I have a 400 sbc with casting#3951509, some say it's a high nickle block and others disagree. Is there another id# somewhere on the block that can determine this?

Also, I have a 305 tpi z28. If I swapped the 305 for a 400 and turned the key, would it run? Or would I have a big PROM problem. I'm just curious if I could put the 400 in without any other adjustments and be able to drive it until I get a chip.
Thanks.

 

509 is what most of the 400 blocks are. It hardly matters whether it's high-nickel or not, it's a 400, if you want a 400, that's what you get.

You would have a MASSIVE PROM problem, especially with a speed-density system (90 up). With larger injectors you could mostly cure it. 26 lbs/hr would put it in the ballpark. A MAF system would tolerate it somewhat more gracefully, but you'd still run out of fuel at around 3800 RPM, and run progressively leaner as the RPMS increased from there.

 

did you check out www.mortec.com?

 

yes I did check out mortec, but it did not say. I think I found out anyway. I read somewhere(can't remember) that and different 400 block with a different casting # was made during the same years as the 509 and it was the high nickel not the 509, oh well.