I've been slowly working out the bugs in my 70 Runner. It's got a 440 that supposed to be mostly stock except for a 509 cam. I didn't build the car or engine-I'm just cleaning up all the messes left by the last guy. It runs hot and I've burped the system, verified (and reset) timing, replaced the fixed fan with a clutch/fan setup, installed a 180 thermostat (ran hot), pulled the thermostat and ran it (still ran hot). I pulled the 974 radiator and had it checked by the local radiator shop. They said it had recently been recored and flowed just fine. The water pump is fine. I'm guessing that the 26" 2 core 974 radiator (from a 340 6 pak E body) is just too small for the 440??? I figured that since it was a 26" radiator it would cool ok, but I guess not???? any guidance? Thanks

440s with 3.23 gears & no AC came with 22" radiators in some cars.

Something here...

What some people do to these cars is amazing. At the local Mopar restoration shop he gets these “rebuilt ready to go” deals all the time. Some running, some not. Last one had timing cover glued down...no timing chain. Another had the timing gears off one tooth. Others have completely mismatched combos and/or combos not based on reality.

Most 40-50 year old blocks and heads have accumulated decades of rust and scale. Hot tanks will not get this stuff out. Someone needs to physically pick the rust and scale out.

factory radiator shroud?
Hood to radiator support seal?
Aftermarket pulleys?
Stock type water pump? Housing?

Does the car have loud exhaust, like flowmaster or glass packs? Might make it hard to hear pinging? Verified compression?

(1) how hot? (2) known accurate gauge? (3) hot in town/slow speeds? (4) hot on the interstate/highway?

The car has no AC or power steering. its just got an alternator (new), fan, and a water pump. The pulleys appear stock. I do not have a fan shroud installed but the new clutched fan is pulling tons of air. I also don't have the hood to radiator seal but I haven't even gotten to driving it really.

At idle, the engine heats steadily up to 220 and hotter if i let it. The water pump has only a few miles on it but its probably 10 years old.I just ran it again and thought I'd check flow. I opened the cap once the temp was past 180 and the coolant flow was very slow. I think I will try a new water pump tomorrow.

I'll be super annoyed if the head gaskets were installed wrong and coolant ports are blocked off.

Have you had it out on the hiway?

Well: This one cooled my 528 just fine. I would buy a shroud for it.

I bet your water pump is bad.

I built a car for a guy and the new water pump he had was bad. The impeller was spinning on the shaft.

It would do the same thing with the slowly rising temperature.

A fan shroud is a must

In some 440 Sixpack cars too.

What is the cast date of the block.? I’ve had two motor home blocks that ran hot because they did not have the matching number heads with the extra cooling holes.

I have a '69 coronet r/t, 440/375hp, stock exhaust, basically stock build, with a 22"radiator. it runs hot. I've re-cored it 3 times, each time going to something bigger, and nothing seems to cool it to my satisfaction. why Chrysler would have put this puny radiator in a high performance car baffles me.

I'd check the carb, could be way to lean. 509 and stock carb don't mix.

retard timing with a after market lumpy cam will heat them up.

my 440 with a Hughes whiplash 230* 245* .518/.518 lift would heat up and had bad fumes like it was rich till I got the dist reworked and the initial timing was way up with very little mech advance. now it is locked on 0* with it at 36* total

runs a steady 180* temp all the time now. I can up the timing and it will ping. lower it and it will steady over heat and give more smelly exhaust fumes

I used the stock mid 80s /6 rad that was in my truck. chased the lean rich carb issues to the WP & housing all in vain.


followed the FBO tuning booklet and dialed in the dist/timing curve/then locked mech advance out and now it runs like a beast for daily driving in traffic now.

you got to get the intake charge to burn in the cyls and not going out the exhaust port and into the header/manifold.

The 340-6 pack radiator (2998974) is a 26" radiator - only thing you might do is have it re-cored with 3 rows vs. 2. Nothing wider than a 26" came in E or B-Bodies. Also, coolant passages in the motor could have a bunch of mud accumulated. I had a '78 Super Coupe 360 that ran hot all the time. I pulled the radiator & had it boiled & inspected, & that did not solve the problem. We pulled the motor to paint it & replaced all the freeze plugs. First one we removed revealed a bunch of sediment (mud) that was all settled in. We took them all out & took a garden hose & really flushed out everything - a LOT of crap came out of the passages! New freeze plugs, got it all painted & detailed, reinstalled the engine & it ran nice & cool! Good luck.

New update:
Ive been busy the last couple days but I finally replaced the water pump, coolant temp sensor (had overspray on it), and installed a second new 180 degree thermostat. I also installed a coil spring in the lower radiator hose since the hose was soft. I just ran the engine and it still overheats. I popped the radiator cap while the engine was warming up and there is still no flow.

So I'm thinking the block passages are full of sediment/rust or perhaps head gaskets were installed wrong, which is blocking off the coolant passages. It's pretty frustrating

Block filler?

Did you check flow with t-stat out?

I removed the thermostat and ran it but that was before the water pump was replaced. Once it cools down I will be removing the thermostat and trying to find a way o to force water through the engine coolant passages.

That thought crossed my mind. I sure hope that’s not the case...

What I should have said, to see if water flows any faster.