Landseer

Am trying to fix the 4th tank now. What a pain.

aaddpp

Thank all. I've been out for the day, but have been keeping tabs on comments via my phone - they are all greatly appreciated. I'll have a look at the areas you've suggested, and dig into a bit deeper and post what I come up with. I think the intake vs. exhaust is a pretty interesting area here. Car has not run since June 2010, and I just changed the tensioner pads this past weekend...so oil pressure is not there as it should be.

I did notice an error in my original post...dial gauge reading was 1.425mm or a discrepancy of 0.575mm. Still well outside the 0.1mm allowance. I should also mention that I got some readings from the passenger side (sorry no photos)...32vr was dead on zero, while the dial indicator was about .2mm off -- should have been 1.8mm but showed 2.0mm. Margin was 0.1mm, so by the dial gauge its off, but not by as much as the drivers side

I had a quick look at indexing, but my 87 seems to be a bit different from the WSM. My cams don't have scores, but rather the "nose" or lobe. They also seem to have only one marked link. As for their being out, I don't have a record of such work. I would not bet that its happened, but who knows?

I suppose chain length could be an issue - and would tie into the intake vs exhaust discrepancy -- but from what I have read / been told, these chains are statistically unlikely to be the culprit. Still it would be an interesting exercise since the drivers side chain seems looser, and has a much larger discrepancy.

Dave

jcorenman

Belt variation??

docmirror

Let's start from the top. Cam PNs: Left bank 928.105.292.04, 928.105.294.02, right bank 928.105.291.04, 928.105.293.04. This is for 87 model year, US build. Or, it could be 928.105.272.00, 274.00, and 271.00, 273.00. The later numbers are for the 88, but I'm betting that's what you have.

Now, if you'll set it up by the book, at TDC, check the marks on the cam gear, and see that they point straight up. 113mm between the marks in the cam, or 12 link holes from gear nub to gear nub. I'm guessing you've got this already. Make sure the belt tension is per the book. At TDC, set for zero on the gauge, then roll the crank around to 20 and leave it there. At this point, get the wrench on the camshaft for adjustment, then loosen the cam bolt while keeping the cam still. Turn the cam around to 2.0 on #6 intake lifter. Hold it there, and lock the cam bolt down. Go around two revs, and see what you've got. Then repeat for #1 intake lifter, and set for the 1.6. Don't let any slack get in the chain by moving the crank backwards.

Once these are set, check it with the 32vR, and go around twice on the crank again. I'm betting they'll line up pretty well. If not, the other thing I would be concerned about is that the harmonic balancer has shifted a bit on the crank inner hub. The difference in the reading could be due to the slope of the cam lobe not starting in the right spot on TDC. If you have a long extension for your gauge, you can check the TDC by performing a plunge test into the spark plug hole, and rock the engine for maximum rise of the piston on either #1 or #6 (they are 90deg crank throw offset, so both are at TDC at the same time).

worf928

I wrote "marks" and should have written "raised triangular-ish bump" as shown in the WSM.

aaddpp

Thanks docmirror, I have some time this AM so I'll try and dive in. The one question that's still there for me is whether the lack of use - including a total lack of oil for several months as I worked on the car - could lead me to have incorrect readings on the intake cam? Is it worth buttoning everything up, seeing how things run, and then go back in for timing, or is the engine layup unliklely to be much of an issue here?

blown 87

Just take the belt off and spin the oil pump.

pjg

Just a question, does the ambient temperature of the engine have any affect on these measurements, is the shop where the work is being done heated ?

docmirror

Not having the oil pumped up makes no difference in the lobe to lifter action. The lifter has oil in the body, and provides a cushion for the valve stem, but the plunge method is done with a light coat of oil on the lifter and cam lobe.

blown 87

Correct, the factory method is only measuring tappet movement, and the chain is under tension so the tensioner is out of the picture.

aaddpp

Ken, 100% sure engine was at T|0 #1 cylinder

Not sure I fully understanding indexing...I followed the WSM, and brought the triangular lobes on the two cam shafts to the vertical position. I had to go a couple of turns to get the bronze colored chain link to line up with the exhaust lobe. Measured the distance between them...was about the 113mm listed in the WSM. Odd that I only seem to have one link plate of a different color...was expecting to see the two plates sitting over the lobes.

Not sure if its material either, but the temp in my garage is 55 - 60 F.

aaddpp

Quick update...

I did a couple of additional checks this evening. They go as follows.

1. Rigged up a dial indicator tip capable of measuring cyl position. Pulled the spark plug and inserted into cyl. On the #6 cylinder, TDC occured at the peak of the indicator cycle, so it looks like my balancer is correct in calling TDC.

2. Chain Index - Not sure I fully understanding indexing...I followed the WSM, and brought the triangular lobes on the two cam shafts to the vertical position. I had to go a couple of turns to get the bronze colored chain link to line up with the exhaust lobe. Measured the distance between them...was about the 113mm listed in the WSM. Odd that I only seem to have one link plate of a different color...was expecting to see the two plates sitting over the lobes.

3. Dial Indicator Method (Round II) - I decided to check my work once again. On #6, I ended up with 1.5mm at 2|0 past TDC (should be 2.0mm +/- 0.1mm). On #1, I recorded 2.1mm at 2|0 past TDC (should be 1.8mm +/1 0.1mm)

4. 32vr Method (Round II) - Similar readings to original test..cylinder Bank 5-8 showed 1 degree advance, and 1-4 showed zero degrees adv / ret.

Based on Greg and docmirror's posts just above, it seems less important now, but chain was taught when taking readings on the drivers side.

Also wanted to mention that I have Porkensioner which I installed as part of this overall service, and that they engine has not turned with tensioner and new belt except by hand.

That it for this evening, but was thinking I would try and adjust the intake cam timing tomorrow (time permitting) and see how the numbers come out.

Cheers,
Dave

docmirror

1. Good job. Cam PNs OK?

2. Your chains are fine. If you don't have the lines inscribed in the gear face, just count the holes between the gear teeth.

3. Do the adjustment for #6, and get it dead on 2.0 at the 20 mark of the crank. go around a few times by hand and then check it with the 32Vr. Then do #1 and get it to the book value. That's the only thing that matters is the mfg reference.

4. Recheck your tension, then check the 32Vr tool, and report what you have.

PorKen

OK, good.

I have found the best way to normalize everything is to clear the belt path (unplug the EZK), then spin the engine with the starter to settle the belt, and equalize the tension. Hand turning makes for uneven tension, and won't do anything to settle a new belt on the gears.

Lizard928

Check TDC on Cyl #1 with the dial indicator. #6 and #1 should be ever so slightly different.

As to the comment about the cams not needing the adjustment. The earlier ones didnt have adjustment. Showing that precision was there. However the factory felt the need for individual adjustment to ensure that one could dial in the cams to proper settings and compensate for belt stretch etc.