Is a 400M crank in a 351w the cheap way to build a 393 stroker?
I thought I read this somewhere,that the stock-car guys came up with this originally. Will a M series crank even fit a windsor block?
This is for my driver, stock 351w that needs a new seal/speedi sleeve on the front main bearing. I don't want to spend a lot of money on it, since that has all gone into the other truck I am building. But, if I have to yank the engine and pull the pan off, I could swap out the crank, and maybe even the rods in a jif while it's onthe engine stand.
I read an article on this years ago, before the mass of stroker kits hit the market. I don't remember all the details, but it intrigued me at the time. The 400 has the same bore spacing and shares the 351W's 3" mains, so it's fits in pretty well (I don't recall if any machining was required) and I don't recall what rods and pistons were used. I'm sure there's someone here who knows...
I recall an article as well- many years ago, probably Superford, even before the net was popular/available - maybe 1990 or so. If I recall correctly they used the 400 crank with 300-6 truck rods and I can't remember which pistons (custom, maybe?) I think it did require some clearance cutting of the block, but I just can't remember for sure.
Yes, the 300-6 rods sounds right, and 1990 or so is about the right time for my memory of reading that article...maybe 1992 or 3. I just can't remember the publication. I have a huge pile of magazines from that time in storage, maybe the next time I get over that way I'll try to dig them out. Don't hold your breath...
One or the other-- 400M crank or 351W has a shoulder just forward of the #1 main, the other doesn't. That's the only sticking point. Clearancing the block, longer rods and shorter pin height pistons are a must for any stroker project. BroncoRoadKill is also correct about the price. Once you do the machinework and buy pistons and reconditioned rods, you've probably spent what a stroker kit goes for. My 331 short block cost me $1500, including the cam. Block was $50 from a local machine shop (the PO abandoned it there) stroker kit, boring, clearancing was $1225, cam was $115. Throw in the oilpump, main girdle and timing set and it added up to around $1500.
I am in he process of building a 393 stroker. Yes the 400M crank will work, but that's the expensive way to do it. If you are building a performance motor, then go with the many stroker rotating assemblies out there. You will get a steel crank, H beams and forged pistons. I am just building a stock street motor, So I picked up a crank for $325 and am using my 351 rods and 302 pistons. It works out to about $150 over a stock rebuild. Two suggestions, if you decide to go the same route as I did. One, get a good crank. There are a lot of 3.85 stroke cranks out there for as little as $150, but most are junk. Buy from a reputable crank supplier. I got mine from Speed O Motive and it is good all around. Second, if you are shooting for 9 to 1 compression, as I am, You will have to do some work to open up the chambers to around 72cc. You may also have to do some work on the piston. Most guys that build these strokers, are building an aluminum head motor at about 10.5 to 1 comp, so they don't have to deal with the issues I am facing. Good luck.
The 400m crank will fit in the windsor block. The snout on the two cranks are different. The 400m crank will have be turned down to look like the windsor crank and then they fit just fine. For all the work and effort in machining a factory crank, you can get an awesome aftermarket crank that simply bolts right in.
Modifying the 400m crank was a good option before the aftermarket pitched in and helped out. Nowadays, it's not real cost effective.
I'd say you're better off just getting a 3.85 crank, stock 351 rods, and stock 302 pistons...that is probably the cheapest way to make a 393. If you can get some 302 pistons out of an 88-92 mustang they'd be forged...but since they're a stock piston the valve reliefs are not large enough for a 2.02 valve and they are a 4" bore not overbore...
But you can still get a 302 type piston like I did.
Actually a 400M crank WON'T fit into a 351W block. Not quite. The crank throws are a tad too big and must be machined down. I kicked around the idea of doing this before the new stroker cranks started becoming widely available. I still have the crank laying around. I tried a mock up assembly once and the crank just wouldn't go in. It didn't miss by much, but no dice. Keep in mind that after a machine shop cuts down the throws for you (never minding the other machine work) you REALLY need to have your rotating assmbly balanced. Plus the usual procedure is to also offset grind the rod journals too as the stock 400 crank doesn't really offer that much gain in stroke all by itself. This is optional though. Crank shops don't seem to like offset grinding cranks judging by their price quotes.
Add all this stuff up and those new stroker crank prices start looking pretty good. Hence I still have that old 400M crank that's been collecting garage dust for like seven years now.
A cool idea in its time, but now there are better ways to go.