Thermostat question 180 or 160?

64nailhead

Goat Herder
Supporting Member
Dec 1, 2014
3,347
113
Upstate NY
I almost hate to ask but what is the ignition timing myth you mentioned?
Ignition timing is the ‘never mentioned’ piece of thermostat and cooling temp discussions.
Retarded timing for extended cruising during high vacuum condition (light throttle highway speeds) will add 10-15 degrees to the coolant temp.

I’m sure you’ve seen, read or experienced 1st hand coolant temps that climb when cruising. The usual suspects are air flow, fan shrouds, t-stats, etc. Rarely do you hear someone try adding 5 degrees to the vacuum advance and seeing what happens.

Of course, poor air flow plays a giant role, but it’s rarely the sole contributor. Same goes for timing at idle. Ported vacuum being used for the distributor means the timing is as low as possible while idling. Increase the timing 10-15 degrees at idle, then adjust the idle back to 750-900 and see what it does to the coolant temp.

You never have to be scared to ask - I could always be wrong lol. I’ve derived a lot of my advice from a couple of summers of driving something for a 60 mile commute every day. I changed timing , jets, power valves, air bleeds every tank of gas and recorded all of it. Coolant temps are a side effect of a good tune which achieves good fuel economy.

I’ll end with I hate Holley carbs , the vehicle I did this with had an 8007 vac secondary Holley and HEI. It was a learning experience with an underpowered heavy vehicle. It’s a lot easier with a turbo and EFI lol.
 
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Dayzedandkonfuzed

G-Body Guru
Feb 9, 2010
838
93
Anglemont, BC
Just cuz it hasn't been mentioned yet, even though you now have plenty of reasons not to run a 160, running too cool will also cause excess carbon buildup. Many early fuel injected engines had problems with carbon buildup, hence why they typically run a 205 stat. The most common application for a 160 (or lower) is marine, as they often run high rpms for extended periods of time, burning off the excess carbon. The same could be said about a race car.
 
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Supercharged111

Royal Smart Person
Oct 25, 2019
2,440
113
Colorado Springs, CO
Ignition timing is the ‘never mentioned’ piece of thermostat and cooling temp discussions.
Retarded timing for extended cruising during high vacuum condition (light throttle highway speeds) will add 10-15 degrees to the coolant temp.

I’m sure you’ve seen, read or experienced 1st hand coolant temps that climb when cruising. The usual suspects are air flow, fan shrouds, t-stats, etc. Rarely do you hear someone try adding 5 degrees to the vacuum advance and seeing what happens.

Of course, poor air flow plays a giant role, but it’s rarely the sole contributor. Same goes for timing at idle. Ported vacuum being used for the distributor means the timing is as low as possible while idling. Increase the timing 10-15 degrees at idle, then adjust the idle back to 750-900 and see what it does to the coolant temp.

You never have to be scared to ask - I could always be wrong lol. I’ve derived a lot of my advice from a couple of summers of driving something for a 60 mile commute every day. I changed timing , jets, power valves, air bleeds every tank of gas and recorded all of it. Coolant temps are a side effect of a good tune which achieves good fuel economy.

I’ll end with I hate Holley carbs , the vehicle I did this with had an 8007 vac secondary Holley and HEI. It was a learning experience with an underpowered heavy vehicle. It’s a lot easier with a turbo and EFI lol.

When I put the blower on my 1500 it ran warmer around town with the trailer. Part of that is the added power, but another part I can do nothing about is all the timing it pulls when it blows hot air. Retarded timing drives up EGT and of course water temps.
 
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herb

Not-quite-so-new-guy
Feb 10, 2018
10
3
i run 180 on carb motors
195 for fuel injected
most modern fuel injection control,, rich or lean,, is controlled by water temp sending unit,,
cold engine runs rich then a warm motor runs leaner..
so mpg will suffer with no stat or a low one,,,,
if you are car computer savy then you can find that switch setting point....
if your not a computer type guy,,but have a factory computer car,,then go 195 ,,or by factory spec...
the bottom line on higher stats ,,,,,,on efi cars is to meet epa,,,less pollution,,,as more of the fuel is burnt in a hotter engine
 

Supercharged111

Royal Smart Person
Oct 25, 2019
2,440
113
Colorado Springs, CO
i run 180 on carb motors
195 for fuel injected
most modern fuel injection control,, rich or lean,, is controlled by water temp sending unit,,
cold engine runs rich then a warm motor runs leaner..
so mpg will suffer with no stat or a low one,,,,
if you are car computer savy then you can find that switch setting point....
if your not a computer type guy,,but have a factory computer car,,then go 195 ,,or by factory spec...
the bottom line on higher stats ,,,,,,on efi cars is to meet epa,,,less pollution,,,as more of the fuel is burnt in a hotter engine

Most EFI cars go into closed loop around 130 and will run stoich starting at that temperature.
 
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