#21  
Old 08-27-2021, 11:51 AM
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Sanding pulleys decreases surface area, and can make them slip. Pulleys need a clean, smooth surface, and true so the belt 'sticks' to it.

You don't have to believe me, but call ram air resto and talk to tech, they can explain it much better.

Some might get lucky when sanding them, but it's most likely due to there not being an issue to begin with. If you have an excessive load, and it only slips sometimes, sanding them will make it worse.

Sometimes a pulley will look perfectly fine, but still slip. Most of the time you can't tell with the naked eye when a pulley(s) has/have been compromised.

On 1st gen birds, an air dam helps considerably, but many refuse to install one for whatever reason(s). Even so, the air dam helps very little to none at a stop.

I honestly believe that the trans cooler has very little to no effect, but I would still do an air gap on it. It might provide that slight margin that could make a difference.

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  #22  
Old 08-27-2021, 12:47 PM
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Much of this problem is Obvious. Wrong Fan shroud.
There is NO way there should be that huge gap at edges of the blade to the shroud.
Just like Fluid dynamics and the water pump plate, the Aerodynamics of the fan shroud / blade is the same.
I am 100% sure there is air turbulence affecting the draw of the fan.
Are the temps verified with an IR gun?
You can eliminate the radiator tank trans cooler and go straight out front if you like.
A 160 T stat with give your cooling system a head start on cooling, and would be full open at a dynamic temp of around 180 on a normal working system when its hot out.
But First., Get that shroud fixed. Pontiac had RA4 cars tested in the desert with automatics for heat and cooling.
Lastly, Folks tend to use a "Recommended" A/F ratio for their injection systems. With the alcohol in fuel , Pontiacs anyway, need a richer Idle mixture to run right and stay within temp parameters.

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Old 08-27-2021, 12:48 PM
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ok, thanks for the explanation. its not a matter of believing you or not, i just never heard of that being a problem before, or at least not for the average light sanding with finer paper to clean light surface rust/debris... light sanding wont reduce the surface area since no metal is really being removed.

now heavy sanding with 80grit to a heavily rusted or pitted pulley i can understand, but for all the factory pulleys i have sanded there has never been any problem. any serious slipping is usually audible & will show signs on the belt like being glassed over etc.

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Old 08-27-2021, 12:51 PM
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Quote:
Originally Posted by Formulabruce View Post
Much of this problem is Obvious. Wrong Fan shroud.
There is NO way there should be that huge gap at edges of the blade to the shroud.
Just like Fluid dynamics and the water pump plate, the Aerodynamics of the fan shroud / blade is the same.
I am 100% sure there is air turbulence affecting the draw of the fan.
Are the temps verified with an IR gun?
You can eliminate the radiator tank trans cooler and go straight out front if you like.
A 160 T stat with give your cooling system a head start on cooling, and would be full open at a dynamic temp of around 180 on a normal working system when its hot out.
But First., Get that shroud fixed. Pontiac had RA4 cars tested in the desert with automatics for heat and cooling.
Lastly, Folks tend to use a "Recommended" A/F ratio for their injection systems. With the alcohol in fuel , Pontiacs anyway, need a richer Idle mixture to run right and stay within temp parameters.

thats what i noticed too... whether its the shroud not being right or the fan im not sure, but one or the other looks like the wrong size.

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Old 08-27-2021, 01:22 PM
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I thought they only make 2 shrouds for 1st gens? One for the 2 core, and one for the 3 core. I don't recall if they ever had 4 cores for them?

I only see 1 shroud listed in Ames catalog?

It was cooling properly before the addition of the A/C condenser, maybe it was borderline then?



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  #26  
Old 08-27-2021, 01:23 PM
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Quote:
Originally Posted by Formulabruce View Post
Much of this problem is Obvious. Wrong Fan shroud.
There is NO way there should be that huge gap at edges of the blade to the shroud.
Just like Fluid dynamics and the water pump plate, the Aerodynamics of the fan shroud / blade is the same.
I am 100% sure there is air turbulence affecting the draw of the fan.
Are the temps verified with an IR gun?
You can eliminate the radiator tank trans cooler and go straight out front if you like.
A 160 T stat with give your cooling system a head start on cooling, and would be full open at a dynamic temp of around 180 on a normal working system when its hot out.
But First., Get that shroud fixed. Pontiac had RA4 cars tested in the desert with automatics for heat and cooling.
Lastly, Folks tend to use a "Recommended" A/F ratio for their injection systems. With the alcohol in fuel , Pontiacs anyway, need a richer Idle mixture to run right and stay within temp parameters.

This is an interesting observation re: fan shroud. It is an OEM 69 Firebird shroud as far as I can tell and the fan is 19.5". The spacing is a little tighter on bottom and sides (1 inch) - and the top is not as bad as picture depicts but Ill get measurements. Also noted on the AFR...

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Old 08-27-2021, 01:32 PM
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What is the idle AFR set at? And your idle RPM?


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Old 08-27-2021, 01:58 PM
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Idle AFR is 14.2 and RPM is 850

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Old 08-27-2021, 03:15 PM
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That should be good, maybe throw 2 degrees in timing at idle at it. What's your timing at idle? 16-18 ?

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  #30  
Old 08-27-2021, 05:00 PM
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Idle timing is 25. So I added spacers at trans cooler mounts and now have about 1.25” between it and the condenser.
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  #31  
Old 08-28-2021, 09:17 AM
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Quote:
Originally Posted by 78w72 View Post
i dont see that mount bracket as "huge", it looks like just a strip of aluminum about the same width as the end part of the cooler, doubt thats a contributing factor to his issue. but i do agree the cooler is on the large side & unless theres a specific reason for needing one that big it would probably help to down size it or add a temp gauge or check the pan with a temp gun after a long hard drive to see if the fluid is getting hot enough to need one. for a mostly street driven car a trans cooler may not be needed.

a big trans cooler like that will definitely increase the heat being put into the radiator since its not allowing any cool air to flow over that area, its all hot air once the trans is up to temp. in series with the rad cooler is the best way to run it since the rad cooler removes a lot of the heat first & as mentioned also warms the fluid in colder temps. bypassing the rad cooler is not a good idea for a street car since there is no cooling unless the car is moving.

i dont think all the other things mentioned like belts or the clutch fan itself are an issue or causing the overheat since they were all functioning good with no overheat issues until adding the condensor, that is the only new change & will definitely reduce air flow & increase temps as shown. if the rest of the system is in good working order & the water pump divider plate set right etc it should be able to handle an a/c condensor, but i have heard these 1st gen firebirds dont have very good air flow through the front end.

couple things to consider trying:
get a smaller aux cooler after checking trans temps or eliminate it if not needed.
use a cooling additive like water wetter or hyper cool & lower the anti freeze concentration as much as you can based on your climate. water cools better than anti freeze.
i doubt the clutch fan is bad just based on time, especially if theres no sign of leaking fluid & the fact it worked fine before adding the condensor. it is hard to tell in the pics, but what size is the fan? it almost looks like its too small in the shroud opening, if it is try a bigger fan that fits tighter in the opening. 19"?
& make sure the shroud is sealed around the radiator & core support with no gaps.
electric fans may help but can be expensive & ive read many times that they can be less efficient than the correct factory shroud set up but that varies for every car/engine.
& maybe play with pulley size, under or over drive to see if that helps.

FWIW, i have a 467 stroker with E heads & a carb & running a measly 3 row champion radiator with a warn out clutch fan & 180t-stat, runs at 180-190 tops in all situations on the street or drag strip in summer temps & on days below ~70 it will barely stay at 180 verified by the gauge & a temp gun. your system should be able to handle an ac condensor. hope you can figure it out.
Thanks for the tips - as you mentioned the trans mount straps are 1" wide aluminum. I've since spaced the cooler out from condenser (pic attached). I have to check trans fluid temp at pan with IR gun - hopefully today or tomorrow. The water pump pulley is 6.5" and fan is 19.5" and it is an OEM shroud. A little testing yesterday - idling for extended period in driveway stays 195 - 200 (95 ambient temp). IR gun pointed at temp sender location on intake confirms temperature gauge.
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  #32  
Old 08-28-2021, 01:14 PM
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The RPO K02 fan has a slightly smaller diameter than the 5 blade. That said, it MUST be centered in the shroud and just barely inside it.
I would try to get a diameter on a factory shroud and compare to this repop.
I would make sure the top plate is on tight and sealed, and make sure the radiator is sealed on the sides to the core support.
I didnt really see it in pics, you do have the top plate?
Even with AL heads, I would run a 160 T stat if you have AC and run alcohol in the fuel.
IF, you are one of the OLD OIL, OLD School folks that feel the need for their "Oil to Boil"
You could try a 170 T stat. I think Stant makes these.
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Old 08-28-2021, 01:24 PM
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Quote:
Originally Posted by Formulabruce View Post
The RPO K02 fan has a slightly smaller diameter than the 5 blade. That said, it MUST be centered in the shroud and just barely inside it.
I would try to get a diameter on a factory shroud and compare to this repop.
I would make sure the top plate is on tight and sealed, and make sure the radiator is sealed on the sides to the core support.
I didnt really see it in pics, you do have the top plate?
Even with AL heads, I would run a 160 T stat if you have AC and run alcohol in the fuel.
The shroud was on the car when I bought it in 1995 so don't think it's a reproduction. It does have the lower and bottom plates but they were removed in picture cause I was working on the condenser.

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Old 08-28-2021, 01:36 PM
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Quote:
Originally Posted by grivera View Post
The shroud was on the car when I bought it in 1995 so don't think it's a reproduction. It does have the lower and bottom plates but they were removed in picture cause I was working on the condenser.
So the TOP plate covering the new cooler is in place?
The shroud looks much smoother on the top than a factory unit.
May have to make sure the core support is not bent and radiator sits in correct spot.
We just fixed a 400 heating issue by tweaking the core so the shroud sit evenly
and lined up to the fan.
A/F closer to 14.0 may help as well. Good luck, youll get it !
Has been a hot summer.

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Old 08-29-2021, 11:13 AM
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I measured the clearance between the fan and the shroud. At the top it’s about 1.5” , sides and bottom 5/8”.

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Old 08-29-2021, 01:04 PM
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Everyone has their own comfort levels, but if you are seeing 195-200F water temp during extended idling in 95F ambient weather, I personally would not be worried about a thing here.

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Old 08-29-2021, 01:32 PM
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Quote:
Originally Posted by Formulabruce View Post
So the TOP plate covering the new cooler is in place?
The shroud looks much smoother on the top than a factory unit.
May have to make sure the core support is not bent and radiator sits in correct spot.
We just fixed a 400 heating issue by tweaking the core so the shroud sit evenly
and lined up to the fan.
A/F closer to 14.0 may help as well. Good luck, youll get it !
Has been a hot summer.
The 170 stat seems like a decent option - I need temp to be at least 160 as that is when Sniper EFI goes into closed loop. Yes- the two top plates are in place - older pic attached showing them. Also a pic of lower baffle.

Quote:
Originally Posted by ZeGermanHam View Post
Everyone has their own comfort levels, but if you are seeing 195-200F water temp during extended idling in 95F ambient weather, I personally would not be worried about a thing here.
Thanks - I hear you - I'm trying to get it in better shape for when AC is operational as the extra load and heat in condenser will make it run even hotter.
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'69 Firebird 400/461, 290+ E D-Ports, HR 230/236, 4l80E, 8.5 Rear, 3.55 gears
'64 LeMans 400/461, #16 Heads, HR 230/236, TKO600, 9inch Rear, 3.89 gears
'69 LeMans Vert, 350, #47 heads: Non-running project

Last edited by grivera; 08-29-2021 at 01:42 PM. Reason: Added pic
  #38  
Old 08-29-2021, 08:58 PM
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The path of least resistance.
IF the fan can suck air from under the hood, vs Through 2-3 "heat exchangers" , it always will.
Adding a exchanger, in use or not, is more load and restriction on the path of the air.
I am not versed in the bracketry of this radiator, vs stock, BUT I think you could try some window
closed cell foam insulation in this area as a temporary measure to force the fan to suck though the radiator.
This will help tell you if you need to do more besides a T stat.
IIRC the HD fan ( 7 blade) is only 17.5 across, vs the 19.5 on a stock 5 blade??
This could be why it looked odd to me.
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Old 08-29-2021, 09:15 PM
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Based on the Parts catalog, Pontiac only used 1 V-8 Shroud, regardless of the fact that the HD 7 blade fan is smaller Diameter.

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Old 08-30-2021, 07:52 AM
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Thanks. The seven blade on this car is 19.5". That is an older pic I have on phone to illustrate top plates - and at the time it had a Summit brand direct-fit radiator. The current Cold Case radiator doesn't fit much differently. That being said, those gaps were there with the prior desert cooler radiator as well - I was just looking at them yesterday - may try backer rod in appropriate size. The 1st gen cars have a crude interface between radiator and radiator support - the gap around perimeter of hole in the radiator support that corresponds with the radiator core is much smaller.

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'69 Firebird 400/461, 290+ E D-Ports, HR 230/236, 4l80E, 8.5 Rear, 3.55 gears
'64 LeMans 400/461, #16 Heads, HR 230/236, TKO600, 9inch Rear, 3.89 gears
'69 LeMans Vert, 350, #47 heads: Non-running project

Last edited by grivera; 08-30-2021 at 07:59 AM.
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