Thanks for all the advice. I,m going to definetly do a cylinder leakage test and pay close attention to the coolant resevoir. On the last repair the heads where resurfaced and the block was decked. How many times can this be done before running into problems. Planning on pulling motor this weekend. Also at 400hrs the cam, mains and rod bearings where replaced. New rings with original pistons replaced. Anything else recommended at 450 hrs

whyle your in their replace the lifters and roller rockers,,the needle bearings ware out..moral on the lifters and scorpion on the rockers..

+1 on the morel lifters, and scorpion rockers. Scorpion makes a nice marine endurance rocker arm, also valvesprings if they havent been done. Although I would like to think they were if the heads were surfaced. As a matter of fact, id like to think if they went as far as refreshing the bottom end, that they also did the top ends.

Lifters, springs, valves and keepers all new. Not sure about rockers.

Pulled motor this winter and found both head gaskets blown. On previous build the guy resused head bolts and admitted to head bolts breaking when retorquing heads. Had mixed matched head bolts and i'm assuming some new head bolts too long and ground ends off to make work. Since then I pulled heads and resurfaced, ARP studs for heads and new commetic gaskets. Completly resealed engine. Replaced timing chain with cloyes double roller and degreed cam in @110 centerline. Set distributor at 0 degrees to my best knowledge from GM world. Removed gen one Whiple computer system and sent Factory 555 pcm to Whipple to be re tuned, new injectors (63lb/hr) and harness, new map sensor. I,m confident my overheating issue is resolved. Thanks for all advise. Now reinstalled and started engine and found engine running severly rich. Fouled new spark plugs in approx 15 mins of idle time on hose to the point wher it would not restart. Ordered new diacom laptop scanner and checked data. Have alarm going off steady 1.5 second beep quit counting after 25 consecutive beeps. No codes stored. Checked TP voltage. .55 volts at idle. Map sensor reading 29.6v key on engine off. Baro reading 14.9v. Is baro sensor a fixed reading??? When alarm goes off idle starts surging like crazy. Have not lake tested yet. Seems to clear up over 3000 rpms. Any ideas would be great. And is there any way to set base timing when running