audisport

supposedly, these are exactly the same.

http://www.mechanicstoolsupply.com/C...9_p_16217.html

http://buy1.snapon.com/catalog/item....group_ID=17363

read under the notes of this Ford TSB
http://www.thedieselgarage.com/forum...p/t-33487.html

Cosmatics951

Informative article audi, thank you.

bebbetufs

Thanks guys for trying to help, but could we please stay on topic?
I have; block, gasket, sanding paper, straight edge. Block is straight and I'm impatiently waiting to install the head. All I need to know is what roughness (in grit) is recommended for the last finishing touches, that's all

Cosmatics951

Sorry bebs, I'm also very interested to hear the solution. Goodluck.

86 951 Driver

Don't really have an answer for you, but I would think that you wouldn't want it that rough? I had someone else replace my headgasket. Wish I could help.

Techno Duck

If the head is o-ringed you will want to use the widefire headgasket.

I personally use a machinists ruler. They are pretty heavy stainless steel. Just my opinion, but unless you have a very keen eye on what to look for i dont think the average home mechanic will be able to tell the difference between using a true straight edge or just a quality machinist ruler for $15.

Tom M'Guinn

Throw the sand paper away. Clean the block mating surface with solvents and, if really needed, a green scotchbrite pad from the super market (but don't be too aggressive with it, and don't let the dust get into the block). Same for the head unless you have had it surfaced. You can check the deck for flatness with a straightedge as people have said, but whatever you find there you will most likely bolt it all back together anyway (since the alternative is an engine-out rebuild to machine the deck surface). If you have not surfaced the head, you can check it for flatness and actually do something about it if not perfectly flat. If using stock studs, torque to spec. If using raceware, I'd cheat up toward 80 or 90 ft lbs. Once together and running, keep in mind that the single most important thing to long head gasket life is a good tune!

bebbetufs

Thanks. Cyl.head has been machined and checked, so I'm good to go.
Would you consider the green scotchbrite less abrasive than 1200 grit wet sanding? I guess you would like the surfaces to be really smooth like 30ra ?`I thought some roughness was a good thing for composite gaskets.

If you guys have had luck using only green scotchbrite it should work for me as well...

APKhaos

Dead flat is much more important than a specific surface finish. Sanding the deck runs the risk of introducing roundness, particularly on the edges. Be uber careful with that. With your freshly skimmed head you should be good to go with a respectably clean deck surface. Scotchbrite works fine for that.

Tom M'Guinn

I've never seen an Ra spec for use with a stock or widefire gaskets. Cometic recommends 50 Ra (non-metric presumably) but it is more sensitive to surface smoothness than the gasket you are using. It's all academic I'd say unless you had some way to measure smoothness to the millionth of an inch there in your garage. Just use scotchbrite and benefit from all your 951 ancestors who have done the R&D for you....

bebbetufs

Wilco. Thanks

Oddjob

Here is the last one I did. I have always used solvent (laquer thinner or brake parts cleaner) and scotch brite to remove old gasket residue. Never sand paper.

Scott H

Possible stupid question: how do you clean the gasket area without getting a bunch of tiny particles in the coolant passages and cylinders? Just a lot of paper towels stuffed in all the holes?

Techno Duck

What i do is stuff paper towels in the oil drain holes. I then use a shop vac to suck out anything that fell in prior to removing the towels i stuffed in. For the waterjacket, i remove the block drain plug and just flush the water jacket out with water. Anything left i will use a shopvac with a straw (yes a drinking straw) to get anything left.

Maybe i should start another thread, but i am interested in hearing about what surface prep was done for those who were successful with the Cometic gasket. I have been using the o-ringed head / wide fire gasket on my car for a few years now. The head needs to be pulled again this spring (unrelated issue to o-ring / widefire combo), so i am thinking of maybe trying something new. It kinda sucks cutting the grooves into the cylinder heads as it limits its future uses i think (limited to only widefire). My friends have been using the Cometic's on their EJ25 WRX's for a few years now (2 of them). No leaks at all from them and they have two separate heads to worry about. Granted they were using resurfaced heads with a brand new factory shortblock.

bebbetufs

To prevent gunk from falling in between the piston and the bore I applied a thick bead of grease around the gap. This can be sucked out with the shop-vac along with the gunk when I'm done. I picked the tip up from Chris White in another thread.