HEMI Tech- Crankshafts. Stock? Billet? Stroker?

Next Hemi subject... Crankshafts!

1) Stock cranks-
- What should be done to a stock crank in a rebuild and for what application?
- When should shot peening be a consideration?

2) Billet cranks-
- worth the money?
- When to use?
- who makes them and who puts out quality?

3) Strokers- (without getting into building a stroker motor)
- what cranks are used and for what motor?
- modifications required to other components or the crank itself to work?

4) Interchangability- (all makes)
- What will work with what?
- When should a change be made?

Plenty to talk about! Have at it! I'll start looking for links to fill out the subject...

 

Some info on rear main seal and crank surface:
http://www.jalopyjournal.com/forum/showthread.php?t=85173&highlight=hemi+crankshaft

 

Some quick info on 392 cams and stroking:
http://www.jalopyjournal.com/forum/showthread.php?t=110852&highlight=hemi+crank
One more:
http://www.jalopyjournal.com/forum/showthread.php?t=35435&highlight=hemi+crank

 

A little note I found on www.thehemi.com about using a 331 crank in a 354:

Contributed by Spence Sharp


The early 331 Hemi crankshafts, while they can be a direct replacement for 354 Hemi crankshafts, have smaller oil feed holes. 1/4" vs 5/16". They work okay for street use, but should not be used for racing unless the holes are opened up and chamfered.

 

Can anyone add anything about oil feed holes? Diameters? Location differences in certain cranks? Lack there of maybe?

Also, what is the difference in counter-weights for various cranks?

 

Also the '55 Chr.301 poly crank.

 

Any info on putting a 392 crank in a 354 block? I now it needs to be turned down a bit. Maybe offset ground . Any other snags?

 

http://victorylibrary.com/mopar/hemi-c2.htm

 

Also, the different makes do not even come close to being interchangable. You can not hook a Desoto low deck hemi to any Chrysler or Dodge hemi and expect the parts to work. Unfortunately, Desoto was on their own in the hemi world. Not many parts will interchange with the small bore, pocket hemi blocks. Just requires too much time and money for machine work.
Just to make a small bore hemi, per say a 276ci unit work properly, the machine shop work will be well over $3K for time alone in mods.
Mopar is one thing, but even in the early Mopar family, they still had great barriers between them. Desoto being the worst step child of all.

Maximo

 

I once saw a 247? inch ('55) Pontiac crank at Ashland grinding, that had had the rod jurnols welded and narrowed to 354 Chrysler width. They were already the correct diameter. A new snout had been welded on over the Pontiac part and the idea was to machine it to recieve the Chrysler timing gear. This would give you a very short stroke engine, making a 331 with an overbore a 300 inch motor. The project was never finished and the crank left out and became quite rusty. I have it now but have agreeed to sell it with the rest of my hemi parts.

 

Anyone have a 392 block for sale in the wisconsin area?

 

Back in the early 60's when I was building a 354 for blown fuel,
Ashland Grinding in Hayward CA, added 2 counter weights and grooved the mains to my stock crank. I also built a bottom end support, and had it linebored.

 

It would probably be easier to swap the pistons and top end on a 301 poly.

 

Dodge, Desoto, and Chrysler parts do not interchange....period..... Please don't nitpick, I don't want to hear about oil filters and valve cover nuts. The three are not even dimensionally the same.

 

Actually there are some hard parts that interchange. All 3 share using the "big block" later valve lifters. All 3 (55-up) share using the LA timing chain and gears. DeSoto and Chrysler from 56-58 share the same oil pump. All Dodge and 55-up Chrysler share same timing covers. Of course there are the spark plug tubes; can't remember the interchange. All the trans bolt patterns are the same except the 51-53 long bell Chrysler. Probably some more but they just don't come to mind.

 

My dad had sonny bryant do a billet stroker for his willys. He had it made with big block chev rod journal size. Started out as a 354", ended up a 420". Too freakin' complicated for me, just turn down the mains on a 392 crank. I think you have to take a smidge off of the counterweights too. Someone please detail this process, I don't think machine shops have butt hair gauges anymore.

 

Sorry, got ahead of myself, click the second link.

 

The 392 crank can be used in a 301-331-354 by turning down the mains as well as the area for the rear seal. Depending on how snug you want the install to be you can trim the counterweights a little or a lot, as long as it fits.
The B engine rod is just about perfect at 6.358". This combo will put the stock piston 0.014" higher in the bore which just about compensates for the current crop of fat head gaskets.
The best solution for the increase in rod width is to weld up the rolled fillet and then refinish the journal to B-RB specs. The savings in bearing costs will almost pay for the journal work.


.

 

If I wanted to build a street blown 331 (I have a '55 C300 block and heads), do I have to go into a stroker or can I build from the 331 using just better rods and pistons? Would a 331 crankshaft hold up to say 7-10lbs boost? Or would I have to go with an off-the-shelf 4340 crankshaft? I am hoping I wouldn't have to go the 392 crank in my 331 block route.

 

I'm sure others will opine...the crank and block are fine!

.

 

To what end? How much money to do something that you might not notice driving? You could offset grind the crank, or do the 392 crank but.... Why bother cutting down a 392 crank in a 331 when you could just get a 354 for not much more than a 331 costs? Doc Fromader offset stroked & bored a 315 up to 340 on webrodder & it is/was up 4 sale @ 10K, no telling how much it actually cost.

 

George, I already have the 331, can't afford to be buying another hemi. Or are you suggesting buying a 354 crank instead of a 331 crank?

 

Thanks Gary, seems some folks just don't like 331's! lol Well, ol Jay isn't buying any more hemi's after what Mama's grand piano just cost! But, at least her piano works and earns decent money every month!

 

331 & 354 cranks are the same. 354 cores usually are only a couple hundred more than a 331, just seems expensive to build a stroker 331 about the size of a 354. Might not be that much more where your going to be buying aftermarket rods to handle the blower though. Personally I'd give it a min overbore & not bother with the stroke.

 

JSRAIL - I have a basicly Stock 291 DeSoto Hemi in my 32. It has a hydraulic roller cam, 2X4's, with a 6-71 blower with 5 lbs of boost...for the street. The rear is a 9" Ford with 3.70 Posi and a GM 200-4R. I run 87 octane in it, can SMOKE the rear tires at will, and at goes like a scalded dog! I would venture to say that a lot of others have gone a similar route with other Hemis, with very similar results. Unless you're going to race your engine, I would suggest that you DON'T need all the whizz-bang ($$$!) stuff you're looking at for your 331. With 40 more cubes than my 291, yours should FLY on the street, too...

 

We have a 354 in the dragster. The crank I send to Henry at Velasco. He offset grinds a smidge off the crank and we run BB chevy rod journal size. Bearings are no problem now. This car is injected on nitro and is a nitrided stock crank. If you don't do anything dumb it will last until it breaks. LOL.

 

George, I was not really planning on building a stroker, in fact, I was hoping I could build a street blower motor without having to add making a stroker out of it. Or, at least as I understand things, a "stroker" motor means using longer rods to build cubes, such as using a 392 crank a longer rods. This is NOT what I wanted to do. I just want to put a street blower on it and have a little fun. Most of what I am asking around here is what kinds of things will I need to build so I can have my blower and fun. Of course I know I could build a decent carbed only street machine, but that's not what I want.

So, are you saying, based on what I'm looking at for my blower motor, that you think a 354 crank would be a better set-up than a stock 331 crank, or that it doesn't matter whether its a 331 or 354 crank? This is exactly what advice I am looking for. I don't have a crank, so I am looking for info on a good crank set-up for my motor. I appreciate your thoughts on this.

The only reason for considering aftermarket rods is "do I need a stronger rod to hold up to moderate boost from a blower." Some feel it is necessary, possibly others feel stock rods are okay. I'm just gathering guys' opinions that have built similar set-ups on what they would use for the build. By some of my reading, I doesn't appear necessary to build a stroker motor in order to use a street blower system. This is a build that will take some time to gather parts and finalize the build specs, but that's okay, my Hudson Coupe has been sitting since 2005 anyway, a couple more years won't hurt it, we don't rust here in Arizona! lol

Thanks again.....Jay

 

lippy, what's the pinion end size on those BBC rods? I thought I saw (maybe it was on Scat, I don't remember) a BBC rod that has a 6.625" rod length, are these the ones you are using?

Jay

 

345 DeSoto, I also am trying to get a sense of what boost level I should be looking at for what I want to do. I read on Dyer's site that they say you can use much of the stock stuff if you run under 5lbs boost. It appears that you are very happy with running 5lbs of boost for your roadster. I do like the fact that you are running on 87 octane, much more cost effective here in AZ. I only wonder if my Hudson Coupe isn't too heavy (about 3,700ibs) to do what I want at 5lbs. of boost, but don't know the answer to that yet though.

Do you also frequent the Forward Look forums? I thought I recognized your user name.

Thanks...Jay

 

The stroke is determined by the lenth of throws on the crank, not the rods. The 354 & short tail 331 cranks are interchangeable. All longer rods do is gives the piston more time @ TDC. When you use a longer stroke you have to shorten the rods or move the wrist pin higher on the piston. a stroked engine has a bit more low end grunt but doesn't rev as high, a destroked engine has higher revs & more upper RPM HP. I'd follow Gary's (73RR) advise on the build.