I have a `75 f-250 with a 390 that has been bored .030" over what size is it now?

 

396

 

If it's the new displacement you seek I calculate out 395.35, but then again a 390 really calculates out to be 389.56; I'm just curious why you care? For all practical purposes you still have a 390. It's kinda esoteric otherwise.

Stock Man
1967 Galaxie 500 Convertible (HELP!---I need 15 x5 factory rims)
1967 F-250 FE 390 4wd
1966 F-250 I6 240 2wd LWB Flare Side
<a href="http://www.hometown.aol.com/tbeeee">http://www.hometown.aol.com/tbeeee</a>

 

I just wanted to know, thats all. I guess what I really want to know is how did you calculate that?

 

The older engines which pertain to this list have a cubic inch displacement which can be calculated by figuring the volume of all of its cylinders in cubic inches. The formula is:

pi(3.1415927) * (bore/2)squared * stroke

Sorry for the mess: standard 390 bore is 4.05" and stroke is 3.78" ; Use the formula to calculate a standard 390 and you should get 3.89.56; I hope this helps.


Stock Man
1967 Galaxie 500 Convertible (HELP!---I need 15 x5 factory rims)
1967 F-250 FE 390 4wd
1966 F-250 I6 240 2wd LWB Flare Side
<a href="http://www.hometown.aol.com/tbeeee">http://www.hometown.aol.com/tbeeee</a>

 

so what's the formula for converting cubic inchs to metric? I have tried to extrapilate ratios based on things like 302=5.0L but chevy says 5.0L=305. 80ci Indian is 1500cc, 74ci Harley 1200cc. When I have tried to do the math I think I have been dogged by close enough and rounded off numbers. I have a 305 Camaro and was surprised how different the bore and stroke are to a 302. The 305 shares the same crank with the 350 but has a much smaller bore than the 302. I'm also intrigued by the new triton v10. I think it's 6.8L isn't that a little bigger than my 390? (actually my 390 is .030 over as well).

 

cubic inches X .01639 = liters

You are right, manufacturers play it fast and loose with rounding off. All part of the marketing scheme.

 

Ford had the 300 I6 and 302 V8, and only one was a 5.0 liter. [img]/dcforum/Images/happy.gif[/img]

John

 

I looked at my dads 96 chev 350 and it says 5.7L if you do the math it actualy is 5.7, and my moms 95 caravan says it is 153CI and that comes out to 2.5L like it says in the manual, so why are some rounded and not others?

 

It appears that Ford is a little bit guiltier of fudging the numbers. It looks like the 300 & the 302 are 4.9L. A 350 is a 5.7L a 351 is not quite 5.8L. I am curious about the new triton family. according to my calculations a 5.4L is 330(almost). I wonder if the same bore and stroke combination was used as the FT 330? Anybody know where to find info about the triton family?