['ol Pinion head]

Originally Posted by steve25

Unfortunately the head flow capability that the Olds heads had be it 425 or 455 cid sucked when compared to even a stock D port high comp head of the era, no less the RA4 heads!

Interesting that you've bench flowed Olds stock B, C, D, & F heads & they flowed less than a '67-70 big valve Dport head's 205-208 cfm. the peak flow data I've consistently seen on many untouched Olds heads with good valve guides is they flowed between 230-240 cfm at .500 lift (28" depression). No port work. From flow sheets all performed the same day on my own round ports that's in the range of the best stock flow '71 HO's to stock 722's.

[steve25]

And what of the exh side of the Olds heads?
On the Exh side there down 15 to 20 cfm @ .200" lift as compared to a high comp D port head with a 1.77" valve.

[Stan Weiss]

Don't the Olds have like 2.072" and 1.625" valves?

Stan

[PAUL K]

Originally Posted by Stan Weiss

Don't the Olds have like 2.072" and 1.625" valves?

Stan

Approximately but there is ample room to use bigger valves.

A race ported factory Olds head will flow around 290 @ 700.

[hurryinhoosier62]

Gentlemen, you are missing a major point in the development of the 455: emissions. Under square engines produce few emissions than over square or square engines. The first emissions control protocols were already in effect in CA.

[PAUL K]

Originally Posted by hurryinhoosier62

Gentlemen, you are missing a major point in the development of the 455: emissions. Under square engines produce few emissions than over square or square engines. The first emissions control protocols were already in effect in CA.

Haven't you ever seen an Internet thread road map... It zig zags all over the place. Kinda like one of those spaghetti maps that predict the path of a hurricane

I thought they added stroke to make up for the loss of compression. I also think they did a lot of bad guessing when diving into the emissions part.

[steve25]

First and foremost it was the switch to the open chamber heads that got most manufacturers in compliance with the Fed's limits on emissions!

Followed by Bigger motors stroke wise made for increase Torque which allowed less rear gear.
Lower rpm and less emissions go hand in hand!

[napster]

One thing you have to remember are the people who replaced DeLorean after he left Pontiac and went to Chevy. None of them starting with James McDonald were car guys. That is why Pontiac got caught with their pants down with the 455. Also, the idiot that was the division manager during 1973 was against the SD455. That is part of the reason why it was late on top of the EPA issue.
These non gear heads screwed Pontiac. That is why I always think of what Pontiac might have been if Delorean was the division manger through the end of the 1970 model year.

Think about it. Bunky Knunsen (SP) was at Ford and they had the BOSS 429 and chevy had Delorean and they came out with the 454 LS-6. All Pontiac guys that were gear heads.

[Stan Weiss]

Originally Posted by hurryinhoosier62

Gentlemen, you are missing a major point in the development of the 455: emissions. Under square engines produce few emissions than over square or square engines. The first emissions control protocols were already in effect in CA.

If that is the case why was the Pontiac 301 so over square?

Stan

[Formulajones]

Originally Posted by hurryinhoosier62

Gentlemen, you are missing a major point in the development of the 455: emissions. Under square engines produce few emissions than over square or square engines. The first emissions control protocols were already in effect in CA.

I tend to believe it was more along the lines of cost. Due to limited bore spacing, the only way Pontiac could increase the CI comparable to other brands was to simply shove a long crank in it, otherwise they would have to spend more money to completely redesign and cast a new block.

[Skip Fix]

So I'll throw a slightly related but tangential question -why did most of the jet boats in the 70s early 80s use Olds 455s vs Chevy 454, Pontiac , Buick 455s?

[PAUL K]

Originally Posted by Skip Fix

So I'll throw a slightly related but tangential question -why did most of the jet boats in the 70s early 80s use Olds 455s vs Chevy 454, Pontiac , Buick 455s?

Tons of torque from the long and relatively small intake tract.... IMO

[Stan Weiss]

Unless I am thinking of something else jet boats were not high RPM.

Stan

[Stan Weiss]

If under square was the way to go why did Pontiac use the Olds 403 - 4.351" x 3.385"?

Stan

[Formulajones]

Originally Posted by Skip Fix

So I'll throw a slightly related but tangential question -why did most of the jet boats in the 70s early 80s use Olds 455s vs Chevy 454, Pontiac , Buick 455s?

Hmmm, all the jet boats and mini off shore racers I ever saw or rode in were mainly BBC's with a few exceptions. My buddies jet boat ran a 460 ford with a tunnel ram. I don't ever recall seeing one with an Olds.

[steve25]

The old 403 has terrible flowing heads which was ashame since it had a great big Bore size.

Buick wise other then the nail head motors they have quite poor oiling systems even for just a steady 4500 rpm, so they out of all of these motors would never survive!

Other then the Olds motor bring lighter then a BBC for use in a Boat I can't see why Edelbrock made the needed water cooled Exh Manifolds for them.

I think Mondello was twisting Vic's Arm a lot to do that!

[chiphead]

Originally Posted by PAUL K

Haven't you ever seen an Internet thread road map... It zig zags all over the place. Kinda like one of those spaghetti maps that predict the path of a hurricane

I thought they added stroke to make up for the loss of compression. I also think they did a lot of bad guessing when diving into the emissions part.

Yeah, now we understand the concept of crevice volume and how much unburned hydrocarbons hide there. This is one reason there are precious few modern engines over 4" bore. The unburned HC emisions go up along with bore size. Top ring placement has an impact on crevice volume, so even that affects emissions. They didn't undertand any of that yet in the late 60s.

There were no overdrive automatics in 1970s american cars, so the only way to move a heavy car around with freeway gears is to put a larger engine in. Think of how fat these cars got by 1975-77. A 8:1 400 with 2.76 gears can't get out of its own way. They also didn't know how low the octane was going to go in the lead free gas. They figured a low compression, lean burn, low RPM tractor motor would get the job done until things got sorted. I assume they killed the 455 after '76 because it was too thirsty and they couldn't lean it out to overcome the crevice volume and pumping losses. The 350s and 400s that were left were woeful weak sauce. The emission laws of the early 80s caused a slaughter of engine families, Pontiac, IHC, Caddy, most Olds and Buick, among others ,were discontinued by '82

[Skip Fix]

Most of the ones her in Texas were Olds motors. My best friends could pop 3 of us up at once skiing! We had a powerplant lake you could ski on so even into the fall after summer jobs or school go out and ski until dark!

[Scarebird]

Originally Posted by Formulajones

I tend to believe it was more along the lines of cost. Due to limited bore spacing, the only way Pontiac could increase the CI comparable to other brands was to simply shove a long crank in it, otherwise they would have to spend more money to completely redesign and cast a new block.

That, and for every high performance platform needing a big motor you had 10+ B bodies and wagons chugging around at low rpms with 2 barrels and 2.56 gears.

[geeteeohguy]

Originally Posted by Skip Fix

So I'll throw a slightly related but tangential question -why did most of the jet boats in the 70s early 80s use Olds 455s vs Chevy 454, Pontiac , Buick 455s?

There were a lot of Olds powered jet boats in the early 80's were I was in CA as well. As a mechanic at a general shop (worked on every make) from the late 70's through the mid '90's, I saw a lot of the old large-bore V8's. Of them all, the Oldsmobile 455 was the most durable, and would put up with the most abuse/neglect. So running an Olds in a boat at high load most of the time would make sense, as there would be less down time. BBC's had valve issues, Cadillacs liked to toss rods, and Pontiacs liked to spin bearings. The old FE Fords were durable, but by then, the 427's were a lot of money. Used Olds 455's were cheap and all over the place...and they held up.