[67Lemons]

Originally Posted by Steve C.

UltraDyne 288/296 HFT

https://web.archive.org/web/20030325..._camshafts.htm



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The 282/290 RAIV replacement cam sounds interesting plus it’s probably a good idea to run something custom ground vs what’s in some of the white box cams in todays market

[Steve C.]

Dave Bisschop's Stump Puller hydraulic roller cam was popular.

230/236 dur @ .050" lift .590"/.592" lift with 1.52 ratio rockers 112 lobe sep

"In a recent dyno test this cam installed in a 464ci engine with 9.5 to 1 compression, a set of our 250-260cfm CNC ported #11 cast iron heads,
CNC ported cast iron Q-jet intake and a prepped Q-jet carb made 503hp and 575+ lb/ft of torque on 91 octane."

SD Performance revised Stump Puller:

Part number 51-000-11
Grind number: P8 3194B / 3196B HR112+5

281 / 287
230 / 236
.3890 / .3910
112.0 LSA / 107 ICL

His old Stump Puller mentioned above used lobes 311B and 3122B / note it has less valve lift

If Dave is not available both can be ordered custom with any Comp Cams dealer.

.

[scott70]

Originally Posted by MarkS57

Could talk of a lot of possibilities in 69 & 70 IF we had a good, forged rod. Sourcing of that rod ended the RAV if what I've read is true. Imagine a 69 428 SD Firebird and as you say, a 70 455 version. From what I've read, there was a design for a 70 455 RAIV type head, a few prototypes were said to exist.

I would think the rods would be fine as the rpms wouldn't need more than 5400 with 455/ ra4 cam but better rods are always a good idea.

[steve25]

Originally Posted by scott70

When they introduced the 455 in 70 that combo should have been an option. 455 with ra4 heads and exhaust manifolds , 1.65 rockers, ra4 intake and carb. Compression would have been high so maybe a ra4 head with 87 cc chambers. Would of been a hell of a combo for 1970. I bet it would of been right there with a LS6 Chevrolet.

The 455SD was already in development in late 1970, in fact its engine model number preceded that of the 1971 455 HO motor.
While Pontiac engineers did test a high comp SD 455 to produce a larger chamber RA4 just for a 455 would have required very expensive changes to the production line machinery and that topped with the fact that they knew low compression motors where coming meant that spending that type of money for a small volume of sales was poor business.

[scott70]

Originally Posted by steve25

The 455SD was already in development in late 1970, in fact its engine model number preceded that of the 1971 455 HO motor.
While Pontiac engineers did test a high comp SD 455 to produce a larger chamber RA4 just for a 455 would have required very expensive changes to the production line machinery and that topped with the fact that they knew low compression motors where coming meant that spending that type of money for a small volume of sales was poor business.

Basically what I'm saying is if they had put a 87cc chamber ra4 head,cam,rockers,intake and exhaust manifolds on the 70 4 bolt 455 it would of been good competition for any factory muscle car of that year. The SD 455 was low compression and a smaller cam. It was just a observation of what could of been from the factory.

[PAUL K]

I think the 70 RAIV 455, which was slated with part numbers in the GM parts catalogs would've been King of the street. It would've developed more useable power at a useful RPM than any of the other car manufacturers.

I remember ordering parts from Pontiac back in the 80's and seeing part numbers designated for that engine. I think it was referred to as the Ram Air Super Duty engine..... We came that close!

[Steve C.]

1970 GTO Ram Air IV - Exception To The Rule
Bigger Isn't Always Faster

https://www.hotrod.com/features/1970...n-to-the-rule/



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[PAUL K]

Originally Posted by Steve C.

1970 GTO Ram Air IV - Exception To The Rule
Bigger Isn't Always Faster

https://www.hotrod.com/features/1970...n-to-the-rule/



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I think I supplied that guy some of those valve cover bolts.

Nice car

[scott70]

Originally Posted by Steve C.

1970 GTO Ram Air IV - Exception To The Rule
Bigger Isn't Always Faster

https://www.hotrod.com/features/1970...n-to-the-rule/



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As we know a 9.5. -1 To 10-1 compression 455 with decent heads and a ra4 sized cam can make 450 hp with ease at 5200 ,5300 rpms. My 70 455 with original #64 heads( 254 cfm ) , ra4 sized cam( hft) ,1.60 rockers, iron intake, Qjet and 1.75” headers made 490/570 at 5200. You ain’t doing that with a 400. I run ra exhaust manifolds on the car for a more stock look and a no hassle fit. It cost me like 16 ish hp on the dyno if I remember correctly. But that was with 2.5” mandrel head pipes.. since then I’ve installed 3” rare head pipes and picked up some mph in the 1/8th. Oh what could of been for 1970 Pontiac.

[joes455]

All and all the engines were detuned but the parts were available to mix and match heads,cam and so on to make competitive hp.Thanks to the one block design.