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Discussion Starter #1
ok, so we fired up the motor again today, brand new head gaskets, intake gaskets (both new again), everything. no smoke out the tail pipes, no leaks of any kind. was running about 3 minutes and climbed up to about 190 and was still going.

about an hour later, took the thermostat out and the motor ran for about 7 minutes, hit about 170 finally and stayed there. when we shut the motor off, it had a minor backfire up thru the carb. why would it be overheating with the thermostat in, and not with it out? there are no vacuum leaks, everything is brand new except coil, distrib, intake, and carb. we need some serious help, so if anyone could chime in, it would be greatly appreciated.

my dad's thoughts were maybe the timing chain is off a tooth or two, the water pump is flowing too rapidly and keeping the thermostat closed, or something else is really wrong causing the overheating.

if this helps, here is a part list:
edelbrock perf rpm 64cc 2.02 heads
" perf intake
" 600cfm carb (bad carb i know)
lunati voodoo 60103 cam/lifters
summit 1.5 roller rockers
gm crate 350 block 9.5:1 comp with 64cc heads
accel super stock coil
stock gm distrib
crane points to electronic ignition kit
hooker 1 5/8" headers
high pressure water pump (don't remember brand)
 

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Have you considered that you may have a bad thermostat? They are cheap, try another one, I use 160 degree thermostats here in Florida. Also set your timing at just a few degrees above TDC until you get it dialed in properly. Just a couple of ideas to try.
 

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Discussion Starter #5
Have you considered that you may have a bad thermostat? They are cheap, try another one, I use 160 degree thermostats here in Florida. Also set your timing at just a few degrees above TDC until you get it dialed in properly. Just a couple of ideas to try.
3rd thermostat already. we haven't really messed with the timing too much yet. we were really concerned with the overheating. i think we can get it timed now that the overheating is hopefully under control. another possible cause my dad mentioned was the carb possibly being too lean for the motor? i'm off to work now, but keep the info comin guys, i need all the help i can get!
 

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Providing you got all the air out of your system and have good flow through the radiator, I am betting on this being a timing problem. The questions I have are...

*What are you using for a fan?
*Are you running a fan shroud?
*What about the radiator... are you sure some of the tubes are not plugged?
*You said high pressure water pump, do you mean high flow? What brand?
*What pulley set are you running? Are you crank and water pump pulleys the same size or is the water pump pulley smaller?
*Don't take this wrong... are you sure your thermostat is not installed upside down.
*Are you sure your lower hose is not collapsing?
*Stewart pumps website talks about the myth of pumps flowing to much and causing overheating.
*What is your timing set to at idle? Do you have vacuum advance? Is it unhooked when you set the timing?

Those are the first thoughts off the top of my head
Tg
 

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IIRC a thermostat (installed) restricts water flow slightly. Thus, water "lingers" in the radiator longer and cools better.
 

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ok, so we fired up the motor again today, brand new head gaskets, intake gaskets (both new again)
Vacuum leak...running lean. All ports on the carb capped off?

And yea you have performance heads with a micro carb on it.

Ever mess with the A/F Ratio?
 

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IIRC a thermostat (installed) restricts water flow slightly. Thus, water "lingers" in the radiator longer and cools better.
Exactly, and when you put a cooler thermostat in (160), it opens sooner and never closes again causing the engine to heat up. People dont realize that.
 

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timing chains are notorious for streching,take the dizzy cap off, rotate crank,and set to zero,make sure no 1 is dead on,with a breaker bar,and socket, turn the crank back and forth watching the dizzy turn,but turn it slowley, and see what happens. and i agree with the other guys about not using the 160 stat,the water needs time to cool in the radiator. vonbondo.
 

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Discussion Starter #12
I had a 180 in it, 3 different ones. the newest one is a 180 but opens fully by 200 degrees, so it seems to be working fine. we have messed with the a/f on the carb, its running perfect right now, but it may be on the lean side due to the lack of gas that the carb can allow thru it (being a 600cfm). no vacuum leaks, unless the intake has a crack on the underside. fan is a flex a lite, dont know model either. high flow* water pump (don't know brand). brand new comp double roller timing chain. brand new summit aluminum radiator.
 

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Discussion Starter #16
electric fan with shroud. my dad and i fired it up again, he tried messing with the air fuel mixture screws, and they did absolutely nothing to the motor. no change whatsoever. is the carb malfunctioning (cracked base, jets stuck)? intake cracked? we have the timing at about 12 advanced with everything capped off.
 

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IIRC a thermostat (installed) restricts water flow slightly. Thus, water "lingers" in the radiator longer and cools better.
Exactly, and when you put a cooler thermostat in (160), it opens sooner and never closes again causing the engine to heat up. People dont realize that.
Especially people who know the physics of cooling. The device is a radiator, not a water cooler. Its job is to radiate heat, and the hotter it gets the better it works. There is no reason to slow the flow or let the water 'linger' in the radiator, this only reduces the efficiency of the cooling system. It also lets the water 'linger' in the engine and get hotter. Since it gets hotter in the engine, your temperature gauge will read higher. When the temperature gauge reads higher, you think you have a cooling problem.
 

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Mike G. has helped me sooo much, thanks for what you do boss good stuff.
My mechanic figured out a cooling prob. that has vexed me for 6 months. The fan shroud was ovalized and the fan did not fill the shroud. What he did was to nudge the shroud back to round'ish and installed an larger fan that runs very close to the shround and eureka! The fan is blowing air like mad for the first time since I've owned this car :) Sometimes it's the simple things.
 

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Especially people who know the physics of cooling. The device is a radiator, not a water cooler. Its job is to radiate heat, and the hotter it gets the better it works. There is no reason to slow the flow or let the water 'linger' in the radiator, this only reduces the efficiency of the cooling system. It also lets the water 'linger' in the engine and get hotter. Since it gets hotter in the engine, your temperature gauge will read higher. When the temperature gauge reads higher, you think you have a cooling problem.
If it was a simple "radiator" you wouldn't have cooling tubes to blow air through you would simply let the heat radiate off like a house heater using steam. It is actually not a radiator, it is a heat exchanger. Radiator was just a name that stuck.

Sometimes I think you like to argue just for the sake of arguing. Now for cooling, yes the faster you can run cool water over a hot surface the better cooling effect you will have, but on the flip side the radiator isnt going to pull the heat off the water as fast. Radiators are only so efficient, if they were 100% efficient the water coming out of the radiator would be the same temp as the outside....not going to happen. The radiators first step is to act as a heat sink, absorb the heat from the water, then radiate the heat off it. So if the water shot through the radiator wicked fast, It isnt going to remain in contact with the metal long enough to exchange heat as good as if it were in contact with the metal longer (traveling slower). Test- light a cigarette lighter...run your finger through the flame as fast as you can....You feel nothing basically. Now do it slower...HOTTER, why? your leaving your finger exposed to the flame longer. So depending on the thermal dynamics of the material your using, finger, radiator, time does matter. The radiators were designed to have the water flowing at a certain speed. YOu put a high flow thermostat in yes it cools the engine faster, but if your radiator wasnt designed to accomodate water of the increased velocity it will not cool the water properly and cause your engine to run hot.
You'll need a more efficient radiator, or return the cooling system to its factory state and concentrate on the radiator end first....increasing the cooling capabilities of the water in it. Better fan, shroud, elect fans...etc.
 
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