Quote:
Originally Posted by frnkeore
I think your best and cheapest route, would be to mill the heads.
Have them take, at least .040 off them and you will notice a difference! From what you say you want, I would guess, it would be just right.
Compression, compression, compression, is that these engines, need the most, whether it's 21 or 24 stud.
If you don't already have headers, they will also help.
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If you're going to all the effort to remove the heads and have them milled, why not go a little bit further and determine how much to mill them to obtain optimum quench. Experience has shown that .050" clearance over the piston tops works best for this. Once the heads are off, make a bunch of foil balls a little larger than a BB and stick them on the top of the piston. Temporarily reinstall the heads and turn the engine over a time or two. Then remove the heads, and measure the thickness of the foil balls. This will give you some idea of how much to mill the heads. If the average thickness is around .080", a .030 cut will be best; if it's .100", you'll need to remove .050".
Don't be surprised if it is already close to .050", as the heads may have been milled before. Also, don't be surprised if the banks are different. I had a set of heads that needed .025" off of one, but .040" off the other. I had another set where the front cylinder on one side had over .100" clearance, the second a little less, the third a little less than that, and the back cylinder was .060". I had to find a machinist that had the experience and equipment to "angle mill" the head, taking more off the front than the back. I have found each situation to be unique to each engine.
After the heads have been milled, I fit them to the engine without gaskets and check to see if there are any areas of contact. I then use a die grinder to clean up any areas of interference. A quick smoothing of these areas is all that remains to be done.
I know this sounds like a lot of extra work, but in most cases, the worst part of the job is going to be getting the heads off the engine, especially if they have been on for a long time. If you're going to go through the grief of taking the heads off, you may as well do the best job of head modification (as opposed to just milling them an arbitrary amount) that you can.
I also like the sound of headers and dual exhaust on a flathead.