HEAD/ DECK FINISH

[Fatman]

What head and deck surface finish works best with copper head gaskets
It's an iron block and iron heads?

Am i right in thinking that as smooth as possible is best?

What about coating the gaskets before installation?

Cheers and thanks

[Cobra]

Head and block must be very flat and smooth. Follow gasket manufacturer's guidelines for copper head gasket installation. Use a "stop-leak" radiator product after installation.

[Wolfplace]

Hi Ari,
I like very smooth surfaces & use Hylomar spray. Good stuff
Also, I always use a reciever groove with an "O" ring.
That said, with the Cometic MLS gaskets I don't find much call for copper anymore except for the 'die hards"

[Fatman]

Thanks Guys

Hi wolfie. Got that dyno happening yet?

Thought about running cometics but the block had been o ringed and run copper in the past. Now been tapped for 1/2 inch head studs and we'll give it another go.

Cheers
Ari

[Trev]

HI Fatman
My block was set up with orings as well. Dont laugh at this and dont anyone else laugh either
I left the stainless steel o-ring in place, went and bought a very fine flat file and spent an hour draw filing over the orings.
I was able to get the orings level with the block and under my coke bottle glasses the finish looks great and I intend to use cometics
Trev

[Fatman]

Hi trev.

Cant see why it wouldn't work as long as that remaining o ring was pretty stable in there

What about pulling the o ring out an filling the groove with something like JB weld. Wonder if that would work.

If you're interested, the motor was a flat tappet 355. VNs, Harrop, holley 950 HP etc. Went 10.30 @ 129/130 in an early Commodore, VC i think. That was with both heads gaskets blown into the valley on the centre 4 cylinders. Hopefully go low tens if the gaskets can hold up. Might give you some idea of the potential of your combination with the superior heads, cam and extra 28 cu inches.

Cheers
Ari

[bsfc9]

I've seen some luck surfacing the the oring right down flush with the deck and then using a cometic(MLS) gasket. For best results with MLS gaskets a smooth surface finish is the way to go--at least 50 Ra, under 30 would be better.

[Wolfplace]

Thanks Guys

Hi wolfie. Got that dyno happening yet?

Thought about running cometics but the block had been o ringed and run copper in the past. Now been tapped for 1/2 inch head studs and we'll give it another go.

Cheers
Ari

Hi Ari,,
LOL,, no, got the old one out & crated & the new one is bolted to the floor with wires going everywhere,,,,
Got a half dozen engines I am supposed to get done & dynoed & the days just seem to disappear
Damn near another week shot in the ass & still don't seem to have anything accomplished

[Fatman]

Wolfie,

Are you saying to spray both sides of the copper gasket with the Hylomar? If so, just a thin coat or what?

What about Ra measurements (hope the terminology is right) for the deck and heads?

Cheers
Ari

[Wolfplace]

Wolfie,

Are you saying to spray both sides of the copper gasket with the Hylomar? If so, just a thin coat or what?

What about Ra measurements (hope the terminology is right) for the deck and heads?

Cheers
Ari

Yes, both sides & a thin coat on copper. Nothing on MLS
I don't think you can get it too smooth with MLS gaskets.
I like 30 or better, especially on the aluminum.
I think copper is a lot more forgiving regarding surface finish but I still don't like surfaces that look like they were done with a dull cutter or a body grinder,,
A lot of the new blocks are too rough the way they come, well over 100
Everything I do is normally around 40 or better but with cast iron you need to check in a number of places to get a true reading as the surface "voids" or "imperfections" will fool the profilometer & you will get a higher number than you really have.
If the surface "looks" good everywhere & you are getting hi readings, check a number of places.
The lower readings are what I feel are more representative of the true finish.

[Fatman]

Thanks Wolfie

please excuse my dumbness here but what Ra for an iron block with iron heads and a copper gasket? assuming we can get an accurate measurement.

Cheers

[Wolfplace]

Doesn't seem to make much difference with copper.
I have taken apart engines I wouldn't think would seal they were so bad & they apparently were fine.
You could "see" the finish in the gasket big time.
I just prefer surfaces on the smoother side,, for a number probably 70ra or so is fine with anything except MLS.
I see a lot of surfaces that are not acceptable to me like some of the new blocks but again, they seem just fine in practice.
A 70 RA finish is still pretty smooth & at one time was considered a very good one.
I think you would have to be pretty bad to cause a problem with most gaskets with cast iron.
Aluminum is another story

[Fatman]

Thanks Wolfie