Farmall M/450 heads

So I see a lot of discussion about "get the LP head, Get the 450 head, etc".

What is the advantage of the different heads? Do they flow better or just a smaller combustion chamber?

Both

(quoted from post at 09:27:23 10/19/12) Both

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Gary, what's your opinion on the China cast heads that are popping up all over now for sale?

Ray the 450 gas head is also 180 cc and the lp head
is 140 cc with 8.34 to 1 cr with flat tops the other
heads are 200 cc

With the shallower combustion chamber, the
ports are longer with a better radius vs the
short runners with a sharp bend in the gas
heads. SM gas heads have 200cc chambers, 450
gas head has 180cc chamber, and 450LP has 140cc
chamber.

Just curious. Of the vast selection of the LP, gas and all fuel
heads that will bolt onto an M series bolt pattern.
Which head(s) have the best factory port flow?

(quoted from post at 05:23:45 10/19/12) So I see a lot of discussion about "get the LP head, Get the 450 head, etc".

What is the advantage of the different heads? Do they flow better or just a smaller combustion chamber?

Click to expand...

Thinking of adding a "red" page to your website?

nah, I could never compete with the likes of Gary, Paul, etc that have been doing this for years.

I get a lot of builds for the H/M though and you see a lot of people in search of the mythical LP heads.

Real question is what are the flow differences between the different heads?

Personally if you're building the motor from scratch, you can utilize whatever chamber is there in your piston design. That's why we do custom pistons (which as many have found out don't cost that much more than shelf pistons), and CNC the combustion chambers to keep them all the same and make subtle changes to them.

I'd rather have a big chamber with little to no valve shrouding than a little bitty chamber that limits what I can do with the valves.

So...
is there a documented CFM for the 3 different heads from the factory?

And what are you seeing after the magic has been done?

I've flow tested these heads. Flow numbers are not as important as port design or shape when the engine is running so I really don't care what they flow on the bench other than it's a good baseline for improvements made. Some people get to caught up in numbers to realize what's really important.

A few weeks agoe I read where some idiot was claiming thar 1 cfm of airflow was worth 2hp...... but he gave no consideration to anything else in engine design. To many magazine articles in the break room at work and not enough experience in the real world.

I'm to busy harvesting corn to get any free time but we'll be done in about a week. My flowbench is in towm at a machine shop and when I get some free time I'll get to my notes and see what the difference is for sure. Going from memory though there isn't much difference in these heads and in stock form I think a 450 head would flow about 170 cfm at .600 lift. But I don't rember any of the low and mid range numbers untill I get to my notes.

Simetimes if a customer has a junk head I'll take and try some things. On the Farmall head what would happen if it was filled part way and the chamber flared back. Most people cut the chamber straight but I cut them at an angle for a better discharge flow around the valve. What would happen if the guide was removed and a solid one made with the valve centerline moved to get more clearance from the valve to the chamber? What if I made that same guide and move the valve centerline and I also angle the valve for a better valve to port angle and as it would open it woud open away from the chamber?

On Allis heads I'll cut holes through the top into the water jacket to gain access around the intake port and blast them clean. Then I fill the area around the port and valve bowls. I cut the port verry wide and in a long sweeping radius into the valve bowl and I cut the floor of the port into a radius. This leaves to large of a port but I build a divider in the center to split the siamesed port and keep the port propper size for the application.
This not only makes the port flow verry well but it keeps a more consistant velocity throughout the port and by dividing it I keep reversion and robbery out because of the fireing order and breathing order on a siamesed port 4 cylinder. If o make a solid guide and move the valve closer to the port centerline it helps but only on bores large enough to allow.

It is possiable to end up with a verry well flowing head that holds water. It'll all a matter of how hard you are willing to work but it's all useless if your engine can't utilize it anyway or your rules dictate a certain manifold and carb. Most important is matching the components. You don't need big valves and big flow numbers when you canlt use them.

Things to think about but not talk much about I suppose.