351m build questions?

[kyle71688]

ok my motor is at the engine shop, when i bought it it was bored .30 over already but the guy didnt do that great of a job. so this engine guy is recommending i go .40 over to fix his mistakes. i dont really care. but here is my question. im going to run a medium duty cam and not sure what brand to use. secondly i need new heads, do i go with aluminum heads or stock again? thanks guys. can i use 400 heads?

[joseph69]

I dont remember what brand of cam I used, but it is an RV Torquer cam. 351 and 400s have the same heads, the crank and rods are different. Look into swapping those out for some more displacement. I just used the stock cast iron heads. Replace all the exhaust valves. The originals are crap. An aluminum intake and 4 barrel will work pretty good too. I went with a better oil pump but not the high volume, not stock either. I am happy with the torque I got out of mine.
You can build the crap out of these engines, or leave them close to stock, stock form they last forever.
In 79 they had 120hp because of emissions and crap, but the cam swap fixes that!

[kyle71688]

yea my uncle has a 68 bronco and he used the RV cam. the only reason i asked about the heads is because the engine shop guy says he has 400 heads but not sure if they would fit. ok bud thanks for your advice.

[jopes]

Originally Posted by kyle71688

yea my uncle has a 68 bronco and he used the RV cam. the only reason i asked about the heads is because the engine shop guy says he has 400 heads but not sure if they would fit. ok bud thanks for your advice.

if the engine shop guy does not know if they will fit you need to find a better shop.

[jopes]

Originally Posted by joseph69

I dont remember what brand of cam I used, but it is an RV Torquer cam. 351 and 400s have the same heads, the crank and rods are different. Look into swapping those out for some more displacement. I just used the stock cast iron heads. Replace all the exhaust valves. The originals are crap. An aluminum intake and 4 barrel will work pretty good too. I went with a better oil pump but not the high volume, not stock either. I am happy with the torque I got out of mine.
You can build the crap out of these engines, or leave them close to stock, stock form they last forever.
In 79 they had 120hp because of emissions and crap, but the cam swap fixes that!

RODS are the same in both engines. Crank and pistons are different.


do a decent cam, your going to need new valve springs so get the cam kit. stick with a stock volume pump and your dizzy gear will thank you. .040 over is getting out there, most perfer to stay @ 0.030 or less, unbored core blocks can be cheap. Also check your date code, alot of the blocks out there are cracked in the valley.

factory heads flow just fine.

[huntsober]

I picked up a 351/400 m motor cheap and currently have it in the process of building a beast. Over time I plan on swaping my OEM 351/400m out of my 78. My build plan can be found by searching "351M/400 Performance Build Up. by Paul Eschenbach." Impressive numbers THere is a lot of info out there on getting high numbers from this platform. I wanted the weight of my 351m with more hp/tor than a built 460. THe added weight of the 460 was the down side to me. To each his on....on that topic. Either way stroking a 351m to a true 400cid by changing the crank is the way for me to go. I think in a year of so I will be done. As for heads....I will spend my money on head work instead of Al heads. porting polishing, larger intake val and ex vals and high end val assembly. I think I can get just as much from iron heads as Al with the money targeted in the right way. My goal is pump gas, reliable 400+ hp with as much if not more tork.

[njtinman]

al heads take the heat away faster alowing higher compression with lower octane fuel or less detonation

[colobronco]

DO NOT install larger valves. Smaller is better. Better velocity. You are not building a NASCAR motor.

The Edelbrock heads are just like the CHI heads. Zero combustion chamber. They will go much better with the TMeyer pistons.

[F250dude302]

Originally Posted by colobronco

DO NOT install larger valves. Smaller is better.

Not true if you get the proper cam / intake / exhaust.

[njtinman]

the 351m engine stock lack compression and getting the compression up makes power