I originally had 180s in my stock 50 V8 flatty but for some reason I was getting a bad temp spike on warmup. I changed to 160s and the spike is gone but I've heard lower temps are bad for cylinder wear. Is this a factor with 160s and if so what's the ideal temp to use? Thanks.

 

Are you sure the spike was real, not a gauge issue? I would stick with the 180's. Flatties will build varnish and sludge in the valve chest if run too cool. You may just have a bad thermostat; try the pressure balanced Robertshaw or Stant ones if available. They cost more because they are made better.

 

I have always heard that the 180 is ideal in most applications. Is this correct? Also, would the 180 be ideal in my 56 F100's straight six?

 

Didn't mean to thread jack.

 

160's are terrible for economy and life of the engine. 180 seems hot to us humans but engines love it. It ensures condensation and gas blown by the rings will be evaporated quickly and it is also the temperature the cylinder clearances are based on.

 

I had the spiking problem when I replaced a RobertShaw 180 with a jobber 195. I was pretty sure it was a quality problem; the jobber being a lower quality part than the RobertShaw part.

The coefficient of friction between aluminum and iron is lowest near 215 degrees F, if I remember correctly. I think for a flattie, a good brand 180 tstat is your best bet. Don't use too much anitfreeze, it should be a 60/40 water/af mix.

 

The only time I've had temp spikes is when I had steam pockets in the heads. Drilling a couple of 1/8" holes in the t-stat flange so the coolant can percolate past them has resolved that problem - which occurs whenever I drain the system and refill it.

With 160's it means they're opening up faster. They don't limit the upper temp range so they shouldn't hurt if you do any distance driving at all. If your travel is limited to short jaunts only, then I'd stick with 180's.

I'm wondering if your spike wasn't caused by a sticking t-stat??

 

Well I got a couple of "premium" 180 degree Stant thermostats from Carquest and installed them today. Seem to be working OK. The sales guy pointed out that they already have some very small steam holes in them so he recommended against drilling a hole or two like I usually do for a SBC.
I also changed out the old H10 Champions I was running for some Autolites. Seems to run a bit better now.
Thanks.

 

Most thermostats have the edge of the disc carved with little "crescents" to let some flow bypass and air escape.

 

I had a pair of 160's which kept the temp fine except when pulling my trailer it would hit 190 and stay. switched to 180's and it stays there loaded or unloaded now. I also noticed less soot in my exhaust when I switched to the 180's.

 

Found this great site on the Flathead.

http://www.vanpeltsales.com/FH_web/flathead_home.htm