8BA head mismatch-I should probably fix

[markdtn]

Originally Posted by Christopher Salty

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.

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.

[Scotty's 52 F3]

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.

[mfirth]

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.

[flatford8]

Originally Posted by 1942deluxe

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.

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

[petehoovie]

Originally Posted by flatford8

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

[Newc]

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

[51504bat]

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

[rotorwrench]

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.

[markdtn]

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.

[leon bee]

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

[Mart]

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.

[oldbugger]

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

[markdtn]

Originally Posted by Mart

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.

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!