cylinder head surface finish

[arlancam509]

we sure do have the means for measuring surface finish. without going into too much detail (not sure if i could get in trouble at work), but i work for a very large machine tool builder. we did 500 million in machine sales for the 2017 fiscal year. it isn't lost on me how lucky i am to work here.
i am the only 'gearhead' here at this particular facility, that i am aware of, so this project has my obvious interest.

[Frankshaft]

we sure do have the means for measuring surface finish. without going into too much detail (not sure if i could get in trouble at work), but i work for a very large machine tool builder. we did 500 million in machine sales for the 2017 fiscal year. it isn't lost on me how lucky i am to work here.
i am the only 'gearhead' here at this particular facility, that i am aware of, so this project has my obvious interest.

So, if I get this straight, you created that finish to mimic the factory, to hide the fact you actually milled a whole bunch off, so as to get thru tech.

[MotionMachine]

Maybe you should reconsider posting pictures of proprietary projects if you want to keep that job.

[arlancam509]

Maybe you should reconsider posting pictures of proprietary projects if you want to keep that job.

that is excellent advice that i will take. my only excuse is that it is a belly button common small block chevy head and if they come from the factory looking this way, we are good... well, because they all look the same.

[arlancam509]

we sure do have the means for measuring surface finish. without going into too much detail (not sure if i could get in trouble at work), but i work for a very large machine tool builder. we did 500 million in machine sales for the 2017 fiscal year. it isn't lost on me how lucky i am to work here.
i am the only 'gearhead' here at this particular facility, that i am aware of, so this project has my obvious interest.

So, if I get this straight, you created that finish to mimic the factory, to hide the fact you actually milled a whole bunch off, so as to get thru tech.

we were told by our customer to create this finish because this is how it looks coming from GM. i have been in the machining business for 28 years now and somehow i had never heard of this trick to create the finish shown here. (probably because i am on the other side of the wall flying a desk 90% of the time.) when it was explained to me how it was being done, i wanted to get the experts opinion, so i posted here. it creates a surface that isn't flat. flat enough for the head bolts (screws?) to pull it flat? probably.

i literally have no pull on how the part gets machine. i can offer my 2 cents, but that is it.

[MotionMachine]

I'm guessing it's a boatload of lines of G91 X.125 Z-.0015, Z0.0, X.125 Z-.0015, Z0.0, etc.etc. You could probably get the same result with a whipped out 570 broach with misaligned cutters.

[David Redszus]

The surface roughness of the head needs to be correct for the gasket design/material.

A surface roughness that is too smooth for the type of gasket you are using will cause problems.

http://scegaskets.com/wp_super_faq/what ... materials/

Jon nailed it.

A call to the head gasket mfg should provide you with their recommendation with regard to surface finish for the
gasket material being used. Generally, a smooth finish is preferred, but not always. The gasket mfg knows.

[pdq67]

Gee, stupid me!

I thought they, "broached', both the heads and the block decks??

Now when I put together old used stuff, I use a small 6" to 8" long triangle fine straight cut file and go from head-bolt to head-bolt while spraying WD-40 to smooth and clean any high spots and crap off all deck surfaces! Now this is one of my, "feelie", deals so go easy...

You can see the results so again, go easy!!

pdq67

[pdq67]

Well, did GM, "broach", their heads and blocks decks??

pdq67

[pdq67]

Well, did GM, "broach", their heads and blocks decks??

pdq67

Please just asking again is all..

pdq67

[arlancam509]

i don't think anyone broaches cylinder heads unless they are putting in keyways

[Frankshaft]

i don't think anyone broaches cylinder heads unless they are putting in keyways

570 Van Norman rotary broach. Very popular back in the day.

[arlancam509]

i don't think anyone broaches cylinder heads unless they are putting in keyways

570 Van Norman rotary broach. Very popular back in the day.

thank you for the info. that is something i have never heard of before. looks more like a blanchard grinder than a broach - at least to me. machines evolve so who i am i to decided what they can or can't be!