We have a 74 mav that we replaced the 200 I6 with a 302 from a 77 Thunderbird. We also replaced the 3 sp manual with a C4 auto trans. With the engine off, we replaced the intake manifold with an Eddlebrock Torker II and put a 600 CFM 4 bbl carb on it. We also bought a new radiator for it. It's really running hot, getting up to 220 on the road. We replaced the thermostat and put a 180 degree thermostat in it. It is still running hot. There is no squealing noises coming from the water pump so I think it is working. The hoses are not bulging out and they are new too. Any thing else to check?
Flush the block out? what Fan are you running and what kind of radiator are you ruunning? I just can't imaginea 302 running hot with a brand new radiator unless there is a blockage somewhere? I ran my 70 Maverick with a pretty good build on the 302 ran it with a 6 cyl. radiator for a long time and it never overheated. Now on the other hand I can make my 200 I6 with PS and AC overheat in traffic if I keep my foot on the gas pedal just a touch to keep the engine idle speed up when I am in traffic. Never had it boil over but I have had it run up to about 200 degrees with a 185 Thermostat in it. But as soon as I start moving the temp drops right back down to 175 or so.
Are you running a reinforcement spring in the lower hose? Do you have an electric or mechanical gauge? Using the correct sensor for your gauge? Are you sure you have the air out of the cooling system?
when does it over heat? at idle, cruising on the streets, or on the freeway. what fan are you using? do you have a shroud? what water pump and pullies are you useing? did you change the head gasketes?
We'll check for a blockage. The engine did sit for a few years in a junk yard. We bought a new radiator telling the parts store to get us one for a 74 mav with a 302 in it. It overheats driving down the road. It does not have a shoud on it. It's got the fan that came on the Thunderbird. We replaced the intake maniforld, but we did not take the heads off. We're using the water pump that came on the 77 Thunderbird. We did take the power steering pump off and the air conditioner off of the engine since the mav doesn't have those things.
get a fan shroud. the stock radiator is barely adequate to cool the factory stock motor in good shape. if that motor is bored over or pluged up with stuff in the cooling passages you may never get it to cool. there are aftermarket alum. radiators that alot of members here are running. you may need one of those but first try geting a fan shroud.
Water Pump Can the water pump spin but not pump? Every water pump I've seen fail screeches and screams right before it seizes up. Could the water pump not be pumping?
Most pumps will leak first. Do you have a spring inside the lower hose to keep it from getting sucked closed?
A junkyard block I would do this first, I would not put a new radiator on a junkyard block woth out flushing first. All kinds of trash could have just ended up in your new radiator drain coolant Remove t-stat remove upper radiator hose fill rad with water and leave the garden hose on a slow speed to keep full start engine and let it run, water will pump through the entire system and out upper radiator hose (I duct tape my shop vac hose on the end to get water away from car) This will aloow you to see what garbage is coming out flush system and verify water pump is working corectly. Keep an eye on temp gauge as you have no pressure in system it may want to heat up, don't let it over heat obv Then I reinstall everything and run 2 bottles of rad flush for a week and half (400 or so miles), and reflush and fill. Then go with your prefered coolant mix and let her buck And a fan shroud is absolutely needed, also a good idea to put a make shift air dam on it to allow the engine compartment a low pressure area to remove the heat (3 inch wide setup the length of radiator core support should do the trick.)
Had the same problem once myself. Had to "burp" the system. You can find a kit to do this at your local autoparts.
