j.kenzie@sbcglobal.net

Measure with a metric hex key to get to within 1 mm. Then measure the keys to verify range. Some of my hex keys are in 1/2 mm steps.
Good luck,
Dave

Adamant1971

I was able to snap a pick of mine. But a little hard to measure with everything in place.

Cosmo Kramer

I think you are fine based on that pic Adam. That doesn't look close to 8-9 mm to me.

Cosmo Kramer

Best I could get mine to with a Gates belt with 500 miles and reaming the tensioner holes to just shy of 8 mm was 7.1-7.5 (changed a bit depending on engine position).

ptuomov

You being paranoid about a perfectly well functioning system was the objective of some people here.

JBGold07

So mine is in 8 to 9mm range. Due to the other thread I had the car off the Rd for the week.
I removed the passenger belt cover and the belt shows no sign of wear.
This is at approx. 1500miles.
Standard gates belt. Porken Black.
86.5 manual. No previous head work.
I had cleaned and left my lower rollers in place and I deemed them as good.
My gears are all original and showing minimal to no wear at true 100k miles.
On the strength of the rollers being in, the belt condition, I put the car back on the Rd last night and for the summer. I will reassess in the fall.
I am on this forum every hour of every day and I may need to put it down for a bit and get some seat time.

Ps. I wish I didn't put on that old Porsche belt that was lying around in the trunk

Adamant1971

LOL. And I get paranoid easily.

PorKen

Which is 5-ish when the engine is hot. Perfect.

Cosmo Kramer

Figured that, but to get there I had to drill my tensioner mounting holes from 6 mm to almost 8 mm and push it all the way up. Without mods it was out of range.

PorKen

Different engines have a different tolerance stack.

FWIW, the tensioner/damper bolt holes are cast in a cone shape. The top is around 6mm, the bottom 8mm. So you just evened it out.

Cosmo Kramer

I am grabbing a new Gates belt just to verify there isn't an issue with mine. I will also be making some sleeves to make sure the tensioner isn't relying on bolt friction to stay in place. I will post pics when I'm done.

Mrmerlin

I think that the water pump pulley must also be measured to figure this into the mix,
the smaller the diameter of the pulley the longer the PKR tensioner will extend.
I have seen many different pulleys on waterpumps,

PorKen

Different plating methods, yes. But different ODs? I would have never thought to check.

I've got a couple of dead ones.

Mrmerlin

not just plating but completely different styles of pulley so that could lead to the fact that the original system would not be bothered by a small change in pulley diameter

Ken this could easily explain the differences your seeing on fitment of the your tensioner

Cosmo Kramer

Put on a new Gates belt and the best I can get is 7.1 with the holes drilled from 6 to 8 mm and the t/d pushed up as far as it will go. I tried a shim to try and pick up some of the slop in the hole but it wouldn't stay in position. So I torqued to spec and applied loctite to the bolts and a bit between the t/d and the bracket and will hope it stays in position.

Here is my setup:

New Gates belt
Recoated cam gears
New steel oil pump gear
Crank gear at 71.5 mm
Ed's pump
Stock heads

If I hadn't drilled the t/d my initial install would have been 9.1 mm.

Ken: I seriously think you should check the black brackets to make sure something hasn't gone askew. My measurements are identical to the one in the other thread that jumped.