Hi guys,
I have not posted in a loooong time, but I have been reading the forums regularly. I'd love some input on a minor problem I'm having with a '78 250 in my wife's '67 Chevelle (not a truck, I know, but hey, it is a Stovebolt 6!).
I recently got this puppy up and running as this is going to be my wife's daily driver. Engine is a replacement out of a 78 Chevy truck and is in great shape. It was running rough and running very hot--I would shut it off at 240 deg. Reading posts here, I determined it could be: bad timing, vacuum leaks, bad distributor. Sure enough, found a leaky intake manifold so I replaced the gasket and properly torqued it. Then I timed it to max vacuum at idle (with vac advance line to dist. plugged). Wow, what an improvement! Finally, I replaced the stock dizzy (which was an HEI on the 78 motor) with one of those coil-in-cap HEI jobs off of Amazon.com. Drove it today, and wow, it runs like new--very smooth, tons of acceleration! Here's my only problem (and maybe it's not even a problem): I have a 180 deg. thermostat in it (with two 1/8" bleeder holes drilled, as I had earlier experienced problems with air bubbles), and now it wants to run quite warm, around 210-220 degrees once it's warmed up. I'm thinking this is too high and it should be running at or under 200 (stock thermostat was 195). Earlier I had pulled the thermostat (this was after the new manifold gasket and re-timing, before the new dizzy) and of course it ran very cool--took forever to move the temp needle and barely got up to 140 maybe (this with ambient temps in the 20s). This confirmed to me that there are no problems with the water pump, radiator, blocked hoses, etc.
So here's my dilemma: known good (I had previously tested it) 180 deg. thermostat is making it run what seems too warm, but no thermostat is running way too cool. Is there a better/ wider opening thermostat I can run? Should I try a 160 deg. thermostat?
Any suggestions would be greatly appreciated!
Last edited by Tyler Watts; 01/14/2019 3:51 AM.
