Is it too much???
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Is it too much???
Hey Guys,I have another question concerning the boring of a 351W, is .065 over too much of an overbore for that motor? I mean am I getting too thin on the cylinder walls? Please let me know. For running a roots type blower the blower company recommends that I don't overbore the block too much. This is why I need an answer to my question above.
Thanks,
S_duty_dude
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Nobody is going to over bore it by .065"
Pistons for that will be custom and too expensive.
It is feasilble to bore it out .060" but a good machinist would want to do a wall thickness check and make sure. I heard that the early (pre 74) blocks are your best bet for that. It is just too cheap to go find a rebuildable block in a junkyard and bore it out .030" or .040"
Structual integrity inside an engine should never be substituted for a few cubic inches. 8 extra hp on the dyno will never make up for an engine that likes to run hot and lives a short life.
Pistons for that will be custom and too expensive.
It is feasilble to bore it out .060" but a good machinist would want to do a wall thickness check and make sure. I heard that the early (pre 74) blocks are your best bet for that. It is just too cheap to go find a rebuildable block in a junkyard and bore it out .030" or .040"
Structual integrity inside an engine should never be substituted for a few cubic inches. 8 extra hp on the dyno will never make up for an engine that likes to run hot and lives a short life.
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Joined: May 2001
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From: Baltimore USA
I haven't seen any kits with more than a .60 overbore so I would guess it safe to assume over that is too much. I've also heard that those pre-74 blocks have enough material that you can install 4 bolt main caps. Finding one in a yard would be much cheaper than getting a new sportsman 351W. Just gotta find one.
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If you plan on building a blower motor, ALWAYS, ALWAYS, ALWAYS have it sonic checked. Never assume. Even on 10 over, you should check it, and make sure it is OK. With mild boost, it isn't as critical, but ONE problem is the flexing of the bores allowing oil to contaminate the intake charge and cause detonation, especially in a properly set up Forced induction because you should be near the ragged edge of detonation for max performance anyways.
The guys before me are correct. 60 is pushing it. Some chebby 283's I have seen go .125 and live a pretty long hard life, though. Just get any block you are using checked, it is cheap insurance, and any builder/machinist who is building a blower block should have the equipment, and knowledge to do this. If he/she doesn't, find someone who does.
The guys before me are correct. 60 is pushing it. Some chebby 283's I have seen go .125 and live a pretty long hard life, though. Just get any block you are using checked, it is cheap insurance, and any builder/machinist who is building a blower block should have the equipment, and knowledge to do this. If he/she doesn't, find someone who does.
