How to cool my 505

Hey Guys I know this has been asked in the past but I'm didn't find anything in tech archives. I have a 64 Plymouth with a 505 Indy EZ heads 10.75 to 1 comp. I have a northern radiator (20-1/2 by 18) in it now with a 16 in electric fan. When I bracket raced car with a 440 I ran electric water pump drive and it worked ok for track. Now with new motor I'm running same radiator with mechanical WP. I have tried 7 blade fixed fan and electric. I'm trying to street drive this now and it doesn't work at all. The temp just keeps climbing. My question where would you start. The radiator has 2 1 inch rows so I don't know if a new radiator would help. I don't mind spending money if it works. Any advice would be great. Thanks Mike

i had the identical setup as you in 520ci big EZ headed RB with 10.5 comp.would not cool to my liking, all i did was change to a 26 in northern rad, and its perfect now.a good shroud is a MUST.

First things first. The water pump needs to be a high volume pump. You need a high flow thermostat. I use only Stewart thermostats.

Second is check your pulleys. The slowest the water pump should turn is 1:1 and IMO that is too slow. I'm at 6% over and I'd rather be at 10% but I couldn't find the right pulleys.

Those are the two most important things I see that you didn't answer. If you have a 26 inch two core radiator that should be plenty big.

I only have the 22 inch opening. The water pump is a high flow from 440 source and pulleys are from them also. Not sure about t-stat I know it's 180 not sure of brand.

not enough timing on the street will also make them run hot.

I'm running 18 degrees initial 36 total in by 2200 rpm

Does it heat up in traffic or going down the highway at 55?
Open up your core support and get a 26 inch radiator.
Make sure you have a shroud sealed against the radiator. Not sure how many CFM your fan pulls. If not enough it would cause it to heat up, but would cool off at highway speeds. Clutch type fan has to me proper distance within the shroud to be most effective.
Not sure if the northern radiator is aluminum or not. If not upgrade to aluminum as it transfers heat better than the old brass stuff.
Make sure you don't have one of those bottleneck aluminum water pump housings from 440 source.

And not enough fuel, running lean and mean will make them run hot.
You don't want them lean and mean on the street.

Richen it up, I bet it helps.

This a new build. I have only driven twice. I live about 3 miles from our little town drove there and back 45mph temp just keeps climbing. Drove once with fixed blade mechanical fan no shroud and once with 16 in electric fan no shroud. Not sure if rich or lean I'm running 2 750 eldebrocks on cross ram. The water pump housing is from 440 source. Northern radiator is aluminum with 2 rows of one inch cores. I checked pulleys both are 6-1/2.

I have a max wedge 505 in my '64 Plymouth Savoy street car, also using an original 22 inch mopar brass/copper radiator, recored with a copper high efficiency 3 core. Using a high flow 440 source water pump (I know some don't like this pump, but works well for me), original aluminum '65 race hemi water pump housing, race hemi 7 blade aluminum fan with Hayden 2947 heavy duty clutch, and original steel shroud, all mechanical, no electric fans. I swapped from a 180 degree, to a 160 degree high flow milodon thermometer, which helps the engine stay cool, as the thermostat opens and lets the much lower temp coolant from the radiator do its job, before the engine goes in to thermal meltdown mode. In my experience, once the engine hits 180 degrees using at 180 thermostat, it is tough to get it the temps below 190 in the summer. Tip, a thin layer of Hylomar blue on the thermostat gaskets and radiator hose ends do miracles for keeping it sealed up. To aid cooling, you could increase the percentage of water in your coolant mix, such as 30% coolant/70% distilled water, or 100% water with water wetter added. I prefer using Zerex G-05 coolant 50/50 mix with distilled water for rust protection.

You could also try flushing your engine cooling system with Evalorust thermocure, even though it is a new build. I would not count on all the rust being removed from the coolant passages of your vintage block. I used this, and was surprised at the amount of crap that came out, new engine build also. It did help cool it a few more degrees by removing some rust from the iron engine block. Easy to do this on a weekend.

A quick experiment you could try, is run some 110 octane leaded race fuel. With no other changes, I added 110 octane leaded race fuel vs. straight 100 octane no lead race fuel, and my engine dropped immediately 15 degrees in temp. This was back to back, filling up at the pump. I usually now mix half and half 110 leaded race fuel, with 88 octane non-ethanol pump gas, which makes 99 octane leaded fuel. Saves a few bucks for gas, and I can get away with 34 degrees total timing, no detonation, and runs cooler. Your 505 will love the 110 leaded race fuel anyway, bump the total timing to 35-36 degrees and hold on!

One other quick help, remove the bottom splash shield behind the front bumper and in front the bottom section of the radiator, it helps to get more air flow into the radiator from below, and will cool your engine few more degrees. Hope any of these ideas help, as they seem to work for keeping my 620 HP 505 cool in the hot Utah summers. Mine stays around 180 degrees in the hot weather, but I have to keep the car moving a decent speed. If I stop at a bunch of stoplights, the temps start climbing to 190-200.

Looking to be over 100 degrees at my home today, so honestly, I don't push my luck with a 620 HP stroker big block mopar on a day like today. I try to wait to drive it until it cools down a bit in the evenings or morning, for fun blasting around.

Here are some links:

https://www.forbbodiesonly.com/moparforum/threads/hayden-fan-clutch-low-profile.115490/

https://www.summitracing.com/parts/hda-2947

https://www.summitracing.com/parts/mil-16405/overview/

https://www.walmart.com/ip/Thermocure-by...9ffb0f66128fa6b

https://www.walmart.com/ip/ZEREX-Antifreeze-Coolant-1-gal-Concentrated-ZXG051/119274583

Most of the aftermarket housings have a huge bypass hole in them.
More bypass = less water through the radiator.

I’m not going to get into a debate about it, but this is “what I would do” to help determine how much of the problem is coolant flow, how much is air flow/radiator capacity.

-get a milodon high flow water pump
-find a stock iron pump housing and plug the bypass hole
-run the milodon pump in the stock housing with no bypass, no heater hoses(heater hose fittings plugged, not “looped”)and no thermostat

If it still runs hot, it’s not a coolant flow problem.

FWIW, I don’t think you’ll have success until you open up the rad support and get a 26” aluminum radiator, and run with a decent fan and shroud.

I agree with fast68. I drill and tape the bypass hole then install a pipe plug in it with a 1/8" hole in the pipe plug. The difference was night and day on my 470 with a 50 year old copper brass 26" radiator

I have a 22 inch aluminum radiator in my '65 Coronet and I have a 512 inch big block with a 7 blade mechanical fan. I use a Mopar aluminum water pump housing. So my combo is pretty close to the OP. My engine gets up to 180 degrees (I have a 180 thermostat) and then it just stays there. I can idle for 20 minutes on a hot day and it doesn't go above 180 or 185. I can drive at low speed, freeway speed, etc and it stays right around 180. My Sniper EFI system has a data logger so I can drive around town and then look at the coolant temp to see what the log says.

Go back to your mechanical fan but with a shroud.

Do you have vacuum spark?

My Duster is a mid 10 second street car with a mild 500" motor, high volume mechanical water pump and aluminum housing from Mancini, along with a Northern aluminum radiator. I use a black plastic flex fan, car never runs hot.


The key factor was the shroud. Without a shroud the motor would get hot, with a crappy shroud it was much better but would eventually get hot.

Now I have a custom fit aluminum shroud and I can drive it all day in the heat. The shroud is on the same angle as the fan, and the fan blades stick out of the shroud about half way.

Unless I missed it ,what is your temperature keep climbing to? New build will run hotter till broke in. Whats your temp gauge say? Are you sure the gauge is accurate?

No vacuum advance. I made 4 passes at strip last year did same thing temp kept climbing. It would get to 220 with no sign of going down. I shut car off and let cool down. It is a auto meter gauge didn't have a temp gun check with. But I could tell it was hot. I'm taking pump off tonight to check housing and I found a smaller WP pulley. I think I need a shroud for sure.

Dwayne, thanks for this info about plugging the water pump housing bypass hole. Easy solution, along with the Milodon high flow water pump and no thermostat to check coolant flow. No heater in my car, so don't have to worry about that.

Does anyone have a pic of the bypass hole mod?

One quick trick. Dump your coolant, flush and put one bottle of Redline Water Wetter and straight water.
We dropped 15 deg doing just this.

https://www.redlineoil.com/waterwetter

I thought I would tell you what I used on my 63 Sport Fury with my 440/493. I am on a tight budget so I use an Afco aluminum rad I got from Mancini along with my aluminum waterpump and housing. But since money was tight I went to the salvage yard and got a fan shroud from a V/6 Dakota truck that was around a 99 I believe. I modified it a little and made it fit and work on my rad and I only paid like $15 dollars for it. I used some of the plastic type holders that come in trans cooler kits that go through the rad fins to hold the shroud on. I use a flex fan with the mech waterpump also. The car works good and the only thing I did not like was if stuck in traffic for an hr or more it could creep up close to 200 so I put an electric pusher fan in front of the rad also on a toggle switch. And if I have to sit still real long in very hot weather I can hit the electric fan and it keeps it at 180 to 190. Once moving I can switch the electric fan back off. But the shroud from the Dakota truck that I made work saved me a lot of money on that as some of them shrouds can run $300 and more. I run about 21 degrees initial timing and 36 total with no vacuum advance since my dist is a race type and has no vacuum advance. I also have my waterpump bypass hole plugged and modified my thermostat and cut openings in it so water flows to the rad even when its shut. Good luck and I would definetly add a shroud to yours. Ron

Another pic of my shroud. You can also use a longer spacer and put the fan a bit closer to my rad which I did later. Ron

That's one nice looking shroud. If you don't mind can I ask what brand it is or who made it and what it cost ? Thanks , Ron

It's just the Northern aluminum shroud kit that came with the radiator.

Ron - what are the dimensions of your rad? I've got a universal cross flow in my charger and have been looking for a shroud that is 'close enough' to adapt to fit.

I would swap out the water pump, if it is the one with the cast spiral impeller. Get the GMB aluminum replacement water pump. It is the same one Milodon sells minus the plate. You can make a plate or buy one cheap.
https://www.summitracing.com/parts/gmb-120-1200/overview/make/chrysler

The 440 source pump & housing work great, it gets over 105 here in Southeast Tx, my 68 Charger 512 , COLD ac will run 180 all day long, sitting in traffic or 100 + MPH, ECP radiator 2 row, 18" 7 blade direct& a fan shroud Timing 24 initial 36 total,10 more in the vacuum adv hooked up to ported vac.

I took WP off last night the bypass hole is same size as factory one. I did notice some rust sediment. So I'm going flush system mod bypass hole get a high flow t-stat and shroud. This radiator is 20 years old so if cleaning it doesn't work a new 26in rad is going in. Thanks for all the advice. Mike

I have a street/strip 511 and use the 26" ECP radiator without core support mods as well. nice piece. I use a shroud from jegs that is a 69 charger replica with a flex a lite alum/steel fan and mechanical milodon hi volume pump. No thermostat and evans coolant. Cools fairly well. On a 85* day about 190* was normal water temp until i mounted an oil cooler to the front of the radiator. Now 195* and at 90*+ day 200-205*. I dont usually drive the car at any thing over 85* air temp anyway. The shroud from jegs is a nice piece and fits real nice as well. Oh, one other thing. My block is filled with hard block damn near to the deck. Hope this helps

I will check into that shroud. I got to looking at my radiator and think it is time to replace with a 26 in ECP unit. Thanks again

I used a 68 camaro shroud on a crossflow Afco ali radiator in a 65 plymouth

Tex

I will have to measure it as its been in there since 2010. I got it from Mancini and I told them it was for my 63 and the guy knew which one would fit. But I forgot the exact size so I will try and measure it tomorrow. Ron

Couple of things that don't help your temp-situation;

No vacuum advance at idle
New engine build
Old radiator + Rust sediment

-

Newly build engines always run hotter than seasoned engines.

If your cam/engine vacuum is mild enough, you'll want vacuum advance connected to the intake manifold.

I'm pretty sure there's quite some rust and scaling inside your cooling system.
This won't be removed by regular flushing.
You'll need a mild acid to dissolve the rust and scale.

I just had a similar issue with a 496ci stroker engine in my '60 New Yorker.
Engine has an older Mancini alum. waterpump and housing.
The car would run hot on the highway and hardly come down again at slower speeds. Found the (old/stock) 3-core radiator had some cores blocked.

Took out the radiator, flushed it with hot water a couple of times, and laid it flat on its back, and filled it with citric acid.
Citric Acid is an organic acid which smells nice too (it's used in about all kinds of cleaning products).
Took about 5 Liters (about 1.3 gallon).

Let it sit for a few days and occassionally move/tilt the radiator at various angles to agitate the acid and prevent sediment from setting.

If there's enough rust and scale inside, the citric acid will turn into a white milky mixture.
This means the rust/scale is being dissolved into a suspended powder.

Poured into a container the milky powder will set on the bottom after a while so the 'clean' acid above it could be reused for other de-rusting jobs.

I did 2 citric acid treatments on the radiator and the engine temps have dropped back to normal again around 160-190.

the jegs shroud is $149 and replica of 67-69 B body, but works perfect in my A body. Heres a couple pics of my combo to give some ideas. Just went for a short 20 minute cruise in 87* weather and temps were 200* coolant and 200* oil. 205* in stop and go traffic. I would like it cooler, but i'll live with it.

I would say the fan is an inch short all the way around which leaves some efficiency on the table.

i think my fan is a 17". not sure whats available for larger sizes.

i've been following this thread because I've always been chasing a heat problem in one of my cars. all of this got me thinking so yesterday I went out in the garage and done something. my 69 r/t is a problem child; all iron stock 440 with a 22" radiator. the stock core only had 76 tubes (2 row), so I upped that to 144 tubes (3 row) several years ago; not a lot of difference. last summer I went thru the engine, nothing special just gaskets, seals, but I did replace the pistons and the rings seemed to have a lot of tension. I also put in a 440 source water pump and new mr.gasket 160 thermostat. had the car out last Saturday, very nice low humidity 81 degree day, and the engine went 210F+ in traffic and stops and would never recover or budge off that 210 even when I got moving.

yesterday I took the thing apart, put a plug in the bypass (but did drill a 1/8" hole in the plug. this is very simple to do by running a 1/4" pipe tap thru the bypass hole.). replaced the 440 source pump with a 6 blade pump (larger o.d. than stock vanes) with the anti-cavitation disc, put in an ancient stant brass 160 thermostat. I did richen the idle mix a little also. started it up this morning and went for a drive. 83-84 degree morning here with high humidity. I didn't get stuck in a lot of traffic but did stop twice and turn the engine off for a few minutes. temps climbed to 210 with the engine sitting but when I did re-start the engine temps began to recover some. driving temps were a little cooler, (no 200+, about 185-190 the highest). I believe there was a real difference in the changes; not huge but enough to restore some comfort level. I believe the pump change plus the bypass plug are improvements. meaningful improvements with this car are hard to come by. it's a shame that temps dampen driving this car because it drive so nicely.


my other car is a 65 coronet; 440, alum heads, headers, small cam, ch28. it has a 22" brass radiator (former a/c car with the inlet on the passenger side) 204 tubes. this thing won't run hot if you drove it thru hell. I use a 180 'stat but, the carbs don't like much heat (heat transfer from heads to intake manifold). ironically the r/t's stock avs doesn't seem to be affected at all by the heat. two cars are as different as dr. Jekyll and mr. hyde.

Lew, you should try either a real “high flow” thermostat, or drill a few 1/4” holes in the one you have.

You shouldn’t try blocking the bypass in the housing without there being some other means of bypass available...... which would be the heater core.

As another experiment, along with drilling holes in the stat, you could try plugging(not looping) the heater hose fittings and seeing what(if any) impact that has on the temps.

With the bypass blocked, and no heater hose bypassing(the holes in the stat become the bypass), all the coolant is pumped through the radiator.

I do have a high flow thermostat. I do run a heater, so are you suggesting keeping flow thru the heater core with the bypass 90% blocked? what are the effects of not having a bypass and flow to the heater core closed off? I almost did the bypass thing last summer but wasn't sure about the effects. all I know is there were some positive effects from using a traditional type pump and bypass restricting. upping the learning curve here. very helpful comments/posts.

Mechanical clutch fan with 1/3 of the fan blade in the shroud, the rest hangs out towards the motor. Shroud must be in good working condition. You cant to pull the air through the rad and shroud....

Lew, the way you have it now, the heater core is your bypass.

If you want to try plugging the heater lines, then there needs to be a bypass somewhere else in the system or there will be no coolant flow through the motor.

This is why if you want to do the experiment of having all the coolant being pushed through the radiator, with no bypasses in the system, you need to have holes drilled in the t-stat flange so the coolant can circulate until the T-stat opens.

ok, got it. the heater and hoses will never be removed (hope I don't jinx myself) so I can keep that circulation going. the high flow 'stats I have won't allow 1/4" holes. the standard flow 160 I have will allow 1/4" holes. the plug I put in the bypass is easy to get out and truth is I don't really know how much difference it made. i'd just about bet the pump change was the bigger help. I tested the three 160 'stats I have with a heat gun (I use laser and infra red temp guns too) and couldn't tell much if any difference in them temperature wise. anyhow i'm better today than I was two days ago. thanks everyone!

I have a stock 7 blade clutch fan with a two row aluminum radiator. Each row is 1:5” long. Stock shrowd as well. ZERO COOLING ISSUES EVEN IN 90 DEGREE HEAT.

conventional brass radiator rows are .5" long. so, a pair of 1.5" tubes would be like a 6 row brass radiator. I can see why you'd be happy with that. wish I just had 4,...lol.

I order a new 26" rad milidon hi volume WP and full flow t-stat. I found a shroud in my stash that I think will work. What is better a fixed 7 blade fan or clutch fan? The parts should be here later this week hopefully be able to see if it works in the next couple weeks.

On mine I had to use the fixed 7 blade fan, #1818 from flex a lite

I've tried every type of fan I could get my hands on, and the factory mopar (non-thermal) viscous with the factory 7 blade fan made a slight difference. I think there may be so many variables that to say "absolutely" that one fan is best for all circumstances may be a little whimsical.

I will say this, when I 1st got my Charger running it had the original 383, full of rust,had been sitting for 31 years so I flushed it real good, pulled all the freeze plugs out, put it all back together with a new 4 core Champion Radiator, put 700 miles on it & it started running hot, what happened was little rust slowly started breaking loose & plugs up the new radiator, The Champion radiator I had has VERY small tubes, little pieces of rust would plug it up, so when I put the new 512 in, I got a ECP 2 row & installed a Gano coolant screen in the upper hose, I also put a litte magnet in the screen area, well the new engine had been hot tanked & cleaned but after 200 miles I pulled the filter out & it had caught a bunch of chunks, it kept it out of my new radiator, 6000 miles later it is still on my car but it is always clean now. I just went on a 30 mile drive, 100deg outside, ac on car ran 180.

CLICK HERE FOR COOLANT FILTER LINK

You can see the double clamps on the upper hose.

That is a great idea I will check filter out. THANKS