[64speed]

Ok if the forged bottom end is overkill for my application then what is the horsepower/torque limit for the scat cast crank? What about rpm limit? The pistons and rods will be forged of course. The cast iron two bolt main caps will be in place but they will be studded. Block is drilled for four bolt main. Is it worth the money to have it fitted for four bolt mains or would you rather have the forged crank? Both are about the same price

[Chief of the 60's]

Weren't you going overkill on everything else? Cheapening out on the crank and/or rods is not the place to do it, especially if you are going to race it. If you do not want to use a good forged crank, find a good Armasteel one.

[Tom Vaught]

I ran 6000+ rpm for years with a Factory GM Cast Iron Crank and proper bottom-end build work. This was with good 455 SD "M" forged connecting rods and heavy TRW pistons.

That being said, I had a GOOD rev limiter on the engine.

Only issue I had was with a lifter that got crap in it and hirt one lifter lobe.

For a street car, if you have the crank inspected by a good crank shop for cracks and proper dimensions you should be ok. Engine prep is everything. Armasteel cranks are not steel, they are cast iron cranks with a trade name Armasteel.

Tom V.

Then I bought my first forged Kellogg steel Crankshaft.

[tom s]

Many have told you your build is kind of over kill for what your going to do with it and the RPM range you intend to run.I have a 421 SD engine in my 63 Lemans with a factory cast crank,does have good rods and pistons.The crank was nitrited,it is a 4in stroke,has seen some race time shifting at 6200,been in the car for 20 plus years now.Has had a Tremic 5 speed in it since built.Just got done building a 421 for my 62 GP that will never be raced,will never see 4000 RPMs.It has a cast factory crank,rebuilt late cast rods and good forged piston.Drove it around for the first time today.Has a 3.42 first gear ST-10 4 speed with a 2.68 in the back,2000 RPMs at highway speeds.All I will ever need.Tom

[64speed]

Well I want to buy the forged crank because I feel like it’s cheap insurance I mean I am on a very slow budget but at this price point another 400 for a superior part is a no brainer. Now if I was being told that people were spinning these eagle or scat cast cranks to 6500 and having no problems day in and day out that’s one thing but if the juice is worth the squeeze I want to do it. This car is going to take me years to do so when it’s all said and done I don’t want to feel like I cut corners anywhere. Just wondering if the new cast cranks made the grade or not. Paul Carter has already said he plans to pick a cam for my engine with brutal low end torque so I figure I will be out of steam by 6200 at the most. I have a rev limiter on the sniper and on the 6AL so I shouldn’t have to worry about it blowing up. Do you think it’s worth getting the caps and having the three in the center upgraded?

[Tom Vaught]

Jim Butler sold a lot of the cast "off-shore" cranks when they first came out.
Never heard much about them failing so much as really rough machine work on the mains and rod journals. Moldex said a .010/.010 cut was almost a standard deal on the Chebby ones. Course that was years and years ago.

Why are you still asking about swapping out main caps on a block?

For a pure street car any 400 block with true mains and stock caps is a good candidate for a build.

Tom V.

[Half-Inch Stud]

...my china forging needed 20/20 because i bought it new 10/10.

Running a 455 N crank and probably will keep going and going beyong the Goodman curve.

[64speed]

Oh I was just wondering. It’s a 455 block and I believe it was Tom or maybe Steve that told me not to leave the 4 bolt main holes open but to put a countersunk bolt in them. I figured if I was gonna do all that I might as well just put the caps on it. Just spit balling ideas. Y’all take it out on me sometimes but it’s my nature to be thorough and attentive to detail and I like to know what’s BEST for my build not just what’s ok. When people see my car at a gas station or at a car show I want them to say wow nice car. I don’t care about trophies but I hate to see a giant tach hose clamped to the column in a street car etc. it’s the attention to detail for me. Just like seeing a dead clutch pedal in an automatic conversion. It takes 10 minutes and 20 dollars on eBay to correct that. I don’t know it’s just me. Must be my traumatic brain injury from getting my head bounced off a basketball court as a cop

[surfsama]

I run a cast factory 3.25 crank with MAXXLite rods and icon pistons. The block has holes for 4-bolt mains but I used the factory two bolt caps with studs and left the others open. I shift at 6000 down the track and I'm way more concerned about breaking a u-joint than my crank.

[6x400gmc]

I don't really beat on it all that hard, but the Chinese rotating assembly with cast crank I got from Ace from PPR back in 2011 is holding up pretty well. Pretty much a 3" main 428 crank with 6.800 rods.

Britt

Sent from my SM-N950U using Tapatalk

[hurryinhoosier62]

If you really want a good street crank that will last, find a good OE nodular crank, take it to a reputable crank grinder who can magnaflux it as well as grind it. Have him make sure all the strokes are equal, grind it to the next undersize if it needs it, have it nitrided and go on with your build. Forged cranks are nice to have but unless you’re planning on thrashing your engine daily they’re unnecessary in street engines.

[PAUL K]

Originally Posted by hurryinhoosier62

If you really want a good street crank that will last, find a good OE nodular crank, take it to a reputable crank grinder who can magnaflux it as well as grind it. Have him make sure all the strokes are equal, grind it to the next undersize if it needs it, have it nitrided and go on with your build. Forged cranks are nice to have but unless you’re planning on thrashing your engine daily they’re unnecessary in street engines.

^^^this^^^ 7200 rpm's, low 9's in 3700 lbs. street car with fourteen years of service.

[HWYSTR455]

IMO it's not much more to go forged, and if you ever go bigger power, you can sleep at night.

I will never use a OE crank in any of my builds anymore, it's just not worth the risk. I've had 2 OE cranks break, you can't tell if a crank is work hardened or fractured internally or not.

Even if a build is not planned to be one that will be abused, I take all the same steps as I would for one that will be. Build it 'right', build it once is my approach.

I do aftermarket caps as SOP on all my builds, for the same reasons. Sure, you can 'get away' with this or that, but if something DOES break, the whole thing is toast, and you will pay anyway.

Too many times I see people cheap out and end up paying in the long run.


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[Half-Inch Stud]

Letsa focuus on the proper Front Damper, that there maks or breaks the arguement.

[HWYSTR455]

Very true. No OE or non-SFI units please.


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[grivera]

Based on the totality of your build, intended application as expressed by you, advice offered over numerous threads/posts, and what others have experienced with both factory blocks, aftermarket forged cranks, it is abundantly clear that a [properly checked]factory cast crank or a forged aftermarket crank are the way to go. Aftermarket caps are really unnecessary. In fact, I believe Cliff who has numerous 11.xx second runs on his Ventura, has done so with factory caps/bolts.

If you’re as thorough as you claim, do a comprehensive search on this forum and read the numerous threads on other successful builds that do not include aftermarket caps.

[mgarblik]

Originally Posted by hurryinhoosier62

If you really want a good street crank that will last, find a good OE nodular crank, take it to a reputable crank grinder who can magnaflux it as well as grind it. Have him make sure all the strokes are equal, grind it to the next undersize if it needs it, have it nitrided and go on with your build. Forged cranks are nice to have but unless you’re planning on thrashing your engine daily they’re unnecessary in street engines.

Agree 100%. I would run a properly prepared OE crank every time vs a Chinese cast crank. Chinese forged like Scat would be fine too, if you have extra money burning a hole in your pocket. But any Chinese crankshaft will need the full inspection, polish and possible regrind before I would run it. So basically you are paying for the Chinese steel, it still needs to be inspected/reworked by someone who knows what they are doing. FWIW, we ran stock OE N cranks properly prepared in the Grocery Getter race car to 8000 RPM's, 3.25" mains in stock early 70's 455's at a little over 1000 HP for years, hundreds of runs. Never a single crankshaft or bearing failure. This was a light rotating assembly with 5 billet straight bolt caps. I don't recommend it, but we did it. Factory Pontiac cranks are not the weak link in stock engines. Lots of other parts will fail first.

[PunchT37]

Originally Posted by HWYSTR455

I've had 2 OE cranks break, you can't tell if a crank is work hardened or fractured internally or not.

3 inch or 3.25?

[chiphead]

Frankly, I've lost track of what you're doing. You need to pick a direction and stick with it. It's frustrating to type out a detailed response, then you change direction and the advice starts over again.

Here is my advice, generic enough to cover your case of schizophrenia mechanica.

Block: main dia doesn't matter: 2-bolt mains, studded and line-honed. Standard prep work as well. 3" main is better, but run whatcha brung.

Crank: Use stock cast or aftermarket forged to achieve stroke you want. Any main dia, any stroke you want, use it. Biggest risk of failure is aftermarket cast crank, since metallurgy is questionable.

Heads: Latest edelbrock or KRE design, round or D-port exhaust, 10.5:1 compression on 93.

Pistons: Autotec 4032 forged, whatever bore or compression height you need.

Rods: Any aftermarket forging, 6.625 or 6.7/6.8" Don't sweat rod length or rod bearing diameter too much.

Balancer: ProRace SFI-cert unit for pontiac.

Intake: RPM

Cam: Hyd roller. OFII grind.

Lifters: HyliftJohnson or Comp HR

Oil pan/tray: Milodon or Canton.

Oil pump: blueprinted M54DS.

Done. Now go build it and let it eat.

[Steve C.]

"Chinese forged like Scat would be fine too, if you have extra money burning a hole in your pocket."

Four months ago I bought a new 3-inch main / 4.250" SCAT forged crank from Paul K and it was fine. Machinist had no issues. And I might add his pricing was very competitive.


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