Just a thoght here about what temp is optimum for 390 performance . The motor has been done up a bit I dont know specs it has a 650 cfm Edelbrock carb 4bbl and headers I finally rigged the gas pedal to fully open but the carb almost hesitates and coughs on real hard acceleration also what timing should this motor be set to 15 - 18deg ? Thanks all it just needs a little refinement sure goes once the revs are up in 3rd .
ktownford
68 4x4 390 ,435np ,
205np 4:10

 

Ktown, I like to see an FE running at least 185*. FWIW, I run all of mine at 205*, cause that is the hottest stat I could find. DF

 

My experience has been the 180 degree thermo is the best. However, I do live in the SouthWest and our winters are very mild at best. Plus, I do have an electric fan setup...which allows me to select when the fans come on for cooling needs.

Timing the 390 goes something like this. Start at 8 degrees BTDC (compression stroke) and work your way up (10, 12, 14, etc.) until you hear the engine ping. At that point, go back down to the previous setting. Takes a little longer, but usually works very well.

Carb issues are difficult. Could be the timing is off enough causing the hesitation. After you have the timing all squared away, then make the fuel/air mix on the carb on the rich side. Again working back to the lean until the 390 responds. This is all said not knowing if you need a tune-up (dist. cap, rotor, wires, spark plugs, fuel filter, etc.)

++PLUS++ When you have the #1 spark plug out centering the 390 for for TDC...check the plug. What does it look like: light, dark, oil covered, etc. Tips you off how the carb is running...lean/rich.

 

I removed the vacume line from the advance rid me of the hesitating acceleration and removed the pinging too much vacuum from the edel 650 carb I guess .

 

For Ktownford, I had hesitation too and disconnected the vac line for a temp fix. What fixed the hesitation was installing new distributor advance springs. I checked the advance w/ a light and mine was advancing early and too much.

 

I run a 160
I had a 190 but I had to replace it (due to water leak)
With a 160 it seems to run good, but I haven't gotten much "road use" out of it yet
But idling it takes forever to warm up still, and I don't have to kick the fan on until after I shut it off. Thats if I let it run for 30 minutes or so

 

I believe factory for these things is 180, but hotter is actually better for engine life, but may sacrifice a small amount of performance. I've always run 180 in mine, but I might bump it up to 190 and see how it works. will post results in a few weeks if I do it on the new motor

 

I've found in Northern Ca. with hot WX and steep grades that 190 has been to much of a head start for water temp. So after some trial and error/high temps i back with 180. How do you join this GOBLIN society?

 

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