[Jay S]

A few 400 Engines that went through our shop and engines we built or tuned with various results.

70 RA 3 GTO Judge, 400 origal 12 heads, all stock carb to pan and RA manifolds 10.04 SCR, melling 041 spec-8 with the stock 1.5 rockers. No issues on pump gas. Had all the characteristics of a big cam. Doing it again I would pick something more aggressive, seemed lazy. Original q jet.

70 RA 3 GTO Judge, 12 heads, upper 9s on the scr, with a straight duration isky, had some issues. Pinged some in the midrange, needed 91, pulling the timing out some mid 30s total, IRC it did fine. Original q jet.

67 Firebird 400 small valve, logs manifolds, tuned it only, reportedly had a 067 cam with 10:0 + compression. Lots of issues on pump gas. Never made it run good. Tuned and tuned on that, had holley 600 and a performer intake.

FWIW, nothing wrong with dropping the compression with the dish and going with a cam that does better filling the cylinders. Like the last cam we did for a 70 455. It was a Ultradyne 280/288 232/240, 112LSA .550/.550 with 1.65 rockers, we dropped the SCR to 9.5. He wants to run on 87 octane if possible.

Seems like low compression stock engines have been just as likely to get hot and the well designed higher compression stuff that we worked over. My t/a w72 had the stock cam with 8.2 Scr and lost a rod bearing. Listening to the radio and not paying attention. Had an some type of issue with the heater core. Looked down saw the temp going up, turned the radio down, it was pinging like crazy. Too late, hammered a rod bearing out.