sHi, been away for about a year from this forum but im back and begining a engine conversion (not going to be a quick process as im a student).

i have the 1.28v engine but would really like more as a base engine, ive read the faq and guids and done some searches just a few quick q's

is there no way to use the punto 75 without mpi conversion (i.e swapping to a spi head or would i gain nothing.?) or even a easy way to swap to mpi? (dont understand the intergrating loom bit.

also while i have the engine on the stand all cleaned up i need help with how to understand shims, ive never done them before. i have a 866 cam to put in it but i have no clue on the clearences needed or how i would even get it all working. but i am here to learn.


any help appreciated.

cheers -|- steve.


OH P.S anyone have a clue where i can get the right colour paint to respray my car? freind has a garage and he has asked me to get the paint any hints greatly welcome

Shims are easy enough to understand. It's easier to do with the head off or the cam belt off.

You'll need to do that anyway to pop the P75 cam on. So, with the cam on, torqued down and oiled up:

You measure the clearance between the cam at base circle on each lobe (forget the other details -- I think the illustration is for a Chevy!)



with a metric feeler guage -- you know the measurement is right when the blade(s) just slide through -- put two or more blades together to make up the thickness.

It's essential to note it down and record the order of the valve you're measuring: say 1-8 (from the timing belt end). Of course, you have to turn the cam to get base circle on each valve.

If the clearance is within limits, leave that shim well alone. If it isn't, you need to pop the shim out and measure it (generally they have a mark etched on the bottom to show the size and if there's no obvious wear you can pretty much trust this). If you need/want to measure the shim you can use one of the cheap digital calipers you get from Aldi and all. A micrometer would give a better indication of weear, but, as said, they don't wear much.

If you've not got one of FIATs special shim extraction tools, and have more than one or two shims to pop out, it's easier to remove the cam.

Then comes the calculation: basically, if the clearance is too big, you need a bigger shim to take up the difference, if the clearance is too small, a smaller shim.

So, if the clearance should be 0.35 to 0.45, but is 0.20, you need a shim 0.15 to 0.25 thinner. Pop in a shim of the appropriate size, bolt it all up again (obviously do all the shims at once!) and measure again to check.

I don't have the P75 clearances in front of me, will try and remember to get them tomorrow.

So, shimming is easy enough.

The P75 cam helps even if you don't go MPI. Well worth doing even if you don't fit the head (some late P60s seem to have come with a P75 cam). Better stiLL with decent induction and a 38 or 40mm TB.

Wow cool i actually understood that cheers. so once i find out what the clearences should be for the cam i can swap it over and find out how much bigger / smaller any shims need to be.

where would i get the new shims from? fiat or a auto factor?

i have herd the cam helps alot ive got the gsr and im trying to track down a larger tb but tricker doesnt seem to be replying and i cant figure out other donor vehicles for mabe the 38mm? thats on a fiat somewhere is it not.


P.S if ive also read the diagram correct the clearence for the hypothetical cam up there would be 0.35? (obviously only for that one)

Cheapest place for shims would (probably) be Fluffy the Impaler or Shop4Parts (a search will find either). But there's a good chance you can shuffle most of them around.

You've read -- I think -- the diagram wrong. The thing is a cross section of the cam, so the light grey bit (the lobe -- the sticky out bit) isn't where you'd be measuring, but the opposite side, the base circle.

If 0.35 was the clearance (in mm,rather than inches) the clearance would be OK, albeit on the tight side.

Somewhere there's alanhelen talking of the 36mm Citroen/Pug one he fitted, but I think Arc has come up with other alternatives. And then, it looks like at least 2 other people are about to put 40mm TBs into production.

If you really want A level shimming, pop down to your local Ducati dealer and ask if you can watch: yer average Ducati has 2 cylinders, 4 valves, and 16 valve shims!

The clearances I find for the P75 cam are: 0.40 inlet, 0.45 exhaust (as opposed to 0.34-0.45 inlet, 0.45-0.55 exhaust for the stock 1108 cam).

The margin, if you will, of 0.05 either way for the stock cam is pretty huge in engineering terms, but to quote no margin for the P75 is even more alarming!

fingers99 said:

Cheapest place for shims would (probably) be Fluffy the Impaler or Shop4Parts (a search will find either). But there's a good chance you can shuffle most of them around.

Click to expand...

Local engine re-builders is also a good place most will do you them exchange
.

fingers99 said:

Somewhere there's alanhelen talking of the 36mm Citroen/Pug one he fitted, but I think Arc has come up with other alternatives. And then, it looks like at least 2 other people are about to put 40mm TBs into production.

Click to expand...

The 36mm one suits the car nicely I actually preferred it to the 40mm on my old NA as the car was more refined with it fitted. I think the 40mm one is actually a bit big for a car in mild/no tune.

totaly agree with martin, i've not tried a 36mm but the 40mm is a bit overkill if all you got is an induction kit and exhaust as many have, me included.. the tricker will be going on the tub though so may have chance to lay with this on the cinq a some point if i don't sell it first (likely)

Thanks for the clearances have it bookmarked!.

As for the pug tb was it easy to fit?

clock34 said:

Thanks for the clearances have it bookmarked!.

As for the pug tb was it easy to fit?

Click to expand...

Yes, you have to bypass the the cooling system from the TB (30mm piece of pipe and 2 jubilee clips) and Dremmel out the spacer (or make a new one at least 15mm tall if you do)