what are the specs of this motor? are they any good? would this be much better than a 400? saw an ad for one at a good price around $1500 for short block what do you guys think? thanks jason

 

Isn't that a .060 over 400? I question cylinder walls that thin. I wouldn't sacrifice my reliability for 15 ci. My fist SBC I built had to go out that far to clean it up. I'm cautious about running more than 400 ponies through it.

 

i thought it was 4.125 bore and a 3.875 stroke crank? is 4.125 60 over standard

 

Your bore is correct, but the stroke for a small block chevrolet I believe is 3.75, not 3.875. With that the .060 overbore should give you a displacement of 412.67 or about 413 cubic inches of displacement

 

i relize all that, and i know that a 400 crank is 3.75, but i also thought a 3.875 was a stroker crank like a 3.75 crank in a 350, thus making 4.125 bore and a 3.875 stroke 415ci, am i wrong?

 

86 SC

You are correct, a stock SBC 400 has a bore of 4.125 and a stroke of 3.75. To get 415 cid you can leave the stock bore and get the longer stroke crank, which is a 3.875. However, most 400 probably will need to be bored, deck,and balance, so might want to go 30 over and have a 420 cid... BTW, be careful when using these kits because you might run into clearance problems with the rods, camshaft and oil pan. here is a displacement calculator that you can add different stoke and bore combination....

http://www.smokemup.com/auto_math/displacement.php

 

thanks dtl504 for your insight and displacement calc, the kit i was looking at was from hye tech and actully it was a dissasembled short block with trw forged pistons and all clearences had been checked the whole thing was blanced decked and all that other good stuff. are there any down falls of this particular combination i should be awear of? thanks jason

 

Maybe your checkbook $$$$.00, if you have long money you should not have any problems. Get a nice set of aluminum heads (AFR 210cc), Comp Roller Cam, RPM Dual Plane, Holley 850 and have fun. Just make sure your drivetrain can handle it.