[north]

And back then I was rarely careful!!!

Much better driving car than a GTO, body was rock solid with almost no flex and just seemed to be a better balanced, more buttoned down car.

[Pontiyak]

Anyone here know of a documented one of the Royal Bobcat 428HO cars .
6 - 4 speeds (M21) or 6 - TH400 cars ?

Any other documented of the 22 (M21/3.90) other than red car posted ?

Dave

[MRGPHO]

Originally Posted by north

I have never seen anything official contradicting what Rich says. All factory authorized documents state that all 428's (in GP's) used 62 heads. But I could see logically how the manual HO's could have followed the GTO pattern of 068 cams going with 48 heads, its possible (but not documented) that 48's were used on man trans HO's. Several clearly untouched never apart original engines would give some credence but given the very low production and the even lower survival rate I doubt there are many possible examples to verify

To me a clearer situation is the myth of lower cc 48 heads in 350 HO's, here there is again absolutely no proof of this, only one part number is listed for all 48 heads, no reference is made to a distinction in any document I am aware of. When people mention lower cc's in some 48 heads as proof there would have to be some proper professional measurement and then also in such circumstances the depth and width of the head casting would need measuring to insure that the lower cc's are not simply the result of repair shops surfacing heads to correct for warpage or to increase performance back in the hi-test gas days.

I found this in "High Performance Pontiac" magazine from March 2009 - volume 30 No.3 on pages 86 and 88 from Jim Taylor under cylinder head clarification on the #48 head for 1969. "the XC code 350 engine w No. 48 heads was and is known as a 350HO, having 325 advertised horsepower. This is a very rare engine. The exact same engine w an XJ code in an A body was rated at 330 hp. Both had #48 heads and the advertised compression ratio was 10:5 to 1. The #48 head was also used in the 400 engine. The WS coded 400 engine was rated at 366 hp, and Pontiac listed the compression ratio at 10:75 to 1. This is a ram air III engine. There were two versions of the 69 #48 head. After 40 years of buying, selling and building #48's we have seen two different chamber volumes - 66 and 70 cc versions".
I thought I saw a very similar reference in Pontiac Enthusiast magazine from Pete McCarthy, but I can't seem to find it! Any way the point is - like you mentioned earlier - to have the heads cc'd to make sure you know what you have!! Seems crazy that Pontiac would have 2 different chamber volumes on the same head number on the same year? Talk about confusing...