#41  
Old 10-17-2020, 08:12 PM
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Originally Posted by Dragncar View Post
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.


Last edited by pastry_chef; 10-17-2020 at 08:39 PM.
  #42  
Old 10-17-2020, 08:38 PM
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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.

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Old 10-18-2020, 08:58 AM
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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.

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Old 10-18-2020, 10:00 AM
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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

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Old 10-18-2020, 06:10 PM
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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.

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Old 10-18-2020, 06:37 PM
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Originally Posted by pastry_chef View Post
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.

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Old 10-18-2020, 07:01 PM
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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.
Yes PMD had constraints, yet PMD knew enthusiast were well practiced in Compression and headers. Swiss Cheese

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Old 10-18-2020, 08:37 PM
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Originally Posted by Dragncar View Post
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.
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.

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Old 10-19-2020, 04:49 PM
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Originally Posted by Formulajones View Post
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.

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Old 10-19-2020, 06:14 PM
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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

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Old 10-19-2020, 07:27 PM
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Corvette is a different ball game, considered a 2 seater sports car and basically the flagship for Chevrolet very early on.
Great car the Corvette, no? Basically, it gave Chebby a way to go ape sh*t in any engine they wanted don't you think? LOL!!

I suspect the '70 Buick Stage 1 caught them totally off guard don't you think? That car, true or not said to be an alternative to to the Hemi, haha. No mention of the LS6 LOL..

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  #52  
Old 10-19-2020, 07:41 PM
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Yeah 70 was an odd year. When the engine size was lifted it wasn't the flag ship Corvette that got the big dog engine, it was the Chevelle that got the LS6. But in 71 the rolls were reversed. Go figure.

Other manufactures did similar things. If you wanted certain engines, you had to buy certain cars to get them.

I'm not complaining how things turned out though. All the manufactures had some pretty hot cars for the time and the competition kept things interesting, and you're right, Buick was right in the mix with them.

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Old 10-19-2020, 09:12 PM
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Originally Posted by Formulajones View Post
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
Come on now we all know Chevrolet made Pontiac build the Aztek. lol

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  #54  
Old 10-19-2020, 09:31 PM
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Come on now we all know Chevrolet made Pontiac build the Aztek. lol

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Old 10-19-2020, 09:55 PM
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Not sure what i can add to this but I had a 390hp 428 in my 1969 Grand Prix SJ model. It had #62 heads. I still have the heads. The block /crank was lost many years ago

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Old 10-19-2020, 10:45 PM
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OK

I have a 2 bolt drilled for 4 bolt 428 block & N crank in good shape. I scored a set of matching Pontiac 4 bolts caps (not really needed but so what), a set of 62's & Crower Sportsman's. Where I go with this is undetermined at the moment. Saving my pennies for now. Maybe a set of 722's or 614's I can afford will turn up. Would love to replicate what could have been in 69 a 428 SD w/ the 041. But that's not likely. I'll probably stick w/ the 62's.

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Old 10-22-2020, 05:38 AM
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Could be a whole lot worse - how boring would it be if all GM cars had the same engine combos like MoPar or FoMoCo... we’d all be getting excited about (1) of (1) purple cars with paisley vinyl tops and green interiors!

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Old 10-22-2020, 08:30 AM
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Could be a whole lot worse - how boring would it be if all GM cars had the same engine combos like MoPar or FoMoCo... we’d all be getting excited about (1) of (1) purple cars with paisley vinyl tops and green interiors!
Absolutely. Happen to believe the internal competition within GM divisions was a good thing and kept GM at the forefront. But, eventually the bean counters won, why have, at one time including GMC, 6 engine foundries & 6 powertrain engineering teams for cars & light trucks?

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  #59  
Old 10-22-2020, 08:53 AM
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How about we go back to the late 50s and early 60s when GMC light trucks came with Pontiac 389 motors, would that not be great?

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Old 10-22-2020, 09:13 AM
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How about we go back to the late 50s and early 60s when GMC light trucks came with Pontiac 389 motors, would that not be great?

I never understood why that was acceptable, but Pontiacs with Chevrolet engines weren't. Even as early as 71 Pontiac was using Chevrolet V8 engines.

People just can't be happy that they were at least still making Pontiacs in some form. Now it's all gone and everyone complains about that too lol

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