#21  
Old 01-19-2022, 09:22 PM
Joe's Garage Joe's Garage is offline
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Default You will LOVE the 428. Guaranteed!

I'm with Tom S on this. 428 428 428 428.

If you're not going to be spinning it past 6k or so, use a known good factory 'N' crank, upgrade the connecting rods to some forged rods and use some quality lightweight pistons.

You just can't beat the feel of a well-thought-out 4" stroke Pontiac.

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Old 01-19-2022, 09:37 PM
tom s tom s is offline
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2 of mine are cast cranks and one of them has rebuilt cast rods in it.Tom

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Old 01-19-2022, 09:38 PM
hurryinhoosier62 hurryinhoosier62 is offline
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Originally Posted by Joe's Garage View Post
I'm with Tom S on this. 428 428 428 428.

If you're not going to be spinning it past 6k or so, use a known good factory 'N' crank, upgrade the connecting rods to some forged rods and use some quality lightweight pistons.

You just can't beat the feel of a well-thought-out 4" stroke Pontiac.
X 2. Nothing wrong with a properly inspected and prepped nodular 428 crank. My personal preference would be to have it nitrided, use either Molnar or Crower rods and a good, lightweight forging (4032 alloy) for pistons with a 1.5mm/1.5mm/3.00mm ring pack.

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  #24  
Old 01-19-2022, 10:07 PM
dmac dmac is offline
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Originally Posted by steve25 View Post
Either engine in a true street car built with good flowing aftermarket heads would be very hard to completely hook up , so to me it really boils down to how heavy your car is and it’s rear gearing in terms of what you build.

If your running a factory 4 speed then the added torque of a well built motor using just a 4.210” stroke no less a 4.250” stroke is going to eat up a factory 8.2” rear in no time!

I came up with a ratio for this in terms of added torque over a well built 400 and being able to beat on the car hard in terms of on the street usage.

Let me know what you folks think please.

The ratio goes like this , for every added 50 ft lbs of torque a given motor makes above a 3.750” stroke motor, you will spend a additional 3000 to 4000 Dollars to not bust up driveshaft, suspension and rear end parts when you beat on it over & over!

So in short the ratio is about 80 to 1.
Beefing up the transmissionisn't cheap either.

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Old 01-19-2022, 10:23 PM
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One of them is nitrated,the one with the Carrilo rods,all have forged pistons.Tom

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Old 01-19-2022, 11:18 PM
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Mike Davis Mike Davis is offline
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I have 3 engines with 4" stroke. 2 have "N" 1969 428 cranks. I ran one for years at 7K RPM with no issues before the forging I run now. I have them cryoed and nitrided. Going back to street use in a 428 4 bolt block, SM heads and a Bathtub intake.
I am a 4" stroke advocate.

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Old 01-19-2022, 11:36 PM
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Originally Posted by tom s View Post
2 of mine are cast cranks and one of them has rebuilt cast rods in it.Tom
Tom,

Are you aware that when you hit 5,501rpm those cast rods will disintegrate?

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Old 01-20-2022, 12:22 AM
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OP said "Going for a low revving 550hp."
But man, a (stock 4" stroke) 428 at 6500 rpm sounds SO GOOD!! And to me, the sound of the engine is a big part of the emotional satisfaction of these cars.

Get a cam with a wide lobe separation (114+) to flatten out the torque curve and make high-rpm horsepower. You can't hook up street tires anyway with too much torque, so sacrifice some mid-range and make up for it on the top end.

I did exactly that with my '66 GTO and the thing still makes enough power to get wheelspin on a 2nd gear roll-on at 55 mph. (3.73 gears/200-4R)

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Old 01-20-2022, 12:23 AM
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That 2500 RPMs higher the engine EVER sees!Tom

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Old 01-20-2022, 03:55 AM
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I'm another one that shifted at a little over 7,000 for years -- but with a 455 4-bolt block. Built it in 1985 and ran the snot out of it until it was retired for the AllPontiac aluminum block in 2015. Absolutely no problem with bearings, and apparently the critical point for bearing speed is above that threshold (and 7,000 RPM with a 428 has the same bearing speed as a 455 at 7,000). That engine demoted to street duty with simply dropping compression and downgrading the solid roller for a hydraulic roller cam and lifters, but it will still give you religion.

For street cars, I have a 421 with 4" stroke, had a 428 with 4" stroke, and currently have the 455 with the original 4.21" crank. Crank of choice for building out engines for friends is the 4.25" stroke with either 3.25" or 3" mains. I obtained a 1969 390 horsepower 428 a long time ago and have been saving it - but sold everything off it except the bare block. There's a great demand for 4" stroke cranks and would have been selfish for me to have held on to it being I just don't see anything magical about it. True, same horsepower just turning the engine about 500 more RPM which in a way is no big deal, and who needs that additional 50 or so foot pounds down low when you're too lazy to downshift and just roll on the throttle.

The 4-bolt 428 block will probably end up in the '65 Catalina wagon but with a 4.5" stroke since "there's no replacement for displacement".

I believe the beefiness of the blocks in descending order are 421, 428, and 455. Seems that Pontiac overkilled the beginning production and trimmed things down after that. Just personal opinion but the thickness of the blocks around the mains and the thickness of the lifter bores leads me to that conclusion. Never had a problem with 455's, but visual inspection says the 421 and 428 have a slight advantage.

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Old 01-20-2022, 09:17 AM
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Quote:
Originally Posted by hgerhardt View Post
OP said "Going for a low revving 550hp."
But man, a (stock 4" stroke) 428 at 6500 rpm sounds SO GOOD!! And to me, the sound of the engine is a big part of the emotional satisfaction of these cars.

Get a cam with a wide lobe separation (114+) to flatten out the torque curve and make high-rpm horsepower. You can't hook up street tires anyway with too much torque, so sacrifice some mid-range and make up for it on the top end.

I did exactly that with my '66 GTO and the thing still makes enough power to get wheelspin on a 2nd gear roll-on at 55 mph. (3.73 gears/200-4R)
I agree. My 455 starts to sing at 6000. It goes to 6500 but usually I buzz to 5800 to 6200. There is a sound difference between 5800 and 6200. And a good one.

  #32  
Old 01-20-2022, 10:01 AM
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Sirrotica Sirrotica is offline
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When Smokey Yunick was complaining to Pontiac about the large main journals, he was running them at superspeedways in NASCAR. It was 1962. If I remember correctly the cars had to be showroom stock, so no oil coolers were used. You may have had an 8 quart pan.

Having pored over Marvin Panch's 1960 replica of his Smokey Yunick prepared car a the POCI show at Charleston W VA back around 2010 (they were parked next to my wife and I's T shirt stand) there was no oil cooler on the reproduction car, so I feel pretty safe in the statement that at that time NASCAR didn't allow oil coolers.

Think about running 3 1/2-4 hours over 500 miles, that older oil formulation wasn't up to handling that much heat. So yes it would become overheated and probably take out the engine. Now running a quarter mile at a time isn't going to overheat the oil, even back then the oils were stout enough to run on a drag strip 4-5 times a night. It's an apples to oranges comparison.

The big deal that Bruce Flopper made about oil overheating in large journal engines wasn't drag cars, it was circle track cars. Having raced a 428 without an oil cooler on a dirt track for 3 years, with a stock oil pan, it was never a problem for me, the engine I put together in 1977 is still in storage now. It ran fine when pulled from the car, so even running 20 laps at a time, I never had oil overheating problems whatsoever. That's a lot more rigorous test than street driving, or running it at a drag strip for an evening. The whole large journal oil overheating thing was a problem on a road course, or a superspeedway, but much different circumstances than what the hobby car guy, or drag racer encounters.

I also have run 455s in my dirt cars, no problems with reliability, but having been limited to a 8 inch tire, they were hard to keep hooked up on the dirt, due to just the abundance of torque. Even on a hard dry track you had to finesse the right pedal to keep from spinning the whole straightaway. I had the same challenge with auto crossing 455 Trans Ams, the 400 cars were much easier to drive than a 455 car was, especially on street tires.

I know Mike and Eric also used 455 large journal nitrous engines in their recreation of the Grocery Getter, for years without running into oil overheating problems. For the average Joe, you're not ever going to run the engine hard enough, long enough, to have that problem. In the Boss Bird nitro car, that could have been a problem, but no one on this board has a drag racing effort like that, and afterall, this is the Street section too.


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Old 01-20-2022, 10:06 AM
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I agree. Now we can stop throwing away large journal blocks along with 350 blocks.

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Old 01-20-2022, 12:03 PM
hurryinhoosier62 hurryinhoosier62 is offline
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Quote:
Originally Posted by lust4speed View Post
I'm another one that shifted at a little over 7,000 for years -- but with a 455 4-bolt block. Built it in 1985 and ran the snot out of it until it was retired for the AllPontiac aluminum block in 2015. Absolutely no problem with bearings, and apparently the critical point for bearing speed is above that threshold (and 7,000 RPM with a 428 has the same bearing speed as a 455 at 7,000). That engine demoted to street duty with simply dropping compression and downgrading the solid roller for a hydraulic roller cam and lifters, but it will still give you religion.

For street cars, I have a 421 with 4" stroke, had a 428 with 4" stroke, and currently have the 455 with the original 4.21" crank. Crank of choice for building out engines for friends is the 4.25" stroke with either 3.25" or 3" mains. I obtained a 1969 390 horsepower 428 a long time ago and have been saving it - but sold everything off it except the bare block. There's a great demand for 4" stroke cranks and would have been selfish for me to have held on to it being I just don't see anything magical about it. True, same horsepower just turning the engine about 500 more RPM which in a way is no big deal, and who needs that additional 50 or so foot pounds down low when you're too lazy to downshift and just roll on the throttle.

The 4-bolt 428 block will probably end up in the '65 Catalina wagon but with a 4.5" stroke since "there's no replacement for displacement".

I believe the beefiness of the blocks in descending order are 421, 428, and 455. Seems that Pontiac overkilled the beginning production and trimmed things down after that. Just personal opinion but the thickness of the blocks around the mains and the thickness of the lifter bores leads me to that conclusion. Never had a problem with 455's, but visual inspection says the 421 and 428 have a slight advantage.
Mick, you are correct; I have a ‘59 389 block. Every part of that block, from the main caps to the cylinder walls, is heavier than its later model compatriots.

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  #35  
Old 01-20-2022, 07:57 PM
soupman soupman is offline
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I am a big 428 advocate. I could have build any engine size I wanted, but I had a 428 15 years ago, sold that car and just build another 428. In a lighter car with a 5 speed, and that 4” stroke really sounds great.

  #36  
Old 01-20-2022, 08:09 PM
jerry455 jerry455 is offline
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I was always told to build the biggest engine you could afford. The more cubes, the more torque. You can call the engine any size you want to. Who can tell?

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