New 512 Stroker Running hot

[Roman1970RR]

Sounds like you found a solution. Let's see timing? I happened to mention that above.



Bottom hose has the spring. Bottom hose has the spring. Bottom hose has the spring.

My latest timing map is in my pictures on original post I was running a smoother one at 36 deg cruise then went to 37 deg cruise which I noticed the most improved.

I am getting a hose with spring this morning, I am getting a hose with spring this morning, I am getting a hose with spring this morning
This must be what Bart Simpson feels like

 

[Virg464]

Good day all,

Hey everyone,

I’m looking for some help diagnosing heating issues with my 1970 Plymouth Roadrunner (512 stroker, 400 block). Interested to hear from others running a similar setup to see if I’m missing something. I am seeing steady temp increase and have to pull over as CTS heads towards 220F mark.

Car & Engine Build Details​

• 512 stroker (400 B block).
• 1080 CFM throttle body with Holley Terminator X EFI.
• Indy single-plane intake, Trick Flow 270 heads, 242/248 cam.
• Mechanical water pump from the 440
• TTI headers ceramic coated 1-7/8" to 3" collector and 2.5" exhaust.
• Cooling system: aluminium 2 core (Large Core) radiator and 2 x electric fans (No shroud and air in isn't sealed to stop hot engine bay air being recirculated.
• Peak power: 682 HP @ 5500 RPM, Peak torque: 702 lb-ft @ 4800 RPM (Allegedly).
• 355 diff ratio (3000 RPM at 100kph or 60MPH)
• 727 torqueflight rebuilt with manual valve body and aluminium drum.

Main Suspicions​

1. Incorrect tune (timing or running lean)—I improved things by increasing timing at cruise, but I don’t want to advance it further because I’m already at 38° and don’t have a knock sensor.
2. Cooling airflow issues—No cowling on the backside of the radiator, and the front airflow seal might not be working properly.
3. Thermostat issues—Possible incorrect thermostat restricting proper cooling.
4. New engine breaking in hot—Could this be a factor?

Anyone see any issues with my maps for a start? I am aware timing map needs smoothing out but this is the third one ive tried and so far coolest on open road with no stop starts. Much appreciate any feedback.​

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Does the engine have very much run time, I know it takes a while for surfaces to mate (rings I think) before they stop generating excess heat. I had to get a few hours of on and off run time on my motor (408 B-Block, 10.5:1 CR, Alum Heads) before temps settled down

 

[Roman1970RR]

I wouldn’t be too worried about the trans cooler. I’m really not a ‘fan’ of electric fans. Pun intended.. those mardyne unit only pull a max of 1600 cfm and aren’t that impressive as far as cfm goes. I would almost bet on it that if you had a proper 3 row copper rad (even though many folks like the larger width 2 rows aluminum like you have) with matching shroud and a 7 blade mechanical you wouldn’t have issue. Post a couple of pictures of broad overview showing the radiator from the top, the whole thing, and its relationship to the rad support (ie:standing a at the battery looking straight across. Also one from the front of the car showing as much of the rad as you can.

I think overheating at speed it blocked airflow going through the rad and or also not escaping the engine bay easily from other obstructions.

Some of the hottest weather I’ve ever experienced was at Monkey Mia in the mid 90’s. I think it was about 43 degrees that day. Swimming felt like a hot tub.. maybe don’t drive your 512 inch mopar on those days. lol. You are using a high flow t-stat? My preference is to always run a thermostat.

So just in my defense the radiator I bought from out of state was a poor fit. Long story. I am unhappy with it and it’s become temporary I think I will get extra cores welded into my original radiator 2 core become 4 core. There is a place that does that here.

As for the fans I needed the space I can’t fit mechanical one on with new motor.

 

[Roman1970RR]

Does the engine have very much run time, I know it takes a while for surfaces to mate (rings I think) before they stop generating excess heat. I had to get a few hours of on and off run time on my motor (408 B-Block, 10.5:1 CR, Alum Heads) before temps settled down

No it’s quite new I have probably driven it under 10 hours total. This was one of my suspicions as I mentioned at the start but I can work through all the simple checks along the way as well so I’ve asked the question.

 

[Dennis H]

Shroud a priority. I never had any luck with fans. Keep us posted.

 

[4mulas]

Well, I could agree more with you more to record the original to a 3 or 4 row if they can (sometimes the tanks can only do 3 row) the aluminum one in there looks to be a 26 and 4" on the passenger side is covered by the rad support anyway which is getting zero airflow. I can’t be there to see for myself but it looks like you might be able to fit a stock 7 blade fan directly into the water pump pulley? (Even maybe with a small spacer?)

If you could a factory shroud would fit..

 

[Roman1970RR]

I have factory guage and the sensor in the efi. Factory guage reads 170-230 but stops moving mid way on the guage and temp keeps rising on sensor. I checked with temp gun when got home the engine block was about 210F and radiator same so my sensor seems accurate. looking at temp guage middle of the range would be 200F I was of te impression that the engine should be running between 190 and 200F. I have definitely at least shaken out a few sanity checks here which is great but my gut tells me I have an issue which I don't know how to articulate here haha.

A stock distributor with vacuum advance may see upwards of 50° timing at cruise. What tempo does it run at? Is it really overheating and puking coolant or just running hotter than you think it should? Factory or aftermarket gauge? 220° is not overheating and yes a new engine with tight clearances can run hot until it get's loosened up.

 

[Orig69]

No it’s quite new I have probably driven it under 10 hours total. This was one of my suspicions as I mentioned at the start but I can work through all the simple checks along the way as well so I’ve asked the question.

What temperature thermostat do you have? 160 -180 -195

 

[multimopes]

I went through 3 bad T-stats in a row from 3 different major manufacturers. I got fed up with not knowing if there was coolant flowing so I installed a "Gano" see through filter. See attached picture. I also have 2 big electric fans & they pull way too much juice. I will be changing to a standard clutch fan in the near future.

 

[Geoff 2]

12" fans belong on toy cars....
[1] I fitted AU Falcon elec fans to my car [ they were 14" from memory ] & I only had to go for a short drive to notice the engine ran noitcably hotter. They came off the same day & the trusty clutch fan was re-fitted. Also, once you get up some speed, those fans act like baffles & hinder airflow.
[2] W/pump needs to be overdriven 10-20%. Does your pump have a stamped steel impeller?
[3] Timing at idle. A 440 I built has a very similar cam to your engine . M1 single plane manifold, 850 TQ carb. It idles at 44*. Runs cool. Black 68 Charger, will be at Chryslers on the Murray in 2 weeks time. Your engine is bigger so it makes the cam look smaller; your engine is going to need about 38-42* for best idle/running AND cool running. A most misundertood topic....

 

[451Mopar]

On the 505" stroker I used the wrong bore size head gaskets. Cometic gaskets that were 4.350" thinking I could get an extra 0.01 of compression, but forgot about how large the chamfer at the top of the bores are, and under load I think compression was leaking into the cooling system.
Anyhow, I usually first worry about air/steam in the system that can block coolant flow.