Inliners International Forums General Discussion Engines Shimming rocker assembly

I have a 848 head that was rebuilt a few years ago and sat in storage since.
It looks like it was milled and the intake valve heads shaved to a smooth surface.

I want to put it on a stock late 235 block.
I have read a few times to use shims for the rocker arm assembly, the same amount as the head was milled.

Problem is I don't know how much the head was milled.
But with a stock block and pistons, do I have to worry about shimming the rockers at all?

Dear RR;

Do NOT shim the rocker arm assembly.

When 'large amounts' are milled from the head the intake valves are 'sunk' into the head to compensate etc.

Simply put a 'straight edge' across the head & see how much clearence you have.

Good luck.

if you look at the bottom of the head, there should be a triangular area at the center of the head and to the pass side (I think) and also at one corner that would still have that rough sand casting look. If these are not there, then you have definitely had alot taken off that head.
Do you have another head to compare it to?
What are you going to use for a camshaft?
You should try to keep around 0.090" clearance between the piston and the intake valve. It may be necessary for you to put it together with some clay on the top of the piston and roll it over and then take it apart to see what you really have for clearance. You could reuse an old head gasket for this purpose, but only if it is the same as what you will be using in the end, as the newer style gaskets are a bit thinner than the original ones.
If you find that you don't have enough clearance, then you have 3 choices, cam with less lift, recess the intake valve or mill some clearance in the piston.
When large amounts are removed from the head, that lowers the centerline of the rocker shaft. Moving the intake valve up higher into the head makes it even worse. Since shorter pushrods aren't available, you need to shim the rocker stands back up to try to get the geometry back to "normal". Just backing off the adjuster is not good enough, because the cup on the pushrod may bind up on the adjuster/rocker arm if the changes are significant enough.
There is a "window" where the tip of the valves, the center of the rocker arm, and the and of the pushrod need to be in order to function properly.

I happen to have a factory NOS 848 head right next to the other one for comparison.
Looking at the bottom of the rebuilt head, it looks like very little was milled, as 1/2-2/3 of the numbers on the corner are still readable and there.
Also the intake valves were shaved to an entire smooth surface.

I only have one gasket and can't do the clearance test unless I find and waste another felpro kind with the steel borders.
But all the new ones are the copper sandwich kind.

The block and cam is stock 1962.
I guess since the head wasn't milled as dramatically and the valves have been shaved, clearance should be fine without any shimming or other mods.

Thanks for the experienced advice.

Well, it doesn't sound like you'll have any problems. Why the valves were surfaced, I can't say. Perhaps they previous owner had too much camshaft and thought shaving the valves was good enough to get by. If he took enough off to make the edges of the valves near "sharp", then I would suggest getting new valves for it.

The copper sandwich type is the original style which requires re-torquing. I wasn't aware they still sold those. The best ones to use are the Felpro or Victor ones with the steel borders. The Victor ones have a couple of the front water holes blocked off to force more water to the back of the engine. I have used both of these gaskets without any noticeable difference in cooling (on the same engine), but I would still opt for the Victor one.

Here is a close-up of the bottom corner of the head....



Looks like the valves still have a healthy .093 of border left.

Too bad I can't polish the chamber area with the valves already installed. But this engine will stay under 3500rpm all the time anyway.

Funny, I thought the copper style gasket was the newer one - I bought it at a local Autozone a couple of years ago and they had it in stock.

Dear RR;

That photo looks just fine.

See the the A 10 in the upper left (photo) ?? This is what Bryan is speaking of. If it were gone you would have a problem.

Now; Just put it together using your old gasket (torque 50#) & run it through to be sure. You'll only need pushrods in 1 & 6.

Then replace the gasket etc.

Good luck.