Tensioner replace and timing question

[sperberj]

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

[yelcab1]

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

[sperberj]

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?

[Bob Kontak]

Originally Posted by sperberj

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?

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.

[sperberj]

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!

[sperberj]

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 ).

[Eagledriver]

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

[Lapkritis]

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

[Bob Kontak]

Originally Posted by sperberj

What think ye?

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.

[Flat6pac]

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

[Flat6pac]

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

[Bob Kontak]

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.

[Alan L]

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

[sperberj]

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

[sperberj]

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?

[Lapkritis]

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.

[sperberj]

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.

[Alan L]

Originally Posted by sperberj

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?

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

[sperberj]

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!

[Bob Kontak]

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.