EAB Cylinder heads

[Bruce Compton, Canada]

Are the EAB heads desireable or are the EACs better? Bruce

[f1builder]

you want the eab's, the eac's aren't very good.

[Leyland]

I am no expert on flatheads but I recently purchased a 54 mercury flathead (with EAC heads) and found out the following through my research...

EAC or Canadian Mercury heads, from what I understand were the most HP produced by a flathead cars engine producing 125hp in 1952 through 1954. They claim to have a 7.2:1 compression ratio. The Ford EAB heads could be either 7.2:1 or 6.8:1 compression ratio according to Venpeltsales.com so maybe it depends on which version of the ford head you have??? As for the final horsepower, I guess it would matter what piston height/design & stroke you are running, gasket thickness, etc as to what head is the better performer. Personally I would run the EAC heads as it appears they have only 1 compression ratio so this eliminates the guess work. especially if using in a stock set up with the 4" crank & stock pistons. http://www.vanpeltsales.com/FH_web/f...0to125late.htm however if you plan to change things up, maybe the EAB heads are a better choice as many claim they flow better.

Hope this helps.

[Newc]

Hi Bruce; About heads, I have two Canadian cars with US heads on them. Old repairs I guess. I need a set of 46-48 c-7 stock Canadian heads. My black 114X Merc cpe is almost judgeable . Thanks Newc in Oregon

[Bruce Compton, Canada]

Newc : Are you looking for cast iron or aluminum? Bruce

[rotorwrench]

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FoMoCo lowered the compression ratio on the Merc 4 inch crank engines to keep them roughly the same at the EAB Ford 3 3/4" crank engines. If you put the EAC heads on a 3 3/4" crank engine, the compression will be lower. The Denver heads (supposedly for use at higher altitudes) were the highest compression heads used by FoMoCo in the 8BA family of engines. They are pretty rare today so the stock EAB heads are close and with a little shave can be pretty much the same. The Canadian Ford engines were still using aluminum so they were popular for looking cool but compression ratios were pretty much the same as for USA cast iron heads.

If you use EAB or Denver heads on a 4 inch crank motor you're starting to get somewhere compression wise.

Kerby

[Jack 34pu]

Be careful which pistons you use if rebuilding and want the EAB heads. I used the EGGE pistons in a 49-50 Merc bored .080. EAB heads were too close to piston domes by a lot.

[Frank Miller]

The Mercury combustion chambers were a little larger to give the same compression ratio for the increased swept volume of the longer stroke. If you increase the stroke in a Ford engine and use the same heads you will increase the compression ratio. The compression ratio is determined by dividing the swept volume by the combustion chamber size.

[Henry/Kokomo]

I had a similar experience to Jack. 8BA bored .125 with 4" crank and EAB heads. Had piston interference about 3/8" - 1/2" in from the circumference of the piston using Ross forged pistons. Required some cutting in the combustion chamber. HOWEVER - I can't be 100% sure the heads hadn't been milled previously.

[rotorwrench]

On 8BA family of cylinder heads, there is a way to tell how much they have been shaved over the years but it will only give you a close figure not exact. The area where the water outlets are on the deck side will have a clearance when set on a surface plate. If there is no clearance, they have been cut a lot. If there still is some clearance there then you have to compare it to a known stock (never been shaved) head. The comparison will give you a ball park figure. The castings aren't perfect there but at least it will give a person some idea.

Kerby

[Henry/Kokomo]

Thanks, Kerby. Good info. Seems like there's a lot of that - good info. - around here.

[Ol' Ron]

I like the idea of measuring the clearance. between the head and piston as well as the volume of the chamber. This is not complicated and eliminates the guess work. The EAC heads are 52-3 Mercury and have a very large combustion chamber similar to the 8RT heads. The Key to good performance and economy is the combustion chamber regardless of the displacement. Keeping the piston and head clearance to .040-050" is the best way to induce turbulence into the chamber getting better combustion. This subject has been covered dozens of times and is important. Spending thousands of dollars on an engine and not understanding the tuning aspects of the engine result in a needeoker engine.

[Elmo Rodge]

Originally Posted by Frank Miller

The Mercury combustion chambers were a little larger to give the same compression ratio for the increased swept volume of the longer stroke. If you increase the stroke in a Ford engine and use the same heads you will increase the compression ratio. The compression ratio is determined by dividing the swept volume by the combustion chamber size.

Frank, It's actually swept volume PLUS chamber size divided by Chamber size. Wayno

[Karl Wolf]

One can also measure the diameter of the head, where the piston goes up into... Figure a bore of 3 3/16" for an unresurfaced head, smaller for a head that has been shaved... Karl

[Frank Miller]

Originally Posted by Elmo Rodge

Frank, It's actually swept volume PLUS chamber size divided by Chamber size. Wayno

You're right! Thanks.

[Charlie ny]

Brice,
I'm running a set of EAB's on my 8ba. One was NOS and other
was milled about .030. I had both milled to match..about .050 on the
NOS heads and ,020 on the other. I installed heads using 4 equally spaced
studs and no head gaskets. With light hand pressure on the heads I
rotated the motor over and found interference at the edges of the exh
chambers and on the comb chambers. I milled clearance for the exh
valves...Isky Max 1 cam....and proceeded to the comb chambers. I
chalked up the top of the pistons and rotated the motor over and it
was pretty evident where the interference was by the witness mark
left in the comb chambers from the chalk on the pistons. With a high
speed air grinder I carefully removed iron from the comb chambers where
the chalk witness was left. It became clear that on one bank the mis-
match was towards the rear of the block on the other bank the mis-
match was towards the front of the block. By repeatedly chalking
and rotating and judicially hand grinding I matched the chambers to
the piston crowns pretty damn close. Remember this was always with
no head gasket in place. What I'm saying here is that I had zero
piston to head clearance with no gasket. I used BEST graphite head
gaskets which when squeezed end up being about .042 thick.
I've run this motor hard and guess it's the best Flathead I've ever
had for performance and fuel mileage. 4" stroke ,+.080 bore, 125 to
130 # compression. I can tell you each head took at least 8 hrs to
prepare but for me it was well worth the effort. The front to back
mismatch is something that I doubt you could dial in accurately any
other way.
Charlie ny

[Bruce Compton, Canada]

Thanks all ,for the in-depth answers and information on these heads. What a great site. Bruce

[quickchange34]

Be carful of the Egge pistons the dome is not correct.

[Ol' Ron]

Charley NY
Great explination, I know this takes time, but the results are worth it. I've been using Egge pistons for over 20 years and never had a problem with them, lucky I guess.

[49r]

My Egge pistons hit my stock unshaved 8BA heads which was fixed by easing the witness marks on the heads.