BB rotating assembly advice needed.
Thread Starter
Safety Car
Joined: Oct 2000
Posts: 4,282
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From: Lake Wylie, South Carolina
BB rotating assembly advice needed.
Hey guys. The BB is going to the machine shop this week to get repaired , cleaned and bored. The crank that came with it is a cast peice and as some of you may already know it spun a rod bearing and chewed up a piston and cylinder. The rods are a standard 3/8 type. Here are my questions.
1. If the crank can be repaired should I repair it and what else should I have done to it if anything? Or should I look for another one?
2. If the 3/8 rods are ok should I stay with them? If so what if anything should I do to them?
3. If I should replace any of these parts please give me some advice on what you would recommend.
The plan for this engine is hopefully about 500hp, with aluminum GMPP heads. Will be used mainly for weekend duty but want it to be dependable enough to drive and take autoXing and an occasional trip down the track. I will be running a 4speed and 3:70 gears if that matters.
Thanks for the help.
1. If the crank can be repaired should I repair it and what else should I have done to it if anything? Or should I look for another one?
2. If the 3/8 rods are ok should I stay with them? If so what if anything should I do to them?
3. If I should replace any of these parts please give me some advice on what you would recommend.
The plan for this engine is hopefully about 500hp, with aluminum GMPP heads. Will be used mainly for weekend duty but want it to be dependable enough to drive and take autoXing and an occasional trip down the track. I will be running a 4speed and 3:70 gears if that matters.
Thanks for the help.
Team Owner
Joined: Feb 1999
Posts: 34,453
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From: Republic of Texas
Re: BB rotating assembly advice needed. (BlackRat)
It all depends on what rpm you plan to spin the motor up. If you plan to keep it under 6,000rpm you should be fine what you have. If you want more rev's I'd get a forged crank and 7/16 rods to be safe. I went with all forged internals, more $$$ but a LOT of piece of mind. :cheers:
[Modified by Corey 68, 7:51 PM 11/3/2002]
[Modified by Corey 68, 7:51 PM 11/3/2002]
Pro
Joined: Jul 2002
Posts: 723
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From: North Port, FL
Re: BB rotating assembly advice needed. (BlackRat)
It depends on what RPM you will be going to. You can achieve 500 HP at the fly wheel and stay below 6000 RPM so you could get by with the cast crank and 3/8 rods. At the very least I would go with a good set of ARP rod bolts. If you want piece of mind go with a forged crank and 7/16 rods.
Safety Car
Joined: Dec 1999
Posts: 4,148
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From: Roxbury NJ
Re: BB rotating assembly advice needed. (BlackRat)
If I were really building a 500 hp big block, I would use a SCAT or similar cast crank ($230). I don't see the need for a forged crank at that power level in a BBC. If it were my money, I would actually go with the new SCAT 4.25" cast stroker crank ($300) and build a 489 or 496 with a 454 block. That way, I could make my 500 hp at a lower rpm. With a low rpm setup, you could probably get away with the 3/8" rod, but why take a chance? You can get a much stronger Crower Sportsman I-beam or SCAT/EAGLE/CAT, etc. H-beam for a very reasonable price. Even the common GM 7/16 rod would be better.
That said, many people seem to run the 3/8" rods without a problem once they're upgraded with good ARP bolts. Once you buy the bolts, and have the rods resized, you've spent 3/4 of the price of a new set of Scats.
This is all based on your 500 hp goal. If you get *the fever* like the rest of us, hide your wallet! :lol:
[Modified by Flareside, 9:02 PM 11/3/2002]
That said, many people seem to run the 3/8" rods without a problem once they're upgraded with good ARP bolts. Once you buy the bolts, and have the rods resized, you've spent 3/4 of the price of a new set of Scats.
This is all based on your 500 hp goal. If you get *the fever* like the rest of us, hide your wallet! :lol:
[Modified by Flareside, 9:02 PM 11/3/2002]
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St. Jude Donor '09
Re: BB rotating assembly advice needed. (BlackRat)
Here's a few more opinions from a while back:
http://forums.corvetteforum.com/zerothread?id=339461
http://forums.corvetteforum.com/zerothread?id=339461
