Judges

[442w30]

I think it was introduced in the middle of the model year for the Judge. That's one reason.

Another is that the RAIII was standard on the Judge. The 455 really is not an improvement.

For years, we didn't know this engine was available on the Judge. It stands to reason why - apparently, no one knew in '70 either!

[gtaa9]

I suppose thats why cars are considered rare today because of that fact.Whats the difference between the 70 455HO and the 71 455HO?

[DaJudge]

A 71 455 HO has an aluminum intake, round port heads, essentially a RA IV top end. A 70 455 has iron intake, d port heads, it was basically a big car engine in a GTO. A 71 455 HO is much more desireable than a 70 455.

[gtaa9]

Big difference between the two.Even with lower compression I would pick the 71 455HO over the 70.Why did Pontiac call the 70 455 a HO motor?Either you or steved said the 70 455 was out of a big pontiac.Was there any differences with the big car 455 and the 70 455 motor?When the factory put the 455 in the 70 GTO was there any mods done to it to made it differant from the big car 455?

[Steve_Hoog]

Jeff

455 in any 70 car was basically the same, the cam was 067 in M40 and 068 MT.

So why the less HP than the 69 428 HO that used the same cams?

The head CC’s had to be more than 400 to present a streetable compression ratio and we know the heads were of less quality than say a 48. So what if they had put a 48 or even RAIV head, guess boost the HP 30 to 50 points for the added compression and flow. Then add the biggest cam, RAIV and you would get an unbelievable motor. Guessing 425 to 450 HP?

As much static as Pontiac got from the Chevrolet division about trying knocking them off the top, you think this dream motor would have helped? And don’t forget, the RAV engine was ever so close to a reality.

I must also correct myself, I believe the 63 SD 421 rated 410 HP making it top chief.

[gtaa9]

I pick it because of the RAlV top end round port heads ect plus driveablity.Does the 428HO have round port heads?I know the 455HO has lower compression than the 428HO but the 455HO motor is more tammer with tons of torque.

[Steve_Hoog]

428 used high compression D 72cc like 16 and 48, the heads on the 455HO are 111cc and it seems maybe they used the 1.5 geometry in the rocker area instead of the RAIV 1.65. Many people have proven the D ports can be made to flow as well as the round ports, and you would probably tell little difference at the track. I will go performance over the stigma of some hard to find heads until such time my pocket book is endless.

In contrast a few lucky people have the rarest exotic Pontiac goodies, for example Tom (TJS). A very nice person who has some of the hardest to find factory stuff, and has the means to use it well. I admire that, but he is in different league than me at this time.

So I go for the quickest my buck can buy, I won't waste time chasing 111cc round ports. There is nothing wrong with it, if that's what a person needs.The may actually be a good head to use with a blower set up.

There is just too much horsepower loss by running 111cc on a flat top with 8.1 compression, compared to the same motor with some 72cc would make 11.0. I have heard it estimated that each compression point is worth about 50 HP.

[Steve_Hoog]

Jeff

Of course if you’re a factory HP nut, then the 70 455 is hands down the winner. Rated at 370, the 70 455 is right there with RAIV ratings. Only topped by the 69 428 HO at 390.

The 71 455 is a mere 335 which puts it in the category of the garden variety high compression 400. Even a 69 350 HO is rated at 330 HP.

Obviously you can tweak any motor around any of these figures, this just makes for some good table top racing.

Some Figures

[GOAT72]

[ QUOTE ]

The 71 455 is a mere 335 which puts it in the category of the garden variety high compression 400. Even a 69 350 HO is rated at 330 HP.


[/ QUOTE ]

But Steve, in '71 GM (and others) went to net HP and all HP ratings were quoted very conservatively in order to keep the Feds off their backs.

I JUST read - in a recent issue of one of the 2 Poncho mags - that the '71 455HO was the all-time most powerful Pontiac engine and many feel it is the most desirable.

Don't make me go looking for the article!!

Mac

(My signature, below, is email from an eBay scammer who tried to sell me a bogus Camaro from London with "free shipping." I sent him a fake Western union transfer receipt and complained to no end when he didn't ship the car! )

[Steve_Hoog]

You sure better not spout off a story like that and not back it up!!!!! Or they will make a little man that holds a sign saying "Mac Sucks", just like Charley's and Belair's



Yes I know all the HP ratings were adjusted for various reasons, that is why I continually said "rated".