Guest Anonymous Posted January 23, 2003 Share Posted January 23, 2003 does anyone know the diffrence between an open chamber head vs a closed chamber head? i was looking on the afr website into 68cc 195 heads. upon e-mailing them for more info i found out i cannot use 68cc heads as they have a closed chamber and i have .100 dome pistons. they told me i could use there 74cc heads milled to 68cc as they are open chamber heads. will a open chamber head make the same power, or more, or less, what really is the diffrence? besides an open chamber allowing the use of a dome piston. Quote Link to comment Share on other sites More sharing options...
Mike C Posted January 23, 2003 Share Posted January 23, 2003 I guess it depends on the manf. of the head and the piston, but the 70 LT-1 350 had .100 dome pistons and the closed chamber (64-68cc heads) Were these AFRs? Quote Link to comment Share on other sites More sharing options...
Guest Anonymous Posted January 23, 2003 Share Posted January 23, 2003 yep AFR 195 heads. and the pistons are trw .100 dome part#2304. they at AFR said there 68cc heads will not accept dome pistons. only flat tops or dish pistons. will a open chamber head make the same power as a closed chamber? or should i find a closed chamber head that will accept the .100 dome pistons? really like the flow numbers of the AFR'S. Quote Link to comment Share on other sites More sharing options...
Mudge Posted January 23, 2003 Share Posted January 23, 2003 Open chamber = smog era heads, closed chamber = muscle car heads, as a generic way to categorize them. Quote Link to comment Share on other sites More sharing options...
Mike C Posted January 23, 2003 Share Posted January 23, 2003 It is a general way of classifying heads, but there is some science to it. With GM heads, there are two different combustion chamber designs, the open (76cc) and closed (64cc) [note this is all based on old stuff as you have 58cc heads for 305's and L98 aluminum heads and some variations as well.] David Vizard says all things being equal, the closed chamber is worth 20 hp. Remember, all of this is in discussing GM production heads. Limited production (Bow Tie) and aftermarket heads throw out all of the rules. If you have bought all of your parts, I would have the dome knocked off the pistons (the difference between the 1970 and 1971 LT-1s) and have the heads angle milled and the intake re-aligned to achieve whatever compression is your goal. Quote Link to comment Share on other sites More sharing options...
Brad-ManQ45 Posted January 23, 2003 Share Posted January 23, 2003 closed chamber=better quench=less tendancy to detonate. I'd either mill the tops of pistons or get another set (JMHO). Quote Link to comment Share on other sites More sharing options...
Guest Anonymous Posted January 23, 2003 Share Posted January 23, 2003 thanks for the replys, going to sell mine of and get flat tops jim Quote Link to comment Share on other sites More sharing options...
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