Flathead Bore Size ?

Whats your favorite bore size using a 4 inch merc crankshaft

  • Total voters
    62
  • Poll closed .
If you want to bore one from standard all the way out to max, you will lose a lot of potential use of the block. If you are already at 3 5/16" then that is a good size for a hot rod. A person can go to sleeves though and use larger if you have a mind to. It just depends on how much you want to spend and how long you want it to last.
 
I did my first a 3 5/16 (276 with a Merc crank) and it worked well. I just bought another set of 3 5/16 pistons (this time for a stock stroke). Pistons, rings, and pins were $100, which is a heck of a lot less than a merc crank (if you can find one) for a comparable increase in displacement.
 
I'am at 3-5/16 with my build and one four inch merc. crank. 276 inch ?? at my age (82) I saved some for the next build ....?? and here I sit with two more complete engines with 59 on the bell ... I just like saving some for the next build or the next guy, and a JWL says just what it take to clean it up ?? Yes the grandkids will have a big yard sale someday ??......OLD.....BILL:cool:
 
tubman said:
I did my first a 3 5/16 (276 with a Merc crank) and it worked well. I just bought another set of 3 5/16 pistons (this time for a stock stroke). Pistons, rings, and pins were $100, which is a heck of a lot less than a merc crank (if you can find one) for a comparable increase in displacement.
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Tubman, where did you get 3-5/16 pistons and rings for $100.00 Walt
 
Egge makes light 3 ring piston in 3 5/16, + .020 and .030. With the thin Metric rings. Saved a 276 with the .020" and rings from a Volvo truck. I now have a 280 (279.4) Milled EAB heads 8.2CR and a stock EAB cam. Talk about torque??? I think even JWL would like it.
 
I've got a 265 by my calculations, I just think, why bore it bigger than you have to, after all they aren't making them anymore.
 
Walt Dupont--Me. said:
Tubman, where did you get 3-5/16 pistons and rings for $100.00 Walt
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Speedway's garage sale section. About a year ago thay had a lot of piston sets (some were advertized as being made by Offenhauser) on closeout. I posted it here and on the H.A.M.B. The pistons came in a "plain brown wrapper", so they may be Chinese. but I took a chance on them. They look real nice and I went over them with a mic and all appears well. We shall see.

(Edit : Just for kicks, I checked the Garage Sale page again; there are still a few sets of pistons, but the prices I paid are long gone,)
 
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Speedway had some hypereutectic flathead pistons for a while that were cast for them. They must not have sold too well but I haven't really heard anything about how they worked out. It would be interesting to know. I always wondered why the piston makers didn't go that route. The expansion factors for those pistons allow for a tighter bore clearance than with forged ones. The cost might be prohibitive in a niche market. How strong they are would be the big question for me.
 
Flathead bores are tougher than some of you give them credit for … part of the reason there still here.
The truth is you’d have a hard time wearing one to the point of needing a rebore in the time any of you have left.

Bore it out all the way ... you cant take it with ya
 
1934calkid said:
The main question was WHAT IS YOUR FAVORITE BORE SIZE FOR A STREET ROD ...
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Hey Calkid; looks like you got your answer 3-5/16...276, hands down, or 75 per/cent .........not good enough for you, :confused:?? all this talk about it, make me want to do it again, all I need is someone to make the "HOLE"
And find me a pieeeekup 39 or 40 I'll do it........OLD.....BILL:cool:
 
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