is there any difference between 351C heads and 351M heads
 

I have a set of 351M/400M heads and want to know if there is any difference between 351C and 351M/400M heads. I want to put these heads on a 351W block. I know I'll have to drill a hole in the intake side of the head for water passages, and I'll have to block off the stock water passage on the combustion side of the head to make them work. Also do these heads even flow better than stock 351W heads(I've got the 2bbl 351M/400M heads)

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1990 Dodge Dynasty with 175,000 miles. Mods:chiped paint, CD player. Sucks but it was free. Praying for a stang.
The "Guetto Glider"

The 351Ms are slightly different than the 351Cs. The "M" stands for "modified" as in modified Cleveland block. I dunno if they'll just bolt on but even if they bolt on you might have problems making the intake fit.

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1984 1/2 GT350 (#842 Hatchback w/ T-tops), 302HO, Comp cams Xtreme Energy cam, Carter 625cfm carb, Weiand Stealth intake, MSD distributor, MSD coil, FMS 9mm wires, 1 5/8" MAC unequal shorties, 2 1/2" MAC Prochamber H-pipe, Flowmaster 2 chambers, KYBs, 16"x8" 4 lug Cobra Rs, Falken 245/45ZR16s

The 351M heads are definitely not performance oriented. If memory serves, breathing and low compression were the major drawbacks. You might want to send a PM to Unit5302. That guy knows a lot about heads from that vintage.

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'91 LX
Procharger, 3 row intercooler, extrude honed Cobra intake, Mac full Length Headers, 30# inj., 73mm C&L, 75mm tb, E303 cam, 289 rods, ported E7 heads, MSD, T-Rex w/255 lph Walbro, 5 lug conversion, Cobra R wheels, 3.27 gears and Moser Axles.

One thing you might wanna check out is the Ford High Performance Parts Interchange book. It's a huge wealth of information. I'd quote from it if it wasn't back at my apartment. It's got quite a bit of info on the 351Ms.

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1984 1/2 GT350 (#842 Hatchback w/ T-tops), 302HO, Comp cams Xtreme Energy cam, Carter 625cfm carb, Weiand Stealth intake, MSD distributor, MSD coil, FMS 9mm wires, 1 5/8" MAC unequal shorties, 2 1/2" MAC Prochamber H-pipe, Flowmaster 2 chambers, KYBs, 16"x8" 4 lug Cobra Rs, Falken 245/45ZR16s

Actually I know almost nothing about the 351M. All I've ever heard is that it's a piece of **** .

I can't even remember why, hehe.

Sorry, I'm no help on this.

yes the part number maybe. but the head is identical. The head flows good on the intake but have poor exhaust ports. Can be help by blending out the bumps.They will make less torque than a windser style head. Its hard to get decent comp. witout a dome and require canted style vavle releifs . If you want a cheap head than port early 351w head .It will make more torque and will be easy to get any comp. you want. The exhaust port on the cleveland killed the really good design of a semi hemispherical head. Its a way lesser version of a yates head.

yes the part number maybe. but the head is identical. The head flows good on the intake but have poor exhaust ports. Can be help by blending out the bumps.They will make less torque than a windser style head. Its hard to get decent comp. witout a dome and require canted style vavle releifs . If you want a cheap head than port early 351w head .It will make more torque and will be easy to get any comp. you want. The exhaust port on the cleveland killed the really good design of a semi hemispherical head. Its a way lesser version of a yates head.

yes the part number maybe. but the head is identical. The head flows good on the intake but have poor exhaust ports. Can be help by blending out the bumps.They will make less torque than a windser style head. Its hard to get decent comp. witout a dome and require canted style vavle releifs . If you want a cheap head than port early 351w head .It will make more torque and will be easy to get any comp. you want. The exhaust port on the cleveland killed the really good design of a semi hemispherical head. Its a way lesser version of a yates head.