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-   -   Cam timing questions (http://forums.pelicanparts.com/911-engine-rebuilding-forum/508335-cam-timing-questions.html)

ahdoman 11-01-2009 04:12 PM

Cam timing questions
 
Ref; 73.5 2.4L CIS - I'm using Wayne's book and I have a couple of questions;
1) In Appendix "A" under "camshafts"; The 73.5 is listed as "911T CLS". Is that a typo? I assume it should be "CIS" not "CLS"?

2) When setting the intake valve overlap; could I not set the crank pulley with the "Z1" at the case split, put on the flywheel lock and then rotate the cam (obviously the pin is out) from it's "dot up" position to get the .090 - 1.10 valve overlap? Then place the pin and tighten everything down? Obviously the rocker arm is on the low part of the cam lobe and valve clearance has been set prior to turning the cam.

Flat6pac 11-01-2009 05:57 PM

I miss what youre trying to do, not having read his book. I dont inderstand turning the crank and locking the flywheel
You need to set the pulley about 40 degrees before AfterDC so you can turn up the dots on the cams. Once the dots are up you turn the pulley to Z1 on center line
Pin both the cams and install the dial guage on #1 intake where youre measurement will be made. Valve lash is already set on #1 intake
Turn 360 degrees to Z1 and you pull the pin and turn the cam to to 1.1 or close, put back pressure on the cam to tighten the chain get your final reading and repin it
put the nut on so the gear doesnt come off.
Move the dial guage to the other side to #4 valve lash set
Turn 360 degrees to Z1. Now this is the art work. You have to match the other side as exactly as you can. Pull the pin and go for the set up, install the pin and put back pressure on the cam to get a tight chain and number.
If you cant get the set you want you go around again and remove the tensioner and remove the chain gear and move it one cog inside the chain and start the 2nd part over. You do this until you can nearly or perfectly match your left cam #.

Bruce

ahdoman 11-01-2009 06:45 PM

Thanks Bruce. In order to help me understand your proceedure; When #1 is at it's TDC compression stroke, what is #4 doing? TDC Exhaust?

Flat6pac 11-02-2009 04:10 AM

If you are pinned with the dots up on both sides the relationship will be #4 will be moving the intake valve.
360 degrees and the #1 intake will be moving and thats your first measurment.
The engine will turn as a unit as soon as you eyeball the pin set. If it binds, change your pin set slightly on the binding cam by retarding the pin set. Remember eyeballing the pins set is a judgement call so you might have to change to make clearance.

Bruce
You have a PM


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