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I was reading that Stewart water pumps might help to end this car having some overheating issues (nothing crazy, but heats up in traffic). My 1968 with a 427 seems to have run cooler. I was looking at the Stewart Stage II, but did not know which model number to order (long, short, rotation). The engine is 100% stock with an added aluminum radiator. I am in Chicago... any recommendations on what temp thermostat to run?
Suggestions on plugs to run in this engine? Stock carb and ignition as well.
Found two mystery wires to track down. I have the AIM for the car, so I hopefully will track most other questions down.
Stock spark plug was the R43T but many feel it's too cold to burn off combustion residue adequately. The commonly recommended spark plug is the AC Delco R45T or equivalent.
How hot is it running? Right around 195°– 205°F is normal.
Most of us run 180° stats but anything between 160° is 190° are also fine. In cold climates a high temp thermostat will ensure the engine gets to operating temperature quickly so that the choke cuts off and cabin heat is available. The thermostat shouldn't affect any instances of running too hot unless it's not opening fully.
There are so many variables affecting coolant temperature; I'm sure I'll miss a few:
Make sure you have all the factory seals around the radiator, shroud, and hood to radiator support.
Make sure your thermostat is operating and fully open by whatever temp is marked on it. You can boil it on your stove top and use a thermometer to check.
Make sure your timing and tune is good; too advanced timing and/or too lean carb will cause the engine to run very hot.
Do you have A/C? The condenser sits in front of the radiator and cuts down on the air flow through the radiator. Make sure the fins are open and there's no debris caught between the two.
With an automatic trans, the fluid gets cooled in a mini-radiator inside the main radiator. Make sure your trans is performing well and not overheating as this will raise the temp of the engine coolant.
Are you running the stock fan blades or an aftermarket flex fan?
If stock fan, make sure your fan clutch is engaging/disengaging properly.
Check the large radiator hoses for being too soft which could indicate they are collapsing and not flowing their full capacity.
Make sure you are using a cap with the proper pressure-rating (either 12lb or 15lb, I forget)
Pics of your engine and radiator from various angles may be helpful to spot a problem.
Where are the wires and what color are they?
Last edited by barkingrats; Oct 24, 2021 at 11:33 PM.
Here are a few pictures. This car was a barn find after 30 + years. Person who found it got it running and driving. Last owner painted it and drove it. Engine bay has seen no love, but the engine and trans are strong. The mystery wires are a brown wire on the passenger side of the engine, and the other is an insulated wire (white insulation) near the distributor. The brown could be for an auto choke, but not sure. Thanks so much for the plug suggestion and all your other thoughts. The car is non-AC.
Plan is to replace the clutch fan and keep the original fan blades (cleaned and painted). Add a 2-stage Stewart water pump (if I can figure out which one fits), 180 degree thermostat and then change out all the hoses and flush the system. I only drove it for a test drive and all was good with the temperature. Lars will rebuild the original carburetor and timing el al will be adjusted accordingly.
Your belt configuration looks wrong, does your ps pump have a 2 groove pulley? The alternator belt should go to the front groove of the ps pulley and the ps belt should go to the middle groove of the wp pulley. The front groove of the wp pulley is for the A/C compressor if equipped.
Do everything BUT the Stewart pump and see what it does.....this includes timing most of all. I bet you do not need it.
Make sure you use Distilled water in your system...or 50/50 as you are in Chi Town.....
Ran out and snapped some photos. This is how it was configured. You certainly have a different set-up. Thoughts on what is better/correct? Thanks!!!!
If you're satisfied with the current belt configuration then keep it. The alternator pulley you have is a 2 groove that comes with rebuilt alternators sold at parts stores. It all depends if you want it to look original as shown on the below diagram at bottom right.
Originally Posted by Boomer880
Plan is to replace the clutch fan and keep the original fan blades (cleaned and painted). Add a 2-stage Stewart water pump (if I can figure out which one fits), 180 degree thermostat and then change out all the hoses and flush the system. I only drove it for a test drive and all was good with the temperature. Lars will rebuild the original carburetor and timing el al will be adjusted accordingly.
I would do the above but wait on replacing the water pump until you test drive it to see if it solved the over heating problem.
If you do decide to replace the water pump, I would suggest you check the timing chain to see if it still has the original nylon tooth cam gear. If so, then install a new Cloyes double roller timing chain set.
Good luck and enjoy your LS5.
Last edited by 71 Green 454; Oct 25, 2021 at 10:11 AM.
Car is currently running AC Delco R43TS. I read the TS is a longer plug than the T. I was thinking of moving to the R45TS, unless there is a good reason to do the R45T. Thoughts?
Any ideas on the two mystery wires in the pictures above?
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1970 LS5 Water Pump and More
