MTFCA Forum

Not. new to old cars but new to Model Ts My question is what is the difference between a low head and a high head? Thanks

One is desirable (the low head), the other you donate keep in a jon boat as an anchor.

The low head gives more compression... the amount, someone else with more expertise may be able to answer that.

The noticeable difference is the water neck is taller. If you don't have much experience, the noticeable giveaway is looking at the passenger side water outlet threads. The deck plane where the head bolts mates to the head is flush to the water inlet threads. The low head you'll have a ~3/8 gap.

The low heads are vulnerable to cracking mostly along the neck. If purchasing a low head anywhere, inspect extremely close. I've also seen them crack on the drivers side.

Value depends on the markings or lack of; and condition of course.

I believe the high heads can be milled 125 thou. and will match a low head. Correct?

The low head was used on the earlier cars, but at the outset of WW 1 the quality of fuel was poorer and the company lowered the compression to keep the engine from knocking. The high head actually has more coolant capacity but it does have lower compression. Please do not cs said. Do not use the high head for a boat anchor. It works very well and if you want to raise compression there are high compression after market heads available from the parts vendors. Many people want the head to match the year model of their car, and because so many later cars have used low heads, they make them more rare and harder to find for the cars which actually came with them. Same thing applies to the 26-27 wire wheels. Those wheels were only used by the manufacturer for those two years and even then not all the cars had the wire wheels and hubs. Many speedster owners have used the later wheels making them more rare and raising the price of those too.
Anyway, I have spoken my opinion. Yours might be different.

If you are looking for a difference to identify which is which, check out the combustion chambers. A low, [earlier] head will have pronounced rim around the spark plug hole, whereas the later high head appears as though they just drilled a hole and tapped it with thread.
Hope this helps.
Allan from down under.

Man! you all made it hard for him, it's simple, the low head is 2" tall at the head bolts and the high head is 2-1/2" tall at the bolts.

Lots of info can be found in previous posts on the old forum. Best way to find them is through a Google search.

https://www.google.com/search?q=mtfca+low+vs+high+head

Found a picture

Thank you all for your replies. Now I know.