Quote:
Originally Posted by Ol' Ron
Pete
My options are limited to a 258 ci displacement. So CR is hard to get. Having flow tested most stock and aftermarket heads. The EAB is probably the best. Thats why they give almost 8;1 on a 276 and with the small piston clearance make for great throttle response. I'd like to have 8.5/9 on the 258 engine and the net valve lift with the D 410 cam is 390. If the new port works, I'll need the better flow of the stock heads. Now, where do you put the brass?? 10cc of brass is about a 5/8 cube in area. If he still has the fixture to hold the heads I can melt it in the transfer area at an angle towards the exhaustside. The fixture was a double gas burner from the dark ages. it held the head about 2" abouve the burners while the head was clamped to it. He heated the head up to some temp that he tested with a stick of something. Then used his acc touch to ment in the brass.. Once it was done he through an abstouse blanket over it. I might skip that part. Gota give JWL some credit here.
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I have never done an engine that small but the same principles should apply as a big one except not as great. You may have to settle for a max of 11 to 1. I can get 14 to 1 on a 321 inch engine.
First, get a set of flat top gas ported 2 ring pistons with narrow low tension rings that come to the deck. Set final piston to head clearance to .035.
Fill the dome on the heads so they will finish flat in that area.
Measure the transfer area at it's max. depth. Fill that part so it will finish about 20% less than original. If you can fill the valve area any to get your .040 clearance, do that.
You can get the job done ok with brass and it will work but if it was me, I would TIG weld it with ER70 rod with preheat, peening and slow cool.
If you put a vacuum pump on that engine and get 15 inches of Hg. you will gain about 20 hp. That will require some minor sealing mods but I can walk you through that if need be.