After going through the posts in this forum I have a few questions:
Dimensionally speaking, is the head for the 400 bigger than the 2v cleveland? what about the 4V cleveland?
What is the difference between the aussie heads and the 400 head besides the chamber?
How much material is there between the coolant passage and the floor of the exhaust port?
And finally, my engine is the 400 with 600carter, comp 268H (soon to be bigger magnum), performer intake manifold, roller rockers, gasket matched intake and exhaust, 3-angle valve job, bored .030 with pistons that have two small (bout 1/4") rings on the top, and hooker super comp. This is in my 73 ranchero (4300 lbs). How much power should I get from going to a single plane for a 351C? How much torque will I lose?
A lot of questions, I know. But I always want to know as much as I possibly can about stuff.

 

After '71 351 Clevland heads, 351 modified heads and 400 heads are all the same. The 4bbl Clevlands have humungous intake ports and smaller combustion chambers. Not really suitable for the street these days.



--Heaven will be inherited by every man who has Ford in his soul--
http://www.angelfire.com/realm2/autotips/index.html

 

>After going through the posts in this forum I have a few
>questions:
>Dimensionally speaking, is the head for the 400 bigger than
>the 2v cleveland? what about the 4V cleveland?
>What is the difference between the aussie heads and the 400
>head besides the chamber?
>How much material is there between the coolant passage and
>the floor of the exhaust port?
>And finally, my engine is the 400 with 600carter, comp 268H
>(soon to be bigger magnum), performer intake manifold,
>roller rockers, gasket matched intake and exhaust, 3-angle
>valve job, bored .030 with pistons that have two small (bout
>1/4") rings on the top, and hooker super comp. This is in my
>73 ranchero (4300 lbs). How much power should I get from
>going to a single plane for a 351C? How much torque will I
>lose?
>A lot of questions, I know. But I always want to know as
>much as I possibly can about stuff.

The 400 heads are ALMOST identical to the 351 2V heads, except that there is a rather obtrusive bump blocking off part of each exhaust port. Some have successfully shaved that off, while others claim that if you do, you strike water. The 4V heads all have larger valves and ports - some are quench chamber while others are open chamber like the 2V. As the other guy said, the 4V heads are unsuitable for most street use as they were designed for high RPM use. The Aussie heads are like the 400 2V heads except the chamber, thicker deck, and no bumps in the exhaust ports.

Your question on the single-plane impact on low end torque depends on the intake. Most single-plane intakes are designed for higher RPM use but I can't quantify your loss - depends on cam, exhaust, etc. Some early single-plane intakes such as the Edelbrock Streetmaster reportedly did not lose much (if any) torque at low RPM. I once had a 400, 9.5:1, Streetmaster, small tube headers, hi-torque cam, 625 Carter - and it was awesome at low RPM...

 

Is the extra bump because they are 400 heads or the year of the casting?I have heads from a 400 with a casting number D3AE with the same exhaust port as my 351C 2V heads.I have another set with a D5AE casting number that has the exhaust port with the extra bump.

 

that is the debate. I have early 400 heads and they are rather different than both 2v and 400 later heads. my heads and engine are a 1971 cast at DIF. so far i have mine and have heard of another DIF cast engine.

castings
MCC - Michigan Casting Center
CF - Cleveland Foundry
DIF - Dearborne Industrial Foundy

 

The extra bump in the exhaust port is in the top side of the port and connects into the cross drilled thermactor air injection port. You should be able to grind them off with no problem except grinding into the drilled air passage. You may be able to fill that passage with a steel rod. I don't know for sure, I haven't tried it... Yet!

GT40 -what is the part number of your heads? D1AE?

 

The extra bump I was talking about isn't the thermactor boss. On my D5AE heads the whole area around the exhaust valve guide is different than my D3AE heads.The valve guide area is flat but on the early heads it protrudes into the port.Just down from the guide there is extra metal as well which pinches off the port.Just looking at the two heads side by side you can see that the early head should flow better.

 

Ahhh... That bump:-) I have heard of that configuration but I have never seen it personally. Do you have any way of getting decent pictures posted?

 

There is a topic already in the forum (right now it is on page 2) called 351m/400 heads.In one of the responses there is a link to a picture of a cutaway port that shows the problem.It is way better than any picture I could produce.

 

Cross section '75 351M/400.
http://users.abilene.com/~dkelly/hotrod/images/motor/headcros.jpg

 

>GT40 -what is the part number of your heads? D1AE?
>
>-Eric, Torque1st,


D1AE-1 1F29

 

I have the D1AE heads and gasket matched them. Do the 351c 2V heads flow much better than these?
Also, I keep hearing that the 351c 2v heads are the same as the 400 heads, this is just port size, correct? I also hear that they are not the same because the 351c heads don't have the bump on the floor.

If the 351c heads are considerably better than mine, would I need a spacer plate to put them on my 400? and would my headers be in the same location on the heads?

 

the only heads you would need the spacer plates for would be the 4v heads, or any of the rare varieties with the HUGE ports (boss 302, boss 351, 351 cobra jet, 351 HO). for those, you neet to use an intake made for a 351 with 4v heads, and the spacers.

for all 351C 2v heads, 400 heads, 351M heads, and aussie heads you just use a 351M/400 intake on a 351M or a 400, and on a 351C you use an intake made for a 351C with 2v heads.

now i'm REALLY confused on the 351c 2v heads - 400 heads - 351M heads - early production - late production - different foundries - thing... all i know is that none of them have the big ports.

 

ok heads as i treat them

351c 2v are all the same

351m/400 are all the same, after 1975

351c 4v are all different, as to year and type

302c 2v are mostly the same

302 boss 69 and 70 are diff (4v ports)

all 2v heads will work with no intake and exhaust mods

all 4v heads need intake spacers and 4v intakes, need 4v exhausts as well.

no i do know i have over symplified them to a point, but you should not have major issues going by this.