**318 OVERHEATING ISSUES**

[temsinc]

Background: 1970 318, Eddie 650, RPM Air Gap, 340 Aluminum Heads, 72K original miles, bottom end has never been done, unknown cam (was told by previous owner it was "mild"), brand new water pump/ 180 thermostat. Just installed KKS 22" 3 row aluminum rad with double 10" electric fans/ shroud to keep the little thumper cool at the lights at 30C/86F.

The engine was and continues to run around 200-210F at idle with both the old and new set up  . I removed electric fans and reinstalled the mechanical fan w/o shroud and same issue.

I noticed that the electric fans have just one speed, not sure if there is any options here to have them bump up to a high speed or not, unfortunately the manufacturer, KKS Motorsports appears to have split the scene and I cannot contact them by phone or email  .

Now I'm contemplating removing the thermostat and replacing it with a restrictor plate...any thought or advise on this is welcome. Thank you in advance.

P.s. the coolant system has been flushed.


Darcy 

[RUNCHARGER]

I expect you got a good deal on the rad and fan setup. Do you have any photos you can share of the tubes in the rad? Hate to say it but it is probably a restrictive rad and second rate fans.

[Cuda Cody]

Was it overheating before the new radiator and if so, what radiator did you have before?

[Chryco Psycho]

Timing is often the issue , you can shorten the timing curve by using an allen key inside the nipple of the vacuum advance , bring the timing up to around 14-16* at idle & 35* at 3000 rpm
Electric fans are not efficient , a clutch fan & shroud are far more effective

[temsinc]

I had the original OEM 22" dual row rad, re-cored 3yrs ago with original tanks, this was due to the rad was leaking profusely. It never had a shroud, the 22" shroud I ordered from Year One never fit and I never sent it back cuz it took me over a year to see if the darn thing would fit since I was piecing the car back together after a moderate resto. With the newly re-cored rad and the clutch fan the car would run at 180 all day long as long as I was moving in hot weather, I.e. 80F+, then she would climb up to 200-210 until the light changes lol  .

After speaking with a local Mopar dude with a 73 Cuda who raved about his aluminum rad and electric fans on a 410 stroker, I thought I would be a pro-active and exchange the OEM rad with the same set up. The rad, fan and shroud set me back approx. $580 Cdn pesos  , so it wasn't cheap.

There is no vac advance, Im running an MSD mechanical distributor because that was the set up when I purchased the car 5yrs ago.

[70 Challenger Lover]

I know several people are going to disagree with me on this but vacuum advance helps a lot, especially at idle if there is enough vacuum signal to make it work at idle.

I set my cars up for around 15 degrees initial advance and I use cans that add another ten at idle for a total of 25. I have watched the temperature drop just by connecting the vacuum advance while it's overheating at idle so I know it actually works. 25 degrees seems like to much at idle but it's not and it won't have starting issues because ten of those degrees don't come in until after the engine is running. If vacuum advance is set up correctly, it won't provide any advance when the engine is working hard so no pinging issues. There is no downside to using it yet people resist it for some reason.

[Shane Kelley]

I'm running a stock 3 row 26" radiator with stock shroud and a clutch fan. Milodon high flow water pump and 160 T stat.  340 Aluminum heads, blah blah blah and 3.91 gears. Timing is locked at 35 degrees and motor rarely ever sees over 180 on the hottest days. Sitting in slow traffic or running continuous 3500 to 4000 rpm on the interstate doesn't really effect anything. I will say I'm no fan of electric fans. I don't think they move enough air over the entire surface of the radiator compared to a correct shroud and clutch fan. Air flow is suspect as well.  IMO

[cordodge]

Anyone run a 7 blade solid instead of the clutch fan?. Just wondering if that would help at idle with moving more air.

[temsinc]

Lots of good information to digest. Thank you all for the feedback.

Question: how can I check to make sure the clutch fan is working properly? Would it be advantageous to go to a 160 T stat and get the proper shroud? Come to think of it, I could modify the aluminum shroud that I already have....

Ill see if I can dig up a pic of the tubes of the new rad.

[Brads70]

With the rad cap off and let it get up to temp so the thermostat opens does it appear like it's flowing lots of coolant?   Stock diameter pulleys  crank and water pump? Do you have access to one of those laser temp guns? ( princess auto?) to verify the gauge is accurate?

[70 Challenger Lover]

Lots of good information to digest. Thank you all for the feedback.

Question: how can I check to make sure the clutch fan is working properly? Would it be advantageous to go to a 160 T stat and get the proper shroud? Come to think of it, I could modify the aluminum shroud that I already have....

Ill see if I can dig up a pic of the tubes of the new rad.

I don't think a lower temp thermostat will change anything. If the engine is not overheating, it would allow it to maintain a lower temp but with it overheating, it just opens sooner and eventually the excess heat will still build.

I've used restrictor plates too and they can work but you would have to find the best opening size that permits just the right amount of flow with enough restriction to let the coolant cool off in the radiator without passing through too quickly. This varies with each engine, water pump, radiator, etc. so you may have to keep removing the plate and opening the hole just a little bit each time until you find the sweet spot. And once you find it for summer conditions , you will find it is too much in the cooler months. I gave up on them in the end. To me, it's a bandaid.

I've used electric fans and found they can work okay but only when they constantly run. On the highway, once they switch off, they create a blockage so the heat builds up and they still have to switch on to let the air move through.

Try this test....with it idling and while the temp is getting hotter, loosen the hold down and increase the distributor advance (while it's running) to 25 degrees total. You will notice the engine increases rpms because it's telling you it runs more efficiently with that extra timing at idle. Readjust idle speed for this test. I'd bet the overheating gets significantly better if not disappears. This is not a solution though since you wouldn't want to drive the car like this. It's just a test to determine if you overheating is related to timing issues rather than something else.

[temsinc]

I do have a infrared digital thermometer...should I take the temp off the T-stat housing? I think I read to also check upper and lower rad hose as well. There should be at least 30F difference between the two....thoughts?

[Shane Kelley]

I usually check the top radiator tank where the hose connects and the lower tank the same way. That lets you see how much your system is cooling down. Is your upper and lower hose on the same side of the radiator or opposite?

[Brads70]

First off confirm that it is actually measuring close to the gauge? Maybe the gauge is off and your not really overheating? Then check as Shane Kelly says. 

[temsinc]

Opposite, top hose on drivers, lower on passenger.

I forgot to mention, I installed a brand new electric temp gauge along with a rad hose temp sensor adapter that's spliced into my top rad hose...this was due to, the mechanical sensor port I needed for the fan sensor and there was no other wet port on the Eddie RPM Air Grabber....fml. Anyhoo, that's whats up. I did check the temp of the rad hose adapter which appeared to be 5-10 degrees less than the temp gauge. The T Stat housing was pretty close to the temp gauge.

I will double check everything tonight after work and record my findings.

Question: should the clutch fan spin freely with minimal resistance by hand when the engine is cold and not running? Is there any other way of testing the fan clutch?