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73-87 Chevy _ GMC Trucks => Engine/Drivetrain => Topic started by: masonjenkins5 on February 26, 2016, 02:38:29 pm

Title: 400 small block RPM limit
Post by: masonjenkins5 on February 26, 2016, 02:38:29 pm

I have a 1976 K20 with a factory 400sb. It's bone stock and I was wondering what the spin limit on it would be. I've been told the redline would be 4500-4800. I have a factory tach to keep an eye on it and I usually like to keep it at 2300 or under (usually around 40, +/- 5), but I've driven it at 60mph before for 4 hours no problem.

Title: Re: 400 small block RPM limit
Post by: Engineer on February 26, 2016, 05:10:04 pm

I would say with the stock valve springs that would be about correct. Maybe 5,000rpm when the springs were new.

I spin my 454 up to 7,000 rpm on stock GM bottom end parts and ARP rod bolts. However the valve train is heavily modified.