i always heard that its normal for engines to run hot during cam break in so would it be a good idea to get a 160* t-stat for break in and switch to a hoter one after that? what would be a good temp for aluminum heads?
thanks

Generally the reason most people's engines run hot during cam breakin is because they do not set the timing to an acceptable value and they do not burp all the air out of their cooling systems.

Another factor is that the car is sitting still while revving. No airflow through the radiator doesn't help. Use a high power fan in front of the radiator like they do at dyno shops if you can.

A good way to get the timing close for stratup is to bump the motor to 10-12 degrees BTDC. Mark the distributor under #1 tower, pull the cap and rotate it untill the rotor is directly lined up with #1 tower, button up and start up.

It is a good idea to put the car front up in the air on jack stands to get the radiator higher than the engine. Pull the thermostat cover off and pull the thermostat out. drill a 1/8 hole in the flange of the thermostat to let trapped air pass out prior to the stat opening. Fill slowly with the stat out untill water level is up at the opening. Reinstall the stat and hosing, continue filling the radiator untill full and start her up.

I use these procedures every time and they work like a charm.

Jon

What i did that helped keep it cool and burp the block at the same time is back it out in the driveway, start it up and put a garden hose in the radiator and turn on the water, keeps things nice and cool and runs all the bubbles out. Just my .02

cooling shouldn't be a problem if you've got a good cooling system. A 3 core radiator, factory 7-blade clutch fan, and a good (factory) shroud should give all the cooling you need. The key, of course, is a good shroud.
Opening the hood will of course give more airflow, and the garden hose trick should ensure it stays cool.

When I broke in my cam, it ran hot because the timing was way retarded, somewhere between 5-10*. But with the hood open and a garden hose it kept plenty cool even with the outside temp being over 100* and the car in full sun. This was with the cooling system mentioned above, and a 180* thermostat.

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-'77 Camaro 'Original' - 357, home-ported heads and intake, Q-jet, headers, hyper flattops, ~8.5:1, 3.42 gears, 214/224-112LSA cam, 1LE rotors, D61 pads, 5642 springs
-'92 LeBaron LX sedan - all family owned, great daily driver and highway cruiser. 52mm TB, rear discs swapped.
-'70 Camaro - 350, 4-sp, nothing power, needs work, lotsa fun
-'65 Nova - 230 I6, 3 on the tree, nothing power. HEI swap.
-'70 Cadillac Sedan Deville. 10:1 472ci, TH400 - stock.

i broke in my freshly rebuilt engine with a 180* stat and it didn't get much higher than 190*. and i had a new engine so it will naaturally run hotter due to the added friction. a 4 blade no clutch fan, a 4 core rad and a fan in front of the rad. i was reving it for 30 mins to break in the cam and it never go to hot. only once did a little coolant come out of the overflow tube but that was probablly becasue i over filled it a little.

i say just get a good fan in front of the rad make sure all the air is out of the system and get the timing close enough so it will run. as long as you have a good water pump and rad it shouldn't be a big problem with the timing as far as making it over heat.

I like to fill er up through the thermostat hole. That way you get zero air in the system.