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Hello. I have an American Iron race car. I have a reoccurring problem with over heating. After about 4-5 minutes of vigorous on track use, the car goes to about 240-250 degrees. I can get it to come back down unless I slow way down to cool down lap speed.

A little background: the car has Tiger Racing bodywork, bumper, heat extracter hood, etc. The radiator is a Fluidyne unit and it is fully ducted. I'm very confident that the issue is not air flow related.

Last year I ran a stockish engine, same issue. This year I'm running a 347 Dart based shortblock. No difference. Ran a Edelbrock counterclockwise water pump in both engines. I've tried running a water flow restrictor in place of the thermostat and no thermostat at all. No difference.

I'm know I have a early factory Fox timing cover. From my research, I gather that they are directionally specific as far as which way the water pump spins. But typically people done have issues running a cw timing cover with a ccw pump. Probably because they are not stressing the system like in a racing environment.

Any ideas? I'm wondering if my pump impeller is slipping on the shaft. I've read they are not staked like the Stewart pump is. Also, I'm wondering if the pump is spinning the wrong way. I ordered the CCW pump but wondering if it was boxed wrong. I've also bought a CCW timing cover, but not optimistic it's going to solve my problem.
 

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Have you boxed in the radiator?

How are you filling the system? It is next to impossible to get all of the air out of the system.

I was having a problem with my CMC car and am determined to solve the problem. I have done a few things that I believe will help but will not be on track again until August...

The first thing I did was to box in the radiator to make sure all of the air was being forced through the radiator.

I had an extra water pump sitting the the shelf and started looking at it pondering ways to make it more effective... one thing I noticed is there was a "water line" at the bottom of the holes were the pump bolts to the timing cover. I gathered from this there is an air pocket that forms in the pump at the impeller... the pump is filled from the bottom and once the cavity were the impeller sits fills up to the block holes there is no place for that air to go... what I did to cure this was drill a 1/16 hole through the top of the pump and into the impeller cavity. I then drilled out the hole in the top of the pump and tapped it for 1/8 npt.

I am running a "remote filler neck" in the top radiator hose with a "blank" radiator cap. Some refer to such a cap as a "zero pressure" cap... it has no pressure relief so that filler neck is exactly that... just a fill point so the system can be filled from the highest point.

The overflow boss on the remote filler neck in the top hose has 1/8 npt threads... I am running a -4 hose from the top of the water pump to the remote filler neck.

While looking at the pump it also dawned on me the bypass is dumping water out of the block right back into the pump. I am now using a "gutted" thermostat so there is no longer a need for the bypass... I tapped the bypass in the thermostat housing and installed a 1/2" npt plug. I then tapped the water pump bottom hole and replaced the hose nipple with a 1/2 npt plug... I plugged the top bypass on the water pump with a 3/8 npt plug... now all of the water coming out of the block has to go through the radiator.

Now whether, or not, any of all of that works remains to be seen...
 

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Discussion Starter #3
Have you boxed in the radiator?

How are you filling the system? It is next to impossible to get all of the air out of the system.

I was having a problem with my CMC car and am determined to solve the problem. I have done a few things that I believe will help but will not be on track again until August...

The first thing I did was to box in the radiator to make sure all of the air was being forced through the radiator.

I had an extra water pump sitting the the shelf and started looking at it pondering ways to make it more effective... one thing I noticed is there was a "water line" at the bottom of the holes were the pump bolts to the timing cover. I gathered from this there is an air pocket that forms in the pump at the impeller... the pump is filled from the bottom and once the cavity were the impeller sits fills up to the block holes there is no place for that air to go... what I did to cure this was drill a 1/16 hole through the top of the pump and into the impeller cavity. I then drilled out the hole in the top of the pump and tapped it for 1/8 npt.

I am running a "remote filler neck" in the top radiator hose with a "blank" radiator cap. Some refer to such a cap as a "zero pressure" cap... it has no pressure relief so that filler neck is exactly that... just a fill point so the system can be filled from the highest point.

The overflow boss on the remote filler neck in the top hose has 1/8 npt threads... I am running a -4 hose from the top of the water pump to the remote filler neck.

While looking at the pump it also dawned on me the bypass is dumping water out of the block right back into the pump. I am now using a "gutted" thermostat so there is no longer a need for the bypass... I tapped the bypass in the thermostat housing and installed a 1/2" npt plug. I then tapped the water pump bottom hole and replaced the hose nipple with a 1/2 npt plug... I plugged the top bypass on the water pump with a 3/8 npt plug... now all of the water coming out of the block has to go through the radiator.

Now whether, or not, any of all of that works remains to be seen...
Radiator is completely boxed in. I forgot to mention that the top of the radiator core support has been completely removed. The radiator is tilted forward. I've also tried with and without a fan. I thought it may be possible that the fan was causing a restriction. No change. Airflow is not my issue.

I think you may be onto something about getting all the air out. I've considered putting a brake bleeder in the thermostat housing to burp the system. However, I'm not completely convinced that is my issue. But I'm pretty desperate for a fix, so it's worth a look.

Btw, there is no bypass in my system. This is a Windsor engine and the heater ports on the pump have been plugged.

What about pulley sizes? My crank pulley is larger than the water pump pulley, effectively overdriving my wp.

I removed the wp tonight. The pump is a reverse rotation and the impeller is secure.
 

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A bleeder at the top of the thermostat housing may be beneficial but you will still have the entire upper hose full of air... this is why I put the filler in the upper hose as it will allow you to completely fill the cooling system.
 

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Lower hose collapsing?
 

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put a temp sensor in rad fins

compare rad and engine temps

that will confirm if you have a water/air flow issue
 

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Discussion Starter #8
How high are you spinning it?

I would imagine if your water pump is over driven it would be no bueno...
6500.

A bleeder at the top of the thermostat housing may be beneficial but you will still have the entire upper hose full of air... this is why I put the filler in the upper hose as it will allow you to completely fill the cooling system.
Good point. I will have to investigate.

Lower hose collapsing?
Could be. Why would this happen? Pump pulling too hard? My lower hose has the spring material inside.
 

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Having a similar problem on my foxbody. Only making 270hp so it is not as if I have a radical engine. I haven't found the cure yet, but when I do I'll share it with you.
 

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Discussion Starter #10
Having a similar problem on my foxbody. Only making 270hp so it is not as if I have a radical engine. I haven't found the cure yet, but when I do I'll share it with you.
Mine is not radical either. Dart block, zero balance forged 347 with little 165 AFR heads. Made about 370 out of the box with no timing or tuning. It's dialed back to 340hp to meet class restrictions. Probably would have made 390-400 if I would have leaned it out and added timing.
 

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With the spring inside of your lower radiator hose it is probably not collapsing...

I would try underdriving your water pump so it is turning 4500 to no more than 5000... from the research I have done some of the a-sedan guys shoot for that pump rpm range... I surmise the excessive pump rpm causes cavitation issues.
 

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The water pump is probably cavitating from too much RPM. Slow it down.

Make sure that the lower radiator core support has a vertical panel below it, unless the bottom section of the nose is also boxed off.

If you have a 347 with 165 heads detuned to 340hp, then your midrange ignition timing probably has very little advance. This is going to raise the EGT very high resulting in higher coolant temperatures and eventually broken exhaust valves. I would lower the CR or drop the displacement to 320 cu in, before your entire engine is destroyed. Changing to dished pistons would be the cheapest proper way to drop the CR.
 

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Discussion Starter #13
The water pump is probably cavitating from too much RPM. Slow it down.

Make sure that the lower radiator core support has a vertical panel below it, unless the bottom section of the nose is also boxed off.

If you have a 347 with 165 heads detuned to 340hp, then your midrange ignition timing probably has very little advance. This is going to raise the EGT very high resulting in higher coolant temperatures and eventually broken exhaust valves. I would lower the CR or drop the displacement to 320 cu in, before your entire engine is destroyed. Changing to dished pistons would be the cheapest proper way to drop the CR.
I put a smaller crank pulley and a larger water pump on. Hopefully I slowed it enough.

The car has a Tiger Racing front end with splitter and heat extraction hood. Are you familiar? Any good/bad experiences?

Can you elaborate a little? The car was detuned using solely a throttle stop (carb). Initial timing is 10* and is maxed out at 30-32* by 3k. Mechanical advance distributor.
 

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32 degrees total timing is fine. I had assumed that the car had EFI and that you reprogrammed the EEC to retard timing in the 4-5,000rpm range to reduce peak torque. When this is done, the timing in this range ends up in the 20-24 degree range, which results in very high EGT at WOT.

I have no experience with the Tiger Racing SN95 body parts.
 

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A bleeder at the top of the thermostat housing may be beneficial but you will still have the entire upper hose full of air... this is why I put the filler in the upper hose as it will allow you to completely fill the cooling system.

Literally just did this.
 

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Discussion Starter #16
I solved this issue. I discovered that the rad ducting wasn’t what I thought it was. I improved that significantly.

Also, I cut the splitter from the radiator to the rear and added a OEM style flap on the bottom of the splitter.

I put a small pulley on crank and a larger pulley on the water pump. No idea what brand, bought them used on eBay.

No thermostat, changed timing cover.

The engine runs 180 all day long now.
 
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