milling iron heads
 

i'm getting near the end of a 59a rebuild,and i want to stay with the 59ab heads. i know ol ron likes 50 thou clearance over the piston, and it seems i remember guys are angle milling it off the valve side. i've searched and cannot find my answer, any thoughts welcome

Re: milling iron heads
 

Ol' Ron will likely weigh in, but I remember milling them on 5 degrees, with more taken off the cylinder end of the head. This gives more compression over the cylinder while not taking so much off the valve end to preserve valve to head clearance.

Re: milling iron heads
 

How much does the stud holes in the head have to be opened to?

Re: milling iron heads
 

i should also mention, this is the motor i cut the gear off a merc cam, and slotted it, so certainly must check valve clearance

Re: milling iron heads
 

40cop has a good idea with a hi lift cam. However if your running a stock cam, no need to worrry. It's still agood idea to measure the clearance over the valves.
Using some alum balls and alittle grease, place them on the eddge and the top of the piston woth a used gaket on the block and the heads held down with your hand. Thus way you can feel if anything is hitting the heads besides the alum balls. Measure the thickness of the balls and subtract .050 from that. ". That's what you want to hav milled from the head. It will usually make a quench area around the edge of the cyl which is all you need. In mosr cases the clearance will be more in the center of the head, but that's OK. For a stock street engine, I like to get it closer near .040/.035, but this requires allot of measuring.

Re: milling iron heads
 

thanks ron. so measure both valves and piston first, and perhaps, depending on results, just mill flat and not 5degree angle?

Re: milling iron heads
 

Angle milling is best , that way transfer and valve area stays more open.
Then turn the head around and go through head bolt holes and straighten the bolt bosses.
And thanks to Ol´Ron for all his shared info in this board.

Re: milling iron heads
 

If you read my book you will learn the most important area to minimize clearance is at the outside edge of the piston. If the heads are milled at an angle maintain the new face flat on the machine table and ream the holes and then spotface the nut/bolt surfaces.

It has been my experience that different head manufacturers can use different drill sizes affecting the reamer diameter requirement.

Re: milling iron heads
 

i'm getting peer pressure here!, most my friends think its nuts to spend the time fooling with stock heads, all say get out the speedway catalogue and order up some fancy aluminum heads. this motor has a merc crank, so 255" stroker already, aluminum looks fancy, but about 800 with studs, and more issues with corrosion, i thought some milled iron heads sounds pretty easy. i think i will put the iron heads on and see what they measure for starters

Re: milling iron heads
 

A set of milled heads with .045 to .050 clearance over the piston are just fine. Paint them and use some chrome acorn nut covers and they look pretty nice. Aluminum heads are mostly for looks. And I wouldn't worry about angle milling them for your application. You'll still have plenty of room over the valves.

Re: milling iron heads
 

I like the look of a set of finned aluminum heads, but functionally, stock heads are fine and in some applications better.

Re: milling iron heads
 

With the first engine I did (about 25 years ago), I did just what your "friends" are recommending. After spending about $3000 on a 276" short block, I just bolted a set of Offenhauser heads on it. The engine ran OK, but I was never real happy with it. The last two engines I have done, I paid a lot of attention to getting the squish right and the combustion chambers the same size. I am much more satisfied with the performance of the last two. I have finned aluminum heads on them, mainly because I like the looks, but also because grinding aluminum is a lot easier than grinding cast iron.

I no longer worry about the compression ratio; I find if I get the everything the way I want it, I end up with about 160 lbs of compression. I don't know what that computes to, but I like it fine. I think Ol' Ron is right on this; the most important things you can do with a flathead is to get the combustion chambers right, and all else will follow.

Re: milling iron heads
 

Now I know where the 5 degrees comes from. When running a hi lift cal, you may have to clearance the heads for valve lift. I reccomend using a 5 degree angle mill to do this. The reason is: it will remove very little material and have little affect on the Cr as the valves come up at aprox the same angle. Find a set of EAB heads these have the smallest chambers and come on all late 51-53 ford engines.

Re: milling iron heads
 

If you are going to use 59AB heads on a 59A engine, there is a slight difference in the valve location on the 59AB. The 59A heads need to have the area surrounding the valve head milled out for side clearance. Also, you should search for the specs on the center water hole mods for better colling and make sure your heads have the later hole sizes. I have those specs someplace and will provide the info if you can't find it.

Re: milling iron heads
 

So, Ron - are all non stock cams high lift cams or only the full race ones? More specifically, is the L100 considered a high lift cam?

Re: milling iron heads
 

Well Tom the stock cam has about .300" net lift. And the L-100 aprox .360" net lift. So the higher lift means a smaller base circle on the cam, and the lifter is further down the bore needing a longer valve. There is a reason for making a modification, or change to any part of the engine.
"Building an engine is different than assembling one"

Re: milling iron heads
 

I don't really consider an L-100 as a high lift cam. The stock Merc cam is .330 lift. I think the L-100 will clear any stock head configuration with ease. When you get over .380 to .390, that's high lift.

Re: milling iron heads
 

According to the spec sheet on my L-100 the intake lift is .373 & the exhaust is .361 .
I have not checked or installed the stock heads yet. They have been surfaced .010. Can't wait to see what will happen, I don't work to fast so my be a while.

Re: milling iron heads
 

Is that gross lift or installed lift?

Re: milling iron heads
 

I assume you would call that installed lift as it came of the cam grinders spec sheet I really don't know to be positive but they ran it on some kind of a test machine. The machine shop sent it to them this all I have.

Re: milling iron heads
 

The original CT L-100 had .375 for both intake and exhaust. with .016 clearance, Thus aprox .360 net lift. However, on a reground stock cam, allot of material is removed from the base circle to get that much lift. I consider any cam over .350 net lift a hi lift cam. again the Isky 400jr ground on a billet would still have allot removed from he base circle due to the fact it must fit through the cam bearings. I'm also Conservative when I build a street engine. I look for reliability and economy, anlong with long life. Thus 50 lbs of valve spring pressure.

Re: milling iron heads
 

The original CT L-100 had .375 for both intake and exhaust. with .016 clearance, Thus aprox .360 net lift. However, on a reground stock cam, allot of material is removed from the base circle to get that much lift. I consider any cam over .350 net lift a hi lift cam. again the Isky 400jr ground on a billet would still have allot removed from he base circle due to the fact it must fit through the cam bearings. I'm also Conservative when I build a street engine. I look for reliability and economy, anlong with long life. Thus 50 lbs of valve spring pressure.

Re: milling iron heads
 

Hey Ron,
Was 50 lbs stock seat pressure on a factory engine ?

Re: milling iron heads
 

Here is the spec sheet on my cam grind L100

Re: milling iron heads
 

The sheet specs lobe lift, so you need to subtract .014 to get actual lift at the valve.

Re: milling iron heads
 

Bob C posted the factory specs a day or two ago.

"I found these valve specs in the Ford truck service manual, I think the car
would be similar.
1949-50 Test Length 2.13" 37-40 lbs
1951 Test Length 1.89" 40-43 lbs"

Don't believe any factory spec was in the 50lb range, that would have been a "Hot Rod" number.

Re: milling iron heads
 

use a stock spring with a .060-" shim, this gives between 50/55 lbs

Re: milling iron heads
 

Very good specs, thanks much !

Re: milling iron heads
 

Thanks much for sharing this information !

Re: milling iron heads
 

Just to clarify, would that be with the longer (Chev.) valves?

Re: milling iron heads
 

My experience: I used the chevy valve and LZ springs from Red's Headers with the keeper in the bottom slot. Jim said the springs would give about 80# on a stock valve. I used one .060 shim all the valves and an additional .010" on some to get 45# to 52#.

Re: milling iron heads
 

That's been my experience also.

Re: milling iron heads
 

I was able to find a new set of Canadian aluminum heads, as I wanted the appearance of stock heads. Then had them modified after a lot of measuring to accommodate a high-lift
Potvin 425 cam. They seem great, but now I think I would rather have the finned heads for the appearance.
Jim