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Discussion Starter #1 (Edited)
Swapped from a 350 to 454, but now I'm battling overheating. On the big block I am running the Chevy serpentine kit with reverse long water pump. The pump is brand new, so is the engine. It's a GM crate 454.

I have a 180 degree thermostat and an aluminum radiator with a core that's approximately 2" thick by 20" wide. Running two 10" 1000 cfm fans that are pulling the right direction. I have a condenser and trans cooler in front of the radiator but ac is not plumbed up yet.

Car will overheat on a 70 degree day quickly. I watch the Temps Creep past 225 and won't stop. The only way to keep it cool is to jump on the hiway. But at 80mph it still climbs to 195 degrees, where it finally stabilizes.

Thoughts? At first I thought the fans were insufficient, but then at 80mph I would expect much better results even with no fan. I also don't have the inner fenders installed right now, but I wouldn't expect a huge difference from that.
 

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I noticed in the build thread that you don't have a shroud on the radiatior. You need a shroud that encloses the fans and covers the entire core of the radiator to pull air over the core.
This explains why the temp stabilizes at 80 mph.
 

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Check your plugs and make sure it's not running lean. Also check your timing. Make sure you have a spring in your bottom radiator hose. It could be collapsing.
 

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What is your timing set at? Are you running vacuum advance?

If you don't have a fan shroud definitely get one of those on there, that will help at idle and low speeds.

Might be better off with a GM 7 blade fan and HD clutch on there. That always worked well for the OEM setups years ago.
 

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Swapped from a 350 to 454, but now I'm battling overheating. On the big block I am running the Chevy serpentine kit with reverse long water pump. The pump is brand new, so is the engine. It's a GM crate 454.


Seems silly, but is the water pump spinning the correct direction for which it was intended too ?
 

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I had a similar issue with my 502. Are you running the kit's water pump? Or another? I have the Chevy serpentine system as well.

My solution was a recored four row, heavy duty rad with a new water pump and a derale steel mechanical fan. Stays at 170 to 180.

Ray
 

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Discussion Starter #7
I'm running a Fitech EFI system with wideband so I know I'm not going lean. I have about 12 degrees of timing at idle, and it advances under power. But I haven't even run this car to full throttle and it's overheating just cruising at low RPMs.

the water pump was brand new and no easy way to get it backwards. I did take off my other brand new water pump that was NOT a reverse rotation one.

What mechanical fan and shroud will fit? I only have about 2.5" of clearance from the radiator core to the water pump. I think I'm going to get the Summit 3 pass radiator. maybe a fan like this:

http://www.speedwaymotors.com/Cooling-Components-CCI-1720-Cooling-Machine-Electric-Fan-Style-20,57482.html?sku=91015621&utm_medium=CSEGoogle&utm_source=CSE&utm_campaign=CSEGOOGLE&gclid=COz8v6-njs8CFZGZGwodneQCJw
 

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My immediate response was to re-jet your carb.

But if you're running EFI with a wide-band O2 sensor, that shouldn't be an issue.

It sounds like you need more flow through the radiator, and/or a stronger water pump.
 

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I'm running a Fitech EFI system with wideband so I know I'm not going lean. I have about 12 degrees of timing at idle, and it advances under power. But I haven't even run this car to full throttle and it's overheating just cruising at low RPMs.

the water pump was brand new and no easy way to get it backwards. I did take off my other brand new water pump that was NOT a reverse rotation one.

What mechanical fan and shroud will fit? I only have about 2.5" of clearance from the radiator core to the water pump. I think I'm going to get the Summit 3 pass radiator. maybe a fan like this:

http://www.speedwaymotors.com/Cooling-Components-CCI-1720-Cooling-Machine-Electric-Fan-Style-20,57482.html?sku=91015621&utm_medium=CSEGoogle&utm_source=CSE&utm_campaign=CSEGOOGLE&gclid=COz8v6-njs8CFZGZGwodneQCJw
Have a sheet metal shop fab a shroud for the fans that you have on there now. The shroud needs to cover the core of the radiator,
 

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Your electric fans are too small. You could switch to a Taurus fan which is well over 2500cfm (some places on the internet say 4000 cfm) and includes a shroud.

https://www.amazon.com/Dorman-620-118-Radiator-Fan-Assembly/dp/B001SGHK1W

Dont forget the wiring harness.

https://www.amazon.com/Cooling-Motor-Harness-Connector-Taurus/dp/B0040CVZN0/ref=pd_lpo_263_tr_t_3?ie=UTF8&psc=1&refRID=EEVE1MKJR6XWNY403V0A
He only has 2.5" clearence. Product Dimensions 30.4 x 22 x 6.8 inches
 

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Not sure what the pulley ratio on your drive setup is, or if you can change it, but it usually helps to drive the pump a little faster, using a smaller pump pulley.
 

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What kind of fans? 2000CFM and no shroud is most likely your issue. The factory mechanical fan pushed more CFM than that.

There are 2 types of CFM ratings when it comes to electric fans and that's what confuses people as well as leads them to ordering inferior parts. Company's like SPAL calculate their fan CFM ratings with the air being pulled thru the radiator (using a special airflow chamber) where as other companies rate free flow (not thru a radiator) CFM which is VERY misleading.

Like mentioned the Taurus Fan or even I Windstar fan setup is the cheapest setup with the most CFM if you can fit it, I run the windstar for my 675HP street driven BBC and keeps it nice and cool with a Champion radiator. If you cant fit it, get a spal fan that will fit that has the highest CFM, they do have a low profile line.

Also, these engines like about 14-16 degrees of initial timing with vacuum plugged (if you're running vacuum advance). May want to play with it a bit.
 

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If you have any sort of cam with decent duration in the engine you will likely want more initial timing than that. I would try at least 16 initial maybe up to 18 initial. Just make sure your total is still around 34-38 or so until you can really dial it in.

I would also plug your vacuum advance to manifold so it's in effect at idle. This will add 10-15 degrees of advance at idle and low speeds which will also help keep the engine running cooler. You could easily add 14-19 degrees more at idle from where you're at now, that should have a pretty good effect on cooling.

Changing your timing is free. I'd try that first and see if it helps any, then move on to things like water pump, fan shroud, radiator, etc.
 

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Swapped from a 350 to 454, but now I'm battling overheating. On the big block I am running the Chevy serpentine kit with reverse long water pump. The pump is brand new, so is the engine. It's a GM crate 454.


Seems silly, but is the water pump spinning the correct direction for which it was intended too ?
the water pump was brand new and no easy way to get it backwards. I did take off my other brand new water pump that was NOT a reverse rotation one.
Still getting hung up on these statements, even though no one else is mentioning it. With the radiator cap off and the thermostat open ( you did confirm it opens in a pot of boiling water), what direction is the coolant flowing ?
 

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I'm thinking more air flow is needed for sure, since it runs cooler at higher speed where the fan(s) would be irrelevant. When I saw those 10" fans on your build thread I had my doubts about their ability to keep up with that sexy ZZ454. Especially since they're also pulling air through the condenser that's sitting in front of the radiator, and your trans cooler is in front of that, further hampering free flow of air and putting additional heat in front of the radiator.

More water flow (smaller pulley or high-flow pump) would probably help too, since even at high speed, and very moderate ambient temperature, the engine heats up. A larger capacity radiator would also increase cooling capacity.

I would also increase initial timing setting to 14° - 16°. As Carl mentioned, with your cam's duration (211/230 int./exh., according to what I found online) more initial advance is in order, and adjusting the timing is free, so that's a good place to start.

I know that pump-to-radiator clearance is a big consideration, so hopefully you can find a fan that meets your needs.

One thing that I don't remember seeing in your build thread is the wiring for your electric fans. Those things need a lot of juice to pull at full capacity. It looks like your alternator is up to the task, but is the wiring to the fans robust enough?

Gerry
 

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You need at 4 core copper brass big block radiator or the BIGGEST and thickest aluminum that can be shoved in the engine compartment.

We have to put 4 cores in anything with a 400+ CID engine with A/C at our Hot Rod Shoppe here in Florida .... as well as the Taurus fan with shroud or a 7 blade GM fan and or clutch fan and the correct shroud.

Anything less and it will not run less than 200 in traffic.
 

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Discussion Starter #19
Thanks for the feedback. I wish I could fit a Mark VIII fan, I've used those in other swaps and they're excellent! But I'd have to find a radiator that is only 1" thick to make that work. So I'm going to try the summit 3-pass radiator and a bigger shrouded electric cooling fan. I'll also check pump flow direction, timing, hose condition, etc. I already confirmed the thermostat was operating.

Thanks again
 

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Discussion Starter #20
OK update!

Replaced the radiator with a summit 3-pass radiator and a nice 3000CFM 16" fan.

Just at idle, after startup the coolant temp creeps up and doesn't stabilize. Fan is blowing hard and it's only 70 degrees ambient out and motor is idling at 800. I have two temp senders in the intake manifold and watched both creep up to 230 before I shut down. I tested the thermostat by boiling it, it does open.

If I open the radiator cap and leave it open, I can't see coolant flowing. I do see bubbles coming up as the car gets warm.

It's a brand new motor. Chevy Performance zz454. The water pump has one hose connected to the intake manifold, the bypass. I suppose I could remove the thermostat and run it without to see what happens? Or I could replace the water pump (which is also brand new). It is a counterclockwise rotating pump since it's a serpentine belt drive.

any other ideas?
 
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