340/6 radiator way too small for 440?

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.

So I removed the thermostat and unhooked the lower radiator hose. I turned the garden hose on and shoved it in the thermostat housing. The water ran right through the block without backing up at all so the block is fine. I just put the thermostat housing back on without the thermostat and I will run it tomorrow since it's too late to bother the neighbors tonight.

When coolant is flowing, shouldn't I be seeing the coolant in the radiator move/flow?

I'm baffled. As was brought up, Perhaps either the advance on the distributor is way off or the carb jets are too small but I'm pretty sure it's got the 72 jets, which should be adequate. I've tried initial timing of 10 degree and 15 degrees and neither seems to make a difference. Any more suggestions?

If you pull the heads check the 3 cooling slots in the top of the head gaskets....they are like .188 wide on late gaskets, .455 on early stuff. Dirt in block, head gasket issue, blocked water passages could be your problem since you have no flow. Thin slots will not let dirt thru. Google bigblock mopar head gasket cooling slot. I have been making them .250 on everything I do with no issue, right or wrong.

I have had a similar problem on my Power Wagon 440 so will have to pull the heads

I removed the thermostat and topped coolant. I could see some movement/flow in the radiator as I idled, but it wasn't fast movement. I also adjusted the timing. After reading some timing threads pertaining to the 509 cam in a 440, i capped the vacuum line from the carb so no vacuum advance. I set initial timing to about 20 deg BTDC. It's 77 degrees Fahrenheit this evening and about 1400' elevation. As I drove temp steadily but came up to about 190-200 as I drove at 55-65 mph for about 5 miles. As I came back into town I decided to slow to 30-35mph and drive about 4 or 5 blocks into town. The temp climbed to 210 pretty quick so I turned around and headed back to my house about 5 blocks away. Temps reached 230 before I could pull in my drive and shut down. I text a buddy to vent my frustration and he said "are you sure your gauge is accurate"?. I grabbed a towel and mashed it over the cap while I slowly lifted the radiator cap lever. The lever came up without spraying a drop of coolant. I slooooooowly twisted the cap and then slowly lifted the cap. I expected some spray but nothing. The coolant was only about 3/4" below the cap and it was letting off a few wisps of steam/vapor but I expected it to be boiling. Also, the radiator cap I removed was a cheap piece of junk that says 14-16psi on it. With it being that hot, it should have some serious pressure. So, I'm starting to think it is my gauge possibly. Thoughts?

$20 harbor freight inferred gun would be an investment applied toward all your cars.

Yes, find a way to check your gauge.

Grab a radiator cap off another one of your other cars you think is good. Or two...

I haven’t made it to harbor freight yet for the infrared temp tester, but I think I ruled the gauge out. I had a stack of clusters that I needed to test anyway so I ran it up to temp and started swapping out clusters. 3 separate temp gauges showed it was running hot.

At this point I believe that head gaskets are impeding flow and/or I have sediment in the block. It is flowing coolant but not enough. I’ve been through the whole system unless someone has another idea. If I’m going to do head gaskets I may as well pull the engine, remove the freeze plugs, clean out the block, and install in one of my 68 Chargers.

Rule of thumb, hot running at speed means radiator. Hot slow means airflow.

It sounds like you are hot running slow. Not enough airflow.

I think that car wants a radiator shroud. Most do.

Also, check pulley sizes... is there an aftermarket "underdrive" pulley installed?

What diameter are stock crank and water pump pulleys?

It runs hot all the time.It overheats at idle and it overheats while cruising; at 60mph with 3.54 gears, the temps climb to 200 (even on a 77 degree evening). Then as I slow down to about 40 they climb to 210. As I slow down to turn into my development (20-25mph) they continue climbing to 220-230.

I'm thinking partly plugged radiator since it is all the time (slow speeds/highway speeds).

The stock crank pulley is usually 7" to 7 1/4". Fan pulleys vary depending on setup... mostly "with" or "without" AC. The "with AC" setup has a smaller fan pulley that overdrives the fan and water pump for better cooling. Bouchillon covers pulleys well (link attached).

Back to the "rule of thumb". You are running 200 on the highway. Warmer than your stat temperature assuming your gauge is accurate but not really overheating. 220 or 230 is getting a little warm.

I think your system could be minimally OK with addition of a shroud to help low speed cooling. The fan without shroud moves air but not so much through the radiator. These cars need a shroud for low speed cooling performance. This is a first step.

If there is question, verify the gauge. I like to use a low cost mechanical gauge from the parts store installed temporarily to measure coolant temp directly. Sometimes you can tell by how your current gauge acts from cold start. Start cold and drive moderately on the highway and watch it. Does temp rise gradually for a while, then level off for a while then start climbing again? If it levels off around your stat temperature (180) then climbs after that suggests gauge is close and stat is working.

It would not hurt to research pulley ratios. At least some overdrive of fan and water pump helps cooling.

And finally, you may need more radiator. FWIW I run a 26" "muscle car" aluminum radiator from Mancini with their matching shroud on a warm 496. This is a high capacity downflow radiator. Cooling is excellent (with AC). It stays right at 180 stat temperature rolling - even racing - and a little warmer with extended stop.

www.bouchillonperformance.com

You still have not answered my question. What year is the block? If it is a late model motor home block, it will have the extra cooling holes along the bottom row of head bolts. If you don’t have the matching holes in the 452 heads, it will get hot just like you describe. I’ve had it happen twice on two MH blocks. Water will not circulate properly. I bought all my buddies Mopar stuff the other day because he’s done restoring cars. He gave me his MH block that cause him all the Problems years ago. I have it at the shop. I’ll get a picture and post it for you.

Sorry-I missed that question. Its a 1970 HP block

Before I touched it I would be putting a thermometer in the water in the radiator.

I pulled the heads this morning and the saw a couple things. 7 of 8 pistons were kissed by valves at one time or another.....but anyway, the cooling slots seemed suspect. They look way too small. I started a separate thread about what the slots should look like but I wanted to update this thread with some new info.
1. The pistons are .060 over
2. The heads are 906 heads so they are the heads that came on a 1970 HP block.

For a couple reasons, I've convinced myself that it had to be the head gaskets.
1. I've been through all the normal stuff
2. The upper radiator hose barely has any coolant flow through it; my survivor 69 Charger with completely untouched original 383 has MUCH more pressure/flow in the upper radiator hose.

We're definitely on to something there. I've wondered about the slit head gaskets too but iirc people have said they are OK for the most part. But we certainly have a restricted flow for some reason that has to be what is causing this. can you post a larger pic that shows all the holes from front to rear? (to try & get an idea if the total/overall restriction is somewhere other than the gaskets). I have a good cooling mod read for you on circle track chat, a subset from moparchat (VERY informative) that relates directly to this but one thing at a time.

So you just want pictures that show the whole mating surface on the block? With or without the headgaskets on the block?

On one side can you take a pic of the deck with the head gasket setting in the valley close to it (to compare holes) and a pic of the head with the gasket next to it (to compare holes) so we can figure out if the restriction is there or somewhere else (you get the jist of what I am trying to say). I ain't a layout photographer but this might easily let us see what is going on with only (2) pics. Wouldn't hurt to just look at the other side (that deck/head/gasket) without pics & see if the holes are the same as the other side & if so, if the photographed side is good or bad then the other side has to be good or bad.

Here's a question for you. Do you have a six or eight blade water pump impeller?

I recently talked to Bob at Glen-ray about this. He said your pulley ratio determines the number of water pump blades you need. I should have wrote down the measurements but didn't. Anyway, I'd measure your pulleys and find out what type of water pump you have and then call Bob -> (715) 842-3352

Bob knows Mopar cooling systems and will be able to offer some advice.

Also, as I recall, small block radiators have a smaller lower inlet which would probably be the crux of the matter. You likely need a big block radiator.

Years ago we tried running a freshly cored 26" small block A/C radiator with a mildly built 383. It would run on the warm side. It's that lower inlet that makes a difference I guess.

Thanks! Will do!

No the slits are not why, there are thousands of big blocks out there running head gaskets like that.

Can anyone confirm the comment about 340 26 inch Radiator lower inlet being smaller than would be on a big block 26 inch radiator? I am using a 340 rad and the lower hose is same diameter from water pump to the lower inlet.

I am working thru a 440 running too warm according to my gages which I am trying to confirm their accuracy. Mine is doing 220 highway and 230 idling.

Mike

Well it's good to see you John (its been awhile) & we've missed you! (ahem). what I was saying which you can see if you reread it is that the minimal flow is an obvious clue. John I am disheartened to see that you have not let this go after all these years.

Also check the WPHousing.. A lot of the aluminum WPH s look OEM but some of the ports narrow down quite considerably (like too a 1/2 inch) on the inside. I put back an old iron OEM WPH and my 383 and it runs cool as a cucumber......

[quote=shaker340]Can anyone confirm the comment about 340 26 inch Radiator lower inlet being smaller than would be on a big block 26 inch radiator? I am using a 340 rad and the lower hose is same diameter from water pump to the lower inlet.

I am working thru a 440 running too warm according to my gages which I am trying to confirm their accuracy. Mine is doing 220 highway and 230 idling.

Inlet outlet are same size 26" 340-440 rad 70 and up. I measured a 2998949, 3673925 both smallblocks, and 2998956,3443959,3443960,bigblock all 1.5 top 1.75 lower only thing changes is hose location. Those temps sound like radiator or gauge to me. I drove 900 miles with no fan, clutch failed so I removed it, home from mopar nats august, hot out, air on, and my 440 ran 180. But my block was is standard bore, original radiator.

4406bbl thanks for checking on the radiator inlet and outlet port sizes.

I did confirm the gage is accurate with a second gage and laser temp gun. So I am going to try less timing, going from 15 initial to 8 initial and a step richer jetting, to see if temp drops. Motor is stock bore motor home, at 8:1 comp so it probably doesn't need all that ignition. If this does nothing, then rad will get pulled and tested, its a used unit I have had for near 20 years hanging around in my parts collection.

Mike

Unless you changed temp sensors, swapping clusters only confirmed your dash gauge is consistent. If the sensor is FUBAR, the gauge only knows what the sensor tells it.

You can get an IR temp gun at any auto parts store if Harbor Freight isn't handy.

My buddy's MaxWedge was doing the run warmer than it should deal. Apparently not all water pumps are created equal because they replaced the new pump they installed when they built the engine with a different new pump and it behaves now.

Years ago my brother had a Sears rebuilt 318 that always ran warm. Drove it that way for years until a frost plug started leaking. Went to replace them all and discovered all the old ones had just been driven thru when the engine was "rebuilt". He fished them all out along with all the crud that had gathered around them and no more warm 318.

Kevin

Tree'd

Where in Eastern Ontario are you?

Kevin

Smiths Falls

I didn't change clusters, I have aftermarket gage cluster in the truck, and used a B&M temp gage to confirm gage cluster reading along with and IR temp gun.

That is correct. My 69 “053” big block radiator has 1.5” inch upper and 1.75” inch lower inlets. Later today I can measure the small block radiators I have.

So if the radiator inlets are right, I’d make sure the pulley ratio is correct for the number of water pump impellers. Also there was a comment about aftermarket aluminum water pump housings. If you have one of those I try going back to the factory cast iron to eleminate that question.

I read it fine, you are claiming his diminished flow is because of the slits in the gasket is how it reads.

There is minimal flow thru those slits , his dimished flow has little to do with the size of those slits, someone a lot smarter than you, or I, redesigned that head gasket. Why ???

Sorry, I thought you were the OP.

We're practically neighbors. I'm down by Spencerville.

If you do the cruise nite on Thursdays we've likely crossed paths. Haven't been this summer but we show up in a 65 Polara wagon.

Kevin

Update: I’ve got a radiator out of a 1968 Dodge Charger with 318 and air conditioning. It is a 26” inch two-core. Part number #2898041. Both upper and lower inlets are 1.5” inch.

Don’t know what the other small block radiator applications had but one would probably want to be aware of potential differences between big block and small block radiators.

Mike I would strongly suggest staying at 15 & not retarding it. Not sure what your total/springs are but 15 is fine & not the problem

Robert it made no difference backing the timing to 5 degrees, and will put it back to 15. Spark plugs looked great too, so mixture is about right.

What happened last nite the gage showed 240 idling but I was able to put my hand on valve cover, I know the gasket can reduce the temp. But the IR temp gun showed heads at 200, water pump was 180, rad top tank was 200, upper hose was 165, lower was 135. So I am not convinced yet I have a heat issue.

I am starting to suspect the temp sender, and have another new one to swap in to see if any change.

Mike

Sounds like your gauge is not reading correctly , what type/brand
is it ?

seeing those temps you posted, i wouldn't be concerned in the least ! just my opinion.

JohnRR I am using the Intellitronix brand of gages and also using a B&M temp gage that reads same number as an alternate. So I will try swap the sender to see if any change in readings.

Moparx I am agreeing with you and hoping its just the sender.


What was interesting that I forgot to post was that the IR temp gun pointed directly at the nut of the sender was reading 240. And the cast area around it was around 200.

I will say it again, first thing I like to do is put a thermometer in the radiator, then I know. 9 times out of 10 there is nothing wrong, other than the gauge.

I have an overflow bottle set up, so I will be getting a thermometer to check that out too.

I've been ridiculously busy lately but this week I made some progress. I pulled the water pump housing and the part number is 3698468, which came on 73-78 Mopar big blocks. I was kind of hoping that it had an after market housing that was the culprit but that doesn't seem to be the case. The big ports were clear/clean.

I pulled the heads and the head gaskets are in good shape with no signs of leaks. My 906 heads are pretty much junk. Most valves seats are sunken; the valves are all cut at different lengths, and I have a couple guides that are working themselves out. The heads "smell hot". I know that's unscientific but you know what I mean. I drained the oil for the first time. The oil only has about 20 miles on it but I wanted to see what was in the oil. It was surprisingly clean but smelled rich.

How about the water pump? Can you describe the type/condition of the water pump?

It's a brand new pump but its a cheap cast parts store unit.

Latest for me was radiator flush and new temp sender and seeing 200 for a 25 to 30 degree improvement. A lot of crud came out of radiator during the flush.

I tested the temp sender/gage to a cooking thermometer in boiling water to confirm gage accuracy.

Mike