451 prep for "Homies"

[Challenger340]

Maybe I been doing it wrong all these years, but I thought maybe some of you, may want to see whats involved in building a "cheapy" 451 stroker, or, anybody, putting an 440 crank in a lowdeck block.

I've never ascribed to the "have to lathe cut the counterweight" idea.
I was just too cheap, and although I DO own a Engine Machine Shop, I DON'T own a lathe, and wasn't about to go buy one either.

To that end, here is how I have been doing 451's since the late 70's or early 80's, I forget ? Anyways, It's well within the capabilities of anybody with a Die Grinder, 4" angle grinder, and some effort.
It's also easy to balance, this one using H-beams and Forged SRP Pistons, was only out 60 grams left plane & 94 grams right plane.

Take a 1/2" Carbide ball, and grind a radius along the bottom of the cylinder @ the main web. Just grind a 'radius", don't keep going to "china", just until it cleans.
A better detail of what you'll need to grind.

Next up; the Crank work. Do the grinding on the counterweights BEFORE you take the Crank to be ground, at whatever shop you use.
Get a 4" angle grinder & some goggles. Grind the counterweights @ 45 degrees, all the way around. Use your boot to steady the Crank as you go.  DON'T grind your FOOT !
As you look at the pictures, you'll get the idea. About 2 hrs should do it.
Note; the Rod throw faces have been ground and polished on this crank. This is NOT necessary on yours, and best left alone, as insurance against "IF", when you go to balance the Crank, the balancing guy says "you're too light", and need "heavy metal" added.
You can then say "no I don't", go home and do the Rod throws faces, to get back in a "heavy" position, or, standard balance job(cheaper).


Ok, so next the Crank gets reground at the Machine Shop.  Note the next photo of the main ground to 400 size, but, with a .080" radius filet, in place of the factory "rolled' filet. DON'T use, or let them put a .125" filet, VERY BAD ! and you'll end up having to chamfer your bearings or buy expensive ones. Just get 'em to put a .080' filet, and the regular "P" eccentricity bearings work "puss".
This is only a street "pump gas" style deal, but the same works for just about all.


So there it is, CHEAP, EASY, and probably a fun project while saving yourself some donairo's. Hope this helps anybody contemplating a stroker lowdeck.

Bob out.

[AKcharger]

Hmmm So ALL the counter weights are angled to 45 degrees or just certian ones? In the picture it looks like just a few are done.

Any down sides to this? It sounds like a no brainer?

[Challenger340]

Hmmm So ALL the counter weights are angled to 45 degrees or just certian ones? In the picture it looks like just a few are done.

Any down sides to this? It sounds like a no brainer?

I do all the counterweights, I probably got no brains, LOL, But, I dunno about any downsides to this, other than it's a stock 440 forged crank, not an expensive 4340 crank.

That, and it's a good way to "recycle, otherwise "junk" 440 cranks, that are too far gone/reground to death. They get "new life" and become 471 inchers.
In that case,
Just do the mains to 400 size on standard, and, if the throws are already MOPAR .030 size and un-regrindable, do them offset to the BB chebby size, "standard sizing", as close to 3.900" stroke as possible. Don't sweat it if it's final is 3.890, just deck the block .005" extra, and PRESTO you got a 471 stroker.

EXAMPLE; I got a couple of old HEMI forged 8 bolt Cranks, .030 mains/.030 Rods already, that aren't serviceable, and need reground. Not likely I want any engines out there running around with .040" bearings, YIKES !
What are ya gonna do with them ? Throw 'em out ? I don't think so !
Regrind the mains to 400 size, regrind the Rod throws to BB Cheb "offset @ 3.900 stroke. Use STD 400 main brg's, use STD 454 Rod brgs.

I can't figure out for the life of me, why everybody always seems to be "lathe cutting" the counterweights ? It has to add cost ? Never have been able to figure that one out. Been doing them "this way" for decades now, 30 ? 40 ? 50 of 'em ? I forget ?
NEVER had a problem, street, brackets, super pro, NEVER ! The stock block starts to kill the #4 maincap, before the Crank fails. Usually we re-block long before that happens.

Like I said, maybe I been doing them wrong all this time, but, hey, "whatever works". This has worked well for me.

Bob out.

[metallicareload99]

Challenger340, thanks for the good info.  What rods did you use when you offset ground the rod Journals down to chubby size?  A 7.1" rod?  Also, would you have the Journals re-nitrided or hardened again after the offset grinding?  I like the idea of the 3.91" or 3.90" crank, but am concerned about the hardness of the Journals and the rod's side clearance on the Journals.  Not sure of how big of an issue that is.  Nice photos and post, thanks again

[Challenger340]

For the 470 lowdeck, 400 Block , "B" engine deals, I use an Eagle H-beam part # CRS6700C3D, and the SRP Forged Piston # 213453. The key here is the Eagle rod has the Cheb big end @ the Mopar 1.007" width, to maintain correct rod side clearance, and has L-19 alloy capscrews. The Piston is the same for the 451 engines as the 470 inchers, @ 1.32 Comp., just the rods are different @ 6.76" for the 451, but with the Mopar journal & width.  Both numbers are for the .990 Cheb Pin as well.

The rod ratio on the 470 is slightly lower than our factory Mopars, but it has proven to be a winner Combo with any of aftermarket aluminum heads out there that can provide around the 300 cfm mark.

No I don't re-harden, or Nitride the Cranks, and have NEVER had a problem. Nitriding only penetrates a few thou, (if that) anyway. So really, it's no different than regrinding your crank. The hardening is gone anyway, even when regrinding at .010/.010 for a standard rebuild.

I had the first ones we did, we had Nitrided, years ago(80's ?), but then lost the capacity to get it done, as our local guy went away. Suffice to say, we kept building them, without the re-hardening, and never experienced any problems.

If you have it available close to you(Nitriding), and you wish to have it done, by all means I'm NOT saying it wouldn't help, I think IT WOULD HELP, just that I don't, and haven't experienced any problems, by staying on the tighter side of clearance, with an H eccentricity brg on the Rods, and a looser "P" on the mains, with VERY straight & round machining.
I'm of the opinion that the majority of the problems with the Non-Nitrided stuff, is a product of .0005" tolerances for "straight & round" on the Crank journals, in other words, not very good Crank grinding.

Just my 2 cents, I'm sure opinions will vary.

[firefighter3931]

Nice thread....lots of great ideas here.  I haven't built a lowdeck stroker before but this sure looks like it would be the ticket for some cost savings. I'm sure turning the counterweights down has to add a few hundred bucks to the machine shop bill. 

Thanks for posting Bob. 



Ron

[AKcharger]

Hey 340...one more question. Where you cut the counter weights at the 45 angle, it looks to be about a 1/4 inch of area. So if you took that to a shop would they  have to mill a 1/4 inch of each weight? That would be a LOT.

Thanks again...I'm still struck by how simple this is!!!!

P.S. Be sure to stick around, I'll have questions for you next winter when I build my 400 stroker!

[Challenger340]

Hey 340...one more question. Where you cut the counter weights at the 45 angle, it looks to be about a 1/4 inch of area. So if you took that to a shop would they have to mill a 1/4 inch of each weight? That would be a LOT.

Thanks again...I'm still struck by how simple this is!!!!

P.S. Be sure to stick around, I'll have questions for you next winter when I build my 400 stroker!

I'm not sure what you mean AKCharger /

Nothing else was turned down, other than the 45 chamfer with an angle grinder. What you see in the pictures is "done & finished", and already blanced, "good to go" Crank that fits well in the 400 block.
The small space, between the 45 degree grinds on the outer edge of the Counterweights, is the "stock" 440 crank diameter, no other turning down required. The only interference the stock diameter 440 crank experiences in a 400 Block, is along the edges of the counerweight, hence grind 'em off @ 45 deg.

I Hope this helps somewhat with your question.

Bob out.

[AKcharger]

I guess a better way to phase the question is how much would have to be machined off the weight if you DIDN'T use your method. The way I was looking at the photos a machine shop would have a LOT of milling to do to get the weights down to size if they did it "normally"

Thanks!

[Challenger340]

You mean "how much has to be cut off on a lathe, from the outer diameter of the 440 crank, doing it the "other way" ?

I dunno ! I always done them this way, and trial fit what I needed.

I've heard others say as much as .300" !

I seem to remember someone, somewhere, saying a Counterweight Diameter of 7.700" was correct for a 2400 gram bobweight, but I don't know for sure.
DON'T TAKE IT TO THE BANK ! I don't know.

Sorry AK.

Anybody, know EXACTLY, how much has to be "lathe" cut off a 440 crank, to fit a 400 block ?

[jg68]

You mean "how much has to be cut off on a lathe, from the outer diameter of the 440 crank, doing it the "other way" ?

I dunno ! I always done them this way, and trial fit what I needed.

I've heard others say as much as .300" !

I seem to remember someone, somewhere, saying a Counterweight Diameter of 7.700" was correct for a 2400 gram bobweight, but I don't know for sure.
DON'T TAKE IT TO THE BANK ! I don't know.

Sorry AK.

Anybody, know EXACTLY, how much has to be "lathe" cut off a 440 crank, to fit a 400 block ?

Don't remember how much they took off mine, i'm thinking .200", but i've slepped sence then

[Nacho-RT74]

I thought cutting counterweights was because diameter and not angle... why is that ?

I'm thinking on that stroker since long time ago, but haven't found a 440 crank locally. I have found 440s, but I don't want to sacriffice a complete engine to that. I'm also thinking on everything stock parts except of course the pistons.

Is the same to casted iron cranks ?


will be great exactly what kind of tools is involved on

Do the grinding on the counterweights BEFORE you take the Crank to be ground

I have absolutelly no idea about how to make that

[Challenger340]

Nacho
Diameter fits, but must be checked. The area where the crank "hits", is at the sides of the counterweights, therefore, the "angle' grinds on the counterweights. See the block photos again.
DO NOT use a CAST Crank for this.  Forged Steel Cranks YES, CAST - NO.

Tools;  Hand held angle grinder with 4 inch grinding wheel will work.

Bob out.

[Challenger340]

The finished product

[idahogrumpy]

Yeah baby, thats my next, next engine build.    Great stuff.       Grumpy

[Nacho-RT74]

pics will need to be updated... they are not available anymore

[Ghoste]

    And maybe moved to the "Proven Combos" forum?

[BBKNARF]

Thanks for the post 

[Cuda620]

I know this is an old posting, but any advice or pictures on hand grinding the counter weights for a 451 would be very appreciated. I can't afford the stroker kit and for my mild 451, I doubt that I need it. 500-550 hp max in a 727 2800# 67 cuda that'll be a daily, in good weather, driver. Stock forged 440 crank,ly rods and wisco Pistons with aluminum heads, etc.  Thanks.