There’s a set of 8BA heads on eBay right now. One of the spark plug holes has been repaired with some type of insert I’ve never seen before. I’m only mildly interested because of the repair and not really knowing the quality of it. Also the 7.5:1 compression ratio and unknown piston squish and ability to shave some off the heads to get to a 8.5:1 compression ratio.

I looked up a Time-Sert kit with the tools needed and it’s over $300, so if someone already had the tooling it could end up being a decent deal for them.

At this point I’m leaning more toward new 1115 heads. With a veterans discount they should end up around the $850 range after taxes and everything.

The seller seems like a nice enough guy. We chatted back and forth while I was pricing out thread repair options. I threw him an offer that made the risk worth it to me, definitely lower than what he wanted, but I explained that between the possible $300 repair cost and the chance the threads might need an even more expensive fix, I had to factor that in. I offered $300, I figured that would put me $600 in if needed repairs couldn’t be done cheaper.

If you’re interested here a link. 8BA Heads

 

I've never seen a repair like that, it almost looks like an anti-fouler was used. I think you'd be buying a pig in a poke with those heads.

What is your basis for shooting for an 8.5:1 CR?

 

Reading Flathead Facts by John W. Lawson.

I’m looking for modifications that improve low RPM torque in the 2000–2500 RPM range. That’s what I’m aiming for with gearing and cruising RPM. From the reading I’ve done and the dyno information I’ve looked at, raising compression into the 8.5:1+ range probably closer to 9.0:1, increases torque at 2000 RPM from about 151 ft-lbs to 164 ft-lbs. That’s roughly a 8% increase from mostly bolt-on parts, if you consider heads bolt-on.

 

Just a thought for consideration. Henry built these to optimum specs for durability and long life. If you bump compression up that much you may find it causes other parts to fail.
Personal experience: I installed unmarked heads with what I measured to be cc equal to Ford EAB (52) on a 51 Merc flathead (4" stroke) and according to an old chart the CR should have been in the area of 8.1.
After 10 years of hard use as a work truck and some long highway miles (3.50 9") I pulled it apart and found all compression rings broken - which accounted for all the blue smoke in the cab on acceleration.
Point is, high compression is fun but for longevity, keep it in a show truck that gets driven on weekends.
Your mileage may vary!

 

My 2c, fwiw, for the small difference in price between brand new heads and those used up, messed up wall hangers, it wouldn't be much of a decision for me. The risk to reward ratio isn't that good for me to waste that much money on those old, broken heads. YMMV.

 

I can’t say I disagree, eBay crowd doesn’t think they’re worth the price either. Looks like someone did buy them. When I look at used heads, most of the time I know I’m going to get the surface cleaned up. Some of those imperfections will be gone. That spark plug hole is hard for me to get passed.