I have a 67 326 HO. Temp runs around 180 when driving. When sitting at an idle the temp immediately start to move up to 210. I have replaced the water pump with a Flow Kooler high volume pump and replaced the radiator with a 4 core dessert cooler. It has the stock fan (4 blade) and shroud which seem to be positioned correctly. Thermostat is a 160 and works fine. The lower hose does have a spring in it. Timing is set to factory specs which is 6 degrees BTC. I have replaced the points with an MSD electronic ignition. It is at the factory advance setting of 21 degrees. There is no coolant in the oil, so I think the head gaskets are o.k. Could it be I have a clog in the engine...if so how would I go about cleaning it out?
Any suggestions would be greatly appreciated...I am running out of options!

How clean does the antifreeze look? If you see rust floating around, there is corrosion in the system. Would be a good idea to have a reputable shop reverse flow the system to try and flush out any possible blockage in th e engine. The engine is pretty old, so something blocking the cooling system is very much a possibility. Good luck and let us know how it goes.

Steve :rolleyes:

4 core and 160 fine for a 326..160 thermo OK. 210 running temp OK at idle and standstill...as long as it is not for too long a period. 205 degrees is the "optimal" engine running temp. DO NOT "sweat" 210!!!

PS the lower hose spring is to prevent hose from caving in from supply/demand..

Over the weekend I bought a flush kit (2.99) and some prestone radiatior flush. I flushed the system for about 10 minutes and then added the prestone flush. My "HO" is now running at about 170 crusing speed and about 195/200 in 90 degree stop and go. They recommend running the flush through the engine for about 3 to 6 hours, so the above temperatures are with pure tap water! Once I go back to 50/50 coolant/distilled water temps should be even better.
Thanks for the replies and additonal info!

must have had some blockage in there! keep 'er cool!!

Steve