cool disscussion on mopar flatties


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Posted by clueless [201.202.24.222] on Tuesday, January 20, 2015 at 12:44:32 :

In Reply to: i also heard that posted by clueless [201.202.24.222] on Tuesday, January 20, 2015 at 12:12:51 :

excert

the chrysler engines are actually a "dry sleeve" design, with a very thick sleeve. If you really clean your block deck good, you can see it, but it is a very good press fit. Dont automaticly assume that you can run without this sleeve, as it is very good hardness and the block is very soft.


Hudson,
Are you sure the sleeved engines aren't just for ag/industrial use? I've never seen a car or truck engine with them. I don't think the block would be too soft to run without, although the sleeve material is probably harder than the iron in the block. Speaking of being too soft, I don't think anything could be softer than a 400 SB Chevy. On the stroking issue, I was looking the other day and found another interesting possibility. The little pre '42 Plymouth of 201 cid has rod journals that are 1.937 with the same length rod as the 217. You could offset grind the crank .187 on the big motors or .125 on the small ones providing the rods are the same width as the rest. Might be a little too far to go on big 2.125 journal motors though. Piston speed is just sort of a non issue these days. For example: an NHRA Pro Stock motor has a stroke in the range of 3.75 to 3.82 ( we built one with the 3.82 stroke ) turn 10,000 rpm plus. That figures out to 6366 @ 10000 rpm. Stock eliminator racers run cast pistons a lot because they are lighter. They do not turn a lot of rpm because the valvetrain is the limiting factor for NHRA Stock class ( have to run stock valve springs so they generally valve float in the 5500/6000 rpm range with the crazy cheater cams they use ). The strength of a cast piston is actually pretty strong considering what it is subjected to. Think of it this way, our old flatheads really don't make enough power to hurt themselves. That's why so many oldies are considered to be so sturdy. Think hp per cylinder and compare to anything else with ohv heads. Ohv engines in the 300 hp + range have cast pistons and are actually subjected to more stress over the long haul. Weight wise the 3.25 bore pistons are probably pretty light, of course there's always room for improvement.

Regards,
Del

The sleeves are a very tight fit in the blocks and are generally hard to detect. We have two 230 blocks, one that came in the tractor, another from a '58 Dodge ton truck-both had sleeves. We also have a 250 "long" engine ,of '56 vintage, from a 2 ton truck that also has the sleeves.
We had to replace one sleeve in the block we are running as it was pitted very badly when we got it. The original block was destroyed by freeze cracking when we got the tractor. This is where we first discovered the sleeves, in the bursted block. The replacement sleeve was a Perfect Circle I believe, but I didn't check to see its complete listing of application. All the engines we have dealt with were the heavy duty series L-6's (there is a difference and I'll look up the id numbers for them).

The blocks seem terribly soft to me, a rotary file ripped through the bursted block almost as easily as aluminum it seemed. I don't know the exact metallurgical composition, but they seem the softest I've ever seen. I know what Del is talking about in the 400 sbc engine, and the siamesed cylinder walls too - most I've ever encountered on the street had a blue haze coming from them.

I spotted the 201 rods too, but really don't know if they are poured babbit or shell type bearings.

I think modern casting technology and metallurgical science has done much to bring the cast pistons up the the demands and piston speeds of the racing applications mentioned. I think the Silvolite pistons would be good choices for these engines. I would really like to have a hypereutectic alloy casting in the L-6 mopar pattern.

Now on to areas I haven't explored fully but represent the next phase in the little tractor. Has anyone done any flowbench work on the actual intake ports/valves. Of course, getting a velocity off the valve seat is one thing, the ability of the air to flow into the cylinder is another consideration for the flathead. Any ideas or numbers would be appreciated.

Hudson

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