8BA block---3.390 bore

[Walt Dupont--Me.]

Hi guys, a friend gave me 8BA bare block a couple day ago. it's been setting in the weather but will the clean in backing oven and short peen. Looking it over yesterday and see that it didn't have a ring ridge, bore is 3.390. I'm getting old but what in h--l piston is that? I got .125 + . 080 I've never heard of that piston. Walt

[19Fordy]

I bet someone overbored it too much by mistake. There can't be much wall thickness left.
Would be interesting to know.

[Charlie ny]

Walt,
"ring' it a small ball peen hammer....3 o'clock to 9 o'clock will be real interesting.
Charlie ny

[rotorwrench]

Maybe they were going to sleeve it before they found a better block.

[Ol' Ron]

I ran a 3 7/16 (.437) over on the track and another is running somewhere in New York. So it can be done. best to have it sonic tested Walt.

[Bored&Stroked]

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I don't know, I figure they went to a 3 3/8 bore - 3.375, then probably another .010 . . . and then some clearance for forged pistons, then maybe a hone or two . . . maybe! LOL

I'd be very interested in knowing what a sonic test of the cylinder walls shows? My guess will be somewhere around .100.

[Ronnieroadster]

I have run a 3.375 plus .030 in the past Jahns made the origianl pistons and Egge made me a replacement set. I have had two complete 3-7/16 bore flathead engines I still have one complete in stock so it can be done like old Ron said.
Just use a sonic tester to figure wall thickness then give Egge a call they will make a 3.375 piston plus oversize up to at least another .030 they did them for me no problem at all. So far I have restored three flathead engines form the ealry days both hot rod and race that were all built larger than 3-3/8 Its just more cubes.

[Walt Dupont--Me.]

Originally Posted by Bored&Stroked

I don't know, I figure they went to a 3 3/8 bore - 3.375, then probably another .010 . . . and then some clearance for forged pistons, then maybe a hone or two . . . maybe! LOL

I'd be very interested in knowing what a sonic test of the cylinder walls shows? My guess will be somewhere around .100.

Bored-Stroked got it about right. Its 4:30pm, just came in from the shop. I dyped the post this morning eating breakfast. I frigged around yesterday after noon about an half hour then it was supper time, my mind was"nt working very good, it don't seem work very fast lately, I thought in the middle of the night, cyl have quite alot of rust and I thought maybe it was bored 3 3/8 and cut the ridge and honed SO, I went in the shop this morning and install a two in.wire brush in electric drill and cleaned the cyl halfway down, did 2 cyl. miked middel of bore, 3.375 top 3.395 === 3/8 overbore with about ,020 tapper. I've run into this crap alot in my 60 years of building these things but with no ring ridge and rust my mind work untill I went to bed.Thanks guys. Walt

[Ol' Ron]

Sometimes I wonder why anything, usually I'm wrong, but my new dog makes me happy. Now what waz the question?

[4tford]

Rumbleseats last motor was 3-3/8 +.030