Boring a flathead

Interesting to see how many here have sliced up a block for research. I have a sliced up port much like hotcoupe's. Did it with a sawzall and a lot of help taking turns. That was some hard iron.
 
OK tried to read thru to get opions on what limit there is to boring a flatty and got a head ache, Here is my question--have 3 1/16 41 engine with raised intake deck, worn out even further the sleeves. I have a set of 3 3/16 40 over pistons I could use-do you think I will overbore my block to use these pistons. A few years back I had a 40 merc block ( 3 3/16) with large journal crank and it was 40 over and these blocks look the same
 
No problem boring the 41 block to 3 3/16, after you remove the sleeves that's only another .040" This will however creat a small lip that will prevent the installation of rings I use a special cutter in the boring bar to remove it. OR you can bore to 3 3/15 +.030 ant this will remove the ridge.. OR you can sonic test the block and bore to 3 5/16.
 
Not to hijack the thread, but reading all these posts this has left my head spinning. SO! for all you Flathead enthusiasts, I am looking to build a 8BA with 2x2 intake for street use. I plan to clean up the ports from years of carbon build up. My worry is that it is already bored 60 over, I plan to sonic test the walls and bore it out to 80, 100, or 125 over and use a stock Merc crank. I am stumped over what cam to use. I know that everyone has their favorites, but what do you all recommend for a good street use that has a good thump at idle.
 
had a 3/ 7/16 x 4 in my 48 conv. bought the engine from New England Speed used -- ex Norwood arena engine--used to drive to Sanford last Sun of the mnth from Arlington Ma, race all day then drive home --often wonder if Walt and i crossed paths back then.
 
alanwoodieman said:
OK tried to read thru to get opions on what limit there is to boring a flatty and got a head ache, Here is my question--have 3 1/16 41 engine with raised intake deck, worn out even further the sleeves. I have a set of 3 3/16 40 over pistons I could use-do you think I will overbore my block to use these pistons. A few years back I had a 40 merc block ( 3 3/16) with large journal crank and it was 40 over and these blocks look the same
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Alan, I think 3-3/16 + .040 will work fine on that 41 engine. I've built alot of those engine by removeing the sleeves and boreing out .045 to 3-3/16. I wouildn't be afraid to go another .040 You stick your finger down the water hole next cly and feel the thickness of those blocks, There really thick. Walt
 
L 100; aggressive idle and most report good performance. Do a search for L100; there are many threads.
 
Hey Vergil, with the scarcity of good blocks, these days, do ya think a good welder can fix that sawed up one of yours and getter goin again?...slim
 
denverslim said:
Hey Vergil, with the scarcity of good blocks, these days, do ya think a good welder can fix that sawed up one of yours and getter goin again?...slim
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hahaha maybe a good welder and a bunch of block filler, I have been looking for another block but as you mentioned they are getting pretty hard to find in my area.


Vergil
 
We are going to do a sonic test, even if I have to purchased a tester. I have been reading on the procedures and it is not really very hard to do. Will keep everyone informed as we build this engine. Thanks Ol Ron
 
i have purchased a set of 3 3/8 pistons the seller says their fore inch stroke they check out 3 3/8,but not sure if they are for my 4 inch crank can you please help my engine has not been tore down yet, is thear any way to measure the pin location to see if they are correct for 4 inch crank they are silvolite pistons does not any nombers on pistons but they check out to 3/8 what do you thank thanks steve
 
The quickest way to check stroke of a piston is to compair the wrist pin location to another piston ofknown stroke. The pin is closer to the top of the piston with the longer stroke, by 1/8"
 
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