do you use the cleveland pistons for the 400 or the 351 M?

 

since the major difference between the 351m and 400 is the stroke (3.5" on the 351 and 4", the bores are all 4" dia.) a cleveland piston can be used in either engine since it too uses a stroke of 3.5" and 4" diameter bore.

The clevelands deck height is about an inch shorter and the rods are also shorter hence the piston will tuck closer to the crank at bottom dead center. There wont be a worry about the piston skirt hitting the crank of the M when a cleveland piston is used.

Even though the counterweights are larger on the 351m/400 cranks, with its 6.58" rod, it still avoids the problem. I should also mention that the cleveland piston wrist pin is .9122" in diameter which is smaller than the M's so the rod will have to be bushed.

I speak from direct experience in that I have done this project myself. Bushing the rods can be expensive!

 

One can use 351C pistons in a 400, as they have the same bore and compatible compression height. However, the cleveland pistons use a different (smaller) wrist pin, so either the 400 rods need to be bushed for the C pins, or (if the C pistons have enuf meat on 'em) the C piston pin bores can be enlarged for the 400 pins...

351C pistons can't be used in a 351M (unless you're re-building it with a 400 crank), because the compression height is nowhere near the same... the tall CH of the 351M pistons makes them pretty much unique and non-interchangeable with anything else...

 

side note, if you use cleveland pistons in a 351M, select some tall rods, possibly have the block decked a little. I was considering a screamer buildup by grinding the 351m crank, placing in 7.1" rods and a cleveland piston from SRP. BOOYA!

 

I tried to figure this out a few times myself. There are a couple problems with the 7.1" rods. Cost is $700 for the Eagles/Scat and $550 from CAT, which I believe are a lessor quality. The rod's width would have to be narrowed quite a bit (.990" vs 351M .8315") and the pin is .990" vs 351C .912" or 400 .975". A finished rod would likely be $750-1000 by the time you were done.

The 2.2" journal won't allow much of an offset grind ($180-200). Even if it did, the stock crank is very heavy. I didn't get any responses to the combo I posted about a week ago but I thought it was a good compromise. If you want a screamer, an aftermarket steel 351W crank would be a better choice. They make one with a 3.75" stroke for about $550. Combined with a 6.795" 240 rods (available with either .975" or .912" pin @ $100) and a 1.63"CH piston would give 0 deck in a 10.300" block. This could rev 8K rpm with no problem as long as the oiling system were up to the task.

 

ok first isn't the shout of a wheezer crank smaller? as i recall the 400 cranks used as a wheezer stroker the snout was cut down to fit

allso the ""budget"" 427ci 400 stoker
i was back at dsc 's website again and saw the 2 different rods(apparently you knew this this) now the number don't fit proper
10.297
-2.085 (half stroke)
-6.795 rod <<<
-1.415 piston
--------------
=0.002 deck

now the rods from dsc
C5AE Length is 6.800" and uses a .912" Pin
C8AE Length is 6.794", Stock .975" Pin size

any idea what i should plan on a redrill the piston /bush or go with a smaller displacement(argggggh)

thanks bri
sorry for hi-jacking i tryied to email ya but you don't allow

 

The 351W crank snout is about .75" shorter if that's what you mean. They need a $22 spacer (M19009-A351) to make the timing gear line up.

Why do you need to redrill the rod or piston?

You can reach me at my Yahoo Forum.
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A 383 combo with a 8000rpm redline?

There are a couple minor details I still need to check out but it looks good so far. I did some number crunching and this seemed to be the best compromise.

Scat makes a 351W forged steel crank with 3.0" mains, 2.1" rod journals & a 3.75" stroke. $550

A set of (8) Inline 6, 240 rods are about $100 from DSC Motorsports. Early rods used a .912" piston pin, while the later ones were .975". The best part about that is you can use either a stock 351C or a stock 400 piston.

Are the 240 rods strong enough? I think so. They are made from 6415 steel and have been used in 460 stroker motors over 700HP, 7500rpm.
http://members.***.net/dusty_mcguire/540%20Buildup.html
http://www.bacomatic.org/~dw/520/520.htm
__
1.875" stroke (3.75/2)
6.795" rod (240 I6)
1.63" piston CH
0.0 deck clearance
------------------------
=10.3"

With a 80cc open chamber and FT piston 4cc valve relief, compression works out to 9.5:1
or a 63cc quench chamber and 13cc dish piston is 10.25:1

3.75" stroke X bore
4.030=383
4.040=385
4.060=388

The down side is you lose 25 cu to the 400. On the up side, the reciprocating assembly is at least 10 lbs lighter than either the 351M or 400 and you can get quench benefits easily. Factor in your new RPM potential and I think this would be a hard engine to beat.

 

Well, i wasnt thinking of an offset grind because i thought of the 3.5" stroke and 2.02 rod/stroke ratio being good tradeoffs for the heavier crank, but 10lbs is an awesome difference and still has a 1.8 ratio.
What pistons would you reccomend for this setup? With your current configuration the piston does rise over the deck .003" but im sure that is imperceptable. Who makes a 1.63 CH piston with enough relief or dish? The .912 rod would make things even taller, the C8AE would be the only choice?

 

For a 98% street engine I would prefer to have the 427/400 stroker and keep rpm under 6500. If a person were rebuilding a 351M, the usual advice is to buy a 400 crank and pistons and build a 400. That's always going to be the easiest way to make more power but the excessive deck clearance (.057+) isn't desirable with a closed chamber head. We've come up with a few ways to eliminate the clearance but most solutions weren't very cost effective.

You'll have to look around for the right piston CH. Stock is 1.647 with a 13cc dish. Aftermarket replacements vary from 1.63 to 1.67. Block heights also vary from 10.297-10.302". With a .040" thick gasket I wouldn't be worried about a piston up to .010" above the block. Pistons can be cut down on a lathe if needed. It's very easy and shouldn't cost much.

Cast pistons are fine for mild 5500 rpm engines.
Consider floating pins over 6000 rpm, hypereuctics up to 7000 rpm.
7K+ rpm, 11+:1 compression, nitrous or forced induction should be forged.

When con rods are reconditioned the large end is resized and the length is reduced slightly.
The 2 things I haven't looked into yet are the Scat crank journal width and the 240 rod width. They should be wide enough if they work on a 460 crank. The crank uses a Chevy journal diameter but I'm not positive if it uses the Chevy journal width.

 

In pistons, i would be expecting something in the 11:1 range, forged is nice and im sure i could find the right ones, but im still looking at cranks. Would the stock windsor crank be lighter than the 351m? I know the bore space is the same between the 2 engines. The rod and main journals are the same diameter, but what about width?

 

well it out to be concidering the 351m uses a 1.9?? compression height pistons that would make for some bigger counter weights

 

There are 302w forged pistons with a 1.6 height and 14.5cc dish. With the scat crank and 240 rod setup this brings 11.4:1 compression with a 50cc head and .030 gasket. Perfect...but, the valve reliefs are different and the dish does not match the chamber well. It is possible i could take the flat top version and mill it.

If i could obtain a lighter crank with a 3.5 stroke that grinds down to a 2.20 journal, i wouldnt mind trying the 7.1 rods and 1.440 pistons. The rods would be the expensive part yes, but everything else would go together nicely.

Note: these ideas started when i was wondering what to do with a 351 crank since its always swapped out for the 400...

 

well of course you can flycut the pistons but think of the machinist cost. first the 400s compression height (the dist between the pin and the deck) is 1.717" not the original pistons but this is the "ideal"size piston to use in a 400. now if i were to cut valve reliefs in i was thinking one of 3 readily available pistons (unfortantly keith blacks site is down) one was a holden piston which was 1.7?? there was a (one of dozens) was a 300 big-six and i beilieve the other was a chrysler piston was a newer "truck" piston from kb
well if kb ever gets their site back up and ya want the part numbers i will get em for ya

 

youre suggesting 1.7s because they have alot of meat for available modification?

 

well that too but the point is
(friggin' A the kb-silvolite site is still down)
(deck height)10.297"-(1/2 stroke or crank throw) 2" -(rod length) 6.580" = 1.717" from pin to deck
this would be the ideal height on a piston it means a more effient burn(being the flame hasn't have to travel as far) (more complete burn)
also essential on a closed chamber head unless your just trying to get it to 8.5+:1
the reason thes engine is so prone to knocking is for this reason the piston is too far down in the bore and there isn't enough turbulance to cool the clinder
kind of hard to believe when you think about what actually happens in there

now whilst your in there un shroud the valve(remove the a little metal around the valve head and polish it up removenig and raw castings
all 335s head out flow regualar heads from .010" lift on and on but the exaust is a bit restricted and any help can be used to help(da) improve scavanging(the point of a "heavy on the exaust" dual pattern cam)

as i recall the kb folks said that the h2323 used in the "budjet" 427ci/400 strocker could be cut near .125" safely can't recall exactly for dishing porposes

but GREAT care must be applied when cutting valve reliefs where they whern't designed to be because the metal on a piston face often follows the face design or in other words ther isn't always a "thick" hunk of metal with a set of reliefs cut where-ever needed the 1.7" holden piston is a flat top with no reliefs but as i recall it is a silv-o-lite/cast piston then
well (after being sidetracked for several hours) valve reliefs will(from memory of a perticular website) is 120 adding a dish is 80 each are per clyinder what another 80 for resizing the pin
thats like 300 for one cast piston (or was it 120 per set it doesn't sound right tho)
for the price ya might as well do the math and see if a longer CUSTOM rod will hit the cyilder wall or get a set of cusom pistons or semi-custom i believe JE or one of the manu has a half dozen pistons that have not the demand to be in production but they still have the tooling think they were 400
i have been thru the numbers and the 427ci stroker looks to be creaper(guesstamate) than otherwise more parts are stock(from domething) or reconn'd