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Discussion Starter · #1 ·
I know, another Big Block heating up. But I was hoping I could get my setup to work with a little help. My 454 specs are in my sig.

What's not in the sig :
I'm running a serpentine belt, which runs the water pump and fan in the opposite direction, so reverse rotation pump. It also forces me to run a LONG waterpump, limiting the size of fan I can put on. It also limits my ability to get an efan in there, to PULL air. So i'm running two 12" Derale fans on the opposite side to push air. I did manage to squeeze a 15" reverse rotation flex fan and a 3/4" shroud with those rubber flaps for highway driving. 160* t-stat (also tried 180), 16 # rad cap with overflow. Rad is a speed cooling rad good for 700HP supposedly 1966 – 1967 Chevelle Aluminum Radiator 50:50 coolant with some water wetter. I'm running a Fitech with timing control, so 13.6 AFR and 16* at idle, 36* at 3000rpm and 14.2 AFR at cruise, and 36* 5000+ and 12.8 AFR on hard acceleration.

All said, I know it's not overheating. My Tahoe Daily runs at 210 all day and doesn't move. But cruising around and getting on it a bit, then getting stuck behind a slow driver, the temp gets up to 195. I think by the time I shut it down, i was up to 198 for a cruise temp this weekend. Seems high? I know it's not going to sit at 160 per my t-stat, but figured it would stay at least 20* away on an 80 degree day?

Should i move my whole shroud out around the fan? or install a ring on the shroud around the fan? I don't know which would be better. right now, the fan sits just flush with the shroud. Any other ideas welcome.

sorry, it's a driver, she's dirty...

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If it stays under 200 in the worst conditions, I'd say you don't need to change anything.

How hot does it get when just idling for long periods of time?
How hot does it get when the car is moving at sustained speeds?

What is your timing curve set to at low load cruising speeds?
 

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Discussion Starter · #3 ·
I haven't really had enough time to stretch it's limits, but it's good to know 200 is a solid threshold. And what would you say the "I should shut her down" temp is?

With the Fitech it does 4 "Break points" so idle, 1100 rpm, 3300 rpm and 5500Rpm, and a cruise "break point" separate from a Fast, getting on it, break point. So to your question, cruising I have it the same for the 1100 and 3300 cruise, 14.2 AFR and all in 36* . I'm not sure of the workings, but I assume it gradually changes the timing from 16 to 36.
 

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I've had mine up past 220 before. That's scary to me, but it didnt blow fluid out. I'd say once it gets past 210 I'd want to get it cooled down asap.

I have a fitech too. I am guessing you are using the stock KPA settings (45 and 95), you can actually change those, but that's a different conversation.

For 45 kpa, bump your timing up! For 3000 @ 45 kpa I have it set to 45 degrees. With a carb, it is not uncommon for people to run up to 52 degrees cruising. It's hard to get that kind of sweep with the EFI control though. 1100 I am at 38 degrees.
 

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Discussion Starter · #6 ·
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Discussion Starter · #8 ·
I've had mine up past 220 before. That's scary to me, but it didnt blow fluid out. I'd say once it gets past 210 I'd want to get it cooled down asap.

I have a fitech too. I am guessing you are using the stock KPA settings (45 and 95), you can actually change those, but that's a different conversation.

For 45 kpa, bump your timing up! For 3000 @ 45 kpa I have it set to 45 degrees. With a carb, it is not uncommon for people to run up to 52 degrees cruising. It's hard to get that kind of sweep with the EFI control though. 1100 I am at 38 degrees.

I had to grab a pic in case my memory is off. So really, your timing is that high?? what's your idle timing? Could I ask what your AFR's are? I often wonder if I'm too Lean, creating the heat?

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I would get a better flex fan and move it closer to the radiator. I used one similar to yours and had the same results. I went with a Flexalite 1818. You should be able to find one similar to your application.

In addition if you can get your initial timing up a little higher leaving your total alone may help also.
 
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Discussion Starter · #10 ·
I understand your limitations with the long water pump. I would just go full electric (2 12 inch fans with at least 30 amps of draw) and put the fans on the engine side. You shroud you have is not that great but I realize there are issues with the long pump on early cars. This is what I did and it work pretty good.
What brand fans are those? I could not find ones thin enough to fit between the PS pump and rad or water pump and rad. And you have a little shroud too??
 

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Discussion Starter · #11 ·
I would get a better flex fan and move it closer to the radiator. I used one similar to yours and had the same results. I went with a Flexalite 1818. You should be able to find one similar to your application.

In addition if you can get your initial timing up a little higher leaving your total alone may help also.
What do you mean when you say "better" fan? I could afford to go 3/4" closer to the rad with the fan.
 

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I had to grab a pic in case my memory is off. So really, your timing is that high?? what's your idle timing? Could I ask what your AFR's are? I often wonder if I'm too Lean, creating the heat?

View attachment 741237
at 19:24 I show my settings. I run around 14.4:1 AFR at cruise.

 

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1. a Rad with 2 Rows of 1.25" Wide Tubes would be better
2. A Flat Metal Shroud will Heat Up and Hold the Heat at the Rad Core / thus not allowing
the Coolant in the Rad to Cool down as much as it could if there was a Cone Shaped
Plastic/Fibre Glass one with Hwy Flaps
3.the current Fan is ONLY Pulling Air thru the Rad Core just Directly in Front of the Fan
as any Air going thru the Rad Core away from the Fan is Hitting the Flat Metal Shroud
and Bouncing/Pushing Back to the Rad Core
4. the Efans infront of the Rad are Restricting more Air Flow from going thru the Rad Core
5. my BBC with a Carb Idles at 750 - 900 rpm
 

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Your Tahoe temperature gauge exhibits something that the GM engineers put in on purpose to prevent owners from complaining so much about overheating - "hysteresis". That dash gauge only responds to changes in temperature slowly when it is in its normal middle of the face range. Your Tahoe is getting hotter than you think but not badly too hot.

My Dakota Digital temperature sender at the passenger rear head port in my LS engine and gauge in the dash of my EC is much quicker to respond to changes - almost no hysteresis at all. I can see twenty degrees of change with just a little time at moderate road speeds and at 500 RPM higher engine speed. Yet, the temperature sender in the drivers side front of the head that feeds the LS engine powertrain control module sees much less change in temperature under the same RPM and vehicle speed conditions.

Bottom line: Using your engine temperature experiences in the Tahoe won't be of much good to you with your 454.

Rick
 

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Discussion Starter · #16 ·
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Discussion Starter · #17 ·
1. a Rad with 2 Rows of 1.25" Wide Tubes would be better
2. A Flat Metal Shroud will Heat Up and Hold the Heat at the Rad Core / thus not allowing
the Coolant in the Rad to Cool down as much as it could if there was a Cone Shaped
Plastic/Fibre Glass one with Hwy Flaps
3.the current Fan is ONLY Pulling Air thru the Rad Core just Directly in Front of the Fan
as any Air going thru the Rad Core away from the Fan is Hitting the Flat Metal Shroud
and Bouncing/Pushing Back to the Rad Core
4. the Efans infront of the Rad are Restricting more Air Flow from going thru the Rad Core
5. my BBC with a Carb Idles at 750 - 900 rpm
Thanks Kirk, I hear everything you're saying, makes sense. Maybe I can try to make a fiberglass shroud with more of a cone shape. Given the space it may not be too much of a cone though.
 
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Discussion Starter · #18 ·
Your Tahoe temperature gauge exhibits something that the GM engineers put in on purpose to prevent owners from complaining so much about overheating - "hysteresis". That dash gauge only responds to changes in temperature slowly when it is in its normal middle of the face range. Your Tahoe is getting hotter than you think but not badly too hot.

My Dakota Digital temperature sender at the passenger rear head port in my LS engine and gauge in the dash of my EC is much quicker to respond to changes - almost no hysteresis at all. I can see twenty degrees of change with just a little time at moderate road speeds and at 500 RPM higher engine speed. Yet, the temperature sender in the drivers side front of the head that feeds the LS engine powertrain control module sees much less change in temperature under the same RPM and vehicle speed conditions.

Bottom line: Using your engine temperature experiences in the Tahoe won't be of much good to you with your 454.

Rick
Man they're smart. I do that with my trans temp while watching it go up and down. haha
 

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Discussion Starter · #19 ·
Would I be wasting my time with remote oil coolers?
 

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1) You need to space that entire fan shroud away from the radiator so it covers about 1/2 of the fan. It still must seal to the radiator so you will need to make some kind of spacer or 1 to 1-1/2" thick frame.

2) Invest in a better flex fan, that one you have does not move much air. Look at a Flex-a-lite 10,000RPM series. If you need a slightly different fan spacer order that with the fan.
 
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