Ok just bought another dent.... 79 150. 351m. And c6. Motor has no ticks or knocks. No blow by. Motor has 160 hp stock. What are the chances of getting 200hp? Would true duals, 4bbl and an intake get me there? I want it to be a daily driver. So what would this motor stock with a 2bbl get me mpgs? With c6 355 gears

 

degree the cam. The modifieds cams are retarded from the factory like 4 degrees. Setting the cam will give more power.The best mileage I ever got was 13 mine was a F250 4x4.

 

Just driving it around, no highway, I'd be happy maintaining 9 - 10 mpg.
The motor is just a low compression smogged up turd. It would not be worth rebuilding if you were not going to turn it into a 400. I don't think anyone even makes a zero deck flat top in a 351M piston anyways. The M stands for mistake, it was a big mistake to destroke the 400.

 

Install a "straight up" timing set, for a 71, that will help along with all your other goodies.

 

I think the intake, exhaust and straight up timing set will help a lot. 200 (net) HP maybe... A mild cam + springs would help more but sometimes with cams and lifters, if it ain't broke don't fix it applies.

 

I've had one of these 351Ms in a '77 since 1986. Long ago, in the '80s ..... I added Edelbrock Performer 400 intake and ran a Holley 600 vac sec carb up until a couple years ago. Now it has Edelbrock 600 carb and Holley FPR (351M fuel pump is rated 6-7 psi, Holley's are OK with that, Edelbrock carbs like 6 psi or less ..... mine's set at 5.5 psi). Always have had dual exhaust, no headers ..... and back in the '80s I installed a Crane Fireball cam and timing set with three key ways, I set it straight up.

Distributor has a set of quick advance springs and I unplug the vag line and plug it when checking timing. My harmonic balancer is marked up to 40 degrees BTC and I set timing at 35-36 degrees BTC at 2000 rpm or so as all centrifugal advance is in by then. Then I unplug vac line and hook back up to vac can on distributor.

There is nothing inherently bad about a 351M. It was a product of the times. It was a time of scrambling for car makers. It will do nearly all a 400 will do all else being equal ..... but a 400 with longer stroke will still out torque it. Both a 400 or a 351M will benefit from higher compression ratios.

In 1992 at 75,xxx I was on a trip to Ga. to see Richard run his last race, oil pressure dropped, no noises, I thought gage. 6-700 miles later when I get home I find I have 4 psi. Bearings in the copper. Measured thickness, all standard on sides so slightly polish crank journals and slip in new rod & main inserts and an oil pump, slip pan back on, and started running a mechanical oil gage off a tee .... 60-65 psi hot at 55-65 mph ever since.

 

351M info...351M guru of guru's http://www.tmeyerinc.com/

History of the Ford 351M

Rumors & Myths

351M/400 Performance Build Up

Bubba's M-Block Ford V8 Workshop

M-Block 351M/400 Parts Reference

How We Got Over 500hp from Ford's 400M Engine - Hot Rod Magazine

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