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351M, 400 piston options

I just joined and haven't read all the postings but have seen this come up a lot. Having built a very healthy 410" 400, I've found a simple way to get any compression you want in a 400. Because the 351C and 400 share every piston dimension except wrist pin diameter, and the 351C has been very popular in the racing circles for years, there is all kinds of aftermarket pistons available for them. The only thing you have to do to take advantage of this for your 400 is to bush the small end of your rods to the size of the Cleaveland wrist pins.(about .060" smaller than the 400, I believe), and run full floating pins. I did that on my engine and intended to get something around 9.5:1. Unfortunately, the machine shop decked the block a little more than I expected and I ended up with more like 10.5:1 instead. With the open chamber M heads I get some detonation at the top of 2nd and third when I'm really flogging it. It doesn't seem to be too bad if you don't do this too much, but I intend to see how it is with racing gas and a little more timing. I could also double the head gaskets but this makes me nervious. I have this in a 79 Ranchero GT and at 4250 pounds, it still scoots! Rear tire wear is a real problem! The only real concern I've heard about with these engine is the strength of the block. I guess if you don't use squeeze or try to build it too wild, you'll be ok. A main girdle could help, too.
 
1,320
82
Or you could have given Tim Meyer a call. He has pistons available for a C/R in that range. :)

After market support for these engines has been increasing. smilieFordlogo

Main girdles are good for nothing but keeping the block together when it splits. If you're making enough power to split the block, you need 4-bolt caps.

I'd love to see pictures of this car, sounds pretty BA!
 
Regarding Tim Meyer...

Had I known about Tim when I was building my motor, I would have contacted him for advice. I did this around 2005 or so. Most of the information I found was from scouring the Internet. I would love to dyno it and see where it is HP and torque-wise. All I can say is it's putting out a LOT more than the original 351M did. I also have a high stall converter, built C-6 and 3:50 posi which I'm sure helps the Ranchero get out of it's way. But, I am realistic, too. I'm pretty sure the 410 that's under the hood now isn't putting out 500 HP, or anything too close to that. My intent when I did the motor was to hopefully be able to run 14s in the quarter as is, and 12s on the juice. Never put the juice on it....probably better off that I didn't....:wasntme:
 

DNFXDLI

The Token Canadian
Staff member
Detonation was my understanding when using the factory open chamered heads...one of the reasons Ford dropped the CR.
 
Detonation problems...

Using the open chamber heads wasn't my first choice, but the heads that I would have preferred to use weren't in my budget. I would have used semi-dished pistons and closed chamber heads to get the C/R to around 10.5:1. It is my understanding that with that combination you could go that high. I would've also used a roller cam and a Cleveland air gap intake with the adapter plates.
As long as I'm pipe-dreaming, I would have upgraded to an AOD trans and 4:10 gears in the rear, too. I think with that combo I could've reached my original goal of at least 14s in the quarter, maybe better.
 

DNFXDLI

The Token Canadian
Staff member
Detonation is more caused by the pistons being too far below the decks surface.

Not sure I follow..the lower the piston is in the bore the lower the CR...detonation is usually from one or more things such as low octane, too high CR, crappy quench area, mismatched piston to head chamber etc.
 

mrxlh

Oilfield Trash
5,904
430
Stigler, OK
Detonation is more caused by the pistons being too far below the decks surface.

I think you are confusing pre-ignition with detonation. A lower CR (pistons below the deck surface would not be prone to detonation) using shallow pistons would be prone to pre-ignition due to carbon buildup in the ridge of the block and being exposed @ tdc.
 

mrxlh

Oilfield Trash
5,904
430
Stigler, OK
Poor turbulance (not really a 351M/400 guy, so I am not an expert on the heads available) is probably what kills this motor the most, as far as detonation goes, as it was a smog motor of the 70's. Head design was not of utmost importance back then. 10.5:1 cr is pretty mild with todays available ignition systems, camshafts and carburators.
 

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