cast iron water pump vs aluminum pump

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bigmoe

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got a 340 in a 65 Dart GT ,it was partly assembled so I don't know whats all in the engine. It overheats after about 20 minutes of driving, have tried 160,180,and no thermostate, 3 core 22" aluminum radiator, with flex fan/and shroud,and even a 16" pusher in front. still slowly gets up to 230f. gets there quicker in traffic. It has a 5" crank pulley and about 7" water pump pully. Will a newer style aluminum water pump help my problem?looks like they use bigger dia crank pulleys and will the the 1970 up crank pulley bolt up to my old balancer? I know the inlets will be on opposite ends and timing marks will be blocked by lower hose and I will probably need another radiator but I am getting desperate. All I know about the engine is it has a big flat tappet cam , Venola pistons, eddy dual plane intake and stock cast exhaust manifolds.
 
My 2 cents:

I think you are treating the symptom, instead of the problem. The later style aluminum water pumps, pull from the passenger side of the radiator, instead of the drivers side, like the early cast iron units.

Is it running lean? It sure sounds like it to me. Can you read a plug?
 
plugs are grey/tan when pulled after cruise shut down, and they are tan/to light black after extended idle check. I found a post about a radiator support seal that mounts to the hood, mine was missing. made a rig with some 1" id water pipe foam and drove it again tonight.now it seeems to hold temp just under 220 at cruise, but still wants to climb in traffic. Could the stock exhaust manifolds be holding back to much exhaust and maybe causing or adding to my heat issue? I have a set of tti headers on order so I will find out soon enough they help or not.
 
radiator is a new aluminum 3 core 22" champion, and cooling system is clean&green, is anybody running a cast iron pump with a built 340 and if so what is the diameter of the crank & water pump pulleys? My car has a 5" crank pulley and 7" water pump. I was wondering if someone put an underdrive pulley system on this engine or if its stock?
 
I,m running a 408 in my 66 Dart,stock 2 core rad(recored)7 blade fan,no shround,no thermostat.I have M1 intake,Eddy heads,Eddy aluminum water pump.I alos added 1 liter of BeCool additive to water(racing)My car runs very cool and have never seen it past 180 on a 90 degree day.Your either too lean or timing is off?With the new 3 core alumi rad you should be running cool.Maybe try some of the additive?
 
Hi big moe, had the exact same problems your experiencing with a 68 Barracuda 318 I once owned, tried all the same things you did, and then I decided to haul off the intake manifold one day, was going to put on an Edelbrock. Discovered all the cooling ports on my heads where all blocked up with that rad leak additive crap, from the previous owner. Problem was fixed after clearing out all those coolant passage ways.
Not saying for sure that's the problem on your car.
 
Cast Iron Water Pump: diameter of fan pulley is 6 1/2" and crank pulley is 6 3/4"(original stock pulleys for sixties 318, 340)
Aluminum Water Pump: diameter of fan pulley is 6 3/4" and crank pulley is 7 1/4"(original stock pulleys for seventies 318, 340)
If you decide to change to an aluminum water pump you will also need to change the alternator bracket, if you have power steering, that bracket also, otherwise none for the pulleys will line up correctly, not only does 70 and up pulleys have a larger diameter they also have a different offset they are deeper or taller. The v-belts might need to be changed, they probably won't be long enough.
Milodon makes a high flow mechanical cast iron water pump part #16251
 
Looks like an underdrive pulley on the crank.
 
The high flow milodon is a misprint not a high flow ask me high I know. Flowkooler does make one but all they do is take an 8 bd and pop-rivet a disc on it.
 
Useless his 65 Dart is more track then street, then obviously if he want's major flow, then put an expensive electric water pump on it. Milodon doesn't claim huge increase in flow, but a 20-25% over the original which is better then a kick in the ***. For people with a car that's more street then track and want to keep the original appearance of some external components then the Milodon water pump is the one to go with. If he changes to a different water pump from the cast iron style then you know as well as I do he will need to fork out cash to change all the other components around it inorder to accommodate it. Yes the Milodon pump has an 8 blade instead of 6 and a full disc instead of an X. It also has a high end bearing to insure better revolutions and a better seal for longevity. With all that being said, he might not even need a pump, problem could be something else.
 
sounds like I have an underdrive crank pulley because it's 5" diameter,I sincerly appreciate all the input from all of you, I checked Mancini and Year One they only stock 1970 up pulleys, Anybody want to sell a set of correct ones for my application? I think the place to start here is to get my pump spinning at correct speed and then see if it helps my problem, before I look for another pump. Update I also had the recovery tank snifed for hydrocarbons from cold up to 220 on gauge and none were present, so that should eliminate a headgasket problem. As stated earlier I think mixture is close, and i have experimented with timing from 8 to 14 inital ,12 degrees seems about correct for my cam but I do not what the total timing is, Distributor is also an odd ball it has a GM style HEI cap with internal coil,(never seen one on a Mopar before).
 
I'm curios to see if a bigger pulley solves your problem,I just bought a 360 with a 5" on the crank.
 
I found some different pulleys to try crank is now 6 3/16" dia, fan is now 6 7/8" dia, they must be mix matched because I had to space out the fan pulley, and re position my alternator a little,anyway I had the car out for almost 2 hrs today in 86 degree weather and the temp gauge stayed at 180 rolling and 185 in traffic, the odd thing I still have the 160 thermostat in and even with the pusher fan running it won,t cool down below 180. I can live with this compared to 220-230 I was seeing. I think if I ever find the correct size pulleys or maybe change to the hi flow pump it may get a little better yet. But for now its running and my new tti headers/exhaust sound real sweeeet.I am a happy camper Bigmoe
 
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