40 over

V

vietnam

New Member

Dec 7, 2000

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Troy Michigan

Feb 8, 2004

#1

• Feb 8, 2004

• #1

Ok all of you old guy's (don't be offended I am over 50!)ha Any ways My 65 that I bought a few years back was i need of a piston slap repair so I just figured rebuild the whole thing cause it just makes sense. Now I found block is .40 over standard bore. There was in the day a way to figure how much HP was given by the bore? Have a Hi Po cam. C90z-6250-C

 

none67

New Member

Oct 19, 2003

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Feb 8, 2004

#2

• Feb 8, 2004

• #2

well i'm not 40, actually i'm not even half way there yet. but, i can tell you that depending on your set up you can get about 5-10 extra hp from a .40 bore. but boreing isn't just ment for gaining extra hp, the cyl. walls could have been damned ect, thus needing the bore.

 

G

GaPonyFarm

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Jan 2, 2004

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Columbus, GA

Feb 8, 2004

#3

• Feb 8, 2004

• #3

You're not getting any substancial, if any, additional power from the bored cylinders. Once the piston comes to the top, its the cylinder head's area that determines the compression ratio in its relationship to the cam.

 

HistoricMustang

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Apr 11, 2003

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Confederate States of America

Feb 8, 2004

#4

• Feb 8, 2004

• #4

My 289 is 40 over and I am over 55 so you are in good company here.

Seems like I did some research several years ago and the 40 over adds about 4 cubic inches. Guys/Girls, does this sound about right? I am sure this info is out on the www somewhere - how many cubes you pick up with a 30, 40, 50 or 60 over on a 289.

HistoricMustang
www.historicmustang.com

 

none67

New Member

Oct 19, 2003

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Feb 8, 2004

#5

• Feb 8, 2004

• #5

well depending on what block you have: 289(bore: 4.005), or 302(bore: 4.004) you have a 289.25, or a 289.10, respectively. when most people bore them out they just go to a 4.030 or a 4.040.

so if your bore is a 4.040 you have a 294.32.

Hope that helps.

 

V

vietnam

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Dec 7, 2000

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Troy Michigan

Feb 8, 2004

#6

• Feb 8, 2004

• #6

Thanks to all of you every piece of info builds to a answer. The prof will be in the dyno.

 

D

DAZ

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Jun 7, 2002

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Endwell, NY

Feb 9, 2004

#7

• Feb 9, 2004

• #7

none67 said:

well depending on what block you have: 289(bore: 4.005), or 302(bore: 4.004) you have a 289.25, or a 289.10, respectively. when most people bore them out they just go to a 4.030 or a 4.040.

so if your bore is a 4.040 you have a 294.32.

Hope that helps.

Click to expand...

So I assume that would make a 302 @ .030 a 305?

 

LMan

Founding Member

Aug 10, 2002

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Mom's basement

Feb 9, 2004

#8

• Feb 9, 2004

• #8

another boreout will take you to .060, which is the block's practical limit. watch out for overheating, or, get another block.

 

SandSprite

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Feb 8, 2003

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L.A., CA

Feb 9, 2004

#9

• Feb 9, 2004

• #9

DAZ said:

So I assume that would make a 302 @ .030 a 305?

Click to expand...

a 30over 302 is a 306. i'm pretty sure on that.

 

67coupe351w

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Jan 31, 2004

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Portland, OR

Feb 9, 2004

#10

• Feb 9, 2004

• #10

Cubes = bore^2 * (pi/4) * stroke * # of cylinders.

 

D

DAZ

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Jun 7, 2002

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Endwell, NY

Feb 11, 2004

#11

• Feb 11, 2004

• #11

SandSprite said:

a 30over 302 is a 306. i'm pretty sure on that.

Click to expand...

Thanks! I am having my 1966 Mustang delivered this weekend. The engine
did not have any knocks or valve taping and it seemed to run very smooth.
Engine compartment barley reacted when it was reved up.
There was a little bi of black smoke when first starting, then it tunred white then turned normal mist. So I don't think there will be any problems... I'll keep my fingers crossed.

 

none67

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Oct 19, 2003

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Feb 11, 2004

#12

• Feb 11, 2004

• #12

A 302 stroke with a 4.03 bore is 306.13, its a good engine.