250 D7 Head on 65 200

Im putting a 250 D7 head onto a stock 200 Mustang engine. The Falcon Performance handbox says to take .060" off of a 200 '77 or later head. What about a 250? And what would be better, milling less off of the head and lowering the deck of the block to 0, somewhere in between, or all off of the head?

This engine is getting a cam with a longer duration than the stock, and a Holley 2300 series 2 bbl carb, and hoping to run 87 octane gas with a CR of about 8.7:1.

In my opinion I would take all of it off the head. The reason being, if you have any troubles with the head down the road and have to put the stock head back on you would have the stock compression ratio. If you mill the block and have to put the stock head back on your compression ratio would be sky high.

For best power 0 deck the block then compute what is needed for the head to achive the CR you desire. The characteristics of the head are very good but some squish/quench is lost to stock piston decking. and since the replacement head gaskets are thicker and stock CR is low seems that is the way to go.
HOWEVER it is a lot cheaper and easier to do just the head and on a stock engine you probally won't reap enough to warrant the work/cost.

After some point ('74-'75???) aren't all 200 and 250 heads the same? Check the book, I think it says in there...

I'd take it off the head - way easier/cheaper/simpler than decking the block.

jamyers":20rq18db said:

After some point ('74-'75???) aren't all 200 and 250 heads the same? Check the book, I think it says in there...

I'd take it off the head - way easier/cheaper/simpler than decking the block.

Click to expand...

Yes. The 250 head in question is identical to a 200 of the same year.

The bore in the block has more area, so it would take less milling to reduce the total volume than just the head. Obviously it would require taking the block out. And that has its own issues. But the best way to increase the CR is to mill the block to 0 deck and then mill the head.

When I put a D7 head on my 200 block, I had the block milled 0.030 to get it to zero deck and then 0.040 to get the head to the cc's I wanted.

The 250 head will have a larger combustion chamber AND the typcial replacement gaskets are thicker than the steel shim. So the CR is going the wrong way to start with. It took all that milling to get to the 9.2 I was targetting.

tanx,
Mugsy 8)