# Best Pontiac Motor...Ever



## tguggino (Aug 31, 2013)

Opinion question

What is the best Poncho Motor of all time?

Categories
1. Best production, out of the box? Why?
2. Best production foundation motor for modifying. Why?
3. Dream motor. Combine anything you want.... But it has to be possible to build using Pontiac parts or period correct items. 


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## oldskool (Apr 26, 2015)

tguggino said:


> Opinion question
> 
> What is the best Poncho Motor of all time?
> 
> ...


I'll play, just for kicks. 

(1) The 421SD, for racing. It's racing history proves why.

The SD455 for street/strip. Forged rods & pistons, round port heads, 800 Q-jet, 4.21 stroke. 

(2) That would be a 1970 Ram Air IV. 3 inch mains with 4-bolt caps and #614 round port heads. Modify it with a forged stroker kit, and a full tilt head job with porting. Yeah, I can see some potential there.

(3) 455HO 4-bolt block. SD455 rotating assembly, '70 RA IV heads, cam & valvetrain, intake & exhaust manifolds, and one of the '76-'79 800cfm Q-jets, modfied by Cliff Ruggles. That should take care of the basics, if limited to Pontiac(non aftermarket) parts. Should be quite steetable, and capable of easy low 12's, in a heavy Goat. 

Hey, Pontiac had some great parts, in the '60's and '70's. They just never seemed to be able to get all the best parts into one engine package. I'll blame the federal gov for that. Without the Gov restraints and GM execs trying to comply, the boys at Pontiac would have built the SD455 to specs similar to those I listed. They did have a RA4 grind cam and an alum intake in mind for it. But the higher ups scrapped those plans. In fact they tried to scrap the SD455 completely. But there were so many orders for 'em, they decided to go ahead and use the parts they already had. As I'm sure most of you guys know, they cancelled the SD455 GTO AFTER 1 of the car mags had already named it "Car of the Year".


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## tguggino (Aug 31, 2013)

Thanks for playing. I agree on the 421 SD. Never seen one in person but you tubed a few videos of early Catalina's. Screams like an all out race motor. 

Thanks for the info on the 70 RA. Didn't know that. I would have thought 73/4 455 SD would be awesome foundation. 

I hear all of folks talking up the late 60's 428 as a perfect bore/ stroke to build a great motor. Anyone have an opinion?


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## oldskool (Apr 26, 2015)

*428*

"...I hear all of folks talking up the late 60's 428 as a perfect bore/ stroke to build a great motor. Anyone have an opinion?"


Yeah, the 428 is OK. But with less cubes than the 455, you'd need to wind it on up to make more power. And since it has the large 3.25 mains, a 400 block would be better, even if you decided to run a 4" stroker crank. (And I'd go with a '70 4-bolt main block, because they have all 5 motor mount bolt holes, so you could run it in any body style without adapters or motor plates.)

Smokey Yunick discovered this, running circle track with the 421. With the big mains he couldn't get 'em to last 500 laps. So, he started using the 389 block, and cutting down the main journals of the 421 crank, to fit. So, he had the 4" 421 stroke, with the 3" 389 mains. Worked out great. He and Fireball Roberts won just about everything they had at Daytona, in '62 ! :thumbsup:


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## BearGFR (Aug 25, 2008)

Fun topic...

1. Tossup - 421SD or RA-V 400

2. 400 stroker - 461 for the street (4.155 bore x 4.25 stroke) because on the street, torque and inches rule the day. 433 for race (4.155 bore X 4.000 stroke) because the shorter stroke means you can cam it 'enough' to spin it up where the power is - all forged internals, solid roller valve train, good single plane intake with "enough" carb, or custom dual plane, dual quad with lots of plenum and long runners. These heads => Aluminum Cylinder Heads - Pontiac - Performer RPM CNC - Edelbrock, LLC. professionally worked and ported. Tri-Y headers.

3. "Maximum effort" RA-IV/V 4-bolt block, 4.000 stroke, with enough cam, intake/carb, exhaust, and heads to be able to live in the stratosphere. Exotic heads: M/T Hemi's, race prepped Tigers or new aluminum RA-V's if we're going racing. Forced induction - turbo(s) or screw type blower. Fueled on alky or race gas.

Bear


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## 1968gto421 (Mar 28, 2014)

Bear and Oldskool have done it so well, I'm just going to watch what happens here. I love my 428 but am planning to keep it a low revver with those big mains. Good excuse to keep the stock 6X-4 heads to keep it down.


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## geeteeohguy (Feb 2, 2008)

Nothing to add here. Oldskool and Bear nailed it. For nostalgic reasons, I really like the 421 SD's and HO's, though.


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## PontiacJim (Dec 29, 2012)

Make mine the SOHC 421 to top the list. Its experimental, but.....
The GM division built three different experimental SOHC 421 CID V8 engines in the early 1960s. According to the engineers who worked on the project, the SOHC 421 engines produced around 625 hp and were capable of turning 7,000 rpm. One version of the engine featured camshafts driven off the front of the engine, another design had the cams driven by gears off the back of the engine.

:thumbsup:


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## BearGFR (Aug 25, 2008)

Oh yeah! Man I forgot about McKellar's cammers!

Bear


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## ALKYGTO (Mar 29, 2010)

Jim, I'll see your SOHC and raise you one, with DOHC Hemi heads!

I wish they would have made THIS engine......

The first line of the story reads "Pontiac's 427 experimental V8 has all the right stuff for showing or going: aluminum block and hemi heads, direct port injection, overhead cams, main bearing girdle _ and the package is wrapped beautifully......

HRM October 1970

This must have been just before the governments EPA noose tightened around the OE's necks.....:00/o:

:nopity:


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## geeteeohguy (Feb 2, 2008)

Great call, Jim! I too forgot all about Mac's cammer motors....he had an OHC 421 in a '63 GP or Cat (can't remember exactly) that was Nocturne Blue with a 4 speed that he drove up until he passed away....a real gearhead! Now how about a Pontiac with the Mickey Thompson Hemi heads? There's a guy on the other forum, Steve Barcak of Pontiac Heaven in Arizona, who has several of these. Talk about hens teeth!!


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## Red1970GTO (Jun 25, 2011)

oldskool said:


> Hey, Pontiac had some great parts, in the '60's and '70's. They just never seemed to be able to get all the best parts into one engine package. I'll blame the federal gov for that.


 The Feds to blame? Maybe a byte, but I'd put the lions' share of the blame squarely on PMD's '40's and '50's stuffy heritage. There were an awful lot of "_old stodgy guys_" at PMD who did *not *like racing in any way, shape or form. The "_We Build Excitement_" guys were brought in to PMD -- not developed there -- and once they left...

Corporate's predisposition towards Chevrolet Motor Division didn't help any either.


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## tguggino (Aug 31, 2013)

Never even knew about these. Awesome dialogue. I knew John D got promoted and I think Bunky went to Ford. Even with all the gov stuff, imagine of the 6 cylinder ohc was allowed to mature. Well engineered Inline 6 was the main BMW engine for decades. 


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## geeteeohguy (Feb 2, 2008)

JZD was the main thrust behind the OHC-6 in the '60's, and saw the need for a more blanced, european style car. The engine was light and powerful, and the cars with this engine had much less dead weight on the front end, and handled better. But the USA of the '60's was not yet ready to embrace this approach, and it wasn't too popular, when a V8 could be had for about the same cost. JZD was ahead of his time, with the GTO and the Sprint.


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## PontiacJim (Dec 29, 2012)

ALKYGTO said:


> Jim, I'll see your SOHC and raise you one, with DOHC Hemi heads!
> 
> I wish they would have made THIS engine......
> 
> ...


AHA! The DOHC on the cover was actually a paper mache model. Very few parts were actually made, but the heads were as well as an aluminum block.

The 1968 Brabham 303CI engine was handbuilt with twin overhead cams and fuel injection. 4 of these were built by Brabham-Repco in Australia on instructions by John Delorean. The engines did not produce as much power as the RA IV engine and no more were built.

A 3-valve cylinder head, 1 big intake & 2 small exhaust valves, was produced in 1964. Engineering planned on producing an overhead cam racing engine but corporate shut down the program - probably due to the corporate racing ban.

Here is another insight, the factory Wide Open Throttle upshifts for the RA V with automatic was to be set at 6,300 RPM's. Pontiac "short-shifted" their automatic cars 400 RPM's under the horsepower peak making the the RA V horsepower peak at 6,700-6,800 RPM's.

Looking over some Super Stock class drag numbers/times, the SD455 seems to be the best getting into the low 11's - but the factory lightweight 421 SD seem to be a close second, but my guess is that they also had to use 7" slicks compared the the later 9" slicks (and perhaps better rubber compounds as well). :thumbsup:


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