i am getting ready to start my car, and was wondering with 12.3-1 compression if i should run a 20 Lb rad cap as opposed to a 16. i hear the 20 lb will help it run cooler.

no idea. new motor?

If you have the aluminum 19x31 rad, prefferably with the larger 1.25 or 1.5 inch tubes and a killer CFM fan you shouldn't have any issues unless the ambient temp is past 40°C.

yes i have a big aluminum rad and a good stewart stage 2 water pump. and a flexalite plastic 17" fan it moves lots of air. 185 stat as well to let things cycle.

yes i have a big aluminum rad and a good stewart stage 2 water pump. and a flexalite plastic 17" fan it moves lots of air. 185 stat as well to let things cycle.
I started off with a 185 stat. was told I should drop down to a 160 and let the engine run cooler, performance is better and temp gauge reads 160 on cool nights and 170-175 when driven, on hot days goes to 180-185 at idle, have the large BeCool rad and 2-1 coolant with Edelbrock aluminum water pump, on a LS7 454 cast heads with Hooker comp. ceramic big tubes, this may only suit this engine, with aluminum heads it would cool quicker

well everytime i ran a 160 stat the thing just stays open and heats up it acts like a restrictor and not a stat. if this doesnt work i will try a 195 stat the idea is to cool whats in the rad and then open the stat and let it in the motor.

I was told the opperating range of a BBc engine is 190-200 the pistons need to be able to heat up enough to expand in the bore properly. i will never run a 160 stat in a BBC engine again.i ran the old 427 last year with this set up with 11.25-1 compression and it was great the car would get to 195 in traffic then go back down to 185 driving.

I was just concerned with this extra point in compression at 12.3-1. i guess all i can do it drive it and see?

Thanks for all the replies i appreciate it.

I can't see any reason you would want to run a 20 lb cap.

well i have a 16lb cap so i will start with that