Inliners International Forums General Discussion Hi Performance 250 over bore

After seeing Rus Gray's 301 I can't stop thinking about building one for myself. But I want to go bigger in the bore if possible.
So how big can you safely go in the 250 block.

Jay

hello...this could be a fun toy to consider, but....1st off you are going to spend more to do this than to build a standard 292...2nd, the rod angle is going to be so bad, you are going to wear the cylinders walls VERY quickly due to pressure on walls, 3rd boring .060 causes even more problems- cylinder wear from wall strength being taken away.....I called Mike Kirby to confirm this very soon after this engine pic was posted-DONT GET ME WRONG, ITS AN AWESOME ENIGINE....the money you spend doing this could get u an awesome standard 292 with MORE HP and torque...to confirm this talk to others who know about it and Mike Kirby-(626) 960 1090...he is the True Lump Port "Guru"....but what ever u do have fun ....its your $$$$$ and passion-and a great passion too!!!!!

Lee

I was just wondering about the bore size.
My dad used to run a 250 bored to 4.00 and I was wondering how much bigger you can safely go. I don't want to do a stroker because of the angles and extra stress it would put on the motor. I am not planning to race just wanted something different in my Chevelle.

jay
http://home.wizard.org/twchevelle

IF THIS IS A STREET ENGINE ONLY BORE ENOUGH TO CLEAN UP THE CYLINDERS.

BORING FOR THE SAKE OF GAINING CUBIC INCHES IS COUNTER PRODUCTIVE, BECAUSE THE LOSS OF CYLINDER WALL STRENGTH USUALLY INCREASES WALL FLEX, LEADING TO HIGHER BLOW BY AND SHORTER ENGINE LIFE.

Put your money into cylinder head improvements, ignition system, and induction. The only safe way to really increase a street motor bore is to sleeve the engine. This is a task that should be trusted to only the most experienced and reputable engine builders, and they are, unfortunately, hard to find and expensive. Often the sleeve will not seat well at the base and eventually leak coolant directly into the oil pan. Besides, if you really want to take advantage of the new bore/stroke ratio, you need to spend (gobs of) money on custom length rods and different pistons that raise all the rings way up toward the deck and put the piston pin right under the oil ring. At this point, you are at the edge of streetable and probably in debt .

I agree with Frenchtown: just clean up the walls.

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David

[This message has been edited by just a six (edited 03-10-2003).]

[This message has been edited by just a six (edited 03-10-2003).]