Shaving a t cylinder head

[Haroldc30]

Hello all
Thinking about having my model t cylinder head shaved to increase the compression it has stock pistons could someone tell me how much could be cut and be safe or would it be worth the time and expense to do so.Thanks Harold

[Steve Jelf]

What year? If it's a high head you could just switch to a low head.

[Rich Bingham]

First question for "shaving" a stock head is whether it has been resurfaced in the past (more than once, possibly ?) and how much you think you want to take off. Do the math first. Just how much greater will the compression ratio be when you're done ? Best way to greatly increase the compression ratio is with one of the new accessory heads. Or perhaps swap for an early "low" head.

(Damn hotrod kids ! )

[Dan McEachern]

Shaving a stock head will give you almost zero performance increase. Unless you nave the capability to do it yourself and have nothing better to do, consider spending the money on a good timer and properly rebuilt coils. If you really want to raise the compression, purchase one of the high compression heads.

[Jerry VanOoteghem]

Many years ago, a friend of mine did that. Don't know just how much he removed, but it had to be a lot to make any difference, (real or imagined). Turns out, unknown to him, one of the cast-in columns that sit above each combustion dome had rusted away. That, coupled with the greatly reduced material around the combustion dome, caused the entire combustion dome to break away and push up into the water jacket. What a mess!!! I believe a "Z" head will do what you want, and do it better.

[Art M]

You could use high compression pistons and a new set of rings. This is fairly easy and more affordable without the corrosion issues of aluminum heads.

[Susanne]

There was a picture a while back (don't remember where, probably tBay) of someone selling a head (IIRC it was a low head) that they had shaved, they had literally chewed well into the coolant passages to where the head looked like a skeleton... they still claimed it was "usable" and it was a "steal" at a couple hundred bucks... That image has stayed with me for a LONG long time... why one doesn't "shave" T heads unless it's absolutely necessary, and then only to the amount it takes to get them flat again.

There are a LOT of ways to up the compression on a T motor... to me, shaving a head isn't one of them.

[Haroldc30]

Thanks everyone I will take your advice I will probably go with high compression pistons .thank's Harold

[Kerry]

Piston replacement will require a check of bore size and wear. More than likely will need to be bored and that will mean pulling the engine out.

[Art M]

If your cylinder bores are worn so badly that they need to be rebored than the crankshaft bearings are most likely worn out. Rings will seat quite satisfactory with as much as .010 in wear. Been done a lot in the old days.

[Kerry]

Art, might get away with .010" wear in the old days as you say, a cast iron piston usually had a bottom ring that could reduce some piston slap, trying .010" on a aluminium piston will sound like a tin can with marbles in it rattling like a machine gun from piston slap.

[Art M]

Kerry, You are right about piston slap. In the late 50s and 60s, I was working with a lot of trucks including cement mixers. Noise didn't seem to bother the ones paying the bill.

[Joe Bell]

I was told years ago that there is a high head that has a thumb nail casting on the back, 20-21 era? That the bottom of the head was thicker and you could shave off 1/4 to get your higher compression? I was also told since you have to use a stock head on the Montana 500 this is the head they use? I have never been to the Montana 500 so I am just saying what some one told me.

[DanTreace]

Joe

The Montana 500 lists what can be done to the cylinder head, these are 2020 Rules from the website.


B2s. Any cast iron original Ford script head is allowed, but the combustion chamber is limited to 270cc minimum. The head will be measured without the head gasket, without spark plugs, and the spark plugs holes will be plugged with clay to be flush. One stock combustion chamber is required, the other chambers to mimic the stock chamber. No material can be added to the combustion chamber to equalize.


On my '27 engine, had the block decked .050" and the cylinder decked .050+". Didn't really notice any 'umpth', runs a Stipe 280 cam.

But when I installed a high compression "Z" head, that did increase performance nicely, then later changed that Z for the Prus head, and that made a better difference, smoothed out engine and higher top end too.

p.s. the Montana Rules state "any cast iron original Ford script head", wonder if they allow the late 1927 Ford iron head? That one has the script deleted!

[StanHowe]

No, it has to have Ford factory script.

[Jim Eubanks]

Harold, its not just the compression but equally important is the combustion chamber. Z heads have a combustion chamber that is much like the one Ford settled on for the Model A to increase its performace.