double hump heads

[Randy Mitton]

My 67 327#s matching has these heads,I've seen a lot of posts regarding these heads as a lot of people talking about wanting these for an upgrade.Do these heads change the horse power rating? My car's production # is 266,is this anything unusual.Thanks,Randy

[VINCE Z28]

Are they P/N 3890462 ?

[69Z28-RS]

There were two different HP 'double hump' heads.   Some were machined for 1.94" intake valve sizes, and were used on the 295/300 hp 327/350 engines, and others were machined for 2.02" intake valve sizes, and were used on the 350 hp engines (327s' used in Corvettes for 1967)...   The casting numbers and external appearances of these heads were identical as installed, and all were called 'double hump' heads for the casting marks on the ends.
PS.  Actually for torquey street engines, the smaller valve head is preferable (IMO)...  the large valve sizes are only beneficial at very high rpms and high horsepower.

[KERR]

They are good heads for old stuff.   I had a set on my vette until about 6 months ago..  as 69Z28 said its more of a upper rpm head.. 

If your thinking about putting them up for sale to get newer aftermarket ones id just keep those if the car is matching number as you say..  last time i looked those heads where not bringing any real moeny..    Only reason i upgraded mine is nut went threw the motor and butsted a hole in the head.. 

[Randy Mitton]

Thanks for the reply's. Will check for casting numbers,I'm not really thinking of changing them but was just courious as to why all the intrest buy other people.Thanks again,Randy