How easily can the 351M and 400s be made into performance engines? I am thinking about buying a truck with a 351M and can have a 400 for free if I go pick it up. I was just wondering, because I like power. Thanks.

 

Read the posts in this forum

 

Start with a 400
Use a dual-pattern cam, some here like the 255 DEH from comp, I would try something a little bigger, something like a XE 256H or XE 262H ground on 112 degree LSA.
Headers help.
Weiand intake or Edelbrock Performer
750 Holley
Should be quite strong from idle to 5500 rpm
R.

 

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What Eric said; ...read the posts on this forum. Not just the performance questions, but check out the smog questions, too, the EGR, smog pump and related stuff. Those always end up in a debate about performance, gas mileage, tuning, etc.

Any modern engine can be made to perform well and the 400 is not an exception. If you're serious, start learning about which block you'll want. There are important differences. Snag that 400 if only for its crank. Look for Cleveland (1971-74 Cleveland) heads. The rest is cake.

 

Good advice all around in this thread. (for once I don't have to argue a point !) I'd go the 400-2V head-aluminum intake/4-barrel route, with headers, and Comp 268H cam. Try that cam, you'll love it. Noticeable idle, powerful midrange, great street cam for a daily driver you want to put lots of miles on.

Don't get hung up on porting. A 400 with 2V heads is plenty for most street applications. You could put the larger Cleveland 4V valves in the 2V heads no problem, easy machine shop operation. A 351M/400 has more performance potential than many other brand X engines, IMO the 335 series is a superior engine to a Cadillac-Olds-Buick-Pontiac-SB Mopar-SB Chevy-AMC. I like the 335 series better than an FE or small block Ford also, cuz the 335 series is more modern. About the only engines out that really surpass a 335 series would be a 460 Ford, 427/454 Chevy BB, or 440 Mopar/426 Hemi.

 

ok
400hp is relitivly easy to reach but this it not "a high rpm/revving" it is meant to be a TOURQUE engine but getting 400 hp out of a 400 is ALOT easier than a 302

cam = dual pattern favoring the exaust the 265CEH from comp cams is right on

alloy intake = the common is edelbrock, get the egr model as the carb flange is less likely to warp ang get a better seal, but have heard good things of the wieland(?model?)

carb = at 100% volumetric efficancy(alsost impossible) the 400 needs only a 670 mild ly built a 600 or 650 will make it run with out wasting gas and various other problems

heads swapping to a 351c 2v head isn't wouth the cost as they are really really close to a 351m/400 with exeption of the egr "bump" in the runner if you jus smooth the casting a bit and knock off sharp corner just clean it up if you actually port just keep it light and focus on the exaust runner... and port match

rig an exernal oil line to the rear if you are planning to rev at 6000 for any time

a "plain" blueprinted oil pmp is all you nead no hv/hp really neaded

exaust headers use a long tube and either 1 1/2 >1 5/8 primaries into a 2 1/2 pipe high flow cat

now if you are rebuilding boost the compression, perxonally i don't care for cutting the heads and block too much
or use a flat top 351c piston and bush the rod

well dozing offf so i am gonna sleep sooooooooo tired

 

That is a Weiand 8010. The Carb Flange is better than the Edelbrock and it is rated to 6000 RPM vs 5500 RPM for the Edelbrock.

 

Remember, we can only get 94 octane gas anymore at Sunoco, and most others are 92-93 octane- and they all cost around 1.80 a gallon locally here, ouch ! Don't put a lot of compression in a street motor, the fuel available just won't support it. Some modern cars use higher CR and get away with it, that's cuz they have knock sensors that retard the timing if the engine pings. An old Ford 400 does not have that system, and you will rattle it to death if more than 9.5 CR is used with regular gas.

If I was starting out with a 400 buildup from ground zero for the street, I'd build an 8.5 or 9:1 motor that would run on the cheapest 86-87 octane, and save around 20-30 cents a gallon. That really adds up over the lifetime of the truck.

 

a 400 buildup, my way

Stock pistons(to cheap for forged)
Aussie heads
edelbrock performer
800 cfm holley dp (modified for single squirt)
2 inch carb spacer, open plenum
hv oil pump
good hyd. roller cam
1.8 intake rockers, 1.73 exhaust
1 3/4 inch headers
3 inch duals w/ h-pipe, running to 5 1/2 inch stacks (no joke)


All this is good for around 550 hp, and while the comp. ratio is a bit high (11:1) for the street, it'll be real fun in the mud.

 

canted i will say normally yes but there is ways around it
i hve a simple daraspark replacement from msd with 15 degrees of spark control(and she plugs into the old harness)
also there is the quench effect on a race car can run 13:1 on lower octane
even tho i wouldnt dare to push it that far i think i can get 10.5 > 11

but yes with a 400 with ..070" (apx) head space above the piston and the original 2v cast iron open chamber 351c/351m/400 head uou are limiteded to 9.5:1