my new toy 351M/400

[ozzy14159]

so i picked up this 351M shortblock wit edlelbrock performer 400 intake and 600cfm carb. everything has only 500 miles on it since rebuild. just enough to break her in. what kind of heads should i put on this beast? i can either put 351 heads and have it a small block or put 400 heads on it and have a big block because its basically the same block as a 400 just the heads are different.

 

[pistonhead351]

4v cleve heads if they will fit. i dont know much about the modified.

 

[xherdlr]

I think Cleveland or Yates heads are your only option. Correct me if Im wrong. The M motors have 8 bolt head pattern where the Winsors have 6 head bolt pattern...M motors are not the best for high performance,but can be made to perform well...

Kelly

 

[Josh79]

4v aussie heads (cleveland). I have a 400 in my old truck with edlebrock intake and carb, comp cam. It is a good motor plenty of torque. Some people say they are just a boat anchor and all that but they have never owned one before and if so they were totally stock so of course they are dogs with all the emmisions **** and a 2 bbl carb. Need to put some headers and a aussie heads on it and it would be a even bigger beast but it does well in the mud already so ill put the $$ in the stang. So are you going to make it a 400 or stay with the 351m? I believe the heads are the same on both motors.

 

[Mr. Rustypwnz]

ooooh, my buddy is building a 400m at the moment and is going to push easily 400 at the crank, in a f100, going to be over sleeper.

 

[795.0pacecar]

Throw a 400 crank, rods, and pistons in it and use 1970 351c 4V closed chamber heads.

 

[85_SS_302_Coupe]

The biggest problem with the M is lack of available parts and/or price of available parts, which is why most people stick with Windsors. I think for the money i'd just do a Cleveland build if i didn't go Windsor.

 

[ozzy14159]

it was just professionally machined and rebuilt with new pistons crank and rods. im not about to tear it apart again. ill probly throw some 400 heads on there. the block is exactly the same in a 351c a 351m and a 400. the only difference is the heads.

should i switch out the cam because this motor came out of a truck that was specifically built for torque... i know people are gonna give me crap but this is goin in my stang. heres the cam specs for the current cam. i might keep it since its brand new but then again new ones arent that expensive for this motor.

Valve Setting: Intake Hyd
lift intake@cam 280 @valve 484 Rocker Arm Ratio
exhaust@cam 295 @Valve 510 1.730

Advertised Duration
intake 270
exhaust 280

thats what it looks like on the cam card. i woulda scanned it but my printer is spazzing

 

[85_SS_302_Coupe]

oops double post!

 

[85_SS_302_Coupe]

it was just professionally machined and rebuilt with new pistons crank and rods. im not about to tear it apart again. ill probly throw some 400 heads on there. the block is exactly the same in a 351c a 351m and a 400. the only difference is the heads.

should i switch out the cam because this motor came out of a truck that was specifically built for torque... i know people are gonna give me crap but this is goin in my stang. heres the cam specs for the current cam. i might keep it since its brand new but then again new ones arent that expensive for this motor.

Valve Setting: Intake Hyd
lift intake@cam 280 @valve 484 Rocker Arm Ratio
exhaust@cam 295 @Valve 510 1.730

Advertised Duration
intake 270
exhaust 280

thats what it looks like on the cam card. i woulda scanned it but my printer is spazzing

If the block and everything else is the exact same as a Cleveland, just put Cleveland heads on it and rock on! Can't go wrong with a 351C in a Fox.

 

[Josh79]

The heads between the 351m and 400 are the same. Of course different years may have had different heads, but there is no 351m head and a 400 head they are the same for the same years(the first few years of the 400 there wasnt a 351m so i guess you could say they are 400 heads just look @ the casting numbers to find out what year). The difference between the 351m,400 and 351c is more than you think. The differences between the 351m and 400 is the crank and pistons. The difference between the 351m/400 and the cleveland is a lot, block (cleveland has a shorter deck height around an inch if i remember right), crank, rods,pistons, and intake. Things like camshafts, heads, water pumps etc do interchange between the 335 series engines.Aussie heads (cleveland,canted valves) would be a good set of heads to put on it. Do some research on the 335 engines and you will find the info you need. Ill see if i can find a link to a site just for the 335 engines. It is a good site with everything you need to know

What you should do is put the aussie heads on it and you will have a good motor. It will basically act like a 400 cube cleveland. the 400 and 351c are good motors and when you combine the two of them together to get the good qualities of each motor you end up with a good combo with very good torque. Basically there is no aftermarket for them that is what really hurts them. Imagine if there was no aftermarket for the 302/351w what that would be like.

 

[ozzy14159]

. The difference between the 351m/400 and the cleveland is a lot, block (cleveland has a shorter deck height around an inch if i remember right), crank, rods,pistons, and intake.

yeah that is true the 400 has a stroke of 4'' while the 351m has 3.5'' im pretty sure

i know 302 heads can be used on 351w is that the case with the 351m? probly not but i dont know.

i was planning on finding 351c heads and getting them machined based on the cam i have. should i got wit 4v or 2v heads? and should they be open or closed chambered? i noticed all these different kinds and i dont know what would make the most power

 

[795.0pacecar]

I have seen countless tests that suggest the 4v closed chamber heads produce the best power curve. If the 2v heads were better ford would have put them on the Q code mach 1s and Boss 351. With enough machining the 2v heads can be a good but you could get just as much machining into the 4v heads and come out on top. Closed chamber heads are the ones you want. Other people here will know more Im sure, you might want to try the classic mustang section since the 351 cleveland was the performance engine of choice back in the day.

 

[Josh79]

To run 4V Cleveland heads on a 400 you will have to have the intake adapters, valley pan cover and a Cleveland intake. Now 2v closed chamber (302c heads aka aussie heads) would be the way to go as you can use the 351m/400 intake. The heads will raise the cr up a good bit so make sure it does not raise it too high for what gas you can run. What ever you do make sure to double check what heads you get (check casting #'s)and that you dont get open chamber when they were supposed to be closed chamber etc. You can pick the heads up off of ebay and i know there are a few places that sell them online but i dont remember who. Do some searching and you should be able to find them. The 4v will be better above 5000, but will loose power down low compared to the 2v so i would say 2v would be better. The 2v closed chamber heads are what is called aussie heads.(had i typo in earlier post)The 4v closed chamber are not refered to as aussie heads. The reason they are called aussie heads is because they were only available in austrailia and were for a motor we never had in the states (302c, a destroked 351c, kind of like the 351m is a destroked 400 ). i just did a quick check on ebay and there are a few aussie heads on there now.

 

[795.0pacecar]

Im not sure what car your putting that in but remember that the 351m/400 use the big block 385 series bellhousing bolt pattern.

Somebody was making a 4v intake manifold for the 351m/400 a while back, but I cant find it now.

 

[ozzy14159]

im puttin this bad boy in an 88 notch. ill probly get a c-6 for it orsome****. i think im gonna go wit the 351c 2v closed chamber heads as u suggested. should i try and find assembled ones or just get bare heads and machine them based on my cam?

 

[emeraldcoupe]

i can either put 351 heads and have it a small block or put 400 heads on it and have a big block because its basically the same block as a 400 just the heads are different.

the 400 is just a 1" taller cleveland. the heads are the (basicly)same
as the 351c 2v heads. cleveland cams work. bolt on a set of 4v closed chambers. your stuck with that ****ty intake unless you buy spacers to use a 351c intake. the difference between the 351m-400 is the stroke. also it uses unique mounts and has a 385 series bellhousing pattern.