68 Charger overheating

[68_R/T_Eric]

I know there are a ton of threads on the overheating issue.  But, thought I would post up my issue for advice, since I don't see a similar fact pattern in other posts.

1968 383, 4 speed, 4-bbl.  Before we started into the full resto mode, it was running firm at about 180*.  Pulled the engine out, but didn't tear it down - just to paint engine and engine bay.  Put it back together and transported in down to my son's place in Las Vegas.  When we put the engine back in, we replaced the water pump, (paddle blades) and kept the stock pump housing.  It has a 160* thermostat and 16lb new pressure cap.  Put new coolant 50/50 mix in.  It has the stock 22" radiator, no shroud but we did put on an electric fan on it - pushes from outside rather than inside pull.  Has the original 7 blade fan - non-clutch type.  It sat at my son's house for about 1+ years with not much driving.  Before putting the electric fan on, he took it out for a spin - after installing straight pipes (no mufflers) off the end of the HP exhaust manifolds that dump to the side and the temp started to climb.  The temp (per the guage) went up to about 160* - 170*, then dropped back down a bit (thermostat opened) before the temp started to climb.  It went to about 220* - 225* before leveling out.  He put the electric fan on, but with the same results - ran up to about 220*+.  I am down in Vegas visiting and we took it out.  Outside temp got up to 75* today.  Ran it for a short distance down the freeway and the temp climbed fairly rapidly to 220* plus. 

Things we have done:
New rad cap - 16 lbs
No apparent outside leaks
took cap off and watched flow from top of rad.  Fluid was calm until the thermostat opened and then it began to circulate and rise in the radiator.  No bubbles or foam.
No fluid in the oil or oil in the fluid.
We pressure checked it with a gauge - started cold and pressure went to about 7lbs and held steady at idle.  Revved it up for a while until the pressure went to 10lbs - it held steady.  The pressure slowly built to the 10lbs - Dash gauge showed about 190*.  The pressure held steady.
We then pressure checked it cold up to around 15 lbs via gauge pump.  The pressure stayed firm for 10 minutes/until we released it.  According to what others have posted, this would indicate there is no internal leaks.

Things we haven't done:
Haven't pulled the thermostat to check if it is opening all of the way.
Haven't flushed the radiator or back flushed the system.
Haven't checked the timing.
Haven't checked the fuel mixture.
Haven't pulled the spark plugs to check on condition.

Will do the above next - but any ideas/suggestions/thoughts to this point would be appreciated.

[Dans 68]

I would check, in order, timing, fuel mixture, water pump (you changed the guts), thermostat operation (was it always a 160 degree?), and radiator operation including the cap. The bottom line is that all the items that were changed are suspect. My 

As the electric fan has no obvious effect, I'm suspecting the cooling system. What was the pressure in the cooling system when the engine was at 220 degrees F? I would also check into the water pump operation as that was changed. Get a thermal digital gauge to read the temperature at the water pump housing to know exactly what the temp is. Helps in adjusting the dash gauge also.

Assuming that the car came from Lehi, Utah, elevation 4,564 ft, to Las Vegas, elevation 2,001 ft, I would say that it also needs corrective adjusting for the heavier air (additional oxygen) available to the carburator. 

A '68 383 4-bbl 4-speed, hmm? Sounds like my kind of car. 

Dan

[68 RT]

Check your temp first with a digital temp meter like Dan said. Check at radiator then see how accurate your gauge in the car is. 

[Cooter]

Get that electric fan off and reinstall a clutch fan with the stock shroud to begin with....

[Dans 68]

Get that electric fan off and reinstall a clutch fan with the stock shroud to begin with....

No shroud came with the '68 383 4-bbl 4-speeds. It should be just fine without it (and as you mention the electric fan, of course).   

Dan

[OldGuy]

Back home from Vegas - I was posting on my son's computer under his handle. 

I agree Dan - it should run at the right temp without the electric fan and no shroud.  Will have to let my son deal with it until I can get down there again in a month or two.  He will take the steps we outlined first and see what happens after that.

Thanks all for your input - will keep you posted on results as time permits us to work on it.

Carl