i am running a 79 302 in my 69 coupe, could the 69 intake (which has no water crossover in back) be causing it to overheat. it overheats after driving 10 minutes or more.  

Thats overheating pretty fast there bright. If you look at aftermarket manifolds some have the rear crossover and some do not. The crossover balances the flow in the rear of the engine and for a street engine is a good idea. You get flow to both sides of the block without the crossover however. You didnt say if you just built this engine or if something has just been changed, but a lot of Ford problems can be traced to upside down head gaskets or mounting the wrong water pump for the application. If this engine has been running fine previously there is another set of problems. Make sure you have no air bubbles in the system by letting it run open for awhile and also make sure your flow is good by feeling the hoses and knowing when the thermostat opens. More info on your situation might help.  

I was going to guess the head gaskets.  

Edelbrock who makes both types, with and without crossover, says they feel the crossover does not help in normal engine cooling and they use it specifically on their emissions intakes where you need to have coolant at the rear of the manifold. So there must be something else going on Bright.  

Thanks mechguy48, it started overheating after i switched from the 79 intake to the 69 intake both are cast iron 2b. On a day that is about 60deg or lower it does ok. I also dropped to a 160 t-stat maybe i got a bad stat, think i will try another t-stat.  

Hey guys - do the 69 and 79 iron heads have the same architexture (location, shape & size) for water passages to the block and intake?  Even if there is just a little difference between them wouldn't this be a potential source for over heating?  

It would if there was a difference but there is none that I am aware of. The heads certainly underwent a lot of changes but the block really didnt so I would have to say the water passages are in the same place and should function even though they may have slight differences. You can get some lousy gaskets that cover up most or part of the water jackets so thats something to look for also. When you have an engine that spans almost 40 years of production there are a lot of parts out there and not all of them are interchangeable so you can get screwed up.  

A thermostat installed backwards will do this.  

I have a 68 289cid put new radiator to a 3 pas high eff put a new water pump went from 6 blade to a 9 blade put 3 thermostats 180 first then 160 then 180 andthen wentback to 160 replace both hoses put spring in lower hose flushed engine 4 times also the temp sensor when running for two hours it is fine when stopped at a stoplight water runs out the overflow tubed and when you shut it off it runs out