HEMI Tech- Crankshafts. Stock? Billet? Stroker?

I believe they are .990 pin. They are aluminum Howards. With Ross coated pistons. Lippy

 

Jay. JMO here that and 90 cents will get you a pack of gum, but. If it was me, bucks down and wanting a blown chrysler for the street, I would build whatever I had, keep the static compression low, maybe 8 to 1, stud the 2-bolt mains, use NEW steel rods with good bolts, stock crank, I would also o-ring the heads and block and run a copper head gskt with head studs just for insurance. Run a decent 6-71 at 1 to 1 speed and throw a couple carbs on it with a good ignition, a decent blower cam of your choice and go play. At least with it studded and o-ringed, you can step on the blower later if you want to. Lippy (make mine injected thankyou).

 

Hey Lippy, got a phone # for Howards? Leon said I could just look it up but I'm having a hard time finding them.

 

what should i expect to spend for a 392 crank that needs welded up on say rods and mains and re nitride it ? who close to iowa should i take it to ? thanks guys

 

Is there any problem in using a crank out of a '53 331 Hemi in a '55 C300 331 Hemi block? (of course assuming the crank is good)

 

I have a 330 DeSoto and I've been looking for a hopped up cam. Anyone know who sells one for this motor?
I've been told to just have mine done by a cam grinder. But, then I'll have to pull my motor apart and I'm afraid that will slow my progress on finishing it anytime soon.

Any suggestion??
Michelle

 

There is a slight diffrence in length. Scooter had problems with starter engagement using a short tail crank in a long tail block.

 

As George notes, the early crank is 0.200" short in the location of the flange...this will screw up flywheel/converter position unless you make accomodations with your adapter supplier for custom parts... =$$$$$

Be aware that there are two different cams used in the 330 and 341. Casting number 792 was used in the 2-bbl engines and has an LSA around 120-122 degrees. Casting number 793 was used in the 4-bbl engines and has an LSA around 110-112 degrees.
Although difficult to find/read, the number is located 'in the rough' just ahead of the gear.
What does the LSA mean to you? It will all depend on wht you want from your engine. The wide LSA will, generally, provide; flatter torque curve, more vacuum, and a bit better idle. This was used in cars to provide that smooth drive with plenty of grunt.

I have some cores available, tell me what you are thinking.

.

 

As already mentioned, yes, but the flywheel offset will be like .200" difference. HOWEVER! I talked with Pat at Wilcap about this and he said he could accommodate a flywheel if needed. Chat with Pat. I'm sure he wouldn't charge much to just make the register a different depth on the flywheel to accommodate what you need.

 

Ok, good to know and thanks for the reply 73RR. My motor had a four barrel factory carb on it when I first got it. I have since put a Wikki three pot intake on it and would like it to really be a goer i.e.(more horse power) while still preforming as a decent daily driver. I am not very much in the know of what to expect from the stock cam vs. a hopped up cam with the additional carb power. Suffice to say, I am quite the novice hot rodder. But, maybe something just short of wild cam. Or is that what is referred to as a mild cam???

Michelle

 

the stock crank is very strong and shouldn't be an issue for a "street" blown car..frankly the stock rods and pistons should be fine too. compression for this stock motor were perfect for a little forced air.

 

has any ever seen a 331/354 crank blueprint my idea is to take a rough forging from a diffrent motor (maybe ford fe) and have it machined too fit my 331 thanks bill

 

Many appologies Michelle, someone should have answered your query long ago.
For a 330 DeSoto I would stay in the vicinity of a 270 or 272 (advertised duration) with lift in the 0.430 to 0.450 range. Either of the 330 cams would be suitable for an otherwise mostly stock engine. If you are still looking for a core let me know.

Gary

 

Any one got info on interchanging Desoto hemi cranks from one displacement to another? ID numbers etc.? Thanks.

Doug.

 

Low deck 276-291 are the same/interchange with each other. High dech 330-341-345 interchange
Low deck forging #s 1327417, 1402034, 1402624, 1419624 part number 1328357
High deck 1635785, 1735785, 1736044. part #s 1635784, 1736043

 

Does anyone know if the 57 300C crankshaft was different from the ordinary 392. I seem to remember that it was specially hardened (nitride or such)? I'm getting ready to sell a cherry 300C motor and dont want to make a mistake in the description.

 

My source doesn't show any special cranks for the 392.

 

What is the best combo for a stroker 392? Let's assume for the moment that a guy is going to ante up for a billet crank, so he has his choice of stroke. From what I've read on the net, it seems that a 4.525 (5/8 stroker) has been done, with minimal grinding. Would an even longer stroke be feasible or worthwhile? More stroke does not always mean more power, but let's figure that this motor will have a killer set of ported heads, but is naturally aspirated.
Does anyone know what rod/piston combo works best? Is there a point where the extra stroke accomplishes very little - the point of diminished returns?

Thanks, Joel

 

DRE, thanks for the reply, but I am not a poser. I don't do fake receipts, fake rubber spray on my quarter panels, nor do I have a rolled up pair of socks in my trousers to impress the ladies.

I'm consdering a street car that would also run in a heads up nostaligic drag race class. (BTW, that means it is a real race, not one that you can lose by going too fast)

In general, more cubes makes for a more reliable street motor, because you can take advantage of the head flow at a lower rpm. But it seems that every engine has a sweet spot with regard to stroke, and going too far either side of it is a waste. I do not know what that sweet spot is on a 392 Hemi, but I would like to learn.

 

Racing on the west coast here for the last 20+ years in Nostalgia, I dont know of any "HEADS-UP" (non index) class of racing where the car can be run both at the track and on the street sucessfuly. Now where you live and race might be different, but out this way AA/gas and Pro/mod are the only classes that are heads-up with doors.

MY opinion is that the stock bottom end is too weak for a stroker and one has to beef it up with caps and girdles when just running a stock stroke. Racers have been waiting a long time for the Lavoie block to appear and it has more material around the main webing so one can drill for 4 bolt caps without weakening the area , but that will cost you $$$$$. A 5/8s is a heavy crank with a lot of torque plus it takes up a lot of windage so a custom pan is needed. Play around with strokes on blocks that are easier and cheaper to get. Again--my opinion

 

I scored a killer deal on a Moldex 5/8" billet stroker crank (4.525)! Now I need to figure out what rods and pistons to use.

 

Hey guys,
I'm trying to get some ideas on building a blown early Hemi motor. I have a 55 331, a 56 354, and 2 57 392's. I planned on using the 354 or a 392. I have a set of really nice, new 4.030 blower pistons with a 1.39ch, basically the pin is .55" higher. I plan on using aluminum rods. I've done some calculations on figuring rod lengths for different stroke combinations with the pistons I have. Here are a few options I came up with. I Figured all these with common off the shelf aftermarket rod lengths. My calculations are rough estimates, I haven't figured in rod stretch, exact deck height etc yet.

354 block
I could put a 392 crank in the 354 block and use a set of 7" rods and have a short deck 392. 398ci
I could have a 354 crank welded and stroked or buy a billet crank with a 4.25 stroke and use a 6.85" rod. 434ci
Or 4.5" stroke with a 6.7" rod. 460ci
392 block
Use a welded/stroked 392 crank or billet with 4.250" stroke with 7.3" rod. 434ci
4.525 stroke 7.2" rods. 462ci
4.750 stroke 7.1" rods. 485ci.

So my question is for the guys that built and raced hemis back in the day, is there any preference between using a short or tall deck motor? How much stroke did you go before you ground threw to the water jackets in the block? I don't mind partially filling the block. Any other suggestions? I'll probably use mfi with either E85 or alcohol, so I'll calculate my compression accordingly.

Thanks
Mark

 

On the 4.525 billet crank, i had the rod jounals reduced to 2.200 (bbc), then used a set of 7.1" oliver steel I beam rods. The 392 block required no grinding for clearance. It all fit right in.

 

Generally speaking...4", 392 std bore is considered max overbore for the 354, with a sonic check. You're wanting to go another .030 with a blower. Might work with filled block, but I think I'd want a bit more wall.

 

Mark,
Although your numbers may work, using aluminum rods may not. Mainly due to the larger big ends, vs those found on steel rods. I would also recommend using a main cap girdle.

 

I have a UT scope I can check the cylinder wall thickness with. I'll try to do that today.

I planned on using one of your girdles tom.

I talked to Ohio crankshafts and they said $750 to weld and offset grind a crank.


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random thoughts:
Plenty of stroke lengths and con-rod lengths to play around with. I won't re-type my list found in Tex Smith's Hemi book (pg 112) but the rod-stroke ratio can be important depending on the intended service. The stock 392 is at 1.78...no too bad, and a few other Mopars a bit higher. The bigger the rod-stoke ratio the less side loading on the cylinder walls and more dwell time at TDC. You can go as low as 1.5 and the engine will run fine, but, it will not run as well as at 1.7 or so or be as dependable. Also, a stud package is mandatory with a big arm.

As Tom says, be aware of just how fat/bulky aluminum rods are. Carving out the pan rail for clearance is not a good idea, especially considering how good the current steel rods are.
As to overbore: removing any metal from any cylinder wall will reduce its ability to work as a heat sink so keep it to the minimum needed for cleanup. Thin walls are also candidates for cracking...not good.

.

 

Ok, I'm scrapping the idea on those pistons I have. To many combinations that will probably end up costing me more just to save the few dollars I saved on the pistons and rods.

So it's probably going to be a stock 392 crank, possibly offset turned down to use bbc rods. A good set of steel H-beam or aluminum rods and a set of custom pistons. I'll probably use splayed 4-bolt center mains and a girdle.

I just picked up a rebuilt/setup 671 for $400. I bought a new Jr. Thompson blower intake. I also picked up a old magnesium bugcatcher. So I'm on the hunt now for a vintage blower drive setup.

I'll keep you guys posted on the motor build.

Mark


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Was over at Jimmy Huff's on Sunday doing some secret Southeast Gasser skunk work stuff - anyway Jimmy is all Ford but he had a box under his bench that he had forgotten about. He pulled it out - it had a crank from Don Dixon's shop that he bought back in the 80's. It was a pretty cool piece of racing history. A Reath crank for a 392. I thought it was cool because I had never seen chromed journals and grooves like this.




Looks like the mains have a full groove. And chrome.


But like most things ran on fuel, its cracked - interesting history though. Says MOXLEY on it.