Timing belt alignment question

harborman · harborman's Garage

Ok, I am to the point of checking the marks. I set the crank at top dead center "0" mark on damper. The right cam mark is in the valley with the cam pointer but the left cam gear mark seems to be on the tip of the gear, not aligned with the little hole in valley of gear. So maybe a half tooth off. I turned the crank several turns and it still looks to be about the same alignment. I took 3 pictures but the camera will not focus so close on those little holes in relation to the pointer on casting of cam housings. What should I do now??

My camera batteries are going out and could not take better pictures at the moment.

76FJ55 · 02-12-2010, 01:28 PM

That is most likely as close as it gets as far as timing the gears is concerned. The next step beyond that would be to actually degree the cams them selves. this could be done the old PITA way with degree wheels and a dial indicator or through the use of Porkerns engenious device the PK32V'r, which greatly simplifies the opperation.

Also for taking close-up pics if you didn't set you camera to "macro" (the llittle flower symbol), you should try it. It will greatly reduce the focal distance, and will help greatly in getting decent clase-up shots.

Landseer · 02-12-2010, 01:30 PM

Well, its fine for now.

Next you will be rotating just shy of two crank revs to get the unit at 45 BTDC
Thats where the belt will be removed and replaced. (flywheel lock in place / crankbolt removed)

Then, after putting on the new belt, lower cover and retightening the crank bolt, you will rotate the crank clockwise facing motor (always clockwise facing motor) the remaining short distance to O degrees for the check. You will probably be a hair closer to the alignment at that point.

Then, you will want to consider using the 32Vr tool to do your fine timing adjustment. Its a separate operation best done before the r and l covers go back on.

(edit / looks like 76' and I are giving you same input)

harborman · harborman's Garage

Quote:

Originally Posted by Landseer

Well, its fine for now.

Next you will be rotating just shy of two crank revs to get the unit at 45 BTDC
Thats where the belt will be removed and replaced. (flywheel lock in place / crankbolt removed)

Then, after putting on the new belt, lower cover and retightening the crank bolt, you will rotate the crank clockwise facing motor (always clockwise facing motor) the remaining short distance to O degrees for the check. You will probably be a hair closer to the alignment at that point.

Then, you will want to consider using the 32Vr tool to do your fine timing adjustment. Its a separate operation best done before the r and l covers go back on.

(edit / looks like 76' and I are giving you same input)

You guys are wonderful!!! I figured it might be a bit of belt stretch possibly. Anyway I will do some more checks and mark those 45 degree positions carefully. I have not removed the center cover yet. I am taking my time no rush on this. I might take a few more pictures. I would say I have about 4 hours in this so far but time is NOT of the essence on this job!!! Actually kind of a fun job, not that intimidating, I am actually enjoying doing it and feel I am accomplishing something! I appreciate all your assistance and advise!

Landseer · 04:51 PM

Very methodical, symphony. Gotta hold-out through the end and not rush, though.

I'd get some new batteries and post some pictures.

And be sure your doublechecking any advice here, including mine, with some sort of WSM pages or write up. Am not waffling at all on you, just being cautious.

harborman · harborman's Garage

Quote:

Originally Posted by Landseer

Very methodical, symphony. Gotta hold-out through the end and not rush, though.

I'd get some new batteries and post some pictures.

And be sure your doublechecking any advice here, including mine, with some sort of WSM pages or write up. Am not waffling at all on you, just being cautious.

I have some new batteries for the camera and will try and get better pictures. This belt must have been replaced as it is a Uniroyal not Porsche! But now that I have gone this far, I will put the new Gates one on along with the water pump which I am waiting to receive next week. The maintenance records did not show a previous belt replacement, but the car has been sitting for many years.

Landseer · 02-13-2010, 04:43 AM

Tiny amounts of wear / wobble in the pivot bolt bushings and associated tensioner roller are important to remedy, I mean very small amounts.

harborman · harborman's Garage

Here are some better pictures.[img]http://forums.pelicanparts.com/uploads16

Right side. Lined up over tooth, valley with hole just to the left of tooth below mark.
/IMG_36971266077615.jpg[/img]

Left side. Lined up in Valley with marking hole.

And my work bench of parts layout.

I may remove the center cover today. No rush, water pump is not here yet.

harborman · harborman's Garage

Right side mark line up.

Landseer · 02-13-2010, 09:22 AM

Aren't there little tiny notches on the backs of the cam gears? Their alignment with the backing plate notches was what I was expecting you to show.
How's about a camera shot on each side shooting downwards behind the gears?

Landseer · 02-13-2010, 09:34 AM

I think the front notches on the 86 align with the actual cam covers so you can check without removing the covers. Look inside your cover vent holes for a similar feature to mine on this 86 cover:

harborman · harborman's Garage

If you look at my pictures of the cam gears, I have put a BLUE pen mark on the side of the gear facing out. On the INSIDE of that exact tooth, or should I say the VALLEY, is a small hole on both gears. I have brought the crank to TDC, 0 mark when those two little holes are each about under those "V" s on the backing plate. My concern was there is a slight variation of the alignment under each V mark. One was maybe a half tooth off from the other. I took a straight edge and marked the exact center of the V mark on each gear. Maybe I am being too exact because of some wear on the belt possibly. Guess I will know when I go to put the new belt on in a few days.

I have now brought the crank from the TDC possibly 3/4 revolution (clockwise) to the 45 degree mark and I have now put marks on each gear. So I think I am ready to install the flywheel lock. (I did turn the engine 2 more revolutions and the 45 degree marks aligned again. Then I can remove the harmonic balancer and remove the center cover.

harborman · harborman's Garage

Ok so I need to turn it almost TWO revolutions AFTER I set it on TDC with the cams lined up NOT directly to 45 degrees from when I set it the first time. In other words you want it at 45 BTDC on Number 1 piston if I understand correctly. Glad I caught this.

Landseer · 02-13-2010, 11:19 AM

Gotcha. No difference: re, notches: just wanted to point out the inner and outer markings, in case you weren't looking at the inner notch. Also, for future when you want to look down the vent holes and ensure timing is approx right.

I normally rotate 1 3/4 before flywheel lock. That way, after putting on the belt, I'm close to coming up on TDC again for a notch check when I remove the flywheel lock.

Looks like we cross posted.

Back to my steering pump rebuild.

harborman · harborman's Garage

Many thanks for info!!!! Will do!

Danglerb · 02-13-2010, 11:40 AM

Belt seems like its tracking too far forward, right at the edge of the gear.

harborman · harborman's Garage

Quote:

Originally Posted by Danglerb

Belt seems like its tracking too far forward, right at the edge of the gear.

I noticed the other gear is out farther for some reason. But it's been running fine. I think this belt is almost new and was not original because it is Uniroyal. Did Porsche use these at the Factory?? Anyway, I am about to remove the center cover soon and then can examine the rest.

Danglerb · 02-13-2010, 06:25 PM

I wonder how long its been since Uniroyal sold timing belts.

Landseer · 02-13-2010, 07:10 PM

Good point.
Changing this one was long overdue by standards of 32V enthusiasts, be they right or wrong.

76FJ55 · 02-13-2010, 09:35 PM

Just to add a little info to the thread. As you note the marks are not lined up identically on the left and right cam gear. this couldbe partially due to design and partially due to build tollerance.
Ideally the cams will be degreed in so the slight varience you see at the V notches is just an visual artifact.
By design with a cold engnine the passenger (rigt) cam will be slightly retarded relative to the driver (left) cam. this is due to the cam timing beingdesigned for normal opperating temp. as the engine warms up it expands which slightly advances the cam timing as the timing beld run from the crank to the left head is increases. the distance between the left and right heads also increases with tends to ad vance the right cam. therefore the righ cam has a cumulative advance of both the belt runs.
Also when degreeing the cams the notch positions will not change. the notch positions are dictated by the location of the teeth on the belt which is static when the crank is locked down during belt replacement. the cams however can be rotated slighly (degreed) relative to the gears to effect tuning.
So essencially the marks are there as a reerence for gross positioning, and beyond that the cams will need to be fine tuned bu degreeing by one of the previosly mentioned methods.