Head Milling Size

[Powerhouse]

OK.. I found out the head I want to mill is a numbered as follows...

P 1326304-6 (1942-54) 4.30.51 = 1951 218CI Plymouth L Head 6

It Measures at 1.81” High, so if I milled off .050 = 1.76”

DOES that sound correct? The head looks stock and not messed with...

[Powerhouse]

DUH...sorry..I was forgetting that I need to CC it for the measurements needed...

what would the stock CC be for the 218? ANYONE KNOW?

[Plymouthy Adams]

'51 is 7.0 stock

[Powerhouse]

'51 is 7.0 stock

WHAT IS THE 7.0?

ON ANOTHER THREAD I JUST FOUND A STOCK HEAD'S CC TO BE 85 TO 87 PER CHAMBER MAKING A TOTAL CC OF 522...

WHILE THE FENTON HEAD IS 75 PER CHAMBER AT 450 TOTAL CC.

[dezeldoc]

Tim was talking about compression ratio not cc. why do you need the cc? this ain't gonna be no race car, cut .75 off the head and it should put you around 8.1.

OH YEH TAKE THE CAPS LOCK OFF AND QUIT YELLING!!

[Powerhouse]

Tim was talking about compression ratio not cc. why do you need the cc? this ain't gonna be no race car, cut .75 off the head and it should put you around 8.1.

OH YEH TAKE THE CAPS LOCK OFF AND QUIT YELLING!!

HAHAHA...caps lock...sorry...I working on a layout and left it on...

I need the cc so I can find out what the head I just got is. If it's stock or milled? So, I can Mill it properly. If it's milled too short won't that render it useless? Wouldn't 8.1 be too high..I don't want to have to use no fancy high grade gas...

.050 should be taken off of a stock 1951 head to get 7.5 to 1 as per a chart I found on this forum. But if a head is allready milled how do ya tell? I was told to CC it.

[greg g]

Nor do you know if you block has ever been decked. So the critical measurment is whether the valves will open to their full lift measurement without hitting the head. According to George Asche you can go up to .090 off the combination without the need to run high octane gas. Also it depends on whether you are buliding a 230 or a 218. Piston on a 230 comes nearly to the deck on a 230, with the 218 it sits a bit lower in the cylinder. this is a 230.

[Plymouthy Adams]

CC'ing IS the only true method to determine your starting point on an UNKNOWN..and is the finishing touch for obtaining the exact CR you be looking for to be exact..anything else is ballparking and would do ok if you do know your head year and if it is still stock to begin with

get out a graduated cylinder and get with it.. where the D is displacement.. you will be working in CC's not hard to convert to CID which is what you will ned to do with the head volume to obtain the CR as you will be doing the cylinder volume in CI's

[Powerhouse]

CC'ing IS the only true method to determine your starting point on an UNKNOWN..and is the finishing touch for obtaining the exact CR you be looking for to be exact..anything else is ballparking and would do ok if you do know your head year and if it is still stock to begin with

get out a graduated cylinder and get with it.. where the D is displacement.. you will be working in CC's not hard to convert to CID which is what you will ned to do with the head volume to obtain the CR as you will be doing the cylinder volume in CI's

what?

so I need to convert cc to cid to determine the compression ratio. Is the formula for cc to ci, cc/16.387=cc ?

[claybill]

ballpark....stock cc, is as you say about 85.cc about 6.5 to 1..comp ratio...... an aluminum fenton head is 75cc. producing about 7.5 to 1. i have been told, and my mechanic confirmed that it looks like you can go easily to 007+ off the head..8-1...

so your idea to shave 005 off your stock head is a safe procedure.

in addition, i have heard that you can use a 218 head on a 230 motor and get the equivalent of 005. thats on a 230 cu.in..

i am doing that very thing on my test motor..still in the testing stage..

bill

[Powerhouse]

GOOD LINK FOR FORMULAS

http://www.ajdesigner.com/phpengine/engine_equations_cubic_inch_displacement_b.php

[Don Coatney]

You might find this chart of interest.

[Don Coatney]

Also look at the compression pressures and ratios below.

[Powerhouse]

thanks Don...

[Powerhouse]

OK...CC'd the head...each chamber is 85cc +/- SO I guess it's stock.

[Reg Evans]

Can you explain how you cc'd the head ? I have several here I'd like to check.

[Young Ed]

The process is something like bolting a piece of plexi over the chamber. You need to plug the holes and the plexi needs to seal well to the head. Then you measure how much liquid will fill the chamber. Thats the basics as I understand them.

[Reg Evans]

Oh yeah, I saw a photo of that here a couple of years ago. Is that how you did it Powerhouse?

[greg g]

When i was tring to compare my edmunds heads chambers to the stock head, I put a plug in filled the chamber with antifreeze. then i compared the amount of antifreeze recovered from the heads by pouring the liquid into graduated container. I can't remembe the exact figures but the edmunds head held about 1 1/2 ounces less than stock. This does not include the amount of space left at the top of the cylinder with the piston at TDC so for a true measure you need to account for it also.

[Powerhouse]

here's a link to how I did it...got a $4 marinating syringe from the market and a cd jewel case clear cover with a hole drilled in it for the plexi. simple cheap easy

http://www.steigerperformance.com/PRODUCTS/sp90005.html

[Don Jordan]

Don:

What book is that page from? It didn't print up very clear for me. What a great idea about blowing air down the spark plug hole.

My engine is a virgin - over 60 and never been touched. Right now it's running about 50 - 65 pounds. I think the old girl is worn out. I guess once you get the engine out the prudent thing is just replace everything. But it's still an interesting test.

Does the P15 have insert or babbet bearings?

[Plymouthy Adams]

use modelers clay to fill the impression..remove and drop in graduated cylinder say 500ml size and then fill to 300 with water..if your clay when dropped into the cyclinder pushes the water level to say 385 then you will have a head volume of 85 CC (ml and cc are equal)

for accuarate measurement..the head cannot be measured by itself..the thickness of the gasket and the area that the piston is below deck is also part of the CR equation...you must take this in account and again..the use of modelers clay pressed onto the piston and filling the area of the head gasket in place during the process will get you on the money...

[greg g]

Insert bearings. Babbit is for stovebolts. If your compression is fairly equal thats a pretty good sign. Was your test done dry or with oil down the plug holes.

[Don Coatney]

Don:

What book is that page from? Does the P15 have insert or babbet bearings?

Don;

Page is from a 1953 MoTors manual.

As mentioned Mopar flathead engines have insert bearings not babbot (poured) bearings.

[grey beard]

I'm afraid some of you gents may have a few things mixed up here, in all this local wisdom dispensing activity, here.

First off, the only reason for anyone to cc a head chamber is in blueprinting a precision race motor, to get the volume exactly the same in each cylinder. This would be a collosal waste of time on our MoPar flatties. You simply do notr need this information. It is totally useless in this situation.

Don's chart is a good rule of thumb to follow, in a perfect world, where no head had ever been resurfaced before, or no block deck was ever trued.

What you DO need to know is how close the valves come to the cylinder head when they're fully opened. Here's the only way to find out - unless you're really quick and can get in there and measure it.

Lay a three-inch long piece of solder over the top of each valve and pinch it down with something so it will not fall off. Now bolt your clean head onto the clean block surface with two or three bolts and torque 'em down. Now roll the engine over two full revolutions, so that each valve has opened and closed one time fully.

When you pull the head off and measure the thickness of the solder crump from each valve, you will know the true clearance you are working with.

My own head and engine assembly measured .110 thou clearance using this test, without the gasket in place. I removed .100 thou from the head and installed a FelPro gasket. Runs great, and no problems.

Just remember we're working with sixty year-old-plus iron here, and no one can be sure what was done to any parts in their past lives. The next guy who pulls my head better not take ANYTING off, or he'll be in trouble.

Good Luck and Keep 'em Crankin'!