Cam timing question
 

I am rebuilding a 1980 930 and I'm about to set the cam timing. I read the other posts here on it and I am pretty clear on how to do it. I also have Wayne's book and have been following that closely.

My question is, his book says to set both cam timing and then take out the tensioners, prime them and put them back in. Taking out the chain tensioners after you set the timing and then putting them back seems like a good way to lose your timing. Wouldn't it be better to prime the tensioners, and install them before setting cam timing, then pull the tensioner pins after timing is set?

Thanks

Which book are you talking about? I looked in "101 Projects for Your Porsche 911" on pages 52-53 which cover Project #15 - Setting and Adjusting the Cam Timing, and I find no reference to removing the tensioners, priming them and putting them back in.

My book is dated 2001. Yours?

Mark

I am rebuilding my engine not just replacing the tensioners.

When setting cam timing it says to put tension on the left idler arm with a vice grip and the right with the mechanical tensioner. Set cam timing then install tensioners after priming. This seems like it would be difficult to keep the tension on the chain while taking off the vice grip and mechanical tensioner to install the pressure fed tensioner.

Seems more logical to install the tensioners then pull the pins after timing is set.

You won't lose the timing. The timing is set with the specs relative to the sprocket and flange. (provided you don't let the chain slip a tooth.)

You will have almost zero tension with the pins in and your timing will be off. Even if you prime your tensioner and pull the pins the chain will still slacken when tightening the nut. You need the mechanical tensioner and vice grips to keep the chain tight.

As Chris says above you wont lose timing as long as you don't let the chain slip a tooth.

He's talking about the rebuld book

Believe these guys when they say you won't screw up your timing. Y

ou can hold up (or down) the chain with a finger while you remove what you were using for chain tensioning and install your primed tensioners.

If really worried, wire the chains together so they are sort of tight.

You really have to work at it to get a chain to slip a tooth on either end (especially the big end). The only way I can think of that happening is to have the engine on a stand and have it on its side. That way slack could fall iinto the case and the chain could come off the IS shaft gear in such a way that when pulled back you might be off a tooth.

So keep the engine horizontal for this operation and you should have no worries.

You'll freak out enough trying to get your timing within 0.001" on the dial indicator until you settle for getting it within spec and calling that good.

Thanks Walt,

You are right. I did get it timed last week and once I did it and relieved the chain tension the teeth stayed in the chain without slipping or jumping. Reading Wayne's book made it sound like it would be very easy to make a tooth slip.

TIMING!!!....WOW! that was the tough part. It was alot of trial and error to get them close.