Cooling Bypass Lines

[Don Norton]

running extra coolant lines to the siamesed exhaust port area can provide marginally better cooling in that area, it was a rather common mod or road racing cars that spend a great deal of time racing well above 4500 rpm.

I have a 406 sb chevy that I just built. This time I put some aluminum heads on it (Skip White NKB-272-SH). I put the mechanical temperature probe in the stock location in the right cylinder head. I also have am MSD Atomic fuel injection on the motor and I installed the temp probe just under the thermostat in the Z28 factory manifold. Once the motor warms up to operating temperature the MSD is reading a perfect 180 degrees but the mechanical gauge in the head is reading 190 to 200 degrees. The motor is setup with 10.8 compression, KB Hypertereutectic pistons, Crane H-272-2 cam, 6 degrees advanced timing, 14.7 A/F. Flex-A-Lite 292 electric fans are set to come on at 180/190 degrees. The fans pull 4600 CFM. Would a bypass show above help bring down the head temp?

 

[Grumpy]

it may help somewhat but Id put a great deal more faith in adding a decent oil cooler,
SBC heads, the temps your reading in those locations are common,
at the temps you list I would not be the least bit worried.
those cylinders always run a bit hot simply because two exhaust ports are placed next to each other,
causing a hotter area with limited cooling,
I would not be concerned at that temp level.

http://garage.grumpysperformance.co...oosing-an-engine-oil-cooler.15375/#post-90261

http://garage.grumpysperformance.co...sion-and-oil-cooler-increases-durability.176/

 

[Don Norton]

I've got a factory oil cooler on it already. The 2 exhaust ports (6 & 8) close together would make sense but I'm also thinking the aluminum heads might be adding to it also because of the greater heat dissipation. I'm going to replace the water pump with a 3.5" 8 vane pump and see what that does. It is the only one item I did not replace on the new motor...DUH!

 

[Grumpy]

exhaust port numbers 3&5 and 4 &6 are next to each other,
a more efficient water pump, forcing a bit more flow volume may help,
as will a larger radiator and adding some
water wetter additives, and many guys find drilling steam holes on 400 sbc heads helps cooling issues,
but keep in mind its oil flow rates that provide a significant percentage of the initial engine cooling.
many guys vastly under appreciate the cooling effect a 7-8 quart baffled oil pan and additional oil cooler,
have on the total heat transfer rates out of an engine compartment.

http://garage.grumpysperformance.com/index.php?threads/thoughts-on-cooling.149/

http://garage.grumpysperformance.com/index.php?threads/how-the-cooling-system-works-basics.853/

http://garage.grumpysperformance.com/index.php?threads/400-sbc-steam-holes-posted-by-dennyw.2991/

http://garage.grumpysperformance.co...pring-cooling-via-engine-oil.6491/#post-56753

http://garage.grumpysperformance.com/index.php?threads/choosing-an-engine-oil-cooler.15375/

http://garage.grumpysperformance.co...ing-system-flow-rates-and-heat-transfer.9880/

http://garage.grumpysperformance.co...g-fans-one-mostly-over-looked-component.2756/

http://garage.grumpysperformance.com/index.php?threads/do-i-need-the-fan-shroud.13847/

 

[Don Norton]

My Bad. I was referring to 6 & 8 but now that you look at it should be between the intake runners. Wonder if that temp probe is hitting the head surface (metal)? I know it's pretty long. Think what I'll do is move the probe out a bit to get a true or better water temp rather than head temp if the probe is hitting or touching the metal. Dealing with a Auto Meter gauge.

By the way, I really liked your article about engine oils.

 

[Don Norton]

I am running a factory 6 qt pan w/trapdoors, Mellings high volume oil pump, factory oil cooler and a tube and fin tranny cooler. Currently using Valvoline 10W-30 VR1 full synthetic. Oil pressure hot is 35 psi at idle, 60 psi at cruz rpm.

 

[Don Norton]

The heads do have steamer hole. All other heads I looked at did not have them and from what I found was that if you did drill them in heads that did not have the steamer holes you would void the warranty.

 

[Grumpy]

just a bit of info, having the steam holes factory drilled is an option,
with some cylinder head manufacturers .....
if you order the heads that way,
I've had BRODIX and AFR send heads factory drilled in the past.
the temps you listed would not concern me , as they are very common,
yes cooler is going to be a slight advantage in reducing the potential for knock or detonation,
but your certainly not running excessively hot by any stretch.
you could try running a 170F t-stat ,
swapping too a more efficient fan and fan shroud combo ,
or a larger radiator and oil cooler, with at least 1/2" inside diameter or AN #8 lines and a powered fan,
if your concerned,
https://www.summitracing.com/parts/der-15800

something like this makes a noticeable improvement
http://garage.grumpysperformance.co...pring-cooling-via-engine-oil.6491/#post-20719

but at the temps you list I would not be the least bit worried.

 

[Loves302Chevy]

You are looking for a problem where there isn't one. The gauge in the head is naturally going to read higher than anyplace else because - think about it - that probe is right at the top of the combustion chambers of 2 cylinders. Perfectly normal. Don't fix a problem that you do not actually have! If you installed even more probes at other locations, you would find that the rear cylinders run hotter than the fronts. Especially #s 5 & 7 since they fire one right after the other. 1-8-4-3-6-5-7-2.

 

[T-Test]

I never run a temp gauge in the heads of a pumped up engine. Always close to t-stat and water pump to get a more accurate reading. JMTCW