Ethre

Some of you may remember me not being very happy with the early year crank timing gear being NLA.
So, I spent a while researching custom timing gears. It would be prohibitively expensive to get a set custom machined, but since many companies offer timing pulley stock in various sizes I was hoping to find one that could be machined down (the crank gear being a very simple design).

Its a 24tooth gear and inch wide, that's simple to see.

The pitch though is problematic. I measured every side I could on both the gear and belt. Comparing these to online catalogs indicated that the pitch should be "L". Unfortunately, the images I could find of "L" pitched pulleys always presented a different image (relative to the gear/belt) of the tooth design.
I also wondered since I would have assumed that Porsche would use a metric pitch, but the closest pitch (T10) seemed far out of spec.

I called around to various manufacturer's without getting any definitive answer (it appears that may be some different standards for industrial timing pulleys v. automotive ones), so I went ahead and mailed off a sample of belt to a H. Neuman to check. Unfortunately, today they got back to me with the bad news - they couldn't find anything to fit the sample I sent them.

Back to square one. Time to call Gates again.

EDIT (2/13/2012): After searching on and off for the last year, it seems almost certainly to be a custom pitch. I've looked into custom plastic gears, but they so far seem to be cost prohibitive for a small run. Still hoping to find something, but looking glum at this point.

hacker-pschorr

I'm confused, why not just upgrade to all OEM parts that use the round tooth belts?

SeanR

Or buy a good used one?

Mike LaBranche

I don't understand why you don't upgrade to round tooth gears all around and be done. <edit> Hell, I have a square tooth cog laying on the bench, you are welcome to it. </edit>

hacker-pschorr

+1

Even if it's for a PCA Concours and the desire to stay square tooth is for judging, you cannot see the belt unless the covers are off.

RCinXS

I have squared tooth gears on Ebay.

Ethre

Because I have an irrational desire to retain the square tooth belt system.

Thank you for the offers all, but I have all the gears I need right now.
I am just looking to hopefully find a way to get new ones if needed in the future.

toofast928

The thing about "upgrading" to the round tooth belt on a 4.5L is the pitch throws-off the left cam timing by 2 deg. Some people run with the cams mis-timed. Others spend more $$ on phasing the cams correctly.
I support you Tom, keep the square tooth belt. (if it's still available)

Ethre

That's interesting, I did not know that.

Am I correct in guessing that this is the result of the keyway channel being slightly offset relative to the teeth (compared to square tooth gear)?