Best Thermostat for SBC with Zip Riser
It looks like this thread is wrapped up and Rodger wants me to start a new thread. I have his directions to start a new thread but this is the SBC Forum and I have almost the same question. Just last Thursday I got my engine started after YEARS of messing around. It is a '76 2-bolt 350 bored 0.030 0ver with a nominal rebuild, mild cam, cleaned exhaust ports in 882 heads and heads milled to give 9:! compression ratio. Several years ago I was advised on this site to get a Zip water pump riser and I have searched this site for further information on the Zip Riser but found most information in the Technical section on the H.A.M.B. I admit making several mistakes but my expert help from Progressive Performance (Ashland, Va) and I ran in the cam for about 10 minutes at 2000 rpm but shut it off when the temp. reached 220 F. I know I made at least three mistakes:
1. I used straight Prestone, no water.
2. I had no fan shroud, although a 17" flex fan.
3. I did not purge the air bubble out of the Zip manifold with a 160 F thermostat.
I have spent the last few days adding a shroud (lots of fun!) and I have added a 3/16" hole in the 160 F thermostat. I have also drained the radiator and diluted the Prestone to about 55/45 with water. I also discovered the air bleed on the top of the Zip manifold and I will bleed it after I add the Preston/water back in the radiator and seal it with a dab of RTV. The Zip instructions specify a 160 F thermostat, maybe because the Chevy-6 water pump does not have equal flow rate to the SBC V8 pump it replaced? Anyhow if folks here think 190 F is optimum I will be glad to run at 170 F with the 3/16 hole in the thermostat. If it runs too cold with the hole in the 160 F stat I will be glad to run with a 180 stat also with a 3/16" hole. Just to keep this thread going I will report the results of this setup in a day or two. A complication is that I will have to modify one of the lines to the trans cooler at the bottom of the Walker Cobra radiator since the old line position conflicts with the bulge of the shroud at the bottom and I may have to bend a new line around the bottom of the shroud. Stay tuned, I am amazed that several of you as well as the H.A.M.B. examples run cool but I have made three change/improvements and I hope it will run cool with these changes. I will welcome any and all suggestions as to what I might do more.
Don Shillady
Retired Scientist/Teen Rodder