351m/400
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FTE Legend
Joined: Jul 2010
Posts: 32,875
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From: Northeast, OK
IF it's a 351M, make it a 400 and see below.
If it's a 400, go through it and add compression and decent cam. You can stop right there for a decent power upgrade. Add intake and 4bbl, add headers if you like. Add an indecent cam.
Look at this link and pick and choose from there.
Ford 400
If it's a 400, go through it and add compression and decent cam. You can stop right there for a decent power upgrade. Add intake and 4bbl, add headers if you like. Add an indecent cam.
Look at this link and pick and choose from there.
Ford 400
As for cam timing, the engines came from the factory with retarded cam timing. I have a friend that recently swapped out the timing set for an aftermarket one with "straight up" timing. That and and Edelbrock intake and carb seemed to wake the stock 400 up significantly. And, it would also help an M.
FTE Legend
Joined: Jul 2010
Posts: 32,875
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From: Northeast, OK
A 4bbl only helps at higher RPM, say maybe from 3000 up. Prior to that the 2bbl has enough flow to satisfy the engine. However, the primaries on a 600 CFM 4bbl are quite a bit smaller than the 2bbl, so part-throttle acceleration feels better or crisper.
So, if you are revving the engine up and it lacks power on the top end then go for a 4bbl. But if you are looking for more torque from a stop then a 4bbl won't help. For that you need a higher compression ratio.
So, if you are revving the engine up and it lacks power on the top end then go for a 4bbl. But if you are looking for more torque from a stop then a 4bbl won't help. For that you need a higher compression ratio.
Tuned
Joined: Sep 2003
Posts: 348
Likes: 2
From: Northern Michigan
While not "indexed", I set my cam 2 degrees advanced.
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351m/400
That's kinda what I was thinking as well. I don't plan on drag racing or an things so I'll stay with the 2bbl for now. Thanks for the help
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Upgrades
The more modern cam will help your engine breath better. Before you invest in a 4bbl conversion, I would suggest headers. Remember that an engine is air pump. If you the slap on a 600+cfm carb and improved flowing intake, with the larger than stock cam you've installed, you're going to be leaving some air pump performance restricted by stock exhaust manifolds. The primary tube size will determine your torque curve. 1 5/8" primaries will work on a 400 CID engine that lives below 5000 RPM. If you have enough cam and intake flow capacity to go north of 5k(5000) RPM, then you'll want a minimum of 1 3/4" primaries, and commonly you'll find 1 7/8" primaries available for most, but not all, trucks that came with the 351M/400. Larger tube headers will sacrifice some marginal low end grunt(off idle), but should still provide more than stock exhaust manifolds, so there's that trade off with the potential for more power to clean the mud out of your tires. Header and collector leaks can be an issue, but a little common sense paying attention on gasket installation goes far.
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351m/400
Well I'm pretty sure my 400 has spit the ghost. I got it going good and than once it warmed up to running temp it started knocking. It got worse the more I ran it. It sounded like a lifter so I pulled the intake and valve cover. The lifters appeared tone okay but I noticed there was a piece missing from my camshaft. I dropped the oil and it's full of metal but it doesn't attract to a magnet. Piston or bearing?