Tensioner replace and timing question
 

Hi All;

I did it. I rebuilt the tensioners (non-PF) on my stock 83 911 SC. I tied the cam chain with zip ties and put the engine at Z1 TDC. When I pulled the tensioners the chains became a little loose with the zip ties attached. I rebuilt the tensioners, re-installed and then checked the Z1 position. It had not moved from Z1 but there are no marks on the cams so I couldn't tell if they had shifted. I want to verify that cam timing had not changed so is there an easy way to tell if a tooth had slipped. Will gently turning the engine by hand clockwise give me enough of an indicator that there is no interference with the valves. Really appreciate any help with this. Pretty sure nothing skipped but is there an easy and quick way to tell?

I know---nothing is easy or quick! Thanx all for the help! http://forums.pelicanparts.com/support/smileys/wavey.gif

If you did not mark it, there is no easy way to check. Do you have the tools for valve timing?

Thanx for the response. Stupidly I did not and I don't have the tools. If it was out of time wouldn't it resist as you moved the crank through its travel? Or does 1 tooth not make that much difference and still allow it to turn unimpeded? Couldn't you put the crank at the Z1 mark and verify that you were at TDC, and also confirm that the valves were fully shut?

I just can't believe that it is that hard to time the cams to the crankshaft on these rigs? If the crank is at Z1 and the chain did not slip, shouldn't the cams be at TDC and wouldn't that also mean the piston is at TDC and the valves fully closed?

Yes, you could verify that the valves were fully shut.

You are asking us to give you an all-is-well on something that is not extremely clear. You do not say where the distributor rotor is pointing. You probably know, but you have not provided input. This is really, really important.

Folks won't shoot from the hip and say that you are ok, when it's not clear that you are ok.

You comment is two step. 1. Verify that you are at TDC. 2. Also confirm the valves are shut.

TDC as far as the crank - ok - no problem. Now, who has done the calcs to determine if your valves should be open or not at TDC with one or more cam drive teeth that may or may not have slipped on the chain?

You are asking for something that no one with integrity will provide.

I don't think you slipped a tooth given the total cluster-**** that would be required to make that occur. Am I going to say you are ok since you said I don't think this occurred? Not a chance.

Hi All;

Guys; I hear ya. The distributor was aligned at the correct mark on the distributor body. At the same time the crank was aligned with the Z1 mark. I tied zip ties around the chains on both sides, however the mistake I believe I made was the zip ties were inboard of the tensioners rather than closest to cam gear. So when I pulled the tensioners the chain slackened at the point where the tensioner was. I don't think the gear slipped but I was just trying to see if there was a quick way to check. With the 83 there is a cover so I can't see it without removing the cam nut.

Maybe this would be a better way to phrase it. If I loosened the cam nut and the distributor was on the right mark, and the crank was on the correct mark, and the two cam marks were pointing vertical---would that indicate that timing did not slip? Again the chain only slackened around where the tensioner was. I appreciate your straight shooting answer and am not trying to get away easy. I am actually going to double check and possibly have a dealer take a look. What think ye?

Thax again!

Hi again guys and thanx. As I read more about the cams, and having lived in Germany for 20 years, I am convinced that there has to be an elegant way to tell this without pulling an engine or utilizing surgical instruments and dials. The Germans were cleverer than that. There has to be secret here somewhere! If it slipped a tooth, wouldn't a piston touch a valve sooner or later or would a one tooth skip not do that. Never experience a one tooth skip so I don't kno----and I don't want to either :o).

You can do an easy rough check to see if you skipped. You are at TDC on the overlap stroke for number 4 (given your distributor information). Turn the crank 360 degrees (slowly incase any valves hit pistons). When you approach z1 again watch the number 1 intake valve. It should start to open before you get to z1 and be open about 1mm at z1. You can measure how much the valve is open when you get to z1 by loosening the adjuster. It moves 1mm per turn. If you loosen it between .5 and 2 turns and the valve closes fully, you didn't skip a tooth. That verifies number 1 cam. Turn the crank 360 again and check the intake valve on number 4 the same way.

Hope this helps.

-Andy

Ehhhh... I'd get the z blocks and time it. Small investment relative to crashed valves.

I think you are fine. Thinking and confirming are two different things, unfortunately. You MUST confirm. No way around this.

The more I think about it, the distributor rotor orientation is meaningless as it is a function of the crankshaft/intermediate shaft - not the cams. At least you know if you are on number one (TDC) or overlap (#4 TDC)

Do this to set your mind at ease for a pretty cheap price but more time than you want to spend.

Drive to Harbor Freight. Buy a magnetic base and a dial indicator. You gotta be able to get outta there for $50-ish.

Put it on Z1 with rotor pointing at #1. Place mag base/dial indicator on some type of rig that will allow the base to be static while you turn the crank to overlap TDC. The tip of the indicator is on the top of the intake valve for #1. At overlap TDC (you need to spin it one revolution of the crank and rotor will now be pointed at #4), the intake valve (for #1) will lift a given amount. That is your measurement for confirmation.

Repeat the procedure for the alternate bank and check the overlap TDC intake valve lift at #4 - rotor pointing at #1.

If you are interested in doing this I can find the exact measurements and walk you through it, even via phone. It's only a small increment of lift but real critical, but I don't have my little spec book. It's at the shop.

Advise.

Andy has it solid. When timing cams I usually get valve movement starting about 35 to 40 degrees before Z-1 when I m checking my set up on a build.
Bruce

There is probably no one qualified at the dealer any more.
Bruce

Eagledriver may have a better alternative check given he knows the lift. Seems simpler than a half baked rig as I suggest.

Lapkritis speaks of the "Z block", the correct tool to mount the indicator. The freight does not have the P201 tool.

Most of the guy here will talk via phone is you are uncomfortable with a solo DIY.

Andy's method is right - I have done this stuff and re timed the cams with the engine in the car before also. His method - for what you want to achieve - determine if still in synch, will work fine. I think you start picking the valve up at around 15Deg BTDC. If the valve starts moving seriously before this, then you should proceed very carefully, or stop.
Alan

Wow---thanx guys! I will probably try all the suggestions just to get this down pat. I really appreciate it. What was really stupid, was that I could have marked the cam gears before I did anything and I wouldn't have this FUD. One question though that I wanted to ask again is this. If the rotor was on its mark on the dizzy body, and the Z1 was at TDC; then if I pulled the cam nut, shouldn't the cam point vertical? The right side cam has a series of part numbers and I did read somewhere that 930 indicates vertical. Problem there is the part number doesn't have a 930. I also believe you are correct about the dealerships so I scratched that
This forum is awesome!

Thanx

Joe

Oh forgot--another question to Andy. I did not open the valve covers yet so when I do this without draining the oil? I know, I know---I pulled the tensioners without having to drain the oil. Any idea how much comes out?

Host (Pelican) is where I picked up my z blocks... I actually bought a pair which makes the job much easier to confirm sync while fiddling and learning.

http://i458.photobucket.com/albums/q...psb64b7fe6.jpg

Those look useful so I will get them and also the dial indicator like Bob said. I just don't want to fool with the timing if I did not skip a tooth.

The top (inlet) covers won't leak any oil. If you choose to take the lower ones off, I usually jack the car up on that side - to tip most of the oil back into the engine - via the drain tubes. That gets rid of most of it.
Alan

Just order the Z-block and dial gauge. In order to check the valves will the engine have to be out of the car (hope not) or do I just pull the lower covers to do the check? I was able to tilt the car forward and didn't lose much to get at the tensioners (1 pint). Agai; you guys are helping me save hundred! Will post pix after its on its wheels again. It is a Zermatt Silver/can-can red Targa!

Valve timing is with intake valves only (#1 and #4). All good. Just the top valve covers off - engine in car. Maybe the ac stuff moved out of the way for #4.

Way easier than you think.

Thanx Bob---tommorow I begin! Ireally appreciate this thread and all your help. Will post pix!

G'nite!

You can do it in the car - you are just doing #1&4. The A/C should be OK. Take the top valve covers off and mount the dial gauge. I use a magnetic dial gauge holder - and bolt a steel plate (just bigger than the base of the block) to the cam cover studs. (You need to place it so the other rocker arms don't interfere/lift the plate) You will have a bit of stuffing around to get the gauge oriented right. Try and position the pointer tip of the gauge in line as much as possible with the travel of the rocker arm - so it is following directly the downward path of the rocker arm. You place the tip on top of the valve adjuster and try and avoid the adjuster slot - because it will often drop into the groove as it travels with the arm.
You then zero the dial with a turn or so pre load in the gauge - so it can record as it extends down. If that all makes sense. It will do 1+ a small bit of a revolution to get the correct timing.
But if you just want a quick check you can avoid all this via Andy's method. But if you go this track, you will be able to reset your valve timing anytime you want. Make sure the valve lash clearance is right before you do this if resetting from scratch.
Alan
Alan

Hi All;

I ordered the Z bracket and the gauge from PP and spent the day prepping the engine to check. I installed the collars and they did not have that much room so I am assuming the chain has not stretched much. Teeth and innards all looked fine also. I cleaned up the engine and replaced a leaking oil line to the left side. Bolted up the tensioners and now wait for the parts.

Thanx again for all the help and I hope to have pix and data as soon as I get the parts. Again, I really appreciate this help and I also think this should go into the 101 projects book as a check for a tensioner install or upgrade --- this was really valuable data!

Thanx again!
:D
Joe

Actually, I would disagree and say you DO want to fool with the timing - it's very easy to reset to factory specs and that will put it back in time even with any stretched chains... I just did this w/o the Z blocks (rigged up my own dial indicator holders) and I can confirm it's super easy once you understand the process.

Chuck.H
'89 TurboLookTarga, 372k miles

Hi All;
I will try all the suggestions but still waiting for the Z and dial gauge. I don't think my chains are very stretched as all the teeth look good and there is not a lot of gap in the tensioners to attach the collars. They barely are able to traverse the full travel without hitting the lip and I can get the supplied gauge to fit the gap. Anxiously awaiting the PP parts and again thanx!!!!!

:eek:

If the chain stays on both sprockets, then I don't se why letting it go loose makes any difference to the cam timing as the two chain wheels will always return to the same plate with respect to each other when the chain is tightened again with the tensioner. As for the chain jumping a tooth, I don't believe that this is possible inside the crankcases as there is not enough clearance around the edge of the chain wheels on the intermediate shaft to allow this to happen. Also, having just reassembled my engine ad done the cam timing (last week) these chains do not just jump a tooth. It is hard enough to get them on to the chainwheels to begin with!

Hi and thanx--that is what I thought also but then I started reading and worrying and thinking about a complete engine rebuild because I missed a tooth slip. 99.9% it did not slip but the .1% keeps me awake at night.

Also, I now have a reason to pull the valve covers and clean them up.

TODAY the parts came in-----and a major snowstorm also!

Thanx and keep ya posted!

Joe

Got the gauge from Pelican and it looks and feels great. More importantly it is made in Germany and it is really nice to see a great product at a good price that is not made by a military or religious dictatorship by slave labor. You GO Pelican!!!!!:D

If you have jumped time, you only need to pull the tensioner, with the dial guage in place, and slide the chain over the gear as you turn the cam in the necessary direction.
Remember the cam turns CCW to advance, clockwise to retard but the timing is already set until it jumped.
If youre out of time you wont be able to measure timing by rotating the crank because if you jumped time you ll run into valves.
Bruce

I wondered about that earlier but there wasn't a reply on that one. I rotated through clockwise gently by hand and did not detect any resistance. I wasn't sure if a one tooth jump would be enough to cause a detectable contact with a valve. Are you saying that a one tooth jump will cause the contact to occur? Any data on this would really be appreciated!

Yes, one tooth jump will cause a hit, either on intake or exhaust valve.
Bruce

Interesting, because if that is true, all one would have to do is gently turn the crank by hand and see if the engine has strong resistance. I turned the engine through and only felt some compression resistance. I will use the checks that the guys have said but I think you are correct that anyone could very easily tell by simply gently turning through the crank 8 times to determine a valve hitting. Am I correct in this?

Really appreciate it!

OH, also---I was worried that you could shift a tooth and the valves would e clear until higher rpms were achieved and then------catastrophe!

No, you will bind if you have jumped.
Bruce

Thats also great news -- the risk of really serious damage is so great that this thread has data that should be very useful to anyone rebuilding or updating their tensioners. Thanx again to everyone for this information.

Pix of the tensioners
 

Hi All; Snow has let up so it was a good time to get you pix! Here they are and I seem to be short of clearance on the collars. Good or bad? And what to do?
Thanx

Joe

http://forums.pelicanparts.com/uploa...1392571254.jpg
http://forums.pelicanparts.com/uploa...1392571274.jpg
http://forums.pelicanparts.com/uploa...1392571328.jpg

Hi Guys; I checked the collars against the specs that everyone on the PP was stating, basically a gap of between 3 to 5 mm. I think at most I was getting 1mm so I decided to pull the collars and then wait about 10,ooo miles till the chains loosen a bit. Pretty good though that there are 97,000 miles on the engine and it is still pretty tight. Just going to check the cam timing on both banks and the button it up. Cleaned and polished the timing covers and valve covers and they are waiting for clear coat. Will keep ya posted!

Here are the components that were polished up nicely for install. I am going to clear coat them with 3x 2 pack. The aluminum is porous so I wanted to make it easier to clean.http://forums.pelicanparts.com/uploa...1392775214.jpg

Tensioner Lessons
 

Hi All; It was a 60 degree day on the East Coast and I completed the polish and paint on the valve covers and cam chain cover. I polished them with a 1500 grit sandpaper and then buffed with rubbing compound followed by Mothers. Then I broke the seal on the new Eastwood 2 pack clear and coated them to seal the Aluminum. It really looks good. I followed all the methods talked about using a Z fixture and micrometer. It indicated that I did not skip a toot. Then I turned the engine through at least 10 times gently to detect any binding. This all seemed fine also. Then I grit my teeth and turned the key! It fired right up (minus muffler) and I let her run about 2 minutes. Everything seemed fine and no cam chain rattle at the moment. I will provide pix tomorrow! Here are the important lessons learned from this process:

1. This forum is amazing and invaluable!
2. Mark all locations of the cams and the settings before you start.
3. Take pictures.
4. Tie up the cam chains on both sides of the tensioners as the tensioners will allow a lot of slack when removed.
5. Tie them up tight.
6. You can tell if the tensioners are bad immediately after you remove them by squeezing and if you can compress beyond 1/8 inch with your fingers, they have gone bad.
7. They rebuild pretty easy but lots of little bits and pieces that can go missing.
8. Re-install of the tensioners is a bit tricky but eventually there is a way!
9. If any doubt about the timing, the methods defined in this thread are great and a simple fail safe seems to be to turn the engine through gently to determine if any binding. If there is no binding between pistons and valves then you are good to go.

This thread is real great for understanding these issues! Thanx again for all the great help!

Joe

Couple more things that I found:

1. You don't have to pull the distributor. I did the entire job with the distro in place. At least ya don't have to worry about that losing timing.
2. I had a rising and falling idle that I never could get completely fixed. After the tensioners were rebuilt this was reduced by a lot. I think that many of the idle issues that I have read about may be related to loose cam chains.....maybe.
3. I couldn't use the collars because the chain was not stretched enough but will have to relook at that in the future.
4. Its a great opportunity to get the engine looking good because this is a pretty messy job with lots of oil drips.

Pix coming and thanks again for all the help as I could not have done this without the experts in this thread!

Joe