Motor Overheating Issue

[Lucky13x]

I am currently running a cast iron .30 over 327 with cast iron heads with a 22" triple bypass radiator, speedway motor race water pump, and am not running a thermostat or restrictor. Car is on race gas with a 750 cfm vacuum secondary carburetor. This past weekend in the feature my water temperature gauge reads from the thermostat housing and said I was at 260 degrees Fahrenheit by the end of the feature. The car didn't loose any fluid out of the radiator and wasn't steaming. My question is do you think that this temperature is too hot for where the temperature gauge is located and if it is, what can I do to make the car run cooler? When we raced micro sprints we always had the temperature gauge mounted into the coolant line going to the water pump so we were getting the temperature of the coolant after it had time to cool down.

[Dirtmod13]

Could have been a air pocket. If coolant was a little low then the steam would be warmer than the coolant. There is a spot on right side head that will take a temp gauge

[z40chief]

You have to have a really good water pump to run a triple pass rad. Double pass is all you really should use. Put a fan shroud on it if you don't have one. 4 blade fan also. Your temp will lower 40 to 60 deg. from my experience.

[stock car driver]

I doubt your water pump can move the water fast enough thru 3 passes.. the hot water is in your radiator 3 times as long so therefore its also in the engine block that long getting hot.

I would get a single pass radiator and consider a stewart pump or at least take the back off yours and see if it has a curved vane cast impellor or just stamped steel.

[powerslide]

^^^^ That's what I said yesterday as well as one other person. Forum looks to of had some issues.

The triple pass is killing you.

Get a Stewart 2 or 3 stage water pump(buy used off ebay if necessary), single pass radiator(chevelle clip mods take 26).

Even if you borrow a single pass radiator for a night I bet that lowers it 20-30 degrees.

[Lucky13x]

We had a single pass on it to begin with and it was running the same temperature. The pump says it's a high flow. We bought a fan shroud and will be putting it on this week.

[stock car driver]

We had a single pass on it to begin with and it was running the same temperature. The pump says it's a high flow. We bought a fan shroud and will be putting it on this week.

In China when they rivet a plate on the back of a stamped impellor they call that high flow. look in the pump and see if it has CAST curved vane impellor or not. you can see it thru the lower hose hole.

I put a two pass in my stock car when I wanted to gain some heat.

did you have a single pass 2 core radiator?

[SRXSRULE]

Looks like my post vanished.
Anyway, just like the others have posted....Get that triple pass out of there! Get a NEW, good quality, the biggest you can fit in there single pass and a 4 blade fan with a custom fitted shroud.

Here is the info I posted on the double and triple pass radiators.

Double pass radiators require 16x more pressure to flow the same volume of coolant through them, as compared to a single pass radiator. Triple pass radiators require 64x more pressure to maintain the same volume. Automotive water pumps are a centrifugal design, not positive displacement, so with a double pass radiator, the pressure is doubled and flow is reduced by approximately 33%. Modern radiator designs, using wide/thin cross sections tubes, seldom benefit from multiple pass configurations. The decrease in flow caused by multiple passes offsets any benefits of a high-flow water pump.

Eric

[Lucky13x]

Ok so what I have gathered is I need to take out the triple and put the single pass back in along with the shroud we purchased. The original radiator was a prc single core single pass radiator 22" wide. I have been told that when running a single pass radiator I should use a 5/8th restrictor in the thermostat housing should I do that, use a bigger restrictor, or leave it wide open? Thanks for all the information by the way. This is our first year in mods and we are figuring things out along the way.

[SRXSRULE]

You should look at a 2 core single pass and the widest you can fit in the spot. the shroud needs to seal well to the entire core of the radiator, tape or caulk the shroud to the core so its air tight. The fan (19" 4 blade) should be 1/2 in and 1/2 out of the shroud. If you have a Good racing pump (200.00 range) you can run the t-stat housing open.

Once you build a good cooling system you will likely need to run a racing thermostat to get it up to temp quicker and hold that temp.

Also, once you have gotten an engine hot 250+, you need to take a close look at the radiator, the flat shaped tubes or cores can balloon from the heat and pressure and once this happens you have greatly reduced the air flow through the radiator and and the radiator needs replaced. this is more of a problem with cheaper radiators because they use less aluminum and the material is thinner and therefore easier to fail. Eric

[Lucky13x]

Our car is a metric front clip and a 22" with a 15" fan is just about as big as we can get. Might be able to squeeze a 24" in possibly.

[twisterf5]

we run a 22'' on a metric chassis with a 18'' single blade with a custom built shroud on race gas we run 190 to 205 on a 180 thermostat with a 602 crate. 15'' will not work will run hot we tried it.

[stock car driver]

I run 18" single blade fan, on gas with a 195 stat and run 190 and the stat opens and closes during races. My carb timing etc is chassis dyno tuned to be absolutely correct though!

You need to check your plugs and make sure your not lean, check timing to ensure you are not too far advanced and you for sure need a fuel pump that flows enough fuel. Your plugs can read ok and your pump can be not flowing enough so you go lean at high rpm for a split second a lap and you will always run hot.

When I ran a block mounted pump the one I went to finally with success on a 500 carb motor was a holley 327-25 170 gph. I had a few 120 and 130 and both would go lean at 6800 rpm with even a 500 cfm carb.

[Reddy Powered]

I noticed no one mentioned the pulleys. The correct pulleys are just as important as anything else in the cooling system. I'm assuming you don't turn over 7500 RPM so you need 1 to 1 pulleys. The perfect system (assuming you're not running lean) is:

Stewart stage 1 or 2 pump
Good single pass radiator
Good shroud
1 to 1 pulleys (if not over 7500rpm)
19" Chevy four blade fan 32 deg. pitch. GM part no. 405442
Make sure fan is between 1 and 2 inches from radiator
NO restrictor. Can run racing t-stat but I don't.