Mighty Shilling

where can I do that? sounds fun...and expensive....ewwwww...I don't like expensive...most college students don't.

Legoland951

I spent $200 with a buddy at the local machine shop including valve job. The machining is the standard price. Just tell them how much to take off.

Otto F. Schug

I have an '84 944. The head has been resurfaced twice. The first resurfacing was .010 and the second was .007. I would like to know how much of the surface of the 944 head can be planed off and still have a usable head. I am aware that the head gasket is .055 thick and that the pistons protrude above the jugs approximately .007. I do not know how to measure the head in order to determine the exact amount that has already been planed off from the head (measured from what point to what point to determine head thickness and amount still available to be removed). Am I correct that there is an alternative head gasket that could be used in the event too much of the head has already been planed off and, if so, where do you get the gasket.

I have read in this Forum area of people planing .025 and .060 off the head, but I am not sure as to the accuracy thereof relative to the head I have in question.

Manning

If you're willing to screw around with cutting valve pockets in the pistons, couldn't you skim more off the head or is it more of a problem with squish and not valve clearance? Wouldn't premium pump gas (93 octane) be sufficient up close to 12:1 compression. Hell, some of the muscle cars from the 60's and early 70's ran higher compression than that right off the shelf.

Mark Parker

It's been my experience that shaving the cylinder head is something you should avoid if at all possible. Besides all the previously mentioned pitfalls, it's possible that the end product, although smooth on the mating surface, can be warped at the cam saddles, causing excess friction at best and a broken camshaft at worst. My machinist only shaves a head after running through a straightening process. Using a straightedge, he finds and guages the low spots, bolts the head to a fixture with shims under the high spots of the previously discovered dimension, and then puts it through 24 hours in an oven which alternately heats and cools. The aim is to be able to true the surface by removing .006" or less. I'd go another way,,but it's your money.

ERAU-944

Manning:

i'd gather the fact that they ran such high compression without detonation on crappy gas was due to the shape/structure of the combustion chamber. perhaps their cylinders/cylinder heads weren't made in such a way as to induce hot spots and/or uneven compression and/or uneven fuel burn causing explosions. in such a high-tolerance engine as the 944 has, one has to wonder to what extent can you change the thickness of the head and still maintain good clearances, and safe operating conditions, and also, is it even worth the minimal at best gains that you'd see by doing this.

some food for thought

-Michael-

Otto F. Schug

How do you measure a '84 944 head to determine the amount that has been already shaved and to determine whether or not the amount remaining is usable? Where do you acquire the data? Can you use thicker gaskets? My questions, following up on prior post, is to determine if my existing 944 head is usable as opposed to attempting to increase compression ratio. Prior reports have said no more than .006 to its okay at .060. What is correct?

david fracolli

The most accurate way is to put modeling clay on the top of the piston. Then install the head gasket and head and torque it to spec. turn the engine over once then pull everything back apart and measure the thickness of the modeling clay. This will give you an accurate reading of what the actual piston to valve clearance is. Remember that you need at least .080 of inch clearance on the intake and .100 on the exhaust valve.
This is what I did after i installed my 88 pistons and the custom ground cam. After measuring I found that I could remove .040 inches and still stay withen those specs.
I have been told that the most you can remove is .060 using a stock head, cam and pistons. Porsche does make 2 different thickness head gaskets though i don't remember what the difference in thickness is.