Surfacing cylinderhead

Inserts pulled at 1951 FL with 1950 heads

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Raytag
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Surfacing cylinderhead

#1

Post by Raytag »

Some inserts in the head are slightly pulled out (subsequently oil leak in left front bolt) and I wanted to mill the cylinder head surface flat.
I drilled/milled a jig to bolt onto the head.
As a reference I use the flat surfaces where the rockerarm blocks are mounted on.
These 2 flat surfaces I use to bolt the jig on.
I am NOT using the surface for the pan cover gasket


With the head mounted onto the jig the cylinder head surface is quite of whack.
Basically the front of the head is higher and the rear of the head lower. A lot.
I refuse to believe this.

Of course I have to use shims below the jig in order to mill the head the least possible but one question I have:
How do you mount the head in order to mill the cylinder head gasket?
You put it onto the pan cover surface or rockerarmblock surface ?

Maybe its like with Shovels where the bore for the rockerarm has a 3 degree angle to make sure that oil flow speeds up into one direction only?

Thanks alot
ray



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Re: Surfacing cylinderhead

#2

Post by pan620 »

I made a plate to mount them in a 4 jaw chuck in the lathe so I can dial them in true, more accurate than a mill in my opinion, then over to the mill to spot face the inserts down aprox .030

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Re: Surfacing cylinderhead

#3

Post by Raytag »

Most definitely easier and quicker.
The only downside of my Cazeneuve lathe is the special spindle nose and data is confidential ... No aftermarket parts available.
OEM ~1 grand. I chickened out of making a backplate by myselves cause I`m not 100% sure what taper it is, something with 5.37.
I tried it already, blueing it, never a 100% and with a 70lbs chuck at 1600rpm in front of my face ... I`m chicken
So no 4 jaw/independent chuck.

I`m not trying to overengineer this thing but maybe someone knows the company way? Rocker geometry bit here bit there you know.
Anyway I shimmed it the best I could with the inserts stand proud some .006. Acc to the dial test I need to skim some .0086
Low spot at the intake manifold.

Ray

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Re: Surfacing cylinderhead

#4

Post by PanPal »

I counter sink the inserts. Then chalk a fine file and lightly file the high spots usually just the steel inserts. Let the file do the cutting, and dont push down hard on the file. Clean and rechalk the file often so the cuttings dont scare the aluminium. The chalk keeps the filing from sticking to the teeth in the file. Then use a piece of glass or mirror 1/4" thick. Tape Emory cloth on three sides, not the side at the edge. Spray the Emory with WD40 and with the exhaust port hanging over the edge of the glass, sand in a figure 8 pattern untill the head is flat. Spray as needed with Wd40 and clean off the sanding dust. It usually takes a few pieces of emory cloth and a lot of beer to do one, but I've always had great success. Machining the head with steel and aluminium bounces or pushes the tool away every time it hits the insert. I never felt they were as flat as sanding them flat. I usually notice the area near the exhaust port is the last area that sands out.

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Re: Surfacing cylinderhead

#5

Post by Larry »

I always sand cylinder heads. It removes less material than milling and it never leaks. I use 36 grit sanding sheets intended for floor sanders. They cut like crazy. Both heads, typically one hour.

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