400 small block RPM limit

[masonjenkins5]

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.

[Engineer]

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.