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Old 09-16-2012, 08:04 PM
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350 with 305 crankshaft

anyone try the 350 sbc with 305 crank ? have heard alot that it will vibrate.But I had the parts laying there sooo ..Lets Try It NON balanced
350 1978 2pc
305 1980s 2pc
I had a perfect set of rods and pistons from a 96 350 1 piece boat motor
new rings bearings and Comp products balancer ,350 flwheel
Just got it done 2 days ago and have to say it worked great and no noticeable vibrations

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Old 09-16-2012, 08:11 PM
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It is common practice in the machine shop/crank grinding business to use the cranks interchangably. Unbalance difference only shows up at higher rpm. Stock rebuilds never rev that high.

The horror stories told on the web are usually just that. Stories..
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Old 09-16-2012, 08:35 PM
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thanks bob just wondering
its a full solid roller motor turns about 7000rpm
just figured i would find out for myself happy so far
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Old 09-16-2012, 09:02 PM
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Back in the early 90's we took a 400 small block, got the spacer bearings, threw a crank in it out of a 305, pressed 350 rods on to the 400 pistons and had a 372. We were shooting 125 horses of nitrous to it and we abused the fire out of that motor on the drag strip for 2 seasons. Never once felt any vibrations.
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Old 09-16-2012, 10:05 PM
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Quote:
Originally Posted by DoubleVision View Post
Back in the early 90's we took a 400 small block, got the spacer bearings, threw a crank in it out of a 305, pressed 350 rods on to the 400 pistons and had a 372. We were shooting 125 horses of nitrous to it and we abused the fire out of that motor on the drag strip for 2 seasons. Never once felt any vibrations.
thanks do you know where the deck ended up?what rpms did it turn
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Old 09-16-2012, 10:42 PM
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I don't recall the deck clearance, but I know it was within a reasonable spec otherwise we wouldn't have built it. If I remember we were shifting at 6800 RPM. The highest it would rev was 7200.
It had great mid range power. We were running wide mickey thompson street tires that didn't hook real good on a Nova against a Monza with a 383 that had slicks and spraying 125. We ran him for fun likely around seven times and he always took us by a half car lenth. Fun days those were.
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Old 09-17-2012, 08:45 AM
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Mixing parts ?

Mixing parts and not balancing is a crap shot, digital scales are a lot cheaper today. matching all the pieces isn't that hard, building a hanger to hold up one end of the rod is easy. when you get everything matched, the balancer should give you a discount, and you know how close you got everything, 5 grams, 2 grams, 1/2 a gram. ? When you have the bob weights on the crank and are spinning it, you can HEAR how much smoother it is when you get it right on.
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Old 09-17-2012, 09:53 AM
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The balance must have been made closer to correct with the use of the late model rod-piston. A early 350 using original weight rods and pistons along with a 305 crank will have a noticeable vibration about 1800 RPM.
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Old 09-23-2012, 11:55 PM
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that was my theory for using the newer powder rods and pistons
i figured i would try ,Happy I did
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