offset grinding?
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Senior User
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From: Balfour
offset grinding?
I was reading hot hod magazine and some guy took a 427 crank
and offset ground it to achieve a 4" stroke. Could this be
done to a 390 crank? or does it gotta be a steel crank?
and offset ground it to achieve a 4" stroke. Could this be
done to a 390 crank? or does it gotta be a steel crank?
Post Fiend
Joined: Feb 2001
Posts: 6,624
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From: Missouri
offset grinding?
Yes it can be done with a 390 crank. You can use BBC rods or mopar slant 6 rods. I would be using for a 650HP nitrous engine. I have never heard of anybody breaking an offset ground 390 crank though.
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From: Montana
offset grinding?
I had reserched this out and in talking with my friend, a crank grinder for many years, and has done many stroker cranks, he says that you have to start with a froged steel crank. I also checked into getting a 391 steel crank but they are hevier and you have to machine down the snout, and if you turn it down to a 390 snout size then it is much weaker because of the large bolt that is used for the 391 ballancer. But the price of the machine work, and the cost of a 391 crank($200.-$400.) you would have a very heavy (less horse power) and expensive crank. What I have decided to do is build a 410 use a 410/428 crank turn flat top 390 .030 hypertechtic pistons down .100 and end up with about 425 or ci. This is the cheapest and most HP gain I can see. 428 crank go for about $300.-$400.
Post Fiend
Joined: Feb 2001
Posts: 6,624
Likes: 8
From: Missouri
offset grinding?
It has been done several times with a 390 crank. Cast FE cranks are much stronger than other cast cranks. I think it depends on which cast crank you are talking about. I would never add .25 inches to a small block crank. It should not be a problem. Adding cubes will hardly ever add peak HP. It will only add torque and move the power band down in the RPM range.
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From: Montana
offset grinding?
Originally posted by ratsmoker
It has been done several times with a 390 crank. Cast FE cranks are much stronger than other cast cranks. I think it depends on which cast crank you are talking about. I would never add .25 inches to a small block crank. It should not be a problem. Adding cubes will hardly ever add peak HP. It will only add torque and move the power band down in the RPM range.
It has been done several times with a 390 crank. Cast FE cranks are much stronger than other cast cranks. I think it depends on which cast crank you are talking about. I would never add .25 inches to a small block crank. It should not be a problem. Adding cubes will hardly ever add peak HP. It will only add torque and move the power band down in the RPM range.
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Senior User
Joined: Jan 2003
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From: Balfour
offset grinding?
The guy in hot rod built a 427 stroker,with dual 4v,and 12.5 to 1
compresion! 1/4mile in 12.3@118mph in a 63 galaxie. I was just
wondering if it would work cause one of my motors will be
biting the dust pretty qwick once I get my 4x4 out,
compresion! 1/4mile in 12.3@118mph in a 63 galaxie. I was just
wondering if it would work cause one of my motors will be
biting the dust pretty qwick once I get my 4x4 out,
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