Cambelt timing piper 270, vernier.

[brian j 31]

Can I just sanity check pls.

 

my 205 has a healthy skim off the head to raise CR, a Piper 270 cam, and a 306 HDI vernier cam pulley machined for width.  I built this 10 years ago before I sold and re bought the car, and I’m digging in my memory. 
 

I don’t know if the timing hole on the 306 vernier is machined in the same spot as a standard 205 pulley. Anyone here know? 

Failing that, I timed it by:

sticking an extension on a dial gauge down plug hole 1, finding the spot the piston moved either side of TDC and taking the mid point as tdc. 
measuring the lift on the cam using the dial guage on the cam lifter and measuring lift at TDC against Piper specs (I remember this feeling sketchy at the time). I followed a Guy Croft article for advice, but the forum no longer appears to be live. (Sad to hear of his death) 

 

does that all seem sane? Is it worth the hassle to recheck at a belt change or just leave well alone seeing as it runs as ok as it can without a remap to suit, and the cam timing may well get adjusted in the remap. (Motronic 3.1) 

 

[pug_ham 240 3 Cars]

That method of setting it up sounds right to me, not too from the way I did mine iirc.

 

I can't remember how the 306 hdi pulley timing key sits compared to the original 8v one but I'd expect they are fairly close / similar.

 

I used a vernier off a 106 1.5d machined down on a friends old 1.6 GTI that had been skimmed and the timing pin was fine on that.

 

As long as nothing moves when you remove the old belt (which it shouldn't imo) then you shouldn't need to recheck it again once set.

 

g.

[brian j 31]

Thanks Graham. 
 

I have my old paint marks too.  It’s just that I’m not trusting myself from 10 years ago to have got it right!

[petert 550]

Checking cam position by measuring lift at TDC is an accurate method, if you know what that point correlates to as a lobe centre line position. Did the cam maker provide a TDC figure? Don’t forget you need to subtract the valve clearance. Thus if you needed 0.100” lift at TDC and you had 0.010” of valve clearance, the exact position would be 0.090” @ TDC.

 

[brian j 31]

Piper quote lift of 1.57mm inlet and 1.52 exhaust at TDC including clearance.

 

they recommend .20mm inlet and .25mm exhaust clearance