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I have a 68 charger w/ 440 and it runs hot at idle

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I have a 68 charger w/ 440 and it runs hot at idle

aboutaqtlow aboutaqtlow
New User | Posts: 4 | Joined: 08/13
Posted: 08/02/13
11:12 AM

My car will run 180 190  down the road but let it idle and 230 look out, and she wont idle in gear at that temp.  I have tried a lot of things and just about at wits end.. new pump, alu. up grade rad from 22inch to 36 inch shroud set timing at 7 degrees, new fan blade,   The car runs great until I have to stop for 6 or 7 lights and the temp gets to 210 then the fun begins putting in neutral works for a couple more lights,  then my temp goes up and nothing works it acts like there's no gas, stalls,  fires right back up then goes after a little coucking??   Ready to pull out the gun.  Any help would be greatly appreciated  PS  its a 750 Holley Crazy  could it be in the carb, when hot Frown  

waynep712222 waynep712222
User | Posts: 127 | Joined: 04/13
Posted: 08/02/13
12:07 PM

1.  install a fuel injection type of fuel filter directly before the fuel pump...  put it in a loop of fuel hose.. this is easily removed if you end up not liking it..

conventional inline fuel filters do not have a fine enough element to catch the super small particles that are causing you issues... the clear ones won't stop beach sand...

throw a big old speaker magnet on the bottom of the fuel tank.. or stick super magnets inside the fuel tank thru the sending unit hole.. make sure they drop to the bottom...  this will pull any iron sediment particles to them that come out of the gas station pumps..

with a cold motor after installing the inline fuel filter before the engine mounted pump... disable the ignition.. so no sparks can be formed..  disconnect the fuel line either at the carb or at the fuel pump outlet..    extend the fuel pump outlet into a clean .. clear plastic 2 or 3 liter soda bottle..  have a friend crank the engine for 15 timed seconds while you observe the pulses of fuel into the plastic bottle.. you could have sediment in the check valves.. that prevents the fuel pump from holding the pressure in the line to the carb or in the fuel pump cavity to prevent it from draining all the way back to the tank...

guess what.. the full flow test will some times allow the clean filtered fuel flowing thru at high speed to flush the sediment from the check valves restoring operation...

you can also blow into the fuel line from the pump...  i have had so many that i could blow bubbles in the fuel tank as both check valves were held off their seat..

this reduced the fuel pressure to the carb.. so the fuel vaporized easier in the lines and the gas vapors prevented the fuel pump from pulling up more fuel and the engine leaned out over heated and died..

the sediment can also allow the needle and seats in the carb to SEEP.. causing you idle problems.

4 bucks worth of magnets and 20 bucks worth of fuel injection type of fuel filter have fixed a LOT of cars with similar issues..

i got started on this on a 440 motor home back in the 80s.. my boss was a former master tech for a dodge dealership.. this motor home gave him fits.. it would only overheat on long uphill grades..   he did radiators.. thermostats.. fans.. water pumps..  even the full flow cranking test with the fuel line open into a bottle for 10 seconds..  and it passed.. but when he rigged up a fuel pressure gauge and drove the MH up the grade. the fuel pressure dropped to about 1 pound and the engine temps skyrocketed..  turned out the camping world generator techs has used an multisized tee in the fuel line from the tank for the generator.. this reduced the size of the fuel hose to 1/8" ..  there was enough volume to supply the pump test for 10 seconds.. but not for 15..  the pulses diminished to just a few drops.. while the engine was still cranking..  not a good thing..

so that's about 30 bucks worth of parts and an hour to install and test the system.
thats for the obvious vapor lock..

what temp thermostat are you running also..

try a 192F thermostat..   and at least a 50% mix of coolant to water..

how much fan blade ??  there are several different blade widths .. some move more air.. some move less.. got a part number or a picture that you uploaded to  the photobucket dot com site??

is there a bypass circuit still working..  most RB motors have a hole under the thermostat that allows water pushed around the cylinders .. up thru the back of the heads and forward thru the heads to the water pump housing where its restricted by the closed thermostat and some is bypassed thru the opening under the thermostat to go around and pick up more heat ..until the opening temp of the thermostat is reached..

if the bypass is blocked. the thermostat is a long ways from where heat is created..

if there is no thermostat or just a restrictor..there will be so much coolant flow thru the radiator that no fan can take the heat out..  

aboutaqtlow aboutaqtlow
New User | Posts: 4 | Joined: 08/13
Posted: 08/03/13
05:08 AM

Thank you for your reply and interesting info,  well first the tank and sender are pretty new 2 years I am running a electric fuel pump at the rear of the car.  the regulator is set at 3.5 lbs.  

I have tried 190 t stat 160 t stat with 1/8 inch holes (6) to allow more flow and the best case is no thermostat .  It takes 3 times longer to get to that point of no return.
I have 50/50 mixture w/ one bottle of wetter. the cooling system is clean.
Fan is a derale 6 blade, w/3'' ss flex paddles 19''    
know there is one thing that I still don't know about , I installed a alum. pulley system and the crank pulley is about 1'' smaller than the stock steel one. I have been told this should have no effect but I still wonder.  
This motor has run hot since I bought the car In 2010,  the motor was rebuilt 25+ years ago, it had about 1000 miles on it , compression was good so I have not taken it apart , could there be wrong head gaskets??
ooo correction I have installed a 26'' alum. rad with two 1'' rows

Thanks for listening do I need a rad. in the trunk too.

I re built the carb, with new needle and seats checked float levels.

Please tell me more about the by pass I don't have one ,but I do have a heater core hooked up and continues flow thru it. there is still a 3/4 port blocked off in the timing cover/water pump housing ??  

waynep712222 waynep712222
User | Posts: 127 | Joined: 04/13
Posted: 08/03/13
11:00 AM

reduce the number of bypass holes in the thermostat... to ONE... you just want those to allow any air pockets to be able to pass thru .. not to allow much of any coolant flow..

bypass...  there are several different designs of RB water pump housings..

some have a big open area that is exposed to the center of the water pump impeller..
others have a drilled hole.. about 1/2"... i would prefer for a street motor the 1/2" version

let me describe the cooling system normal operation..

water pump pushes water into the block and around the cylinders.. up thru the back of the head gasket into the head.. then forward thru the head.. and back into the thermostat crossover... where its blocked by a closed thermostat.. the mechanical pressure pushes the coolant thru the bypass hole into the water pump where it goes around again..

this closed thermostat operation has several good reasons..  the constant flow around inside the engine picks up heat gradually.. evens the internal engine temps as it takes a while for the coolant to pick up enough heat ..

the flow going thru the bypass goes right past the brass bulb in the thermostat.. if there was no bypass.. how long would the blocked coolant flow take to get enough heat to open the thermostat..  its just going to sit and boil around the exhaust ports and around the top of the cylinders...

the 1/2" hole that is the bypass under the thermostat.. there is a good reason for the smaller opening..  think of the mechanical pressure created by the water pump above the cooling system at speed..  this is going to raise the pressure on the coolant inside the block and heads... each pound of pressure increases the boiling point of the coolant 3F...  so 3F x 15 at the cap is 45F increase.. think of the massive amount of flow the water pump can create with the thermostat out.. now block that with a 1/2" hole.. and you are going to have significant mechanical pressure inside the block and heads .. this is the other reason that the heater core gets as much circulation as it does.. the mechanical pressure behind the closed thermostat..

the water pump housings with the GIANT opening for a bypass.. were probably designed for nascar racing to keep as much coolant flow around inside the engine and reduce pumping pressure restrictions..  i don't have any proof of this other than completely understanding how the cooling system works..

want to see whats happening.. hook a pressure gauge to the heater hose fitting.. the same one in passage with the thermostat.. not the one that goes back into the water pump ..  rev the engine and with a thermostat you will have mechanical pressure above what you measure at the radiator cap... use a 50 pound gauge..

this is something that you should probably perform as its a cheep test and you seem to have an under drive pulley on the crank.. that will slow down the water pump and fan.. increase your top end power at the cost of overheating at idle.. a very expensive trick of the week part.. (read the HRM article called the surfers)

i have not personally tested this. but its real.. there was an image from a water pump design test on their dyno mule.. it was studded with temp gauges and pressure gauges.. not just in normal openings.. this engine was drilled and tapped all over the place...

invest 25 to 40 bucks in an infrared non contact thermometer..  wave it around the engine.  if you find the front of the heads cooler than the back of the heads.. you will find you have the gaskets on wrong.. or a mix up with 440-3 motorhome industrial engine parts.  i love 440-3 motors.. something that can drive a massive irrigation pump 24 hours a day or push a massive motor home down the highway without issues.. is impressive..


now.. why the slow build up of heat...  all those holes you drilled..

thermodynamics is not a light issue on engines..

with the coolant flow thru the radiator blocked by the thermostat. this leaves the coolant in the radiator almost completely stationary.. so the ram air thru the grill and the radiator cooling fans can take the heat out of it...

with so many holes.. you are circulating coolant from the engine to the radiator and back to the engine so fast that the fans or ram air cannot cool the flowing coolant.. eventually the temp of the coolant in the radiator outlet is above the closing point of the thermostat... at this point its going to be a runaway cooling system..  as the thermostat will open farther and farther.. until its wide open.. the water pump is going to be pushing the coolant thru the radiator at high speed..

think about this.. you are eating a bowl of hot soup.. take a spoon full and blow on it to cool it..  easily cooled..  now.. try blowing on it as its scooped into your bowl..  that's not going to cool it very much either.. try blowing on it.. as the waitress has brought out the 5 gallon pot and is pouring it into your bowl.. blow on that ... as hard as you blow.. you are not going to make a difference..

put a 192F back in it..  if you are really worried.. put a 1/16" hole in it..

this will keep the coolant circulating inside the block and heads while the coolant is mostly stopped in the radiator..

if you really needed a hole in the thermostat.. they would come drilled..  thermostats on some applications actually have a rattle valve.. some are a trapped ball bearing.. that when there is coolant flow.. it pushes it against the opening. but when there is air .. it does not have the ability to push the ball bearing against the hole..  these thermostat are usually found when in applications with the thermostat mounted on the vertical opening.. on its side.. not flat.. with the check valve at the top..  this takes care of the bubbles that form after a hot shut down where the internal engine temps are above the boiling point of the coolant..


now.. why a 192F thermostat.. a 180F will also work in some areas..

there is a greater difference in coolant temp in the radiator and the ambient air passing thru so it looses heat faster...

with 13 to 16 pounds of pressure at the cap.. this takes the boiling point of the coolant to about 265F.  read the percentage label on your coolant bottle..

current engines normally operate with 192F thermostats and have coolant temps from 195 to 230F without any issues..


radiator fans..  mechanical fans.. does the fan create enough pull thru the radiator to hold a shop rag flat when you raise the engine speed..  like i said. there are various sizes and shapes of blades to move air at different speeds..

fan clutches.. the ones with the coil spring on the front face are thermostatic..
the thermostat opens and hot coolant flows into the radiator. this heat unwinds the bimetallic spring on the fan clutch and diverts the silicone oil between the two faces inside.. this turns increases the torque applied to the fan so the fan speeds up.. almost all of these are designed to operate with a 192F thermostat..

if you had a 160 or a 180 thermostat.. the hot coolant could cycle thru the radiator several times without engaging the fan clutch.. a runaway cooling system will result..

hope this helps.. it took over an out to one finger this out..  

waynep712222 waynep712222
User | Posts: 127 | Joined: 04/13
Posted: 08/03/13
11:09 AM

here is the article on the SURFERS.. where you will understand the term TRICK of the WEEK..

some guys that changed the drag racing world..  

aboutaqtlow aboutaqtlow
New User | Posts: 4 | Joined: 08/13
Posted: 08/06/13
11:00 AM

Well I started today with the fuel system, the electric pump is mounted in the rear of the car between the tank and the frame. Now first let me say that when I turned off the fuel pump the pressure goes right to 0. So first I installed a filter for fuel inj.   off the line in the engine compartment, then I re-installed the mech. pump less the arm, so I would have the benefit of the checks to retain pressure. then to the regulator, set at 6 psi when running.  I ran the car for about 15 min. in that time the temp was showing close to 230.   I used the inferred therm. and found out that the ft. of the heads read 209 and the rear of the heads were 180 so I think I am good with the head gaskets. At this point I think I have a false reading temp gauge in the car rad in 207 leaving 175,  still no thermostat yet. I will install the thermo. tomorrow and see what happens then, but I may have a carb problem or something when idling. Intake temp near carb 209  at base of carb, 178.  all looking pretty good so far  to me Still wont Idle when warm and smells very rich. more to come.  tks Anthony  

waynep712222 waynep712222
User | Posts: 127 | Joined: 04/13
Posted: 08/06/13
09:51 PM

i can help with the carb idle issues also..

please specific which brand and model vacuum assisted fuel leak do you operate..

in case i missed it..  different brands of fuel leaks have slightly different issues..

and it gets confusing to talk about a bunch of different carbs at the same time..

oh.. i am having some fun with the fuel leak.. i am talking about the carb brand model and actual carb number...

with the thermostat.. you should have EQUAL temps with only a few degrees of difference from the back of the head to the front..

are you running stock gauges????  you could also have a ground issue.. between the engine and the firewall.. as the ground is half the circuit for the gauge sending units..  dorman/ help has a great premade braided ground strap at most parts stores hanging out on the isles for 5 or 6 bucks.. works great from the back of one of the heads to the firewall..  

aboutaqtlow aboutaqtlow
New User | Posts: 4 | Joined: 08/13
Posted: 08/14/13
10:31 AM

Hey Wayne, yes I am using the stock gauges at this time. After doing some checking with the pulley supplier, he does have a alt. for the under drive, a 6.7 crank pulley which brings me close to stock.  So I am waiting on it, I will check the ground to the fire wall Tks. I am also installing a manual temp gauge under the hood. as soon as the crank pulley arrives I should know more..

AS far as the fuel leaker it is a 750 Holley sq. bore ,duel feed, single pump w/ vac. second airs. There are metering blocks ft. and back w/ adj. in front only. 30 cc pump. The # is List 3310-3   1640  w/#72 jets in the prim. and # 76 jets in second.  I am drawing a blank on the power valve, must be my age or past catching up with me!!  lol   Tks Wayne,  Anthony  

waynep712222 waynep712222
User | Posts: 127 | Joined: 04/13
Posted: 08/14/13
11:13 PM

there are a bunch of articles on the holley 4150 style carbs around..   4150s have a secondary metering block.. 4160's have a secondary metering plate..

there are a bunch of articles spread out in the many magazines on this site on holley carbs...