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Old 07-16-2006, 09:10 PM
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351 Modified More Hp???????


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Old 07-16-2006, 09:17 PM
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351M's are a variant of the Clevelands some stuff for the clevlands work but there is not much of an aftermarket for the Modefieds. maby an intake manifold and headders, that will net a little. your engine is probably rated at 200 RWHP, putting it at just over 250 or so at the flywheel. don't cam it, they don't help power, in other words, if your engine dosn't have it, they won't give you it, they may restrict an engine that does have it tho.
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Old 07-16-2006, 10:42 PM
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Any Cleveland cam will work, and heads too.

You have basically 2bbl Cleveland open chamber heads,
although with a slightly more restricted exhaust port.

Edelbrock makes Performer intakes for them which does help.

I'm sure a number of the major header makers make headers
for stock truck applications.

The REAL way to more power - especially torque - is to
convert it to a 400. All you need is a 400 crank and pistons.
The rods are the same.

You really need higher compression pistons anyway.

There was an article a number of years ago about a 400 that
just had the stock heads cleaned up, rebuilt w/a good 3 angle
valve job, a Performer intake and I think a 650 Holley, replacement
cast pistons with a little higher compression, and a moderate Crane
hydraulic cam with something like 220 intake duration @ 050,
and even used the stock exhaust manifolds, that made something
like 380 hp and 430+ torque at moderate rpms (flywheel numbers).

Do a search on "Ford 400 engine", there's a surprising amount of info
out there, even some Forums with lots of tech info & performance

The same basic info applies to your 351m, you'll just have less
torque especially.

For a real budget upgrade, the Performer intake, a garden variety
Holley 600 or 650 cfm vac secondary, a regular hydraulic flat tappet
cam (use the cam kit springs) in the neighborhood of 210 intake
duration @ 050 (check the cam mfg catalogues for usage recommendations), a distributor recurve, and just plain decent ~2-1/4" dual exhaust with free flowing turbo type mufflers like Summit Racing's (or is it Jegs?) for about $15 apiece. All major cam makers make Cleveland hydraulic cams. Don't
overlook Lunati - they have a reputation for big mid range torque in a
cam in that range.

Shop around for used intakes, you can find them occasionally.
If your engine needs any work, clean up the exhaust ports some
if you have the heads off and have a 3 angle valve job done.

If not, just skip that.

Those mods address the biggest choke points on that engine -
the intake & carb, the cam, the ignition curve, and the exhaust.
I think you'd be surprised what those mods would do.

Last edited by macx; 07-16-2006 at 10:50 PM.
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Old 07-16-2006, 10:52 PM
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The cheapest modification to wake up those motors is a timing set swap. Ford retarded the cam timing of the 335's in '73 by using a different crank gear, simply installing a '70 351C timing set will advance the cam.
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Old 07-17-2006, 01:12 AM
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This was covered extensively about 4 months ago, wish I could find the thread.

It is rated at 150 hp.
You don't need intake, you need cam and exhaust first. The intake won't hinder much below 4500 rpm even with the 2 bbl.

1) timing gear and chain, for '71 timing

2) CompCams XE 252H cam or 4x4 cam, the original cam is lame with .380 lift and 185 duration= low compression mandates short cam with lift up to .475 max. (valve guides won't do more)

3) dist curve

4) Dual exhaust

5) headers

6) then, last, manifold and 600 4bbl., Edel or vac secondary

7) cold air intake, sooner the better.
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Old 07-17-2006, 08:38 PM
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