I just got a 2nd pair of M heads. and want to get them redone over the winter. so they are ready to go on in the spring. What should I tell the machine shop i want done. I've been doing a little reasurch some say only port the exhaust side and don't touch the intake side. Some say it's ok to port match some say it's bad. Some say put bigger valves in some say dont. So I'm a little confused on what I should have done to them. I would like them to be able to support 400hp and 500+tq when done. Thanks in advance for any one who can steer me in the right direction.

 

RE porting the exhaust only, I think that that mainly applies to heads which have a thermactor bump in the exhaust port - at least as far as small blocks go..

 

Just tell you shop you want them rebuilt, everything they need but nothing more. if they're worth a crap they'll know exactly what you mean.

If you really want the performance you're talking about save some money and heartache and convert to a 385 series engine. you're going to need cases of lipstick on the pig you're trying to make a powerhouse. believe me now or believe me later.

 

While I won't condemn the 400, I will say it's easier to make power with the big blocks.

That being said if you have your heart set on a powerhouse 400, why would you invest in another pair of stock heads? The cost of the heads and the cost to rebuild them and modify them is almost equal to a set of aluminum heads nowadays.

Granted, I didn't opt for aluminum heads on my latest 460 build, but that's because I wanted the motor to look relatively stock from the outside.

 

I did not pay much for the heads with a 2nd set I can drive my truck while I build the new engine. and I got a quote to get the work done for $600 with valves. Most aluminum heads that are not chinese junk are $900+for just one side and those are usaly bare. So for me the iron heads are more cost effective for what I plan on doing. and should get close to my power goals at least.

 

You are not going to get the power you're asking for with a cheapo build on a 351 that's a simple fact.

 

Id listen to 440 if I were you. The cast heads just don't flow much. The more you can flow the more HP you can make. Even if you hog out the ports and throw bigger valves at them, they don't flow much. Couple that to the fact they leave your compression ratio in the crapper unless you change your pistons and rods, and you've got a lot of lost potential.

 

I agree on this, I warmed my 400 over at least twice and finally switched to a 385. Wish I would have done it the first time. I won't go back.

 

I'm getting some pistons from tmi shooting for 9.5:1 compretion. And I know aluminum heads are better but I don't have 2k extra in the budget for them. I know I could make more power from a big block. But to swap one in would take up most of the budget. and not leave much money for mods. I might not make quite my goal with iron heads. but they are not that hard to swap out later for aluminium when I have the money for them. And I know I'll make at least 2x what this engine had stock hp wise. So it will be better than what I have now. I'm not looking to build a race truck just something to pull an occasional load and drive with enough power to get out of its own way.

 

Don't listen to the "gotta have a 460" crowd. Unless you've got a 69 Lincoln 460 or a CJ or SCJ motor, you've got a great big heavy slow low compression weak headed motorhome box truck engine on your hands. I won far more races with my Cleveland motors than I ever did with my CJ. And if you want to compare apples to apples, stuff the same spec cam into a stock 351M/400 against a stock 351W of the same vintage and see which one makes substantially more power.

Any engine that's lasted over 40 years and hundreds of thousands of miles and EASILY makes horsepower with minor changes is probably a very, very good engine. A ton of FTE members running these motors for decades with 2,3, and 500,000 miles on them, others making massive hp/tq numbers.

That said, stock heads are prone to detonation due to the open Chambers. Using TMI pistons should help considerably. This will be a premium fuel affair. Flow is good for the HP/TQ you are looking for, but I'd save your pennies for a set of CHI 3Vs in the future, or a set of Australian closed chamber Cleveland 2vs.

I'm using a set of stock heads on my current build, they get the job done. Had them milled, added a set of ferrea 1 pc stainless valves, smoothed the exhaust and the smog bumps (don't remove them, just get them smooth) 3 angle valve job, and port matched the intake, which was a necessity due to zero decking the block. A set of 1:73 scorpion roller rockers (460 part number) and other than the valvetrain being a little noisy, I'm pleased with the results.

Don't grind the smog bumps completely out. IIRC, there's a water jacket close to the surface of one of them and you don't want to hit that. Teardop them, then polish. Get the one piece valves, or you'll be picking an intake valve out of the top of your new TMI pistons, which was the death of two of my Cleveland's and one M block......this occurs at sustained high RPM beatings. Better safe than sorry with a decent set of valves.

Good luck

 

400 HP can be had with the M head. Round off the plateau around the exhaust valve, but be careful as there is water under there, and clean up the intake - no need for larger valves.

I'd look around for a 400 crank while you're getting the heads done.

 

If you are already getting the pistons from TMI ask him about heads. He has forgotten more about these engines then most people know about any engine!
I rebuilt my 400 about 20 years ago using the low compression pistons and used a straight up timing set with a 4 barrel intake and Edelbrock carb.
My machinist at the time was an old ford ******* and he did a little porting on the heads and shaved a little bit off but nothing crazy along with the normal valve job and guides and seals.
It is in a 77 F350 with a custom welding bed with a Lincoln portable welder on the back along with 2 oxygen cylinders and a huge acetylene bottle.
I have a winch and it is loaded down with tools as well. I have always hammed on it ever time I drive it and I have always been happy with the performance.

 

I ordered a 400 reman short block yeasterday. and told them to leave out the piston cam and timeing chain. so I can put better stuff in. I looked for a few weeks and could not find a crank to put in my 351. And thanks to every one that has given helpful advise. And those that have not tried to force a 460 down my throat.

 

Nobody is trying to force anything on you , nothing in it for me if your pickup ever moves again or not . but the advice was nevertheless good advice and you chose to ignore it. to build a long life efficient higher performance engine the cost of the conversion will be offset by the cost of the lipstick on your pig.

Maybe we're wrong and that's why all those performance Ford engine builders love the 400 engines so much ( HA !) and why Ford dumped the 400 but kept the 429 and 460 for years. . whatever.

 

It's not really a matter of saying you've got to have anything. Sure I've had a few 400s before. They're okay motors for what they are, and when rebuilt correctly they'll last a long time. My logic is just that of you're going to spend money, spend it the right way the first time. But if the budget simply can't do it then it is what it is. In reality even a goal of 300 or so HP is better than what you have now, is more streetable than 500hp because you can run lower octane gas, and will be easier to achieve with your given parts.