I have a 1978 F250 with a stock 351m. I put an Edlebrock dual plane high rise on it with a 650 cfm thunder series carb. Put a new Mallory ignition in it and headers. No pollution parts at all. Took the A/C pump off and did away with all unnecessary vacuum lines. New E3 spark plugs and indexed them. Does anyone have any idea how much HP I may be producing?

 

I don't know what the base HP numbers are on the 351, but you probably added 50-75 HP with your parts.

 

Base HP is 132 or 137, depending on auto or manual.

Engine_Specifications

Smog parts gone: 3 to 5 hp.

Ignition: 1 or 2, maybe more if you recurved the ignition advance.

AC pump and plugs: 0

Headers, carb and manifold: Maybe 50-60.

Does it rev over 3500 rpm?

Does it feel vastly more powerful, outside of the extra noise it makes?

Spin the tires easily?

The power killers for the 351m are the low compression with sunken piston and the cam.

You've pretty much done all you can without opening it up, so you'll have to see what you think. Next step is a 400 crank, decent pistons, decent cam and related items. 300 horse. Add heads and a few other tweeks and you are 400 horse.

Engine_Specifications

Bubba's M-Block Ford V8 Workshop

M-Block 351M/400 Parts Reference

Everything you need and more:

TMeyer, Inc. Precision Automotive Machining

 

First does it feel more powerful to you ? Hopefully but like 85e150 says, cam and compression next or at least the cam and chain.

Intake, carb, headers, ingition, - All good stuff.

These motor have 2 major isuues heads and cam timing. ( yeah, no compression either)

Heads are too expensive, but a cam with a straight up timing chain should really wake it up.

 

Use your seat of the pants dyno and divide by two.

 

I have the same modifications done to my truck and asked the same question on here a while ago. The answer I got was, I gained somewhere between 30-40hp with intake, 4bbl, headers, and exhaust.