428 ho talk
 

Let's talk about how in the world Pontiac gave the 1969 428 HO motor a 390 hp rating when the 1969 366 hp 400 RAIII manual trans motors atleast for the first half of the production run had more Cam and with the small chamber casting number 48 heads far more compression !

Also note that the then new 1970 455 in the A body cars where only rated at 370 hp with everything being the same but for the hp Exh Manifolds.

You already know the answer. The pre-72 HP ratings are very suspect. They would tweak up or down the settings on the dyno to suit the situation. Got a weak engine that needs the numbers padded for marketing? Remove accys, air filter and set tune on kill. Need to shave a few to pass HP/weight mandates? Detune and re-test. The 72-newer SAE test clarified a lot of the gamesmanship.

Did to 70 455's come with the 068 cam? I believe the 428 HO's did; at least the MT ones (WZ's?). :)

In the top of the B body line Grand Prix, yes it came with the 068 Cam as shown in this Pontiac literature.

Note the higher rpm Torque peak besides the 10 extra hp.

Of the '70 Pontiac 455 big valve engines, only the stick coded engines had the S grind (068) cam. Have torn down too many originals, a WA, 2 YA's, a YC, & over a half dozen XF's with original cams. Have not removed the original cam from my '69 428 HO GP's XG engine, but am betting since its an auto code, it will also have the P cam.

I've explained this before.

330 hp in Firebird --->3300 lbs
360 hp in GTO ---> 3600 lbs
390 hp in GP ---> 3900 lbs

Adverised HP ratings were to a degree, arbitrary, & were totally tied to GM's policy of the hp to weight ratio could not be less than 10.0-1 (other than Chevrolet's golden child, the corvette. Several before discussed examples include:

- the throttle limiting tab on the '67 & '68 Firebird 400 Qjet with resultant advertised HP ratings in the 325-340 range.

- the 330hp rating on '70 400 4bbl engines in a '70 Tempest or LeMans. In hindsight, the automatic engine offered could have easily been the base 400 4bbl YS instead of the small valve XV 400, as either engine was backed by a Turbo 400 transmission which adds weight over the HD 3spd manual. When so ordered, even a super strippo 70 Tempest Coupe with 400 WT engine & a HD Muncie 3sod, the resulting car will not weigh under 3500 lbs, wet.

Selecting the '69 GrandPrix, near the first month of production, power disc brakes were not standard. Very soon after, power disc brakes & their accompanying 7" wide wheels became standard, & as such added more weight to the vehicle. Ordering out a total strippo non AC, manual steering, drum brake Model J with the 428HO engine & a Muncie 4sod... I'd bet with fluids (wet) such a stripped '69 GP would not weigh under 3900 lbs. In effect, the 10.0-1 "rule" would be safe.

According to the Wallace site, the 69 428 HO looks similar to the 70. The 390 MT's got the 068 cam and the AT's the 067. However, it also says the 390 HO MT got the 48 heads and the AT's 62's.

Since we are talking about the 428 are you saying 242177P that the 360 hp 428 came in the GTO, because they did not!

And the other kicker her since we are talking about 428 motors is the 1967 428 360 hp motor that was a 2bbl motor!

So if we are too believe the numbers here we have a 428 2bbl motor making 10 hp more then 4 bbl 400 350 hp base line motor in the A body line.

The only 360 hp rated non 389 motor in the GTO was the 1968 mid year 400 option RAII motor, or as I posted above the 1970 455.

I had 2 1969 mt trans 428 motors and they did not have casting number 48 heads.

Sigh. In 1967, the base 400 in the GTO was rated at 335 hp. Meanwhile, the top of the line Ram Air 400 in the 67 Firebird only had "325 hp". If I put you in a room that has an eight foot ceiling, and ask you to bounce a ball off the ground as hard as you can, you're never going to bounce it any higher than the ceiling.

Oh, and the 67 GTO had two motors rated at 360 hp. The 400HO, and the Ram Air.

1st, great thread!

For 1968 GTO's, there was some mis-information out there years ago regarding the 360 HP engines. When I got my first 68 GTO (1975), it was the base 400 4BBL engine w/ a 4 speed & 3.36 rear, I had a go around with my insurance company regarding the horsepower figure. The ins company was saying even the base engine was 360HP. It took a bit to get them to see that there was a difference between the various RA & HO engines & the base 400. Eventually, they determined I had a 350HP 400 and they didn't jack my rates. :)

Yeah, the 48 heads were a surprise to me. 62's & I think 216's (?) I've seen before. :confused2

The lower hp ratings in the F body's was due to limited throttle openings when you are comparing motors in the A body cars fitted with the same Cam, heads and stock Exh Manifolds or not.

my 69 YK 428 HO had long Branch manifolds, 48s, and a decent Q-JET. 390 HP seems to be an honest Rating.

GTO HO EXH manifolds and Cams vs Long Branch...hmmm seems the RPM for HP was set low.

Interesting thread, moreso since my '68 GTO has a '69 Grand Prix 428. I know it needs work cuz it pulls like a worn 350 with its 6X-4 heads and any guess as to quality and actual mileage on the previous, previous owner's rebuild.

I ❤ 428. There. I said it.
 

The limited throttle openings were there because of the corporate edict. And, I hate to
be the one that has to break it to you, but the 69 Grand Prix isn't an A-body.

Honestly, I love the 428s. And I'd love it even more if my 69 428 possessed some kind of
extra-magical kick to it, but let's be realistic. Even though mine was factory rated at 370
horsepower, it was never in the same league as a RamAirIV. Weird.

I know you're smarter than this, what's the hang up??

What is sad is that "corporate" kept us from having 428s with RAIV heads and all the rest of the goodies in GTOs and Firebirds. The street wars would have been a whole lot different.
Ah, then you have the 1970 10-1 SD 455 street monster that Chevy was NEVER going to let us have. That project eventually became the 73-74 low compression SD 455. Which still was a great engine. But the original intent was far different and more powerful.
Chevrolet could not have that now.

You are just dreaming. That would still not be enough head to produce the HP to hang with the Chevy's. Now a 428 (I like the shorter stroke) with good forged rods and pistons and a street / production version of the RAV head would be a different story.. :D

Stan

For want of a forged rod perhaps & not so much focus on the tunnel ports? But point taken, Bowtie management had a lot of pull. As in 63 when it was obvious PMD was a bonafide challenge to Chebby.

No, not dreaming anything Stan. There was actually 2 sets of 90cc SD455 heads made. Dan Whitmore had a PMD engineer bring a set by his shop back in the day. Casting # 96. They even had the pushrod tubes like the 73-74 SD 455 heads. Dan held the heads in his hands, its all true.

The engine was going to be a 455, 10-1, forged pistons and rods, the SD 455 block, N crank, RAIV aluminum intake with the SD 455 Q jet, RAIV cam and valve train, Ram Air ex.
A street monster. It would have made well over 450HP and more than a equal to the LS6 454 on the street.
Not "dreaming" at all Stan. This thing almost happened.
And there were 428s with forged cranks and 2x4 tunnel ram intakes for RAV heads in the works too. They made some intakes and some Kellogg cranks also but 3" main for the RAV block.
Chevy killed a LOT of PMDs plans that would have put them at the top on the street.
A person who knew what they were doing could keep up with a LS6 with a RAIV in stock form. This 10-1 455SD would have pummeled the LS6.

Really?

Stan

I think so Stan. Its my opinion. And was Dan Whitmores also. That engine would have made as much HP as the stock LS6 and more torque.
It would have ruled the streets.

I never said that the GP was a A body, please go reread what I posted.

Stan is right. I love Pontiacs just as much as anyone here but I build both BBC and Pontiacs and I can tell you it's much easier, and cheaper, to make power with the BBC's. Especially if you are going to use all production parts.

Get into all the aftermarket stuff and it starts to become a more even playing field thanks to some companies stepping up to the plate for Pontiac, but even with that the BBC just has a more superior head design to start with.

You can bench race it all you want and talk about could have or would have, lol. It makes an entertaining discussion but at the end of the day it's not what I'm seeing on the dyno or at the track.

I have absolutely nothing constructive to add to this thread.

BUT, as just a casual observer, it seems that more & more often, when discussing Pontiac engines, somebody always eventually says how much more power some other brand will make, & how much cheaper a Chevy based engine can be built.

My opinion is WHO CARES ?

If somebody wants a Chevy engine, buy or build one. If someone wants a 10,000hp nitro engine & has the money to build one, do it.

But if someone just wants to badmouth the Pontiac engine & post how inferior it is, why post that on a Pontiac forum ?

I suspect there are FAR more Chevy forums where the greatness of Chevy engines can be discussed.

Opinions differ.

PS: Not meant as a put down to any particular member here. LOTS of members here have been guilty of it. I've also mentioned the fact that a small block Chevy engine can be built much cheaper than a Pontiac. But, I always recommend a Pontiac, for those who can afford it, NOT because it's the greatest engine design ever. But mostly because I'm a Pontiac freek, & I like to see a Pontiac engine in a Pontiac body, especially if that body came from the factory with a Pontiac engine. We're all entitled to our opinion.

Pontiac special parts
 

Hello all, In the early 70's I was attending a Pontiac class at the G.M. tech center in Warren,Mich. The instructor told me that George Delorean had a shop a little north off of rt. 75. I called and George said I could come by after class.I drove up and found Leader Automotive .He gave me a tour and showed me a lot of parts I never knew existed. There were aluminum blocks,small chamber S.D.455 heads, forged cranks, and RAM V parts. There was a mock-up V engine with V intake flanges and a ford tunnel port 2 four barrel top they were mating together for a customer. If the instructor hadn't sent me I probably wouldn't have got past the counter. :old:

I think if you read through the thread you'll get the impression that most in here do care. Don't think anyone is bad mouthing Pontiac either. Least I haven't seen that here. Not even sure why the comparison was brought up in the first place, it's not what Steve was asking about. I was simply stating the facts that I've seen with my experience building both engines in response to Stan and Dragncar, and it appears at least one of them is on the same page.
I suspect that most here that are diehard Pontiac fans wouldn't know or have experience with other brands. So you have to take those opinions with a grain of salt.
Besides, it's just bench racing, chit chat, interesting discussion. Like it or not.

No one said to build or use a Chevy engine.

Dragncar like to say IF Pontiac did this or that, how much more power the Pontiac would have made as compared to the Chevy. A couple of us I just trying to tell it as it is.

Stan

In the end, it is what it is.

Thanks for that. A lot of people do not realize just how much effort, how much want there was a PMD to bring us up in the horsepower department to equal or pass up Chevy.
Thing is, the Vette had to be the fastest, most powerful GM car period. Its not that Pontiac did not want to compete with them, they did. You all remember the Opal GT ? 2 seater that looked sort of like the Vette ? THAT was a Pontiac design, they wanted to compete head to head with Chevy on their terms. But were not allowed to. You know that little "bulge" on the hood just to the driver side ? It was there because the only engine corporate would let them install was a inline 6. It was too high for the hood. Pontiac took a Chevy inline 6 and made their own far better head for it. Kinda like we did with a SD 4cyl head too.
Pontiac plans were a 428 with RAV heads, forged crank and a 2x4 tunnel. Like the intake that burned up in the Beswick barn fire.
There are LOTs of other stories about things like this. Dan Whitmore was my friend, new PMD engineers, knew all the dirt. The 1970 Pontiac 427 SOHC Hemi that was never allowed to see the light of day. It would have changed the rules. Far ahead of any Chevy engine, but Chevy could not have that now.
The people behind Pontiac had the biggest balls at GM and wanted to be the best but were artificially kept down.
I have said it before and will say it again, Pontiac are a BETTER street engine than Chevy. You can use mostly factory parts and get a street car in the 10s without turning big RPM. That means they last a long time.
At our track there are no 9-1 454s in Chevelles running quicker than me. Sure are not any running longer making the power I am. Built in 1990 and still running. They have all blown up 3-4 engines in that period running close ET-MPH.
This is a PONTIAC forum and full of Pontiac nuts like me. Is the BBC a better race engine, sure. Who cares, we like Pontiacs.
We all know in the end a BBC will out run a Pontiac. BUT, in the 500-650 HP street engines Pontiacs are better. Pontiacs have their niche. A lot of die hards love the Pontiac, no other long dead engine has so many hard core race parts available and developed on the dime's than our old Stratostreak V8.
The 1970 10-1 455 SD engine that got nixed by Chevy would have been a lot like my 455 HO, its a great street engine.

Opel GT was offered with the buyer's choice of a 68 cubic inch 4 cylinder OHV engine or a 116 cubic inch 4 cylinder OHC engine. There was never a 6 cylinder engine offered.

Cracks me up how so many people get their panties in a twist over this brand is better than this or that. I've never really cared, I enjoy them all and love building, driving and racing any brand. Just poke the bear and sit back and giggle :D

If that Pontiac street car you have is so fast Dragncar, bring it out here to the muscle car drags and show everyone here in Arizona how it's done. I'm sure the PSCA has a class that fits your car. They are in Vegas next month. If ya want we can set up a friendly wager with my slow 454 that could blow up at anytime, it's been together for 20 years now making 600hp so it must be a ticking time bomb :poke:

Too funny. Self declared champions and rulers of the roost after the chickens have been gone for 50+ years...

It's all just fun. If we can't enjoy a little rivalry and appreciate all classic cars in general then we are probably in the wrong hobby. :beerchug:

The 455 Pontiac's stroke suggests that it would have had more low end torque. And on
the street, torque monsters were a force to be reckoned with. The Stage1 Buicks are fine
examples. Take the 440 SixPack versus the Hemi, being forced to run someone down on
the top end isn't much fun on the street.

A sharp tune also makes a difference. Is it fair to say that Chevies are more sensitive? :noidea:

When quoting me Please don't snip my post to make it look I said something other that what I posted.

Stan

Lighten up. I did that with Dragncar's post too. I was trying to keep things a little simpler,
uncluttered perhaps. And it's not like I didn't use ellipses to indicate there was a change
made. Hell, I was tempted to lose the pointless "Stan" at the bottom, I declined because
there was a chance it might offend you.

It's Friday, crack open a cold one and relax.

Jim Mino not only ran with - but Out Ran LS6's and Hemi's with a 68 Firebird Ram2 400 in Pure Stock Musclecar classes in the 80's - 90's

Bruno did the exact same thing with his 69 GTO Ram4 400 , 20 years later in the 2010's.

^These are Facts ^

Jim is no longer with us, but I'm sure Bruno would say 28 or 55 more cubic inches would have been very welcome. And Jim Mino would probably have agreed too.

Don't see any reason why the 70 LS-1 455 SD Pontiac wouldn't have banged all their azzes in 1/4 mile Pure Stock racing, even more so.
It just seems kind of logical - in my opinion.
Especially if guys like Mino or Bruno were driving them.
But it wouldn't re-write all the record books or changed all the history in all the other classes or racing forms.
Don Garlits Richard Petty and John Force would have still used Hemi's
Big Chief Justin wouldn't be using LS-1 455SD today either


The 68 GTO 400 H/O was also rated 360hp, same as the 68 Ram1

Never was a 2bbl 428 in anything 67-68-69
67 4bbl Base 428 was 360hp
67 428 HO was 376hp

After Paul Goldsmith outran everything , lapped AJ Foyts 2nd Place 427 Corvette TWICE (5 mile spread) in 1963 at Daytona in a 421 SD Tempest/Lemans - Pontiac got put in their place.

That's what carved/curbed our history more than anything right there and then.
Chevy NEVER stopped race development, Ford and Mopar never had to.
Pontiac played secret squirrel just a little here and there until DeLorean left.
We got some decent stuff though, and the best looking cars.
Not so bad all in all

I think you are right.
Pontiacs are a great street engine. We did pretty good for having one hand tied behind our back IMO.
But you know, Big Chief kinda is using a 455 SD. Eddy Ram Air style aluminum heads with a 4" stroke engine to boot !! So its a fat bore 421 with aluminum Ram Air heads and twin hair dryers.
Must drive his competition nuts. Billet this, billet that vs cast-cast PMD style !

Pontiac stands for:

Poor
Old
Nobody
Thinks
It's
A
Cadillac

If there were no cast parts there would have been no Pontiac

Not in these parts that I've seen but so variables in play.

Length of street that can safely full throttle.
how contaminated and slick the asphalt is, type of tires, setup of the car, driving skill and aggressiveness.

We did some crazy stuff in the past, street racing 3 cars across 3 lanes.
These days I feel street racing is just not worth the risk, just take it to the track. Maybe you won't lose traction but what if the guy beside you does and hits you near the start.

I have never seen a 428 Factory issued engine with a 2-bbl carburetor. 455, yes, but not a 428. Wondering where that info came from? Not saying they didn't make them, but my factory literature, factory service manual doesn't mention this combo. As far as I know, all 428 engines had Q-jets, iron manifolds, and an 067/068 cam. I had a bone stock 421 oversized to a 428. 068 cam, 093 heads, factory tri-power with long branch manifolds. It made 411 HP at 5800 RPM's. So it's not a stretch that a 428 HO, with same cam, better intake and a Q-jet, and better heads would make 390 HP.

Resetting expectations: I'm strongly pro-455 for GTO-type cars yet admire the nimble feeling of a 400 for Trams-AM type cars. This makes the 428 an exciting balance between to teo subtle traits of Long-Stroke vs correct stroke.

OHC-6 Spring engine is also a dramatic example of the 400 advantage; most pronounced with 4-Speed cars.

On paper an OHC-6 SPRINT with a 5000 rpm stall converter ought play well against other near-stock RPM combos.

Bottomline thought: Power is Power. HP applied beats any gearing to a wind-up spring.

As far as hp and trq output,,,a little detail goes a long ways. The original 455 motor in my 70 gto made 491 hp and 570 trq. To me its so very close to something GM could of easily put out. 9.7 -1 comp,stock intake, qjet,ra4 sized hft cam. #64 heads at 254 cfm. Jetting and timing optimized. Remove 18 hp when adding ra exhaust manifolds. Could of made something like that production seems to me. When I bought my car it still had the original 068 cam and dist setup. Taking the original springs off the dist advance weights i had to use pliers. Total timing would of probably happened after the engine redline

The 390 HP 428 was the highest rated factory HP of any Pontiac in the muscle car era. The 1970 D port 64 head 455 was rated at 370 HP. The RA IVs were close to that also.
They are all under rated. But its still sad that 390 HO 48 headed 428 with dished pistons never made it into a GTO or Firebird. And they all had cast rods, just sad. And we never got a 455 with real compression and real cam either.
Pontiac always had one hand tied behind their back.

That was more about a street Pontiac 550 HP engine will usually have more torque than a 550HP Chevy so its a advantage IMO.
You can do it with factory blocks and heads and low enough RPM the engines last a long time.
Street racing is all but dead around here. But the track has free street drags on race weekends for the kids to let off stream. Very popular but mostly tuner cars.
In the 80s street muscle car racing was so big we had lunchtime drags in High School. Talk $h!t in the morning, settle it at lunch. It was great.

Yes PMD had constraints, yet PMD knew enthusiast were well practiced in Compression and headers. Swiss Cheese

It really wasn't just Pontiac, but all of them dealt with the same cubic inch limit up through 1969. It wasn't until 1970 when that was lifted so by then with other manufactures going to 450+ cubes it only made sense Pontiac would do the same. I mean lets face it, with the cubic inch limit lifted it killed the playing field for the 428, or anything smaller than 450 cubes for that matter if you wanted to keep up.

Besides, 242177P answered Steve's question at the very beginning of this thread about the HP wars and the reasoning behind the ratings. It was all weight related.
And as you said, pretty much all those HP ratings are under the mark anyway and in most cases doesn't represent what the engines really made from any of the manufactures, not just Pontiac. It's kind of a dead topic that's been hashed out for decades since.

I had a friend in High school who's parents had a 66 Vette with a 427 and 3 carbs.
Chevy found a way, they always did. In 70 they got the LS6 monster while we got the anemic 455 with D ports, puny cam and all the rest. Only 'good" engine was a 400 with cast rods.
Chevy actually did hold Pontiac back. The 10-1 SD 455 not being built in 1970 while they got the good stuff came from Chevy's corporate power.
I will never forgive them for that.

Corvette is a different ball game, considered a 2 seater sports car and basically the flagship for Chevrolet very early on. That's basically a different discussion with different engine options that other Chevrolets didn't have, and we'd have to write a book if we open that can of worms.

But if you're trying to tell me Pontiac's demise is all Chevrolet's fault and they dictated what Pontiac did with their engines, I'm not buying it. LOL