74 maverick grabber. frustrating over heat problem!

Is your '87 fuel injected?

 

I'm in with this suggestion. Just because you have a new radiator, doesn't mean its not got a manufacturing defect and isn't cooling. Seems like a nominal cost with everything you are doing to verify that it is getting water from the engine and is atleast trying to do its job.

 

yes. it is fuel injected.

 

Perhaps the shop has one. I'm not sure. Maybe that's why they think there is a blockage in the motor.

 

Without a thermostat the coolant stays in the right temperature range for the fuel injection to go closed-loop? Or you purposely run it rich for the supercharger?

 

It's actually set up open loop if I recall. When we went to MAF from speed density we swapped the computer from a 93' mustang to try to keep some fuel efficiency while it would run a bit rich. With a set of GT40 heads and oversized valves and a Vortech V1 and MSD ignition, I still get 16 miles to a gallon. I mean given my setup that's really good. It also let me use a stand alone fuel return to max out my stock injectors before I bought 60 pound injectors.

I'm a carb guy so I had a LOT of help with this car. I can get around FI but my best friend really helped me out especially the performance side of things.
That was before the head swap.

 

Reverse pumps have different bolt pattern on the flange for fan pulley(slightly wider), unless wrong pulley is used ain't possible. Even that's not possible, because reverse water pump pulleys run from back side of serpentine belt.

 

Are you sure about that? Reason I ask is; a friend of mine built a 351w for a '75 Grabber. During initial break-in, it immediately boiled over. According to him, the auto parts store sold him a reverse-flow water pump by mistake. All I know is that after replacing the pump with the "correct" one, it never overheated again...

 

Yes, reverse rotation pumps have a different pulley bolt circle diameter than a standard rotation pump. This was also mentioned back on post #42.

 

Look, I don't mean to be critical, but...

• You haven't confirmed the thermostat is good and it's installed properly, but you assume it is.
• You don't know what radiator is in it, but you assume the shop installed the right one.
• You're inclined to think the block has some sort of blockage in it, but you assume that's the case even though it's not the first engine with this problem.

You should back to basics, check the cheapest thing first. You're listening to your mechanics because you presume them to be experts. If they were experts they would have found it by now. Instead they have you throwing money at the thing without improving the situation.

 

Over 3 decades ago, I teplaced tne thermostat in my sister's '77 Monte Carlo, but like a
dumb-###, I wasn't paying attention, & installed it upside down.
It boiled over real quick and was incredibly embarassing.
It's easy enough to verify that the thermostat is at least installed in the proper direction...

 

Okay, I have stated some of this before and it's okay to be critical, I am open to anything even if you're not the first to ask it. The car overheated with a new thermostat. It overheated without a thermostat. It overheated with a 2nd new thermostat. I changed the head gaskets because they appeared to be on backwards. When I could not figure the problem out I took it to the local car shop. They had a hard time with it. thinking the radiator was the problem they replaced it. It did not and I have been told I will not be charged for it. That pretty much leaves a restriction somewhere. I would say they are no more experts on the 389/302 than I. I have had many apart and own many and this is the first time I have been stumped to the point of taking it somewhere.

 

Yeah that was the first thing I checked when I had it. What puzzled me was I could drive it around town. Hit the freeway and it was all over.

 

That's usually a sign of a lower radiator hose collapsing with sustained high water pump rpm at highway speeds. But you said the hoses are new and the lower has a spring so I dunno... Have you checked the ignition timing as asked earlier in the thread? Small block Fords like a lot of timing advance. Do the plugs look ok?

 

Yes, the ignition was checked and we made sure the vacuum advance was working.