cometic head gaskets

[pmrphil]

Looks like a broach was used, certainly not CBN or grinder.

[BillK]

Originally Posted by bry-war

Bill,
the difference in pattern and where the combustion escaped.
.
Bryce

Bryce,
I was thinking about this a little. Do you have a picture of the entire deck surface in one shot ? Did it look like it was done in two different cuts ?? I have seen some Dart blocks come with a pretty terrible finish from the factory that almost looks like they made two passes with different cutters. I does not matter because I am going to surface it anyway but I wonder if yours is just the factory finish ?

Just thinking out loud

[Rich Biebel]

Milling machines like a Storm Vulcan 85 B can leave a poor finish if the carbide cutters are not kept sharp and or the speed is too fast.

You hit some weld spots on factory blocks and just general wear causes them to leave a "file finish"after a while.

I ran one for years.....

I never got to use the CBN cutters and we never had a grinder....

Wheel had to be crated up and sent out or replace your own cutters but that was usually not a good scenario.......all it took was one cutter to be slightly high or low....

I have an old Van Norman rotary broach at home and it's a real dinosoar.....it needs to go to the scrap pile....

[BillK]

Originally Posted by Rich Biebel

replace your own cutters but that was usually not a good scenario.......all it took was one cutter to be slightly high or low....

I remember those days well. I used to spend hours getting the new bits set up perfect. So glad for modern technology

[carl hinkson]

When I deck my blocks I actually get a back cut which is the flattest surface and most tub grinders have lead built into them which when the head is tipped its not as flat as most think.

[bry-war]

Originally Posted by BillK

Bryce,
I was thinking about this a little. Do you have a picture of the entire deck surface in one shot ? Did it look like it was done in two different cuts ?? I have seen some Dart blocks come with a pretty terrible finish from the factory that almost looks like they made two passes with different cutters. I does not matter because I am going to surface it anyway but I wonder if yours is just the factory finish ?

Just thinking out loud

Bill,
I do not have an overall pic of the decks but it was definitely just one pattern. No return travel pattern or variance other than how it looked like an angular path as mentioned before. If I recall correctly, the deck height was 9.804. seems like not alot left for a factory cut. I will be running some Fel-pro 1057 (wire ring composite) gaskets for this go-round.
Thanks
Bryce

[Bob Mulry]

Originally Posted by BillK

Rick,

Are they ARP studs ? Did you use ARP lube or just oil ? If they are ARP studs the torque spec is 80 lb ft with ARP lube. If you used oil it would be higher.

I personally think that the finish would really have to be bad to make them leak. If you could see some of the factory cylinder head finishes that I see you would understand why I say that. They are pretty terrible yet they don't leak. I always put the proper finish on them when I machine them but I don't know if it is your problem.

Now if the deck or the heads have low spots in them I could see it.

Years ago one of the Fel Pro performance engineers told me to do the following when torqueing race engine heads.
1. Torque the heads as usual to the correct torque.
2. Let them sit overnight
3. Start with the first bolt in the pattern, loosen it 1/2 turn and then torque it back to specs in one step. Continue through the pattern one bolt at a time doing the same thing.

This method works much better than just putting your toque wrench on and re-torqueing the fastener because typically the breakaway torque to get the bolt or nut moving again is a lot more than the final torque spec.

If you try this, mark one of the bolts or nuts before you loosen it. Then re-torque it and see how much more it turns. I typically see close to 1/8 turn.

I do this on almost every engine I do and have basically not had any head gasket issues.

That's a good one...

I'm going to file that away with my old guy tricks....

I hope that you don't mind me stealing it....

That how I will re-torque in the future, even though I don't have sealing problems....

I don't think that would work with head bolts that have the bolt holes that extend into the water jacket???

Would breaking the bond of sealer between the bolt threads and the tapped hole cause a coolant leak???

My Pontiacs have blind holes and now that studded blocks are legal it isn't a problem for my race engines. So I am gathering info for other projects....

Thanks again for the info...

Bob

[Jeff Stout]

Originally Posted by Bob Mulry

That's a good one...

I'm going to file that away with my old guy tricks....

I hope that you don't mind me stealing it....

That how I will re-torque in the future, even though I don't have sealing problems....

I don't think that would work with head bolts that have the bolt holes that extend into the water jacket???

Would breaking the bond of sealer between the bolt threads and the tapped hole cause a coolant leak???

My Pontiacs have blind holes and now that studded blocks are legal it isn't a problem for my race engines. So I am gathering info for other projects....

Thanks again for the info...

Bob

I brought this procedure up at a racers breakfast I go to on Saturday mornings and the guys thought I had 2 heads. My engine builder from years ago told me of this procedure. But it was on studs not bolts. I think using cometic gaskets you do not need to do this step anymore.

[Jim Bailey]

I have a simple practice that I use with MLS gaskets. The problem is with the stretch of the fastener. I use plenty of copper coat ( like a whole can on two gaskets). After the head is torked on, I let it set 24 hours. Then, "one at a time", I untork the fastener and re tork it to spec with one pull on the tork wrench. I've actually had motors stop weeping, doing this on the dyno. Right or wrong....works for me.

[Jeff Stout]

Originally Posted by Jim Bailey

I have a simple practice that I use with MLS gaskets. The problem is with the stretch of the fastener. I use plenty of copper coat ( like a whole can on two gaskets). After the head is torked on, I let it set 24 hours. Then, "one at a time", I untork the fastener and re tork it to spec with one pull on the tork wrench. I've actually had motors stop weeping, doing this on the dyno. Right or wrong....works for me.

On my sbc I didn't spray coating as I was informed by many not to. If you had good luck spraying then I will on next rebuild for piece of mind as I run alot of nitrous and feel leary of not coating them. Thanks for the info.