1970 Z28
New Member
I just picked up a set of 781 BBC heads oval port, are these heads any good? What cars did these come on ?
BBC Heads need info
- Thread starter 1970 Z28
- Start date
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according to mortec.com:
336781.....73-85...oval...OPEN...454, 118cc chamber, 256/114cc ports
336781.....73-85...oval...OPEN...454, 118cc chamber, 256/114cc ports
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1970 Z28
New Member
Thanks for the help guys
7
73454
Guest
781's are one of the best flowing oval ports made. There are several versions, so the only way you will know the chamber size is to CC them.
pdq67
BANNED
Just match piston dome shape and quench distance and headgasket thickness such that you create the CR. you want is all.
I use the ROSS Racing Pistons CR. Calculating site.
I use a stock piston down in the hole of .025". Then try to shoot for about 9.5 to a schosh under 10 to 1 CR., (depending on the intake valve closing point for a good Eff/Dynamic CR. of about 8 to 1), and a from .035" to .045" quench distance.
Hope this helps..
pdq67
I use the ROSS Racing Pistons CR. Calculating site.
I use a stock piston down in the hole of .025". Then try to shoot for about 9.5 to a schosh under 10 to 1 CR., (depending on the intake valve closing point for a good Eff/Dynamic CR. of about 8 to 1), and a from .035" to .045" quench distance.
Hope this helps..
pdq67
