z's used a 2 piece crank pulley and yours could very well have slipped. One of my vendors rebuilds them and gives them a limited lifetime warrantee. I've been using him for years, that's all he does and has always give me back a crank pulley that is better than when it was new. I do have good cores on hand that I can send in for rebuilding if I don't have a specific year in stock already done. Did you know that running a loose fan belt can cause a buildup of static electricity. When it builds up to a certain point it can jump across the 2 pieces of the crank pulley and fry the rubber between the 2 pieces. The rebuilder I use connects the 2 pieces with special wires so they're grounded to each other. They do any 2 piece crank pulley for just about any kind of car, even 1932 Rolls Knardlys. Low vacuum, and low idle speed is indicative of retarded timing. There is an extra slot on the underside of the dizzy that uses an 8mm headed bolt so you may be able to get a little more advance. The 8mm headed bolt holds the dizzy to the mounting plate, and the 10mm headed bolt you used to adjust your timing holds the mounting plate to the adaptor that fits into the timing cover. I'd suggest putting everything back where it was before you started this little episode, try advancing the dizzy a little more using what I told you above, and order a rebuilt crank pulley. You've already mentioned that you know how to check for a slipped crank pulley. I charge 209.95 for a rebuilt pulley BUT for zcar.com users the cost is 188.96. If you want to order one just call me at 360-668-2979 or send me an e-mail. Z man of Washington
 

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According to the picture of the cam gear in the FSM there are 36 teeth which would be 10 degrees per tooth. If the chain is so slack it's possible it has jumped a tooth at the cam or the crank. IF the chain jumped on engine shutdown and the spring loads on all the cam lobes were such that it caused (continued) momentary rotation or reverse rotation of the cam as the chain jumped.
 

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Discussion Starter #15
Thanks for the feedback guys. I was definitely off the mark after my #3 position adjustment so I corrected that last night. On the other hand it still didn't effect my problem. In fact, the slot wound up too far advanced (looking at the cam retainer slot) when I put it in the proper position for the #3 groove. In spite of that, the timing mark on the balancer was still off to the retarded side. So, yeah, it may have slipped.
The reason I jumped to the chain adjustment was because of the way it's running. Low vacuum at idle and backfiring through the intake. Seemed to have late valve timing more than late ignition timing. I do know and understand the difference...but then again, I still have the problem of running out of adjustment on the distributor.
Also, the car has always seemed to get a definite boost in the seat of the pants feel right at about 4K rpm. Also a symptom of retarded cam position...so I went that way, plus it's easy to try.
The slipped crank is a definite possibility. I knew that some cars...even the old '60s cars I'm more accustomed to ...do have two piece balancers that do this. I wasn't sure about this car so thanks for that info zman. Also, did not know about the other screw..not sure where it's located but will search for it.
Thanks for all the suggestions, it gives me something to try before going to the trouble of a chain replacement.
This forum and my web searches are the only input and source of second opinions I have on this car.
 

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Sorry for the interruption. o_O When the car is shutdown, what does the chain tension look like on the driver's side of engine? Again, if the chain is too loose, it might be possible that the cam comes into a rest position that is determined by the loading of the springs on the slopes of all the lobes, and which might cause the rocker tip(s) to "slide" on the lobe(s,) to effect the relative location of the notch and the window. Try turning the crank to see how much slop play there is on the driver's side chain. .... Another .02c, and I'm not there to look at it, so I might be all wet.
 

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Discussion Starter #17
Sorry for this long post but here goes...
Ok, I may be giving myself tunnel vision from doing this so many times over the last few days. I'm going to back off the timing chain 'stretch' claim. I put it back into the number one position and it actually runs better there. What I cannot understand fully is why the balancer and scale marks seem to match at TDC now! Obviously I wasn't careful enough using my 'feel' to figure where the piston was. As we know, there are a few degrees of 'dwell' in regard to piston movement at the top so that's probably where the error occurred.
I recognize now also that the loose chain is probably normal since I'm rotating it the easy way, at the cam gear. It unloads the chain. No way it's loose enough to have jumped a tooth.
Although it's running and starting better, and using both bolts (Yes, I found the 8mm bolt.) I can get 10 degrees of advance with vacuum disconnected..but that's with the distributor maxed out. I'm sure that's not normal? I still have somewhat low vacuum (about 12") and a ragged idle...especially at 700 RPM. It sounds like a big V-8 with a long duration performance cam instead of the normal smooth idle.
The improvement is that it hardly backfires, if at all, through the intake or exhaust at all right now. That is an important (to me) improvement but something isn't quite right. It also sounds like I may have an exhaust leak which may be the problem. All of this seems to have happened while the car has been in the garage for the last year or so while I did a lot of body work and replaced the exhaust (a year ago) from head to bumper. I ran it several times and even went for a short drive back then and no real problems.I really don't want to have to pull the intake again to get to the header...what a pain! Even having to max it out to get 10 degrees I would think my low vacuum isn't a timing issue since maxed out or not, 10 degrees is 10 degrees and that's the spec.
I need to step away from it for a while i think. I'm still open to suggestions.
By the way, if you've read this far.....Where are you guys taking your distributor advance vacuum from? I'm getting more advance and a little smoother idle taking it directly off the intake but I know that's not where it should come from.
 

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Vacuum advance is supposed be hooked up to secondary vacuum only on z's. There is a secondary vac port on your throttle body. You mentioned that you get the initial timing up to 10 degrees, is that with the dizzy hooked up to primary vacuum or secondary? In case you don't know the difference primary is the same as straight manifold vacuum. Look for a port that doesn't have any vacuum at idle and once you crack the throttle open you have vacuum. Also, now that you found the seconds slot on the dizzy, did you get that maxed out or do you still have room on it? If you still have room on it advance it more and see what happens. If you don't get pre ignition or rattle on acceleration it's not hurting anything to advance it more. When these cars were new, we could set the timing at 10 degrees and 99% of the time we were getting full timing at 3500+ rpm. After 8+ years of running the distributor function started to decrease on a lot of z's. I don't use stock primary timing settings anymore and I haven't in many years. I check full advance at 3500 to 4000 rpm and it should be 35 degrees on the flat top piston engines and 42 degrees on the dished piston engines. I advance the dizzy until I get that setting and lock it down. Then I go drive the car and make sure that there isn't any rattle on accel. If there is then I retard it a degree or two on the side of the road and try it again. If there is more rattle then I retard it again, until there isn't any rattle on accel. Then I go back to the shop, and put a timing light on it again. I check the timing at 4K and log the setting. Next I set the idle speed at 900 and check the initial timing. Use this formula to help. A is initial timing, B is vacuum advance timing, C is mechanical advance timing and D is the combination of AB&C. So the formula reads A+B+C=D. Let's say that D=42 degrees now and when you check intial timing A it is now 22 degrees. That's your new timing setting at idle. I've seen cars that I had to set A at 28 degrees to get full advance of 42 and I've seen it where 15 is the new setting. This all depends on how much mechanical and vacuum advance you're getting or B and C and also has your crank pulley slipped any. Once in awhile I do a car that I can still set it at the original factory timing setting A and get the full D. ZMOW
 

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Discussion Starter #19
Thanks for the detailed response!
The initial timing is with no vacuum and with all the travel I can get out of the dizzy that initial measurement is 10 degrees BTDC. I am using the secondary vacuum source but haven't measured and recorded the advance at different rpms to check mechanical advance nor with the vacuum hooked up. I only know that the vacuum is advancing the timing and I'm pretty sure that the mechanical is working too but like I said, I haven't recorded it through the different speeds.
Again, I can't get any more travel out of the distributor but I follow you on everything you are saying. I don't know what kind of pistons it has. I don't think the engine has ever been rebuilt but it has had a valve job/head gasket before I purchased it.


Questions-
-What is the typical straight manifold vacuum with one of these cars and also, should the secondary vacuum source read full vacuum once it begins? In other words, I'm getting vacuum there at part throttle but I don't think it's reaching the level of full vacuum at any time.
-How sensitive are these cars to intake or exhaust manifold leaks? All of this seems to have started since I replaced the header and all exhaust to the rear bumper. I don't like what I'm hearing in that arena and was wondering if some of the ragged idle and what sounds like a miss at initial acceleration from idle could be due to what sounds to me like an exhaust leak. It really sounds more like my old GTO with a big cam instead of an inline 6.
One thing that I have not done that I think I should do is a compression test. I adjusted the valves with no real improvement even though a couple were a little out of spec.
 

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Greg, don't worry about checking what the mechanical and vacuum advance is at this time. Your car should have dished pistons in it so you want to get to 42 degrees total between 3500 and 4000 rpm. Then check your initial timing at idle and that will be your new initial timing provided you don't get any pinging on accel up a hill. Typical vacuum is about 18 inches at idle. Seeing as how the issue wasn't there until you worked on it, deductive reasoning suggests that you didn't put something back together correctly. Did you use a fuel injected header gasket with the round exhaust ports? What brand of header did you use and was it new? Check the intake manifold over for a vacuum leak while it's running by using a 3 to 4 foot long rubber hose sticking one end in your ear and moving the other end around the entire intake area topside, underside, & front to back. If you want to shoot a pic of the intake from the top side and post it then I can check your vacuum hoses for proper routing. There are 3 hoses connected to a vacuum valve on the t-stat housing. Those could be deleted if you want to, at least temporarily if not permanently. The cars prior to 1980 didn't use that valve and they routed the dizzy vacuum from throttle body to a T, one side goes to the dizzy, and the other side goes across the engine next to the fuel rail and hooks up to the carbon canister on the right front of the engine bay. Next, with the engine idling check your egr valve. You can reach your finger inside it and push up on the diaphragm. The engine should drop down a couple of hundred rpm and stumble, then release the diaphragm. I think that someone already mentioned it but just in case they didn't, check your firing order on the plug wires going counter clockwise. 153624 #1 position is usually about 8:00 on the dizzy cap. Let me know. ZMOW
 
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