69 Heads

I have a 1969 400 YS engine block, but it has 4x heads that I'm looking to change. I would like the best performing heads available. Is there any reason I couldn't use the #48 ram air III heads? Would I definitely need to convert my intake to ram air?

Thanks.

WHY WOULD YOU WANT TO CHANGE THEM? THE 4X AND 6X HEAD ARE SOME OF THE BEST HEADS OUT THERE THEY HAVE BIG BIG VALVES AND THEY HAVE SCREW IN STUDS FROM THE FACTORY THE ONLY THING THAT MIGHT NEED TO BE DONE TO THEM IS A LITTLE MACHINE WORK TO REMOVE THE SHROUDING AROUND THE VALVES THAT OCCUR ON SOME OF THESE HEADS BUT THE 4X AND 6X ARE SERIOUS POWER MAKERS !! I HAVE 6X HEADS AND THEY HAVE THE 2.11 INTAKE AND 1.77 EXHAUST VALES AND MAN DO THEY FLOW I WENT OUT OF MY WAY TO LOCATE A PAIR OF THEM! AND YOU HAVE SOME ALREADY!!! PLEASE RECONSIDER


JOHN GREEN

#48 heads flow just as well if not better
all youll nead to do is change exhaust the exhaust ports are bigger.
but #16 heads flow nice also w/some port n polishing,,,,but if you want to sell the 4Xheads looking to buy Travis williams @EdWilliams Machine e-mail me Travis and for 4x and 6 x being serius horse power maker's ill disagree #48 #31 #16 are the best for horse power
older 6x are good flower's but not some thing I would put on my goat's
anoingu@yahoo.com



travis williams

What about the 670 heads? That's what my Goat has. I thought about taking them to a machine shop and having them ported.



New Pontiac owner

Yes, bigger valves-more flow, but doesn't that reduce the compression ratio, which would reduce HP?

I know the 4X heads are not original to the 69 GTO, I have a chance to get the #48 RAIII which were available on the Judge model in 1969. I looked at some numbers on the 73GTO with the 4X heads, and the HP was around 250. I know the heads arent completely to blame, but could they be a major reason for the HP dropoff?

Some time in the early 70's the way horse power was measered changed. It became net horse as opposed to however they did it in the 60's. It is not fair to compare the two but i am not an expert on 70's heads so i really dont know. Hope this can help, Lance

they are the major reason yes..not made for horse power made for every day driver's grandmas car.
best bet get the #48 head's nice for high horse power plus they were made for it..bigger valves are not always best to much flow is not always best. if your not set up for a high flowing head youll lose horse power, (spark) etc.
#16 heads are very nice for all around use very nice for high horse power motor's up to 420 hp. but with ram air heads youl nead to change header's
#31 heads are from 68 ram air 1 very rare $$$ so #16 48 are the best for high horse power 6x heads are nice also but not my choice and also if intrested in #16 heads not all 16 heads are the same youll nead to look at the date codes because 72 #16 head is not worth haveing you want #16 head's dated from 68 to 70 hope this helps travis @ edWilliams machine,



travis williams