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Pinto Camshaft Vernier Pulley Recommendation


megadodo
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My Piper 4 bolt vernier slipped fully retarded. Slippery hard anodising between inner and outer. Bolts were really tight still and undid with a snap.

However on the cam aspect, are you using the standard Pinto injection inlet manifold or a single throttle body on a plenum? If so, high overlap cams will be horrible. High lift ones are fine. With a Piper 285 ultimate road cam I couldn’t get a reliable tick over without bad hunting below 1700rpm. Changing to a Piper 134 fast road injection cam worked well.

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The Pinto is a non-interference engine so with the limitation of a few degrees either side you won't bust a valve

I am worried that this thread is turning into an urban myth of pin works others don't

You may well come across one that has slipped but I know dozens that have not.

So let's not get all scaremongering about this and go with the probabilities of a slip on general use.

 

I'll start, 2 engines I've built no problem

Several race engines that Elite Motorsport are running no problem

3 Super Rods, although these run a cam in block chain vernier no problem

Hundreds of people on Turbosports forum and thousands on Locost builders no problem.

 

I think we need to keep this in perspective

You are bang on with your comments on this Snapper. No need for anyone to panic and go stripping parts of just in case.

However I would still be inclined for belt and braces. Either when fitting one, or timing belt change.

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I concur

You can't be carefull enough

Perhaps a key with wet & dry & some lock tire

Defo new belt and tensioner.

As you won't fit a vernier without fitting a new cam a new cam belt and tensioner is just part of the process, that and a spraybar, followers and springs

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Like many things man made it takes a man to break it! in to many years to remember never had a cam belt slip, a chain jump ,points close other than wear, first rule of mechanics do it right and you only do it once.I supose I've been lucky or was it the bum kicking I got as an apprentice in an old school garage if I didnt do as I was shown ? ,attention to detail taking time to recheck use of proper tools ,parts etc and if you are not sure ask !!! :crazy: :acute:

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Once again folks, thanks for the advice.

Okay so a red (matches the cylinder head colour) 6 bolt vernier cam pulley ordered from turbosports, 1 piper fast road cam and matching followers I have already, cam belt was new 3290 miles ago as was the tensioner (do you think they really need changing?). Oil feed pipe was cleaned when the head was rebuilt at the same time. Timing looks a simple operation but I wont pin it until its been rolling roaded (is that really a verb?) I looked at pre pegged pulleys but by their nature they must be a compromise unless you are lucky as there are only a finite number of positions you can have? One may be spot on but it's more likely to be a few degrees form optimal (especially with my luck!). I'll do my oil change at the same time (post 20 minutes camshaft bedding in period!). I'm going to do it in situ, I just need to make a neat round opening in my firewall.

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tensioner should be fine if fairly new, cam belt is only a tenner which is very cheap insurance if it's interference

 

Pin type vernier pulleys give 0.5° increments in cam timing (360 degrees split into 40 different belt rib positions and 18 adjustment positions)

Edited by Grim
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Not positive on the next statement but here goes --- are not some more modern engines cam wheels only taper mounted with NO key ,spline or other locating system , I believe the k series is like this are not the zetec and dura tech similar note this may be senile rambling ! don,t know about the mazda any one outhere lighten my darkness? .If its true why do you need vernier wheels ? as you can a/r the cam any where [if you know what you are doing.] mick :sorry:

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Duratec is friction fit on cams and crank

Most tuned engines have jetways machined for woodruf keys

I would

A Pinto with a heavily skimmed head and high lift cam could hit a piston if the belt broke but unlikelly to if the vernier slipped as they only move a few degrees either side of TDC

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