I recently picked up a low(higher compression) head with the intent of putting it on my 26 engine. Engine has just shy of 2000 miles since a short block rebuild with a reconditioned crank that's 0.010 under stock diameter on the mains and rod journals. I'm running 0.040 over stock aluminum pistons(not high compression)and have stainless valves on a stock cam. I've heard some discussi0n that upping the compression could break the crank and I've also heard that the early low heads don't really increase the compression that much. Before I do something I might regret, what's the consensus on putting this head on my engine? Is it safe to do?
The low head won't line up with your '26 radiator. You need a Z-head. It won't break your crank. There are hundreds of them out there running just fine. It is the best thing you can do for a T.
Should not have a problem, I ran one for about four years then found a higher compression and liked it a whole lot more.
The stock unmilled low head will increase compression a little and will help some and will not hurt anything. When people talk about higher compression they are talking about 6 or 7 to 1 compression. With the stock low head you will still be under 4 to 1 compression. I could be off on the numbers but I think the stock high head is about 3.65 to 1 and the low head 3.85 (or there about's) to 1.
Remember, one of the differences between low and high head is also water volume and may adversely affect cooling if you have a heavier car and live in warmer climes.
I've had a low head on my 27 for 20 years and it was on the car at least 10 years before I bought it. Uses 26 27 fan assy. No problems with lineup or overheating. Removed water pump when I bought the car.
If the low head has "Made in USA" it is only a point or two higher compression than a later high head.
The low heads made through the end of 1912 model year have slightly smaller combustion chambers. So they give better performance than the 1913 and later heads. These early heads have a date code above the "Ford" script and again, do not say "Made in USA".