[72LuxuryLeMansLa.]

Originally Posted by Jay S

Nothing wrong with the 3.75” combo with forged rods and pistons in that. With the 3.73 gears and the 4 speed I think you’d like the 4” stroke combo the best. You’d notice the extra tq and it would still run really hard on the top end. You could put some more cam in it also with the bigger cid against the 400, not really much for a downside to me other than cost. I’d only do a forged crank (not a Chinese nodular) in that since it is numbers matching, it is going to be quite a more money over the 3.75” stock crank, but the forged 4” crank and rotating assembly would be a nice upgrade over stock. Rebalancing the stock crank again narrows the cost difference up some too. Easy to spend someone else’s money lol.

6000 miles it shouldn’t need bored, just honed.

These days you're getting Chinese whether it's cast or forged unless I'm missing something? Is there an American crank made from American steel these days?

[Jay S]

Originally Posted by 72LuxuryLeMansLa.

These days you're getting Chinese whether it's cast or forged unless I'm missing something? Is there an American crank made from American steel these days?

Your not missing anything. I sure WISH there was a forged in the USA crank available. All the forged aftermarket cranks I know of are forged in China. I think Scat and Ohio crankshaft are about the only options right now in a forged 4” cranks that are at least machined over here. Eagle, SGI (star galaxy), and speedmaster (pro comp electronics have been out of stock for a long time in 4” forged.

I added Chinese nodular to differentiate between that and a PMD factory nodular crank. I have 2 Pontiac 400 strokers with PMD 455 nodular cranks cut down to fit in 400s with shimmed Olds thrust bearings.

[Jay S]

New timing chain is likely fine installed dot to too dot. Nice to know what the ICL is exactly, but odds are it is fine.

[Cliff R]

"These days you're getting Chinese whether it's cast or forged unless I'm missing something? Is there an American crank made from American steel these days?"

You can get a USA made crank, but your are NOT going to like the price!

We demand cheap so China stepped up nicely. When they first came out, the cast steel cranks from China, I carried one to the guy who does my spinning assemblies. He told me it was a little off everyplace, stroke, out of round, balance, indexing, surface finish, etc. He said by the time he got it where it really needed to be I could have bought a custom made USA forged crank instead.

That was at least 20 years ago. Despite the warnings I built ONE engine with a cast steel crankshaft a few years later, after they supposedly correct most of the issues with them and it burned the thrust bearing out of the engine in 15 minutes running it in on the dyno.....yikes!

About 10 years later I was hired to build a 455 using a cast steel crank, I had no input into any of the parts chosen, just to assemble and dyno it. The crank and "no-name" rods were from Butler. It was noticeably better than previous cast steel cranks I've seen, and fit/finish was fine, went together and dyno'd without a glitch. The dyno numbers were off quite a bit for the combination of parts, but it was the only 455 engine I've ever done with those huge dished pistons to get the compression down to reasonable numbers.

The Star Galaxy forgings in contrast were a LOT better. All the ones I've installed here have been spot on and survive just fine clear up to 750hp in a 505 we did must close to 20 years ago now. Personally I wouldn't even glance at a cast steel crank for one of my own engines and would go forged and even then put it under the "microscope" before using it.

Just some tid-bits from someone who's actually had some direct experience with them........Cliff

[racerboy]

Thanks Cliff. I sent a note over to SGI through their eBay store to see what a forged 3.00 main/4.00 stroke with BBC journals might cost.


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[racerboy]

Interestingly, SGI does list a nodular iron 3.00” main 4.00” stroker crank (w BBC journals). The price is $300 (+ shipping) which does not seem unreasonable to me, but I’m guessing the recommendation here would be to go with a forged unit. They do say this nodular unit is good up to 550 hp.

[Jay S]

With stock heads and and RA manifolds at your power levels the 4” nodular is a pretty good fit. I am guessing if you talked to Butler’s they will tell you exactly that also. Butler’s have sold a lot of 4” nodular stroker cranks. It has the same metallurgy as the other Chinese nodulars, but is considered stronger than a 4.25” nodular since it has less stroke, and generally has less stress.

The numbers matching part of the equation on a pretty rare and cool car part is the thing that makes me hesitant and want to run a forged. No real good reasoning for that from 4” crank failures that I know of. It is more the forged is a nicer unit, and it is a upgrade over what it was stock. Again, easy to spend someone else’s money! You just get to say “It has a forged crank” and we all go:

[Dragncar]

There are no modern forged Pontiac cranks available I know of. There are old PMD forgings around.
But all modern forged Pontiac cranks are billet.
I asked Tom Molnar what it would take to make us some forgings. The fully counter-weighted type you can buy for a BBC for 1200$ This was 3-4 years ago. He said just the dies if made in the USA, 150K back then. About 50K if made in China.
Then you need to make a run of 100-200 or so and sit on them for 10+ years before you make your money back, let alone profit.
Its not happening unless some very rich Pontiac fan throws a bunch of money at it.
Might as well light that money on fire.
I say even if you charged 1500$ for them and they were made in China with the quality of Scat-Molnar people would buy them.

[racerboy]

I’m confused. I went to the Butler website and they say they do have a forged 3.00/4.00 crank made by Scat:

https://butlerperformance.com/i-2445...tegory:1234870

Granted, this costs 3x what the nodular one cost, but to Jay’s point, the WS block in my Trans Am is worth it to spend the money (at least to me).

But Dragncar said there are no new forged Pontiac cranks. Did you mean, “no forged cranks made in the US”? Are there different grades of ‘forging’ that I just don’t know about, and what Butler/Scat calls ‘forged’ is different? Or is billet different than forged?

Wouldn’t any new forged crank be better than the factory crank from 1970?

Just for kicks, I saw that Jegs has some Pontiac cranks (mostly 4.21 stroke) from Eagle that cost $1800. Why are they twice the cost of the Scat ones? Are they 2x as strong?

[Cliff R]

One of the 505's I did with a Star Galaxy forged crank has CNC ported High Port heads, 14 to 1 compression, 270-280 something @ .050" solid roller cam, Victor intake, 1050 Dominator carb, and cranked out just shy of 750hp on the dyno. It has lived in a full race application coming up on 20 years with one tear down. It got new Pac springs and we tossed out the Scorpion rocker arms because 13 out of 16 of them were cracked.

The main and rod bearings were mint condition, but replaced the rod bearings anyhow..

An offshore cast steel crank wouldn't have last 20 passes at the track at that power level.....IMHO.

IF you want to sleep better at night hold out for the forging.........FWIW.......Cliff

[Jay S]

For $1800 at jegs from something from Eagle you may have been looking at complete Eagle rotating assembly?

Eagle crankshafts are generally a little cheaper than Scat. Use to be a quality difference between the two brands, Eagle seems like they caught up though.

Scat forged 4” gets my vote.

[Steve C.]

In early April 2018 I bought a SCAT 4.250" forged crank with 3" mains from Paul Knippen. It replaced a Crower 4.250" Billet crank I purchased in 2005 that went bad.
Paul's pricing was as good as you can get !



.

[racerboy]

Star Galaxy got back to me and confirmed that they do not have any 4.00" stroker cranks in stock. I also reached out to Paul K. If he doesn't have them, I'll call Butler.

[racerboy]

Working with Paul K offline to put together my 4.00” stroker rotating assembly.

I need to pull the 400 and determine if it just needs a clean-up home (hopefully) or a re-bore, so we can get the process started regarding pistons. Seems like they will be the biggest bottleneck. With less than 6000 miles since the rebuild in 2009, I’m hoping it doesn’t need a re-bore.

In the interim, I want to drop the 428/670 combo I have in the Trans Am while the 400 is being built. That is also a relatively low mileage engine since it’s rebuild in 2002 (maybe 8k miles, but probably more like 6k). This engine was in my ‘67 GTO for 10+ years before it’s frame-off. A couple of questions regarding this swap:

1. I used an aftermarket clutch on the engine when it was in the GTO with an M-20. Can I reuse this clutch in the Trans Am with an M-21? Or should I just get a new clutch/disc?

2. I also used an aftermarket steel flywheel that is drilled for both a 10.5 and 11 inch clutch. Do I need to have this cut or can I just use it ‘as is’?

3. Someone told me to replace the pilot bushing since engine is out of the car anyway. Is it better to use a pilot bearing instead of a bushing?

Thanks. I posted another question over on the 70-73 Trans Am board about which motor mount adapters to use to fit a ‘69 428 in a ‘70 Trans Am chassis.


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[Half-Inch Stud]

Sold my SGI forged crank moments before this Thread started. It was 4.21 Stroke 3.25"Main BBC rod and sitting nicley in my Spare 462 (sold the Short Block).

Sounds like the buyer got a bargain moreso than I intended. I intend to stay N103 if need be.

[tom s]

replace throw out and pilot bearing whenever you see them.You would need to determine the condition of the flywheel and clutch.If me I would put a new disc in forsure.Depends on the trans,most M20s and 21s are 10 spline disc.Many M22 were 26 spline.Tom

[racerboy]

Originally Posted by Half-Inch Stud

Sold my SGI forged crank moments before this Thread started. It was 4.21 Stroke 3.25"Main BBC rod and sitting nicley in my Spare 462 (sold the Short Block).

Sounds like the buyer got a bargain moreso than I intended. I intend to stay N103 if need be.

No worries HIS. I’m just going to do a 4.00 stroke on my 400 (I think it nets out to around 433 CID) and run my #12 heads. I really want to try and keep the car number-matching (other than internals like crank, cam, pistons, etc.)


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[racerboy]

Originally Posted by tom s

replace throw out and pilot bearing whenever you see them.You would need to determine the condition of the flywheel and clutch.If me I would put a new disc in forsure.Depends on the trans,most M20s and 21s are 10 spline disc.Many M22 were 26 spline.Tom

Thanks Tom. I’ll take the flywheel down to the machine shop and ask them what they think.

I have no qualms with buying a clutch, I just hate spending $$$ needlessly (like most of us). lol


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