Crankshaft
Thread Starter
Drifting
Joined: Sep 2004
Posts: 1,307
Likes: 1
From: Milford Haven Pembrokeshire
Crankshaft
Just a quick question - how much will a 2 bolt bottom end take before you have to buy a wheelbarrow and yard brush to sweep up the bits.
Asking this because on the various chatter about starting with a 4 bolt main set up.
Asking this because on the various chatter about starting with a 4 bolt main set up.
Safety Car
Joined: May 2001
Posts: 3,758
Likes: 3
From: Surrey
As nobody has replied yet......
I've read on here that it should handle 400hp as long as it wasn't taken over 6000rpm by much, or run continually at high revs. Can't remember the max figures, but I do remember that I'd be OK with 400 hp (at the crank) & running at up to 5500rpm. Why? You looking at bolting a blower on by any chance?
I've read on here that it should handle 400hp as long as it wasn't taken over 6000rpm by much, or run continually at high revs. Can't remember the max figures, but I do remember that I'd be OK with 400 hp (at the crank) & running at up to 5500rpm. Why? You looking at bolting a blower on by any chance?
Race Director
Joined: Jul 2002
Posts: 10,153
Likes: 15
From: Texas
Even with a blower, the two-bolt main SBC is plenty strong. The 4-bolt is one of those "real man" myths. A 4-bolt main doesn't offer much advantage unless two of the bolts are splayed (i.e. Moroso's 4 bolt retrofit) or cross bolted (i.e. F*rd big block). Find a serious racer, engine builder, or hot rodder in your area, and they'll tell you the same.
Race Director
Joined: Apr 2000
Posts: 17,665
Likes: 194
From: Who says "Nothing is impossible" ? I've been doing nothing for years.
Put ARP main studs in a 2 bolt and it will handle any power you want to throw at it
I had to edit this in case anyone wanted to get technical. A 2 bolt will handle just about any power level in a street/strip application where there are no extended high RPM's.
I had to edit this in case anyone wanted to get technical. A 2 bolt will handle just about any power level in a street/strip application where there are no extended high RPM's.
Last edited by MotorHead; Sep 30, 2004 at 12:39 PM.
Burning Brakes
Joined: Sep 2004
Posts: 917
Likes: 0
From: Vernon British Columbia
St. Jude Donor '05
First C3 General Poster!
I wouldnt pay much extra to just get a 4 bolt as opposed to a 2 bolt. I had a bored .60 over 350 in my 81 (ya I have a thing about 1981...) Olds Cutty. I never had a problem with the strength factor of the block, an I used it as a daily driver with over 400lbft of torque.
Abby Normal
Joined: Dec 2001
Posts: 53,293
Likes: 92
From: Press "2" for English
agree with most of the above. i you really want four bolt mains, the only way to go is with the aftermarket splayed main caps.
some engine builders i've talked to have even said the factory four bolt mains are weaker than the two bolts because you've taken "meat" out of the block and created a thinner area to spread out the load.
some engine builders i've talked to have even said the factory four bolt mains are weaker than the two bolts because you've taken "meat" out of the block and created a thinner area to spread out the load.
Safety Car
Joined: May 2001
Posts: 3,758
Likes: 3
From: Surrey
Originally Posted by clutchdust
some engine builders i've talked to have even said the factory four bolt mains are weaker than the two bolts because you've taken "meat" out of the block and created a thinner area to spread out the load.
The only SBC I've seen that had blown apart due to mains failure was a 4 bolt & it had failed in that thin area. At the risk of appearing dumb (again!), is it really an issue with a street driven motor? If it's running street tyres & the power being output is enough to rip the mains apart, wouldn't the tyres just lose traction b4 any damage was done? Or am I missing something here?
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Melting Slicks
Joined: Jan 2004
Posts: 2,672
Likes: 1
From: New Cumberland PA
If I were buying a block, I would go with a 4 bolt main. If you are reusing a 2 bolt and want to convert to a 4 bolt you can buy caps to do so, http://www.jegs.com/cgi-bin/ncommerc...60&prmenbr=361 .
The 388ci block I have was origanlly a 4 bolt and it came with new Milodon straight bolt caps. If you look around and are not in a rush, you can pick up a block at a good price. I paid $350 for a complete ready to use block (with the Milodon caps). Some people start projects only to find out they want/need something different and are willing to cut their losses.
The 388ci block I have was origanlly a 4 bolt and it came with new Milodon straight bolt caps. If you look around and are not in a rush, you can pick up a block at a good price. I paid $350 for a complete ready to use block (with the Milodon caps). Some people start projects only to find out they want/need something different and are willing to cut their losses.