I have a 351m i built up. The heads has a 3 angle valve job, and shaved .0030", I was worndering if anyone could tell me why dont the stock 351m' heads flow like the Cleveland heads did?
What else could i do to get them to flow.. anyone know the specs on the heads, please tell me!

Thanx,

 

there are only slight differences in the heads. they should flow about the same. the 351M/400 heads are almost exactly like 351C 2V heads. what do yours flow?

 

That I dont know really, see I took my heads to the mechine shop.Wel the guy calls me back saying that i have a crack between the intake and exhaust seats in the head. He also tells me that the heads I sent him does not match up, two different #'s. So he found me a set of mating heads and done a 3 angle valve job, shaved the heads 0.0030", new guids, new valves, seals, and high performance valve springs... I was worndering how much more power could i get out of those heads and roller rockers??..

PS..I have no idea what year the heads are..

Thanx

 

most 335 series engines i have seen have mis matched heads. 2 of hte 400's i bought at the junk yard had mis matched heads. the heads themselves make a lot of power. the flow is great. did you have your heads flowed to find out what is going on?

this site has good flow figures
http://www.waldens.com/waldens/fmotorsp.htm

see how close you are to these

 

It was my understanding that the 400 heads up until 1975 were basically the same head as the 351C 2V, except the 73 and up had AIR bumps. But the 75 and up 351M/400 head had a very restrictive exhaust port because of a water jacket Ford cast around the guide (?), and you can't port that restriction out without hitting water. Just what I've read/been told.

 

I think Tulsa nailed it. The later heads are exhaust restrictive.

 

No, i never have had them flow test yet. I got the heads i was talking about hat i had redone, i still got both factory heads on my 351m right at the moment, but i'll take them back to the shop to see what they flow..Are there any other types of intakes for the 351m besides the Edlebrock Performer 400? thats whats on it now, and i got a .510 intake and .536exh. lift cam. Advertised duration lift is .280 int. 290 exh.. Is that a good lift cam?, will it flow better with the heads i have to put on? Also i have a 750cfm edelbrock carb. I that to big?

 

carb is to big, you can get betterperformance out of a 650. your cam may also be to big, thats close to what i have in my 400, mine is in a car and spins rpms.

did you dyno, or is it just not making power.

 

I just wanted to get the most I could get out of a 351m..
The engine is bored 0.0030" over, TRW Flatt top pistons,
that cam, 400 performer edelbrock intake, and the 750cfm carb,
Long tube hedman headers, the new heads i had redone,(not put on yet), roller rockers(not put on yet)..A whole MSD ingnition system (distributer, box, and coil). What kind of power would you say I would have at the fly?

 

ok i get 372hp at 5.5k and 375 tq at 4.5k you get the same numbers with a 650 carb.

what i dont understand is this; no one really complains about the flow of these heads. Where did you get 351M flat top pistons?, I didnt think anyone made them at all. If you are that concerned about power why did you not just convert it to a 400? After all, you just have to change the pistons and crank, poss the balancer.

I really have to ask, are you sure its a 351M and not a 351W? I dont want to imply you dont know what your doing, it just seems odd. Thats a lot of rpms, but you have to expect that with a high duration and lift cam.

 

The reason I asked about the flow of the heads was because everyone I talked to about it told me that the later model "M" heads was restrictive, that really all i wanted to know, sorry If I was any trouble to you man.. Yes im sure its a 351m, I built it myself, as for the pistons they cam out of the P.A.W. book..
Also i wanted to know could i use smaller jets in my carb, and maybe take it down to a 650?

 

From what I recall reading a few times back, The stock 335 Series Engine heads, the 351M in particular is capable of enough flow to support right around 385HP

 

Thanks Ranger, thats where i wanna get...

 

ouch, i didnt mean to come out like that. sorry if i did. the heads will flow more than enough. the reason they are considered restrictive, is they flow slightley less that the 351C 2v heads. we are talking about 10-15% less. they still flow better than most of the aftermarket 351W heads. they will make more than 400hp. the best thing to do, if you really are after power, is to put in the 4V valves.

remember these motors are dogs, thats why some of us make a lot of power. do beleive everything you hear.

 

Yeah, I have a guy here at work that is a 460 man. He just keeps saying that the 351M and particularly the 400 are "unreliable". Gotta love it.