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Old 05-23-2011, 12:30 PM
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Big Block Chevy Overheating w/ Factory Serp Setup

I have an 86 chevy 454 with 93 serpentine belt setup in a 70 Nova. I have the water pump for a 93 setup(reverse rotation). I just completely rebuilt the engine(stock) and installed a comp solid 252 camshaft. The engine overheats during break in(10-15 minutes); never get to finish(tried twice). I also have a 3 core radiator(small block) with an electric fan(1150 cfm) with a 195 t-stat(stock for 86). The cap is rated at 16lbs. The car hasn't puked, I just shut it down at 230 degrees.

My question is: do I need the headgaskets from a reverse rotation engine? I rebuilt engine with a 70's kit. I noticed the head gaskets block the holes in the block towards the exhaust side(only steam holes). The gaskets for the newer engine style has the holes completely open.

I have tried mechanical(reverse rotation) mechanical fans of different sizes plus electric fans and redline water wetter.

I am confident it is not an air pocket; I put tylenol in t-stat holding it open and used a vacuum lift to fill cooling system.

I am going to try running a 160 thermostat and plumb in a crossover from head to head at the rear.

Any help is appreciated. Thanks!

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Old 05-23-2011, 01:22 PM
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Id say that raditor is too small for ur big block. Also right after a rebuild when the engine is at it tightest point it produces some extra heat. Try running a water hose threw ur raditor to keep it cool for break in or a big shop fan. Putting a 160 thermo in there wont do anything since temp isnt going low enough for it to close. You really need to run a mechical fan with a shroud. I run a electric in front of the raditor and a mech on the engine and i never see above 185 with a 180 thermo and thats in 100+ florida heat. Whats the core size of that radiator? And the crossover is a good idea but its only gonna help a little.
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Old 05-23-2011, 01:31 PM
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Also my radiator is a 3 row 23x17x 2 3/4. Most people i know use a 4row with a big block. And on a side note after u get the heating problem fixed dont run a 160 thermo, almost all engine damage is done during cold start up 160 is just to low. It doesnt let the thermo close long enough. Run the 180 and enjoy
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Old 05-23-2011, 01:33 PM
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It is the griffen(sp?) 3 core 17x21 aluminum. The core is slightly over 2.25 inches thick. I would think it could keep it cool. It kept my 355 w/ a 671 cool.

Anyways, I just ordered an aluminum factory replacement. It is 2 inches wider same core number, but I don't know how thick.

Mechanical flex fan made no difference(18 inches), but I don't have a shroud that will fit.
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Old 05-23-2011, 01:49 PM
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Shroud would make a difference. Are the pulleys underdriven? I did a custom shroud using sheet aluminum from home depot. I mocked it up with some carbboard first.
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Old 05-23-2011, 02:07 PM
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The radiator I ordered is only a 2 core aluminum, so I canceled it. I'm waiting for griffen to call me back on a better radiator. I usually run a 180 t-stat. I guess I will try a mechanical with a shroud.
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Old 05-23-2011, 02:10 PM
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The belt system is a stock setup.
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Old 05-23-2011, 02:37 PM
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Set the base timing to around 16*

And if you have a timing tape on the balancer---with vacuum advance----you will want to see nearly 45* or better at 2500 rpm

Bumping up the timing on my 454HO made a world of difference in the temps.

Also---make sure the water pump is working------had one engine where the impeller slipped off the shaft and was not pumping the water thru.
That was a head scratcher
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Old 05-23-2011, 08:07 PM
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Quote:
Originally Posted by Bryan59EC
Set the base timing to around 16*

And if you have a timing tape on the balancer---with vacuum advance----you will want to see nearly 45* or better at 2500 rpm

Bumping up the timing on my 454HO made a world of difference in the temps.

Also---make sure the water pump is working------had one engine where the impeller slipped off the shaft and was not pumping the water thru.
That was a head scratcher
My base timing is at 18*. The throttle response is excellent and the plugs are nice and Tan. I don't think it is a bad tune.
I have triple checked the water pump. My heater core hoses are hot and my upper and lower are hot. I didn't use my temp gun on them, I felt them with my hand. I even checked flow with the radiator cap off. I had previously suspected a non reverse rotation water pump was given to me by mistake so I actually disassembled the pump to check. It is correct and working properly.
I'm working on making a shroud for the flex fan. Griffen said 3-5 days for a new radiator. I will update when I have some more information. Thanks.
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Old 05-24-2011, 11:32 AM
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I run one mother of an aggresive flex-fan on my 66 with a 454, along with a
brand new (stock) 3-row 1966 Chevy truck rad, Spectra-Premium part number CU-284.

The original 6-cyl rad was only a 2-core, which was marginal during engine break-in even at a 50F ambient temp. It ran up to about 220 on the guage, but never boiled over.


Part Specifications
Core Material : Copper
Tank Material : Brass
Row No : 3
Core Height : 17-5/16''
Core Width : 25-1/4''
Core Depth : 1-7/8''
Inlet Header : 2-3/4'' x 25-1/4''
Outlet Header : 2-3/4'' x 25-1/4''
Inlet : 1-3/4''
Outlet : 1-3/4''
Eoc : None
Toc : 14-3/4'' (Concentric)
Notes : Installation Kit:
1 x Installation Sheet


When it runs around 2000 RPM, it moves a LOT of air, and will tug at my shop coat on the way by.

With this new rad (No shroud), and it runs at a consistent 195F ... matching the thermostat that I have installed. I may swap that out for a 180 one later.
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Old 05-24-2011, 12:53 PM
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I have a spectre 18 inch reverse rotation. I hope to get this shroud done soon. I will update when I have some information.
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Old 05-24-2011, 03:20 PM
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You definitely need to get it broken in, multiple tries is taking a huge chance with the cam. As mentioned before, a 160 thermostat won't keep water in the radiator to cool it and you absolutely need a shroud. IMHO you have enough radiator, and flex fans aren't the best setup around, a clutch fan will do you better.
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Old 05-25-2011, 09:46 AM
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Success! Flex fan with a shroud and 160 T-stat. My car runs at a cool 160 degrees now. Thanks for the help. I finished the break in and took it for a test drive. I am now ready to tackle the a/c.

Thanks again for the help.
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