Over Heating 604 Crate Question

[toyracer]

Have new 604 w/ Willis Carb. Only thing different is running ethanol free 93 pump gas and new motor (has not been rebuilt). Carb was sent off to Willis in off season and we told them would be running 93 gas. Car is over heating.

Have timing at 32 Running 74 jets and appear a little fat. Went up 2 jet sizes still ran hot and seemed like we were buring raw fuel b/c got very hot under the seat. Went down 2 sizes and pipe is light gray but still running 220 or better.

Last year had problem getting car over 190.

Put in new radiator this week. Has 19" fan w/ shroud and KRC pulleys. We checked tension on the belt this week and it is good.

Put distilled water and 1 bottle of water weter and still ran 220 in a 6 lap heat and was climbing.
Main event was rained out but has been approacing 230 in main event

Questions.

Do we need to run different timing, plugs, jets etc on pump gas?
Any other suggestions appreciated.

I know Stewart has info on there site but we never had heating problem before.
Just looking for suggestions to see if I am overlooking something simple.

thx

[scottracer]

On our carb we changed the jets to 74 on the left side of the carb, ( drivers side ) and 71 on the right, , we found as we went through the corner and fuel washed to the right it was leaning out the left side and created heat, , other then that we runa 6 blade fan and a shroud, and 1 to 1 pullys, and run 210 to 220 in a 50 lap feature, tach 6500 to 6800 ,

[toyracer]

Thanks had not thought of that.

[Matt49]

I agree. You shouldn't have to run different size jets on one side.

For what it's worth, I don't think 220 is that hot for these motors. And 230 doesn't scare me at all.

[toyracer]

I've seen a post about pulleys being worn out and belts slipping. Question is how can you tell pulley's are worn out. Is it if you can turn the fan and belt slips and you have adjusted the tension?

[jedclampit]

I've seen a post about pulleys being worn out and belts slipping. Question is how can you tell pulley's are worn out. Is it if you can turn the fan and belt slips and you have adjusted the tension?

Pretty much a true statement. V belts run on the v of the belt if the inside diameter flat surface of the belt is riding on the pulley its time for a new belt and if still slips its time for pulleys(V belt type). The crank pulley is usually the worst.

I'd try some race fuel to determine if its detonation. Fuel is what you changed that started all this correct?

[toyracer]

Yes fuel is main thing we have changed. Is new motor and Carb was sent off to Willis. We thought same thing of changing to race fuel to try.

The belt is new and we are getting some slippage.

When you say the crank pulley is usually the worst. Due you mean has the most wear and causes most of the slippage?

[brad hibbard]

in a recent fan blade test on the dyno we tried loosening the belt to see when the HP would come up

with a high pitch fan and the belt backed off just a bit from our normal tightness---the HP increased substantially from 5000 to 6500---we are NOT telling you to loosen your belts we are telling you that they NEED to be tight or slippage will occur creating an overheat condition

the reason for the HP increase was the fan and pump were slipping

we like to be able to turn the crank 15 or 20 degress with the fan for proper belt tightness (plugs in of course)

hope that helps

Brad

[brett4]

brad,have you noticed on the dyno one fan taking away less horse power over another??? i run methanol,imca car and 6400 rule..... only running 170 with 19" 4 blade fan

[brad hibbard]

definatly get that big fan off of there--------on methanol you don't need much fan---but its always best to stay on the safe side

I would drop immediatly to a 17 inch and if you are still under 200 go to a 16 or even 15

Brad

[inmodfan]

Brad,
What is the desired running temperature for a 604?

[brad hibbard]

Thats a great question and i wish i had a great answer--------but I don't

maybe Steve Hendren will see this and chime in

Brad

[7uptruckracer]

What kind of radiator and what size? Single or double pass? Is the engine broke in fully? Ive had them to that when they are new because the rings and what not arent seated well and creating extra friction. Do you run a valance off the nose crates normally need the middle of the valance notched out for the extra air flow and to change the pressure up under the nose to help draw the air in. Its very surprising how much the notch helps..

[rubbinsracin]

7up makes a good point. our valance is just made of rolled plastic and it is right on the track. we are fine until about lap 18-20 as it starts to get above 210. i cut a notch about 2"tall and 4 inches wide and it runs 190-5 all night long.
i pulled the valance off one night when i spun all alone and caught the inside berm and never got any hotter than 180.

i have also seen guys take a hole saw and create about 4 or 5 holes aross the front right by the radiator and from what they said its good for about 10-15* also, but it sure looks ugly.

[7uptruckracer]

Yeah I hate nose holes looks so so ugly. I cut a ton one time just to find out that my radiators cooling capacity was off. I don't like running any restrictors in the system either you just create more heat in the heat and hot pockets in the head. The crates do have a cooling issue at times from my experience. Good Pump and Underdrive pulleys are key, the notch. and a good radiator the biggest you can fit between the rails

[rubbinsracin]

We run a 602 with our nose on the ground, notch in the valance, 27" double pass afco rad (only because when we put a rock through our old single pass the double was all they had on hand to replace it on saturday morning ), 1:1 pulleys (the belts we buy from our local auto store are always looser than we like but after reading what brad said its not such a bad thing), we run a racing thermostat only because up north half of our season it is 45* to help the car warm up. stewart stage 2 pump with a 17" GM style 4 blade fan when its hot and a plastic flex fan when it is cooler.

i would say the biggest thing you can do is a good shroud. makes a huge difference.

[7uptruckracer]

Yeah I run Double as well keeps it in the radiator longer for more heat exchange it gets hot here in VA sometimes. I just set my belt tension like you would any other car. I run Alternators on my stuff to so maybe I'm just weird. Good Pump, Good Pulleys, good shroud and some nose ducting in front on mine to direct air flow into the radiator, and a good valance notch with a good GM 4 blade fan, and you should be ok I'd even check your cap for good measure. I take mine out and clean them or soak them/ boil them ever few weeks they will get packed through out the season. I baby oil mine and run shaker screens as well to keep dirt off of them

[toyracer]

thanks for the responses

Figured out last weekend distributor was going bad and timing was jumping around. Glad we didn't melt it down.

Put in new distributor and it ran 195-200 all night long.

[dirtslinger71]

Maybe this has been answered and I over looked it... what is the standard set up for these 604s? I ran a steel head motor forever with a double pass radiator, Stewart pump, 30% reduction pulleys and a 3/4 restrictor and no shroud with 18 inch 4 blade fan. Ran 210 always! Same set up with 604 and runs 230 in dry slick and not hard on the throttle. Next track is big half mile that's always heavy and know my problem will b worse... any suggestions would help. Thanks.

[Egoracing]

Single pass radiator, no restrictor, good pump, 1:1 pulleys, GM fan and a good shroud. Ran all over the south east and never had a cooling issue, even with 100+ degree air temps.