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Author Topic:   351w overheating
modi25
Dirt Full Roller

Total posts: 26
posted May 24, 2005 09:09 PM  
ok i am a new ford guy, i have a 351w gt40p heads, first time out this weekend. it ran 240 in the feature, i am using a 30% reduction pulley set, with no type of restrictor. the water pump is supposed to be a high flow pump but it is not a name brand unit, it was free i couldnt refuse. my question is should i try some type of restrictor ?, also i have read about plumbing in water from the back of the intake to water pump will this help ? also i have a 2 row inch core radiator and a very nice shroud that i built. went to the
chassis dyno today and had to really go from
69 jets in rear and 67 in front to 64's front and rear too make good power and i am \afraid this may only make haeting problem worse. this is a 2400 pound car, thanks in advanvce for any tips or advice.


modi25
Dirt Full Roller

Total posts: 26
posted May 24, 2005 09:24 PM  
also had a question about rpms i am turning, we turned 6700 sat is that too much for kb pistons and stock rods and crank, i left my dyne sheet at the machine shop so i dont know where it made peak hp,so iam sure that will affect how i gear. also woluld like to give credit to camcraft for my custom cam made about 30 more hp than my chevy, this is a restricted lift and vacuum class so they came up with acam to fit my needs.

4jw
Dirt Roller

Total posts: 10
posted May 25, 2005 12:14 AM  
Not sure about the kb pistons, but the stock 351w crank and rods are good for 6700 rpm. Wouldn't push them over 7000 though. Also the gt40p heads flow real good up to about 6500 rpm, they start choking over 6500.


hotrodenford
Dirt Full Roller

Total posts: 60
posted May 25, 2005 10:25 AM  
Your problem is the high flow waterpump and no restrictor. With this combo the water is moving through the block and radator so fast that it dosen't have time to absorb or discharge any heat. Add in a restrictor or a thurmostat with a bypas hole and your temp should come down drasticly. I would go to a bigger radiator before I tryed the rear water bypas. More cooling capcity and more water.

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If it has wheels or a skirt, you can't afford it! But they shure are fun...

ispin
Dirt Full Roller

Total posts: 48
posted May 25, 2005 02:07 PM  
I run a windsor with a 6 blade plastic flex fan with a 160 t-stat and a good shroud. But on 15% reduction pulley. It runs 180 after feature. Rule of thumb I use on ford is 15%=6 blade plastic 30%=4 blade steel(no flex). I do agree that you need some restrictor in the system and I swear by water wetter additive.
On the RPM 6500 is a lot on the stock parts would not feel comfortable with much more. Cause at that RPM when it goes the space station can see it!

USAFsince99
Dirt Newbie

Total posts: 4
posted May 30, 2005 12:22 AM  
quote:
Originally posted by hotrodenford:
Your problem is the high flow waterpump and no restrictor. With this combo the water is moving through the block and radator so fast that it dosen't have time to absorb or discharge any heat. Add in a restrictor or a thurmostat with a bypas hole and your temp should come down drasticly. I would go to a bigger radiator before I tryed the rear water bypas. More cooling capcity and more water.



This is WAY the correct answer. You cant run a race engine without a restrictor. Exactly as explained above, its moving through the radiator so fast that it has no time to dissapate heat. Put a restrictor in with a hole about the size of a quarter, and run it. You will see temp drop bigtime. Pistons, just like ol boy said, dont take them above 7k, use a rev limiter chip (if you can due to rules at your track) with a MSD type ignition. It costs a bit to get it, but think of the money it will save you in engine parts.

modi25
Dirt Full Roller

Total posts: 26
posted June 05, 2005 07:59 PM  
we ran again this week and it made about 10
laps in the feature before it got hot, i took out the resistor after heat race because it still ran hot. one thing i noticed with it is if you rev engine in pits
the lower hose will try too **** flat and the upper hose swells up, could the lower hose be sucking flat while racing ? it has a spring in it now, or does this indicate
a possible restriction in the radiator. thanks for help, i am going to replace the hose and i may go ahead and buy either a
stewart or edelbrock water pump.

IowaFuzzy1
Dirt Maniac

Total posts: 136
posted June 05, 2005 10:59 PM  
If your lower hose is sucking flat and your upper is swelling you do not have good flow through your radiator.Did it do that when you had the restrictor in? How many rows dose your radiator have? It takes a lot to flatten a hose with a spring in it,so I think I'd start with checking out that radiator

IowaFuzzy1
Dirt Maniac

Total posts: 136
posted June 05, 2005 11:09 PM  
Went back and read your original post,a 2 row inch core radiator dosen't have the flow capacity for a high volume pump.Look at the size of radiators in cars and trucks that use that engine with a stock pump.4 core radiator,3/4 inch restrictor should fix it.Good luck

pforsythe
Dirt Maniac

Total posts: 133
posted June 07, 2005 10:43 AM  
pretty sure i found the problem tonight, i pulled the radiator to look at it. ran water with water hose into the upper hose
connection and then looked into the cap there was not a smooth flow of water, so i cut the end of the tank offof radiator to get a better look. i would say over half of the tubes were not flowing water, going to tak it tommorrow and have it cleaned. thanks for all replies, maybe we can finish this week.

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