[steve25]

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.

[chiphead]

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.

[MarkS57]

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

['ol Pinion head]

Originally Posted by MarkS57

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

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.

[MarkS57]

Originally Posted by 'ol Pinion head

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.

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.

[steve25]

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.

[AC445]

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.

[Dragncar]

Originally Posted by AC445

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.

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.

[Bill Hanlon]

Originally Posted by Dragncar

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.

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.

[Formulajones]

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

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

[pastry_chef]

Originally Posted by Dragncar

in the 500-650 HP street engines Pontiacs are better.

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.

[Dragncar]

Originally Posted by pastry_chef

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.

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.

[242177P]

Originally Posted by steve25

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 ...

I've explained this before.

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

['ol Pinion head]

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.

[steve25]

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.

[242177P]

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.

[MarkS57]

Originally Posted by steve25

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.

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.

[mgarblik]

Originally Posted by steve25

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.

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.

[steve25]

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.

[242177P]

Originally Posted by steve25

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.

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??