I am needing an opinion from you guys. I have a 351-M in my 79 custom and it is either in need of rebuilding or replacement. I was wondering if anyone had any good Ideas on a quality motor should I stick with the M or something else. wanting more horsepower not so much top end speed just pulling power. I like the Modified but is there something better and if so what carb and manifold combos should I use? High performance coil, exhaust, breathers, any ideas???

 

well, anything is better than a 351m as far as performance. When rebuilding, your only option is pretty much the stock 7.9:1 cp pistons, unless you want to pay 500 dollars for a set of federal mogule pistons. You can put a 4x4 off road cam in it, a 4 barrell intake, some cleveland heads, some headers, and i am not a really big fan of super hot ignition systems. A MSD blaster 2 coil is about the only performance igintion part i would put on a truck. The MSD boxes seem to wear out fast, and there is not enough gained for the rpm ranges we are talking about. 6000 rpm and up is where you will see the power differences. The stock electronic ford ignition system is a really good reliable system. As for carbs, i would go with a edelbrock 650 for you truck, and a performer intake from edelbrock. I have a 750 with a performer on my 390, and a world of difference compared to my 2 barrell. I would keep the pvc system, i think it is better than having just breathers, keeps the oil a little cleaner. Low cp ratio will be better for low end anyhow. If you want a real low end torque monster, swap in a 460, or a 390. I do not know what your budget is, but you can make some decent low end torque off the M, but its not going to be a race car.

 

I Disagree totally on that... The 351m is way out of tune from factory, only because of the emissions and stuff like that in the 70's. Tune them up and you'll have you a real screamer. I know cuz I have one. The main key to get POWER out of the 351m is in the heads. They do have low compression too, but its not 7.9:1.. More like 8.4:1. To take care of my compression I shaved the heads and milled the deck of the engine. My compression Ratio is around in the 9's now. Its a changed machine, Dont let anyone tell you that a 351m wont crank past 6k RPM's.. I have broke that several times. But it isnt a stock engine either, But you should really keep the 351m and swap pistons out and get 400 pistons and a 400 crankshaft. Thats what Im wanting to do, Id really like to have a 408...

 

If you are looking for a lot of low end grunt, go with the 400. With it's 4" stroke, you can easily produce 400# of torque with just bolt ons and a cam. Good luck.

 

400 crank, badger pistons, stock heads ported, headers, Weiand 8010 Intake, Edelbrock Performer 600CFM carb, double roller timing chain, and Comp Cams 255DEH for stump pulling grunt or Comp Cam 265DEH for highway towing. Comp Cams 260HR Hydraulic Roller is a little better, but more expensive. Roller rockers and guide plates are nice too, but unnecessary.

 

I agree...the 400 can be a torque monster with some bolt on goodies. I did use the Comp Cam 268H, Performer intake and Carter 625 breathing out thru 2 1/2 duals. Had the 351M for 185K...decided at rebiuld time that for pretty much the same price i can get 49 more cubes and more low end. I'm happy with the performance. Still only gets 10m.p.g...but so did the 351.

 

Dont mean to hi-jack the thread but Danlee, I noticed you made reference to the comp cams 260HR. I had no idea there was a hydraulic roller cam conversion available for the M's? How much does it cost? From what I have seen Hyd Rollers are the way to go for street longevity, not to mention effeciency and power!

 

I am using a 'Preditor' Hydraulic Roller, which is similar to Comp Cams 284HR, but with more lift. Look at the photos in my Users gallery.

Yes, there are Hydraulic Roller Conversions available for M's. PAWs list them for $250.00. Then you need lifters $150.00 - 5.0 liter replacement, and COM-31-1000 Ford Retro-fit Hydraulic Roller Conversion Kit - $43.95, then you need new pushrods. I am using 8.8" Trick Flow hardened pushrods ($90.00), but you don't need hardened unless you have guide plates.

 

Thanks! Thats good to know. Maybe I will include a hydraulic cam in one of my upcomming builds.