The Ford Barn

Mike Mayer · 03-30-2017, 10:25 AM

I was checking an old mercury flathead and I found it is has a .030 over bore . My Math skills are such that I can't figure out the cubes .

Jason in TX · 03-30-2017, 10:31 AM

All flatheads did not start with the same stock bore, so .030 over what? What block do you have? Even further, what crank do you have? That's important also.

Mac VanPelt's site is a great one to bookmark and refer back to a LOT.

Displacement chart:
http://www.vanpeltsales.com/FH_web/f...ifications.htm

There were varios bores in the different flatheads across the range of years from 1932-1953 and different for Ford and Mercury. And a "Mercury" engine could really be a Ford engine that someone bolted on Mercury heads.

And in 1949, merc motors went to 4 inch stroke, rather than 3 3/4 stroke. That also effects cubic inch displacement.

so, measure the bore size, and the throw of the piston, and repost and we can help you out.

Mike Mayer · 03-30-2017, 10:34 AM

sorry about the lack of info the block is a 255 cu from a 1953 mercury

Jason in TX · 03-30-2017, 10:40 AM

Editing my wrong answer. I said 274.

It's actually 260 cubic inches like estout 81 said below.

Formula: Pi (3.1416) times r² (radius is 1/2 the actual bore size) times stroke times 8 cylinders.

So 3.1416 times (half the bore diameter squared) 2.5881 times 4 times 8 = 260.185 cu. in.

Mike Mayer · 03-30-2017, 10:41 AM

Thank you Jason it looks like it is a 274 . Very helpful

estout81 · 03-30-2017, 11:12 AM

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Better redo your math. A .030 over bore on a 255 Merc.= 260ci.

Jason in TX · 03-30-2017, 11:27 AM

Ooops! You're right! Sorry about that. I was going up to the .125 bore. Staring at that chart a little too much.

Formula: Pi (3.1416) times r² (radius is 1/2 the actual bore size) times stroke times 8 cylinders.

So 3.1416 times (half the bore diameter squared) 2.5881 times 4 times 8 = 260.185 cu. in.

Good catch estout81!

Tim Ayers · 03-30-2017, 11:50 AM

Quote:

Originally Posted by Mike Mayer

Thank you Jason it looks like it is a 274 . Very helpful

Well, .125 over would be 276 so I think there is a math error.

Mike Mayer · 03-30-2017, 12:10 PM

Thank You all for your help If needed I am a Chaplain.

V8COOPMAN · 03-30-2017, 12:26 PM

Bore (3.2175) x 3.2175 x 4 x .7854 x 8 = 260.1824 cu. In.

03-30-2017, 10:25 AM	#1
Mike Mayer Senior Member Join Date: Aug 2010 Posts: 108	Cubes I was checking an old mercury flathead and I found it is has a .030 over bore . My Math skills are such that I can't figure out the cubes .

03-30-2017, 10:31 AM	#2
Jason in TX Senior Member Join Date: May 2010 Location: ⓉⒺXⒶⓈ Posts: 2,047	Re: Cubes All flatheads did not start with the same stock bore, so .030 over what? What block do you have? Even further, what crank do you have? That's important also. Mac VanPelt's site is a great one to bookmark and refer back to a LOT. Displacement chart: http://www.vanpeltsales.com/FH_web/f...ifications.htm There were varios bores in the different flatheads across the range of years from 1932-1953 and different for Ford and Mercury. And a "Mercury" engine could really be a Ford engine that someone bolted on Mercury heads. And in 1949, merc motors went to 4 inch stroke, rather than 3 3/4 stroke. That also effects cubic inch displacement. so, measure the bore size, and the throw of the piston, and repost and we can help you out. __________________ -------------- Drive it like you know how to fix it! DMAFC / OILERS CC-MC Last edited by Jason in TX; 03-30-2017 at 11:23 AM.

03-30-2017, 10:34 AM	#3
Mike Mayer Senior Member Join Date: Aug 2010 Posts: 108	Re: Cubes sorry about the lack of info the block is a 255 cu from a 1953 mercury

03-30-2017, 10:40 AM	#4
Jason in TX Senior Member Join Date: May 2010 Location: ⓉⒺXⒶⓈ Posts: 2,047	Re: Cubes Editing my wrong answer. I said 274. It's actually 260 cubic inches like estout 81 said below. Formula: Pi (3.1416) times r² (radius is 1/2 the actual bore size) times stroke times 8 cylinders. So 3.1416 times (half the bore diameter squared) 2.5881 times 4 times 8 = 260.185 cu. in. __________________ -------------- Drive it like you know how to fix it! DMAFC / OILERS CC-MC Last edited by Jason in TX; 03-30-2017 at 11:29 AM.

03-30-2017, 10:41 AM	#5
Mike Mayer Senior Member Join Date: Aug 2010 Posts: 108	Re: Cubes Thank you Jason it looks like it is a 274 . Very helpful

03-30-2017, 11:12 AM	#6
estout81 BANNED Join Date: Jun 2010 Location: Utica, Ohio Posts: 522	Re: Cubes Sponsored Links (Register now to hide all advertisements) Better redo your math. A .030 over bore on a 255 Merc.= 260ci.

03-30-2017, 11:27 AM	#7
Jason in TX Senior Member Join Date: May 2010 Location: ⓉⒺXⒶⓈ Posts: 2,047	Re: Cubes Ooops! You're right! Sorry about that. I was going up to the .125 bore. Staring at that chart a little too much. Formula: Pi (3.1416) times r² (radius is 1/2 the actual bore size) times stroke times 8 cylinders. So 3.1416 times (half the bore diameter squared) 2.5881 times 4 times 8 = 260.185 cu. in. Good catch estout81! __________________ -------------- Drive it like you know how to fix it! DMAFC / OILERS CC-MC

03-30-2017, 12:10 PM	#9
Mike Mayer Senior Member Join Date: Aug 2010 Posts: 108	Re: Cubes Thank You all for your help If needed I am a Chaplain.

03-30-2017, 12:26 PM	#10
V8COOPMAN Senior Member Join Date: May 2010 Location: East Shore of LAKE HOUSTON Posts: 11,113	Re: Cubes Bore (3.2175) x 3.2175 x 4 x .7854 x 8 = 260.1824 cu. In. __________________ *Click Links Below* __ ▼ *'35-'36 W/8BA & MECHANICAL FAN* *T5 W/TORQUE TUBE*