Canadian Heads

[jjk]

Doing some work with a buddy and came across a pair of mismatched heads. Can anyone give me the rundown on what the difference could be between the two?

[Newc]

C8BA Ford, C8CM-B Merc; Merc heads were supposed to have a larger combustion chamber in the USA. Compensating for the extra stroke. Canada ?? Newc

[petehoovie]

Originally Posted by jjk

Doing some work with a buddy and came across a pair of mismatched heads. Can anyone give me the rundown on what the difference could be between the two?

[tubman]

Those look pretty good from what I can see (no combustion chamber pics). They can be made functionally the same with a little milling and grinder work to bring the "squish" (over the piston clearance) and chamber size to consistency. You could also "clean up" the markings, but that would be a personal choice.

[jjk]

great , so there's two different combustion chambers?

[38 coupe]

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Originally Posted by jjk

great , so there's two different combustion chambers?

Yes. The shape of the combustion chambers will be very similar, the Mercury head (the one with the "M" in the part number) will have a larger volume in the combustion chambers.


What is the motor going into and what do you want from the motor? Depending no application we can guide you to either the correct head for the vehicle (preserving originality) or the smallest combustion chamber commonly available (maximizing cheap performance).

[tubman]

Since it can't be seen and has a major effect on both performance and fuel economy. I believe that optimizing the combustion chamber is the single most effective thing you can to to a Ford flathead.

There is simply no downside.

[Tim Ayers]

If you flip the heads over and compare them, I'll bet you'll be able to see some differences.

[tubman]

Pictures of the bottoms of the heads would be useful for a number of reasons. I think that the differences might be difficult to see, but could probably be measured.

[Ol' Ron]

Why does everybody send pics of the wrong side of the heads when they want to know sone thing about them. But Aesthetics are important too????
Gramps

[51504bat]

Find a set of EBA heads. Not as pretty but problem solved. IMO

[Tim Ayers]

Originally Posted by 51504bat

Find a set of EBA heads. Not as pretty but problem solved. IMO

Agreed. Anyone know if there was a Canadian version of the EAB's?

[tubman]

Originally Posted by 51504bat

Find a set of EBA heads. Not as pretty but problem solved. IMO

I would respectively disagree with this. It assumes that the Ford factory specs are gospel and the heads are right on. I have found that every set of heads I have used required work to get them to where I wanted them to be. Also, who knows what might have been done to a set of heads in the 70 years (yep, it's been that long) since the heads were cast and machined? In my opinion. any one that just slaps a set of heads on an engine without checking clearances is not doing the project justice. I will tell you from experience that aluminum heads are easier to work with than stock iron units.

Anyone concerned with flathead performance should have at least a passing familiarity with the works of Sir Harry Ricardo

[Ziggster]

Thanks for posting about Sir Harry Ricardo. Had never heard of him until now. Read his wiki page. It just amazes me that all these folks just started designing and building all kinds of engines seemingly out of the blue. There are only a handfull of folks today that repeat such fears, even with all the marvels of our modern technology.

[Tim Ayers]

Originally Posted by tubman

I would respectively disagree with this. It assumes that the Ford factory specs are gospel and the heads are right on. I have found that every set of heads I have used required work to get them to where I wanted them to be. Also, who knows what might have been done to a set of heads in the 70 years (yep, it's been that long) since the heads were cast and machined? In my opinion. any one that just slaps a set of heads on an engine without checking clearances is not doing the project justice. I will tell you from experience that aluminum heads are easier to work with than stock iron units.

Anyone concerned with flathead performance should have at least a passing familiarity with the works of Sir Harry Ricardo

I guess a lot of us assume that someone would check the clearances, but you know what they say about assuming

[Newc]

Thought that C8BA was an EAB??? Just aluminum and prettier. Newc

[jjk]

FORD ON THE LEFT
MERC ON THE RIGH

Both come in around 40CC

[petehoovie]

Originally Posted by jjk

FORD ON THE LEFT
MERC ON THE RIGH

Both come in around 40CC

[tubman]

Thanks for the picture. 40 CC seems kinda low, but it depends on how you measure them. They look pretty good from what I can see. I have seem them milled so much that the "step" behind the water outlet is hardly visible. (I'm not much of an expert as I have only one set of C8BA's.)

[Tim Ayers]

Originally Posted by jjk

FORD ON THE LEFT
MERC ON THE RIGH

Both come in around 40CC

Did you use plexiglass so the water can fill the entire chamber? As Tubman mentioned, 40CC is quite low.

[glorydime]

Hey these are my heads and I filled the chambers with solvent and then used a syringe to pull the liquid out. Obviously I was unable to get the entire amount of solvent out however both chambers were measured in the same manner and both came back to the same result. So yes 40cc is low because I was unable to get all of the solvent back out. I’m going to run them mismatched. I’ll post back here once I switch heads and let yall know how it runs.

[cadillac512]

I believe the C8BA heads are 70cc and the C8CM are 76cc. That is from the comprehensive list posted in the past.

[glorydime]

Thoughts on running as is till I find another matching head.

[tubman]

It sounds like the chambers are close to equal (if your method of measuring was consistent). If such is the case, there should be no problem running the mismatched heads. Even if they're not, in my opinion, it would still be OK.

Good luck in finding a "match" for either one; as somewhat a connoisseur of Canadian aluminum 8BA components, I can tell you they are quite scarce, and anybody that has them will be loathe to break up a set. I have also found that usable pieces are quite expensive. I have tried to match single 8BA heads twice in my life. The first time I ended up selling the single, and the second is now a "wall-hanger" in a good friends shop. I believe the best thing to do would be to massage both heads to optimize quench and compression and do what you want with the id marks.

[Ron_r1959]

The only head harder to find is the earlier head for the 59AB block, It took me quite awhile to find a set of them. I have seen them on eBay occasionally for the 8BA block but not verry often for sure. Good luck finding one, i would agree with Tubman, match the cc volume to get even squish and move on unless it just has to match aesthetically. If what I have read on here is true, a lot of the time, the piston clearance from one end of the head to the other is rarely the same, so if that is true, the 5 cc if accurate may not matter that much truthfully.

[Ol' Ron]

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THANKS tUBMAN, yES hARRY;S ONE OF MY FAVORIT PEOPLE
gRAMPS
sORRY ABOUTTHE COMPUTER PROBLEM

[Ol' Ron]

Daughter to the rescue "CapLock" Stupidity iz my name, Boy these modern computers hard to figgerout..
Gramps

[tubman]

Don't worry Ron, I'm sure we all got the message.

[cadillac512]

Originally Posted by glorydime

Thoughts on running as is till I find another matching head.

Sure, it'll run mismatched...and probably well enough you won't really notice it. As mentioned, really machining and matching the domes to the pistons to achieve approx .040" clearance between piston tops and head domes is quite beneficial and you WILL notice it then. But to make it run and drive...sure-bolt 'em on and no worry.

[Ron_r1959]

Just ordered me a book, i love the bits of information shared here, your never to young or old to learn from each other!!

[GB SISSON]

'Low' meaning they already have small combustion chambers and therefore would produce high compression? Is there a number that is used to indicate the proper volume?

[glorydime]

Y’all are great thank you for all the replies. I will repost when I fire it back up after paint and head and intake swaps.

[tubman]

If you think about it, you can't see the different markings on both heads at the same time when it's in the car.