Has anyone seen a .090 over 390? The pistons have 90 or 06 on them. Thanks. Shawn. To the 390's

 

You found one? That's odd. I've never heard of .090" oversize pistons. OBTW, 4.050" + .090" = 4.140". That's beyond 428 dimensions...

 

But under 427 (4.23") bores.

 

Maybe it means .06" ??? That's a .060 overbore.

Or, it's just nonsense and doesn't mean anything besides a part # ...

What are these pistons out of? Got a crank # ???

 

Where is the crank# at? I looked and can't find a cast #, witch counter weight is it on? The main and rod bearings are std. Timing chain is steached bad. Thanks for the help.

 

Measure the piston diameter. That will tell you what size it is.

 

Crank number is on the edge of the 7th counterweight. Could be a 2U, 3U or a full casting number. I bet those slugs are .060. if they are 4.14 428 slugs they'd be marked .010 possibly???

G.

 

I can't see any # 's on the 7 th one. The top of the pistons are marked 90 or 06 .

 

It should be on the side of one of them unless it was ground off for some reason. Look on the inside edge also. It should be there somewhere. My 428 crank has IUB stamped on the inside edge of #7. My old 2U 390 was stamped there also. I think your slugs are .060 giving you a 4.11 bore.

G.

 

D3TE is on the block. 4 1/16 with a tape. I was told it was a 390, by the guy I bought it from.I fond 2T on the 3rd conterweight.

 

Thanks for the help, Shawn.

 

Sounds like you've got a 360.

Maybe this 90 or 06 number is meaningless in terms of piston oversize. 1/16" = .0625", so that's close enough to 4.050" on a tape measurement.

That is a good block BTW.

 

Yep 2T is a 3.50" stroke 360 crank.


G.

 

Ohhhh, I hate it when that happens... Wonder how many 352's/360's have been passed off as 390's?

 

Or how many 390's wound up as scrap because it said "352" on the block.