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Author Topic:   sbc 350 standard vs .030 bore
BK19
Dirt Freak

Total posts: 285
posted March 14, 2003 10:11 PM UIN: 40696038
does boring it to .030 really make that much more horse, power, compression etc.....or is it done just to straighten the bore out or what ?

sdhnc29
Dirt Freak

Total posts: 467
posted March 15, 2003 12:00 AM
I assume your speaking about a stock block . If you are , then .030" oversize is simply the most common overbore . Unless a guy is using custom made piston's for a certain application , then it's most common to find .030" over piston's on most any piston manufacturers shelf . The reason for that .030" is so common for stock block's , is simply because it's very rare to find a stock block with 100,000 miles on it , that will clean at .010" or .020" .

When building a race engine out of an aftermarket block , then you will find most engine builder's opting for the smallest bore to start with . For instance , our little engines that we build for dirt late model's will start life with a 3.335" stroke crank , and a 4.125" bore . You only see a very small difference in horse power between a 4.155" bore (.030"over) and a 4.125" bore , generally around 7HP . The smaller bore in a new engine will give the customer quite a few option's when it comes time to bore the engine again .

Hope this answered your question .

Steve

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Hendren Racing Engines
Rutherfordton , NC
(828)286-0780

BK19
Dirt Freak

Total posts: 285
posted March 17, 2003 12:29 PM UIN: 40696038
so boring a standard 350 that has good cyl. bores would not give that much of a boost to the motor,would a standard bore 350 do as good as a .030 350 with the same heads on both motors?

sdhnc29
Dirt Freak

Total posts: 467
posted March 17, 2003 05:24 PM
I've actually never seen a stock 350 block that has come from a stock production car that did not need to be bored . No matter what you might be able to see in the bore , there will be taper if it's measured with a dial bore gauge . So , you will be far better off to go ahead and bore your block .030" over . If it's a race engine , then I'd use torque plates as well .

To answer your question , a stock bore 350 that has been run , will not run up to par with a .030" over engine that has been bored correctly . Most of this is fact is due to ring seal .

Steve

------------------
Hendren Racing Engines
Rutherfordton , NC
(828)286-0780

BK19
Dirt Freak

Total posts: 285
posted March 17, 2003 07:11 PM UIN: 40696038
ok now i see the light that was the explaination i was looking for thanks, Bill

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