I'm looking for what would be the safe maximum (red line) rpm. I've built a 250 that was the stock block in a '67 C20 bored .030. I used stock bearings, oil pump, rod and main bolts, rods, pistons, rockers and push rods. I've put a comp cam 252 duration cam with recommended the comp cam springs and lifters. Opened the valves to 1.84 intake and 1.60 exhaust and mildly ported (basically smootherd all surfaces and cleaned off the rough surfaces on the valve guides), and installed bolt in lumps from Tom Lowe. I had the block decked to zero clearance (cut .032) and cut the head .020 on the deck surface. I have Langdon cast iron headers and an Offenhauser 4 barrel intake with a 450 Holley. It also has HEI from a '76 250. It seems to run with the most power between 3000 and 4000 rpm's, but I'm a little nervous to take it much over 4300. My bearing clearances and crank journals measured in spec according to the numbers in my '67 engine manual. I think it should take 5000 rpm's with no problem, but I'm not sure.
Also, what components(s) are keeping me from running more rpm's?
p.s. - your posts have been extremely helpful and value your opinions!
