Inliners International Forums General Discussion MOPAR Flathead head questions

In continuing my...um..."research project," I've come up with alot of questions. Are the 218 head and the 230 head the same head? Will a 218 head on a 230 increase compression? Are the combustion chambers the same volume? What about casting thicknesses? Valve shrouding? Which flows better and why? Which specific head is the best for performance and why(i've heard the '59 car head is the best)? I need to know everything you know about the factory flathead heads. Thanks.

-Jeff

Jeff-

Not sure about the differences between the years in terms of performance. However, there is a difference between the thermostat external bypass and internal bypass engines and heads.

My 1950 block is the external bypass type. The internal bypass types have an internal passage in the front of the block and a corresponding port in the head that replaces the external bypass system.

I think the Edgy head can be used on either, but the internal bypass port has to be drilled in the head to match the block. In this pic, you can see a slight bump on the left end, which is the front end of the head. This bump out in the face of the head is where the internal bypass port is located on the later blocks.

Food for thought.

Pete

Never thought about this before... put a big cam in and you might need to flycut the head!

How close is the chamber shape of the Eddy head to the standard, 'skies?

Do you know the year split between the internal and external bypass motors?

Here's a shot of the factory head for comparison





I polished the chambers a bit to remove the sand cast finish. The EDGY head has 9:1 compression on a 230.

Pete

I don't when the change was made, but I'm sure someone over on the P15-D24 site could tell you.

Pete

Blueskies,
Bob. here,.....the photo of your aluminum head is very interesting,.....it appears to have ridges cast in,......are they there to improve flow characteristics ?

My stock iron heads seem lame by comparison,....yes they are polished and milled .080 but they sure don't look like that.

Bob.

There is no difference in the heads due to the internal/external bypass issue, it's all in the block or external bolt-ons. There is an extra 0.400" hole adjacent to one of the three bolts that fasten it to the block, which feeds water from the block to the center of the waterpump for the internal bypass. The external bypass is in the thermostat housing on the head, feeding water into the heater connection on the top of the waterpump.

A word of caution; don't use the external bypass parts on an internal bypass motor. Can you guess how I know this?

Marty

PS. I do know that the change from external to internal bypass occured between the production of the 1947 218 that was original in my Business coupe, and the production fo the 1952 Dodge 230 that resides in it now. I wonder if the change was made when they came up with the "stroker" 230's?

Marty

Marty-

I may be incorrect, but I believe there is also an extra water passage hole in the front of the head, right next to the middle front head bolt.

The EDGY head has a bump cast into the front face to accomodate this hole, but it is not drilled into the water jacket. The head gasket I bought also had this hole, but my external block does not have the corresponding hole.

I had a chat with Earl Edgerton, maker of the head, about the possibility of converting my block to the internal bypass type by drilling the holes, but elected not to. I was going to use the head gasket to locate the hole in the head and block.

The reason I wanted to do this is because the thermostat housing on the head is slightly off-alignment with the waterpump bypass fitting. I had to find a pre-bent hose at the auto parts store to make the connection.

In this pic, you can see the bump cast into the face of the head, down between the two left side water pump backing plate bolt heads.



Here's the same shot, with the hose that I found to make the bypass connection.



And the hose I cut this little section from:


Pete

9:1 is pretty good for a flathead...

My nephew is keen to see what happens when we get my flathead and start work on it. He wants to put the block on the flowbench!

Ray,
I'd be real interested in seeing flow numbers from a flathead block. I wonder how hard it would be to rig up.

Question. Unlike an OHV engine, the area around the valves does not change with stroke on a flahead(the valve shrouding is unaffected by the piston). If you did the flow testing with the head on, once you had your baseline could you play with chamber shapes, shifting the head, etc, to increase flow into or out of the cylinder? Guess what I'm asking is could a flow bench be used to fine tune chamber shape?

Ray,
right about now there is a whole bunch of folks with eyes focused on your nephew and his flow bench initiative. It's something we the flathead gang would be very interested in seeing,....encouragement is all I can offer at this point.

Cheers
Bob.

Thanks Bob... Bugman... I'm certainly looking forward to it myself!

It's a fair way off. He has a major development job to do on the Poly yet, but it's possible that he might look at gasflowing the flathead at the same time if I can get what's needed ready in time.

I would think that plasticine in the chambers could be one way of experimenting for improvement. Certainly it would be a way of checking if filling the chamber for compression might affect flow.

Hey, the 218 have a shorter head than the 230

Nope, the 218 and 230 both have the same length head/block. The blocks are identical, the only difference is the stroke, 1/4" longer for the 230, thus a different crank and rods.

Pete