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Discussion Starter #1
Excuse me for being short and to the point, I'm a little frustrated with this car at the moment. It's 85* outside and she's still climbing up to 210*, causing the fuel to boil in the carb which floods the motor out. Sitting at an idle the temp creeps back down. It doesn't matter how fast or slow I'm driving, it gets too hot.

1970 Nova
1966 396 +.090
11:1 forged
GM large oval port heads
Edelbrock torker II (for hood clearance reasons)
12 bolt rear with 4.10 gears
TH400 with 3000 stall

I'm using a B&M oil cooler and B&M trans cooler.
I'm mixing 15 gallons of 91 pump gas with 1 quart octane supreme 130 (~96 octane)
Holley 750 dp with HP main body. Using the jets that came with the main body. Plugs don't look lean.
38* total timing, all in by 3000 or so
16* at idle

water pump
http://www.summitracing.com/parts/BRA-1673/

just installed this radiator today
http://www.summitracing.com/parts/GRI-1-55272-X/

Just installed these fans with the new radiator
http://www.summitracing.com/parts/SUM-G4850/

Using the middle size restrictor
http://www.summitracing.com/parts/MOR-63440/

I flushed the whole system out and added 2 gallons of antifreeze. Didn't check the specific gravity.

The lower rad hose is a flex unit so it can't collapse.
The fans are wired key-hot, they run all the time.

I used a digital meat themometer between the fins on the radiator after it had been idleing for 5 minutes so the temp probably came down a bit, but the drivers side was 202 and the passenger side was 172.

I'm going to pull the hood off tomorrow to see if that helps. If that doesn't do the trick, I'm stumped.

My only other idea is to switch to E85 but I'm not convinced that will solve the heat problem.


Any ideas?

(While typing this post I thought about the exhaust crossover in the intake not being blocked. Maybe that would help the fuel boiling problem but 210 is still getting too hot for comfort.)


Bartstop
 

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Try giving it at least 2 degrees(even 4) more of initial timing. What kind of distributor - The reason I ask is because one time I had a broken advance spring which was given me half of my mechanical advance at idle. So when I would put a timing light on it and it would read 18 degrees initial, it was actually retarded on the timing because I was seeing the 10 degrees or so of mechanical advance that wasn't suppose to be there. I have broken two of those advance springs on a Mallory distributor before. The more initial timing it will take without dragging down the starter the better. Your timing doesn't sound to low or retarded but badly retarded timing will definitely make one run hot. Seems like your radiator is cooling with the difference between the two sides. Don't put more than 50/50 antifreeze and water. The motor wil actually run cooler with more water. Might add some water wetter or one of the other coolant additives also. I am going 18 initial and 18 mechanical on my 383 project and I might even go to 20 initial and 18 mechanical.
 

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You are probably lean in your carb jets also which will make it run hotter. I would definitely add timing. Check and see what jets you have in that carb.
 

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Discussion Starter #4
You are probably lean in your carb jets also which will make it run hotter. I would definitely add timing. Check and see what jets you have in that carb.
The main body came with 72 primary, 84 secondary.
http://www.summitracing.com/parts/HLY-134-300C/

I will bump the primary up to 74 to see what happens.

The ignition is a MSD pro-billet (no vacuum advance) and 6AL.
http://www.summitracing.com/parts/MSD-85551/

I'm getting the total timing number with one hand on the timing light and the other hand on the carb. There's no tach under the hood so the 3000 rpm number is a guestimate. I wonder if I should lock the timing at 38* to eliminate that variable?
 

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Discussion Starter #5
I'm starting to wonder if the FlowKooler water pump is the problem. They claim higher flow at idle speeds. As with most things, there is a tradeoff. With 4.10 gears and a 3000 stall, I'm always turning a decent RPM. I wonder if the pump isn't flowing enough at higher rpm's to keep up? It would also explain why the temp drops at idle.

Bartstop
 

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Discussion Starter #7
Wow with the fan/rad set up you have my BB ran way cool. Poss. water pump issue. Maybe running lean.
I settled on that combo after reading your posts and talking to the tech line at summit. You aren't having problems using 1" tubes, this one has 1.25".

So far I've ruled out the radiator, fans, thermostat.

The plugs have a nice brownish gray coating. They look normal so I don't think that's the problem but I'm not 100% sure.

I've read that overheating at idle is an airflow issue. Overheating at cruising speeds is a water flow issue. That makes me lean more towards changing the water pump.

After reading this article, I'm leaning even more towards the pump being the problem.
http://www.arrowheadradiator.com/14_rules_for_improving_engine_cooling_system_capability_in_high-performance_automobiles.htm

Especially the "coolant flow rate" part. I've got 30* temp drop across the radiator, which would point to insuffecient flow. But, that was after a few minutes of idle. I need to check the temp drop when it's hot and the motor is turning 3000 or so.


Bartstop
 

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Are ypou running a radiator by pass hose between the water pump and intake?
 

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Sounds like it could be the water pump. The high flow pumps need a high flow thermostat which I bought for my 383 project. I would at the very least try a 160 thermostat and even without a thermostat to see what happens.
 

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Discussion Starter #11
Restrictor plates or 160 stat?
Restrictor plate, the middle size.


Are ypou running a radiator by pass hose between the water pump and intake?
Yes.


Sounds like it could be the water pump. The high flow pumps need a high flow thermostat which I bought for my 383 project. I would at the very least try a 160 thermostat and even without a thermostat to see what happens.
With the old radiator and fan setup (small block 2 row aluminum with Black Magic fan) I tried regular and high flow 160* and 180*. When I took the thermostat out, I didn't notice much difference other than it took a little longer to heat up. I put the restrictor plate in to eliminate the posibility of a stuck thermostat. When trouble shooting, the fewer variables the better.


Bartstop
 

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Discussion Starter #12 (Edited)
Just got back from a little cruise. Once the temp got up there we stopped and I had the ball-n-chain hold the rpm at 3000 while I checked the temp drop across the radiator. Cool side was 216 but climbing slowly and the hot side was 234 and climbing. That's the hottest I've seen it get. Got back in, drove 35-40 mph and it started dropping. By the time we drove across town (.75 miles) at 30 mph it was back down to 215 or so. It never flooded out while driving it, which is a big improvement over the old radiator, until I hit the bump going in to the driveway. I don't know why but when it's boderline overheating, that bump will make it flood everytime. When it's cool, no problems. Weird.

I don't know what the optimum temp drop is but it seems like the radiator is doing it's job. I think another call to the summit tech line is in order.


Bartstop

EDIT: Once it cools down I'm going to bump the primary jets by 2 sizes and go for another cruise. Of course it will be 95* outside by then.
 

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heat

i saw my bbc buddies battle is why i stayed away from 'em ,,, it was scary to watch the temp gauge riding around with 'em. Shut 'em off , the gauge would go to 240 in no time.

i'd get the biggest mechanical fan ,, like a 19 in , with the largest blades and try it

the carb problem , i had a friend try this and it worked ,

http://www.jegs.com/i/Mr.+Gasket/720/98A/10002/-1

are you heat crossovers blocked on the intake ?
 

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Sounds like the float level may be a little high. I have used those Mr. Gasket plates and gaskets before. I like to run the wooden spacer under my carbs now. You can also put one of those 1/4" thick gaskets for a heat dissipator.
 

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I am running a 383 and have the same problems. Took the hood off and temps dropped 20 degrees. I have an airflow problem. Looking at doing a cowl induction hood along with other things.
 

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Discussion Starter #16
Changed the primary jets to 76 (it's all I had). Changed to the lightest advace springs. Took the hood off. Went for a drive. 87* outside. It still climbed up to 210*. So, I came back to the house and let it idle in the driveway. After 20 minutes or so the hot side was down to 165* and the cool side 143*. Go figure.

It has to be a water flow issue. Thinking about an Edelbrock Victor pump.

http://www.summitracing.com/parts/EDL-8850/
 

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im a little confused , you say " hot side " and " cold side " , what are you refering too ? have you tried pulling some timing out , what heads are you running ? seems weird to me although 200 degrees is the normal for all the new LS motors. my little 357 with 11:1 compression gets to 200 in the hot california summer time 110 degrees , running a victor pump , mechanical fan , stock nova fan shroud , and a jegs universal aluminum radiator , im also using water / antifreeze as well
 

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Discussion Starter #18
im a little confused , you say " hot side " and " cold side " , what are you refering too ? have you tried pulling some timing out , what heads are you running ? seems weird to me although 200 degrees is the normal for all the new LS motors. my little 357 with 11:1 compression gets to 200 in the hot california summer time 110 degrees , running a victor pump , mechanical fan , stock nova fan shroud , and a jegs universal aluminum radiator , im also using water / antifreeze as well
Drivers side is the hot side of the radiator, passenger side is the cool side of the radiator. I've tried 34, 36 and 38. No difference.

Heads are gm cast iron large oval ports. 1972 402 I believe.
 

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ok how are you checking the heat on both sides of the radiator , the lower radiator hose is " in to the motor " and the upper is " back to the radiator " , if anything the hole radiator should be warm if checking with a thermometer , cool water goes back into the motor from the lower radiator hose , while hot water goes back into the radiator ( upper hose ) to be cooled off by air flow , i dont thing you have an air flow problem , try pulling out the restricter plate and just running the thermostat i think your keeping the hot water in the block to long
 

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If the coolant goes through the rad too fast it will run hot too, because it doesn't get a chance to cool as it goes through the rad.
 
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