8BA head mismatch-I should probably fix
 

On my 8BA in an 8N tractor I have an 8BA head on the right and an EAB head on the left. The machine shop that I used gave me the EAB head because the LH 8BA had a crack. It's been running fine for almost 10 years now, but from what I am reading, I think I should probably find a match. Seems like the EAB is a more desirable head. Not seeing any RH EABs on Evilbay right now but I do see some (pairs) of EAC Mercury heads. Of course, these are heavy and shipping is expensive.

So some questions: 1-is this even worth worrying about? 2-Is EAC equivalent to EAB? 3-I assume cracks are a real concern on used heads or not usually?

When I built it, I used a stud kit for aluminum heads but I just can't see paying up for those. I don't need more power, it's scary enough as it is. Thanks for your advice.

Re: 8BA head mismatch-I should probably fix
 

If it runs fine I wouldn’t mess with it!

Re: 8BA head mismatch-I should probably fix
 

my thoughts too. i WISH i had an old engine that ran reliably for ten years! :)

in fact if i knew the perfectly matched heads on my v8 would run reliably for ten years if i installed a mismatched set, i think i might do it. ha

Re: 8BA head mismatch-I should probably fix
 

Some things are not worth worrying about. This is one of them. Congrats on a good running trouble free combo!

Re: 8BA head mismatch-I should probably fix
 

Sounds like leave it alone then. So the volume is similar on both 8BA and EAB heads?

Re: 8BA head mismatch-I should probably fix
 

I don't know about the volume, and I'm not saying you should change anything, but in the interest of science, why not do a compression test? It would be interesting to see if there is a discernible difference that can be associated with each bank. Or it might be that the difference is lost within normal variances between cylinders on an old engine. I'd be interested in the results.
I am the guy with an engine that has seven 30 over bores and one 60 over bore by the way!
Mart.

Re: 8BA head mismatch-I should probably fix
 

i like to recognize talent when i see it and when it is deserved...

you know...i've been looking at the pic in your signature for about a year now, and just realized that it's the combustion chamber of a head intentionally making good use of shadow. i thought it a some sort of post-expressionist portrait...truly inventive and a real work of art!

i have to know...is the pic your inspiration or did you find it somewhere?

Re: 8BA head mismatch-I should probably fix
 

Ha ha Hi Huey. It was just a pic I found online many years ago. It's a Y block head with a crack in it. The human brain automatically "recognises" faces even if it isn't really a face. I like that it appears to be looking at the thread.
Mart.

Re: 8BA head mismatch-I should probably fix
 

thanks...

i find that type of "taken out of context and it's something else entirely" type of artwork captivating. :)

my father was a shop teacher and his students used a piece of plywood under their projects to protect the workbench from overspray and general abuse. as you can imagine, over the years many layers of accretion revealed themselves from time to time creating quite a complex image. my father framed it and hung it on the wall at home. and you wouldn't believe how many people thought it a remarkable piece of artwork.

anyway...kudos on recognizing its value.

Re: 8BA head mismatch-I should probably fix
 

Just in case you think about swapping both heads for Merc's cause you got a deal on them, think again. Merc heads on a 3 3/4" stroke 8ba is a step backward.

Re: 8BA head mismatch-I should probably fix
 

OK. Thanks. I will do a compression test and report back. I was reading that EAB engines had 7.2:1 compression ratio while 8BA was 6.8. 69-71cc vs: 75-77cc. Just thought that it might be too much of an imbalance. I'm not looking for power, only want smooth and cool running.

https://myflatheadford.com/know-your-1948-1953-head/
https://myflatheadford.com/decoding-flathead-v8-heads/

Re: 8BA head mismatch-I should probably fix
 

As an old guy in Maine once told me, “If it ain’t broke, don’t fix it”!

Re: 8BA head mismatch-I should probably fix
 

Just saw a set of EAB heads for sale last weekend at the NEGA swap meet. The seller still has them. I can try to track down his contact info if you are interested.

Re: 8BA head mismatch-I should probably fix
 

Yes leave it be. John Gibson says it all.

Re: 8BA head mismatch-I should probably fix
 

I would change that old saying to : "If it ain't broke in any way don't fix it, but if it's not perfect, at least take a look at it". In this case, I would wait and see what a compression test shows. If there is no significant difference between sides, the plugs would go back in; if there is, the head would come off. The only problem is if the low readings are on the EAB side.

After all, we are car guys, and as such, a step above the average "back yard mechanic".

Re: 8BA head mismatch-I should probably fix
 

While EAB heads were designed to give a bit better performance, it is getting harder to find known to be good used heads. EABs used to be available NOS with no tampering but folks tend to like to skim those heads to get even more compression. Most sellers wouldn't know if it was ever shaved or not and buyers are in the same boat. I've purchased some that were cut clear down to the bottoms of the thermostat pockets. 8BA and EAB are both safe heads to get as long as a person checks the piston to dome clearance to keep it at .050" or more clearance. I don't like shimming heads with more than one gasket but I know folks that have done that.

Mercury 8CM /EAC and truck 8RT stuff are made to lower compression so they won't help much for power. Merc 255s have the longer stroke so they needed that to keep the ratio similar to the smaller 239 engines and trucks just had to be able to pull max power with reliability.

Re: 8BA head mismatch-I should probably fix
 

I have an 8BA L.H. head that I'm pretty sure is NOS that was in the basement of my Ford dealership I closed in 2004 if you wanted to go that route. I'm sure the shipping would be excessive though.

Re: 8BA head mismatch-I should probably fix
 

I will do a compression test over the weekend and report back.

Re: 8BA head mismatch-I should probably fix
 

Put a set of Edelbrock aluminum heads PN 1115 on there gives a compression ratio of about 8:1. Maybe shave them down a bit to get a squish of 0.050 and get compression up to about 8.25:1.

Re: 8BA head mismatch-I should probably fix
 

You might want to consider 'wheelie bars' if you make this mod. As far as balanced compression on both sides, there are videos of our V8s running quite nicely with one head removed entirely.

Re: 8BA head mismatch-I should probably fix
 

My application is very different than most. I don't need/care about more power. A tractor had 25HP. I have 3-4 times that with a bone stock 8BA. I want it to run smoothly, if it will idle very low I might win a slow tractor race :) I want it to run cool. I am very handicapped in radiator size over a car or truck. Had a lot of cooling issues early on that I am now on top of, but cooling is marginal. I want to be able to drive in a parade or tractor drive. I have been on 2 tractor drives now and it did fine. So the only reason I might consider aluminum heads was if they would make it run cooler-but doing so would destroy the "1950 look" that I have tried to create.

From what I am hearing here I will probably leave it alone. I will do a compression test and if radically different will seek out an appropriate 8BA or EAB head to match.

Re: 8BA head mismatch-I should probably fix
 

You said it's been running really well for over ten years. The gear head tinkerer in me would probably put on a matching head. But if I never saw the part number difference, it wouldn't even be a thought. Do what lets you sleep at night.

Maybe keep an eye out for a matching head but don't sweat it if it's been going over ten years.

Cool tractor

Scott in AZ.

Re: 8BA head mismatch-I should probably fix
 

Before I had my 52 8BA rebuilt it had a Merc head on one side and a truck head on the other. Ran smooth as silk. The main reason for rebuild was excessive oil use & piston slap. Those heads caused NO PROBLEM.

Re: 8BA head mismatch-I should probably fix
 

I’m really interested in seeing the compression numbers….but if it runs fine and you're happy (the main reason), I’d probably leave it alone…..But just to be a wise guy and not be out done by John above…..I have two right side EAB heads and your welcome to both or one if you like…if you want them, I’ll chase the threads to make sure they’re good……Mark

Re: 8BA head mismatch-I should probably fix
 

Re: 8BA head mismatch-I should probably fix
 

Note; USPS Used to have a flat rate box that fit heads, but now discontinued. I used them tooo much I guess. Newc

Re: 8BA head mismatch-I should probably fix
 

If you still have those boxes they still work. Just used one a couple of months ago.

Re: 8BA head mismatch-I should probably fix
 

Since I've had purchasing issues with heads before, I would compare the clearance volume depths between heads to at least verify the depth dimensions to be close to the same. A person can use the beam end of a dial or vernier caliper to check them unless a depth mike is available. I just do it on the valve relief areas on both a front end and rear of each head. Readings should be very close. There should also be a fair amount of distance from the head gasket surface to the bottom side of the thermostat pocket, ie, the underside of each head. Since that part is rough casting then the dimensions are like the previous check to allow for variations in castings. This should give at least an idea of whether the heads have been decked before.

Re: 8BA head mismatch-I should probably fix
 

Over the weekend I pulled all the plugs and tested. They were all right at 100psi (dry). I think the highest number actually came from the 8BA side. Any differences were very small. Looks like I need to leave well enough alone. Thank you to all that responded.

Re: 8BA head mismatch-I should probably fix
 

Thanks for that, I was curious about it. Would convince me to leave it alone as well.

Re: 8BA head mismatch-I should probably fix
 

Don't forget: You can only see one side at once. No-one would notice. It runs great. Comp numbers are good. It ain't broke.
Mart.

Re: 8BA head mismatch-I should probably fix
 

Get in there with your Dremel and take the numbers off. If it bothers you

Re: 8BA head mismatch-I should probably fix
 

Actually someone did notice and asked me why once. I had always assumed that when the machine shop gave me that head that it was pretty similar to the one I had. This is the first flathead I have owned. I'm actually a pretty hard core GM guy. But if I am going to do something, I want to do it right. That is much of the original reason I completely rebuilt this engine instead of just rings and bearings (and a sleeve) and go some more. I'm used to SB Chevy stuff where you never mismatch chamber size. But I suppose the compression ratio on a flathead is lower so it isn't as big a deal-or maybe the 8BA head was decked some. I'm not curious enough to tear it apart and cc the heads to know. The compression test numbers tell me that however we got here, that it is "close enough". Thanks!