hey guys, i got a 455 olds160 t-stat in a 70 cutlass and my dad also has a 70 cutlass 455 in it(160t-stat), is runs around 160 idle and drving while mine on the other hand runs around 190 going 25-35 but will climb up to 205 almost sometimes getting to 210. i want mine to run cooler. any idea on what to do, im running a 4 core radiaotr with two electric fans that kick on around 130 and then cycle off and on with the temperautre. please help me out! i want to get it to run cooler. i also have a 160 thermostat in it and have recently flushed it out. ive read someplace online that for 455s you need to run 20-30% coolent to 70-80% water. is this true. bc i put a 50/50 mixture in there.

on the other hand,, earlier on we had to advance the timing bc when i shut it off it would continue to run until it finaly quit. we decided to retard it alilltbe bit one mark past the timing tab. well now sicnnce i started driving it,when i reach 3500 rpm i haer this rattling noise.. we thought it was loose rockers, but retarded the timing again qnd now makes the rattling noise ever so slighty at 4500 rpms. idk whats going on. please help! thanks

 

You're not saying what year the engine is, but I'd suspect '70 or under, which is on the high side of compression for todays fuel!
The 'rattling noise' you're hearing is probably pinging from your advanced timing, or low octane fuel, or both - not good at all, for longevity of your engine!!
Fill it with premium, which should help, and after it's circulated in the motor, re-set the timing to about 4 degrees advanced.
If that cures the problem, but kills performance, advance it 2 more degrees and drive it like you stole it!
If it pings, turn it back, but if not, do it again, and again, until it does, and go back 2 degrees! If it pings or overheats, go back 2 degrees.
Been doing that since uneaded gas came out, and it works for me!
One of my 'Burbans woud run hotter with regular, as it was set for mid-range, and got 18 MPG highway w/3:73's!

 

What does the temp do at standing idle for a period of time after it warms up? You don't mention what type of dist. you run or how many mile are on the engine since it's last rebuild?

 

50/50 mixture. I wonder if the carb is running lean? Back off that timing like rickman said.