Question about limits on a stock 350 bottom end
10-26-2002, 07:25 AM
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Car: '82 Z28
Engine: 350
Transmission: TH400 4,000 stall
Axle/Gears: Currie 9", 4.56 gears
Question about limits on a stock 350 bottom end
On an '87 350, what are the RPM and HP limits using the stock crank and rods? Crank will have 4 bolt splayed main caps and rods will use the ARP rod bolts. Pistons are Speed Pro forged flat tops. Just doing some research on building a new engine, thanks for any info.
10-26-2002, 08:32 AM
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Car: 4
Engine: 6
Transmission: 5
The main cap work is a complete waste of money with a stock cast crank.
The stock rods are good to around 6200 RPM regularly with stck bolts, and around 6600 with the ARP rod bolts. The stock crank will break eventually at that kind of RPMs no matter what; usually the snout will break off or something like that, I had one for instance where it broke right at the front of the #1 rod journal.
With a good quality forged crank and some better rods, not necessarily a mega$$$$ one, you can run 6500-7000 RPM as much as you want and not have to worry about it. The cheaper Eagle crank and GM PM rods would make a decent low $$$ combo.
Much past 7000 RPM, the main caps become a good idea. They don't do anything to address the actual failure issues of the stock rotating assembly (excessive flexing of the crank, and elongation of the big end of the rods), and so are unnecessary.
The stock rods are good to around 6200 RPM regularly with stck bolts, and around 6600 with the ARP rod bolts. The stock crank will break eventually at that kind of RPMs no matter what; usually the snout will break off or something like that, I had one for instance where it broke right at the front of the #1 rod journal.
With a good quality forged crank and some better rods, not necessarily a mega$$$$ one, you can run 6500-7000 RPM as much as you want and not have to worry about it. The cheaper Eagle crank and GM PM rods would make a decent low $$$ combo.
Much past 7000 RPM, the main caps become a good idea. They don't do anything to address the actual failure issues of the stock rotating assembly (excessive flexing of the crank, and elongation of the big end of the rods), and so are unnecessary.
10-27-2002, 06:49 AM
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Car: '82 Z28
Engine: 350
Transmission: TH400 4,000 stall
Axle/Gears: Currie 9", 4.56 gears
Guess I'll be upgrading the rods and crank then cause I'm planning on spinning it up to about 7,000. Thanks for the info.
10-27-2002, 11:31 PM
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Car: 1992 Camaro RS
Engine: Yet another 350 TPI
Transmission: Borg Warner 6 spd
Axle/Gears: 3.73
How long would the stock crank last under 6000 rpm? I don't mean sustained rpm, just an occassional rev to 6000 rpm.
10-28-2002, 01:51 AM
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Car: '82 Z28
Engine: 350
Transmission: TH400 4,000 stall
Axle/Gears: Currie 9", 4.56 gears
My little 305 has survived a few revs to 6,000 but it has only 15k or so miles on it. Wouldn't recommend doing it hehe. This new engine I'm trying to plan out will peak around 6,500 rpm but would like a bit of a safty buffer. 450 - 475 hp with a 200 or 250 shot of nitrous depending on how well I do against my friend car lol.
10-28-2002, 04:45 PM
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I don't think anyone can really say how much punishment an engine can take stock or modified. I know in Hot Rod magizine I read about a early 90's firebird that the guy is running mid 10's in on a weekly basis and has done just about every performance option you can do to a 3rd gen car except mess with the bottom end. So the car with the factory 350 bottom end withstood over 1000 passes, 70,000miles and over 7,000 rpms through the traps and is still running. And did I mention the car had nitrous too. I know there is estimates of what an engine can go through, but you can never be sure. It could be run harder than you think. So I would say. If you aren't going to spin the engine to 7,000 on a daily basis, I think it is capable of living quite a while. The valve train is a different story. I don't think I would spin any stock valvetrain to 7K hardly ever, given it wasn't a 302.
12-23-2023, 02:41 PM
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Re: Question about limits on a stock 350 bottom end
The main cap work is a complete waste of money with a stock cast crank.
The stock rods are good to around 6200 RPM regularly with stck bolts, and around 6600 with the ARP rod bolts. The stock crank will break eventually at that kind of RPMs no matter what; usually the snout will break off or something like that, I had one for instance where it broke right at the front of the #1 rod journal.
With a good quality forged crank and some better rods, not necessarily a mega$$$$ one, you can run 6500-7000 RPM as much as you want and not have to worry about it. The cheaper Eagle crank and GM PM rods would make a decent low $$$ combo.
Much past 7000 RPM, the main caps become a good idea. They don't do anything to address the actual failure issues of the stock rotating assembly (excessive flexing of the crank, and elongation of the big end of the rods), and so are unnecessary.
The stock rods are good to around 6200 RPM regularly with stck bolts, and around 6600 with the ARP rod bolts. The stock crank will break eventually at that kind of RPMs no matter what; usually the snout will break off or something like that, I had one for instance where it broke right at the front of the #1 rod journal.
With a good quality forged crank and some better rods, not necessarily a mega$$$$ one, you can run 6500-7000 RPM as much as you want and not have to worry about it. The cheaper Eagle crank and GM PM rods would make a decent low $$$ combo.
Much past 7000 RPM, the main caps become a good idea. They don't do anything to address the actual failure issues of the stock rotating assembly (excessive flexing of the crank, and elongation of the big end of the rods), and so are unnecessary.
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12-23-2023, 05:10 PM
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Re: Question about limits on a stock 350 bottom end
old thread 
I think both of the brands you mention are chinese forgings finished in the US-Howards cranks were US forgings some 10 yrs ago-don;t know about now.
I think both of the brands you mention are chinese forgings finished in the US-Howards cranks were US forgings some 10 yrs ago-don;t know about now. 
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