cometic head gaskets

[Ed Wright]

Originally Posted by Jeff Niceswanger

Gulius always has us use 72 with lube Ed ,,,, All his motors are studded

I use 70 with lube. But, Gulius would know. If I could afford it, I would have one of his instead of my home made engine.
And, the surface finish, Cometic told me I need a smooth finish. Those rough ones like composite gaskets better.

[carl hinkson]

If the block was plate honed its best to go with what was used for hardware and torque during the plate honing procedure if it was plate honed to achieve good ring seal.

Studs do to the fine thread seem to distort cylinders more then bolts from what I have seen.

[bry-war]

I have a big Chevy from Schmidt that failed between 5-7 due to cutter marks using cometic gaskets. Only posting to say that composite is my only fix but why is the cutter pattern not the same between bores. It's as if the block machine was cutting at angle (side to side) making most of the between bore deck verticle pattern and others a bit more /// direct between bores. Is there a standard for deck tooling path? I just assumed parallel to crank. Sorry if I'm hi-jacking.
Thanks
Bryce

[gmeyer]

Thin coat of copper coat on all three pieces will fix the problem I have done it that way for a while now. greg

[BillK]

Originally Posted by bry-war

I have a big Chevy from Schmidt that failed between 5-7 due to cutter marks using cometic gaskets. Only posting to say that composite is my only fix but why is the cutter pattern not the same between bores. It's as if the block machine was cutting at angle (side to side) making most of the between bore deck verticle pattern and others a bit more /// direct between bores. Is there a standard for deck tooling path? I just assumed parallel to crank. Sorry if I'm hi-jacking.
Thanks
Bryce

Bryce,
The finish should be the same across the entire deck surface including between the bores. Here is an Olds block I just finished.

[bry-war]

Bill,
That is a fantastic finish. Here's the Steve Schmidt finish and the difference in pattern and where the combustion escaped.
Pretty terrible. Thanks for sharing.
Bryce

[BillK]

Originally Posted by bry-war

Bill,
That is a fantastic finish. Here's the Steve Schmidt finish and the difference in pattern and where the combustion escaped.
Pretty terrible. Thanks for sharing.
Bryce

Good grief that is pretty terrible for a modern shop. Wonder if someone wasn't paying attention

[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....