Flathead math

Ok guys, help me out, I'm having a brain fart...If a '49 ford flathead had a 4" Merc crank an was bored .040 over...what would the total displacement be?

 

About 262, 263. A .030 over 255 was always called a 260, whether that's rounded of to a nice number or not, I don't know.

 

bore x stroke x no. of cylinders x pie

 

I find that apple pi works best, but cherry is OK, too

 

1/2 bore squared x 3.14 x stroke x no. of cylinders

I came up with 261.7 cu. in.

 

I like pie.


CB

 

Algebra and pie! Making math fun and yummie!

 

thanks, now i have to go get some pie

 

I bought a race 59ab factory relief motor today. It is bored 1/8 in or.125 over with an isky 77b cam, 4'' stroke merc crank. I was also wondering how to do the math. Any help would be great.

 

<TABLE border=1 width="100%"><TBODY><TR><TD><CENTER>Bore in Inches
Stroke in Inches</CENTER></TD><TD><CENTER>3-3/4"</CENTER></TD><TD><CENTER>4"</CENTER></TD><TD><CENTER>4-1/8"</CENTER></TD></TR><TR><TD><CENTER>3-1/16"</CENTER></TD><TD><CENTER>220</CENTER></TD><TD><CENTER>236</CENTER></TD><TD><CENTER>243</CENTER></TD></TR><TR><TD><CENTER>3-3/16"</CENTER></TD><TD><CENTER>239</CENTER></TD><TD><CENTER>255</CENTER></TD><TD><CENTER>263</CENTER></TD></TR><TR><TD><CENTER>3-5/16"</CENTER></TD><TD><CENTER>258</CENTER></TD><TD><CENTER>274</CENTER></TD><TD><CENTER>284</CENTER></TD></TR><TR><TD><CENTER>3-5/16"[SIZE=-1] (+ .030 over)[/SIZE]</CENTER></TD><TD><CENTER>263</CENTER></TD><TD><CENTER>281</CENTER></TD><TD><CENTER>289</CENTER></TD></TR><TR><TD><CENTER>3-3/8"</CENTER></TD><TD><CENTER>268</CENTER></TD><TD><CENTER>286</CENTER></TD><TD><CENTER>296</CENTER></TD></TR></TBODY></TABLE>

Bore choices...
3 1/4, is 3 3/16 +.060 makes a 255 merc into about 264 ci.
3 5/16, almost always safe. 3 3/16 + .125 = 3 5/16 (.125 = 1/8" ) 276 ci.
3 3/8, slightly scarier, usually OK
3 7/16, for perfect prewar blocks or crazed racers running filled water passages

Boring .060-.080 is practically nothing.The bore is only controversial because you are obviously dealing with modern machinists...they are used to SBC and SBF thin wall egines that are so thin they lose power when bored past .030 and are scrap at .060. On a 239 flathead the metal loss at .060 is insignificant. There will be enough left for repeated rebuilds by your grandchildren.

That'swhat I found -Gene

 

Thanks Gene, and xix32. I am at 3 & 5/16 so Im figuring its a 276 cu.in. Great info, and chart.

 

bore X bore X .7854 X stroke X number of cylinders. It's not hard. Or if you like Bore divided by 2 X bore divided by 2 X 3.147 X stroke X number of cylinders. Pi R squared X stroke X number of cylinders. The first one is used by the SCTA/BNI to check engine sizes at Bonneville. Good enough for me.