2nd Test Drive 1970 Duster Rebuild

[KMS]

Just an update on some discovery and one question;

Temperature was up over 70F today se we thought this would be good to test out some of the overheating problems we had back in October when the temperature was ambient 50F and we were seeing the temp gauge up to 220F on the Duster. Temp gauge is acurate as tested at 140F where the gauge showed 145 and actual temp of the liquid was 140.

We put a bigger raidiator in ( a new 3row soild coper core out of a 1970 big block Chevy Bellair) , changed to 160F thermostat, reduced the bypass hose size 7/8" dia, installed a heater, installed a 3000cfm electric fan as a pusher, and put 17" flex fan on the water pump.

It still gets up over 195F tooling around slow about 200F (less than 30mph) and holds 195F at idle.......195F at 45mph. This is not what we wanted. We are hoping to get it down to 160 all the time. I guess I will have to try and find...or build a shroud and I was hoping to avoid that. Any ideas on this I would appricieate. Where can I find a shroud for the 17" blade and a close fit for the Bellair rad?

Intersting discovery when we put the new 90/10 Lakewood front shocks on today;

We took a look at the torsion bar adjustment bolts and we could plainly see that very recently someone had lowered the tension (red rust in the threads and a line where orginal undercoat still remaned on the rest of the bolt).

So we turned the bolts back to the spot where the undercoating line was and presto the car sets level in all directions and the header that we dinged last week on our first test ride is now rideing 3" off the pavement (it was riding 3/4" off the pavement and the driver side control arm stop is gone). So we decided to take it for a drive.....we did not manual shift....just left it in auto and everything seems fine....I didn't notice any significant or noticable things I can say about the 90/10 Lakewood shocks except I paid alot of money for them.

I put the gas pedal almost to the floor at about 40mph where this brand new 408cci Crate 360Mag stoker with 750 Edlebrock carb and high rise with a brand new 3800 stall converter from Turbo Action in a brand new rebuilt 727 with 4.10 posi sounds great, has fair exceleration....but did not break the tires loose. I'm not sure if this Duster would have out run my 1984 turbo Lazer with the 2.2 4cyl....which I no longer have....sadly.

Maybe we will have a better run next time shifting into manual mode and runing through the gears at higher RPM......I hope.

Any advise on this?

Thanks,

Kurt

[RacerHog]

Sound to me like the wrong water pump pulley to drive the pump...

Driving her to slow....

Must have a fan shroud...For sure.......

hi-flow water pump a must....

180 thermostat....better for the block,oil,cooling system,fuel,and street driving...

As for it being a Dog.......408 maybe with that old lazy mopar 300dur./509lift cam????? I've only found that cam to work if you leave at 4500rpm and your matted all the time....

Try drive it up in the working power band and see who she likes it......

Just my 2 cents

Keep us posted on what you find....

[TrashedCharger]

I assume that you aren't running a pulley driven fan with that electric fan? I've actually discovered in any car with an alternator that it is just as efficient to run a six blade clutch fan, even with no shroud, in comparison to an electric fan, only you lose all of the quirky problems that come with running a single speed electric fan.

The alternator ends up pushing more volts to keep that electric motor running with everything else and because of that, you end up with more electrical resistance inside the alternator. This ends up creating about as much additional drag on the alternator pulley as you save from going away from the pulley driven clutch fan.

The only thing that you gain from an electric fan over a clutch fan is more fan RPM at idle and the ability to run a fan when the engine is off, but sometimes that's not a good thing.

Unlike factory cars that have at least two fan speed settings controlled either by a thermostat switch or by the ECU itself, most aftermarket electric fans don't vary in RPM, so you usually end up with too much fan at idle and not enough on top end for any length of time longer than 15 seconds, or you end up with enough at top end and way too much at idle, if the fan gets more power.

This usually contributes to switching your thermostat on and off constantly, messing with the flow of your cooling system. Especially if you run a hotter thermostat. I've seen cars with electric fans that overheat at higher RPM, then drop below the thermostat openning point at idle. Then the driver thinks that it's okay to get back into it, the engine heats up again, only to not have enough fan at high RPM and the cycle repeats.

The reason most new cars run electric fans is because they want to keep the radiator at the front of the car and want to run a horizontally opposed cylinder bank configuration.

195 degrees is perfectly acceptable for average coolant temp. Your engine's oil runs at an average of 212F. You shouldn't be having any overheating issues with your list of gear, even with the added heat of headers. As a matter of fact, your fuel is designed to atomize inside your intake manifold at 195F. Any colder than that and you are actually hurting fuel economy and robbing your engine of torque and horsepower, because your fuel isn't doing what it should be doing and your oil is not up to full running temp and has added viscosity at colder temperatures that create more motion resistance inside your engine. Multi-grade oil is designed to run it's best at 212F oil temp. You need to be running at least 180F coolant temp to acheve that.

Whenever I drag race, I make sure that my car is at running temp at the staging beams. Everyone that I race with does the same and we usually end up in the final four because of our consistancy and we can expect our numbers to be the same every time.

A 160 degree thermostat will not usually keep an engine at 160 F unless the ambient temperature outside is cold. a 160F thermostat is designed for warmer climate and operating temperatures. Sometimes in order to run at 180-200F water temperature, which is right about at 212F average oil temp, you need a thermostat that opens at 160F, but this doesn't mean that it will run at 160F. It only means that the thermostat opens at 160F.

My Scamp has a POS 2 row radiator that weeps at full throttle (soon to be replaced) and had a 160 thermostat in it on a tired 318 and I couldn't get it warm enough to defog the windshield when it rained in the summer. It was one cold blodded bitch.

I recently replaced the thermostat with a 195, because that's what it came with from the factory. The car seems to get better fuel economy, more power, my heater works like a charm and I haven't had any overheating issues at all.

What kind of antifreeze are you running? You may want to double check your mixture, just to be sure. I've made that mistake once. You might also want to run a high flow water pump and a smaller pulley as suggested above.

[KMS]

Racer Hog

Thanks

the specs on the cam;
Hydraulic Flat Tappet
Duration @ .050'' Lift: 233 Intake / 240 Exhaust
Lift: .474'' Intake / .474'' Exhaust
Lobe Separation: 110°

I have no idea what those numbers mean and I guess I would have to do some deep research to understand it.

The water pump is Edelbrock....that's all I know about it.

I think you hit on a point about the pully on the pump that could help.

We bought pullys for a 360 without AC. The pully is 6.75"dia outer edge and inner V is about 6.0"dia. The alternator seems to charge correct so I guess the main pully is OK....but there is room for a smaller pump pully. That would also rotate the fan faster too and I notice that the fan is not that noisy.

We did not get up over 60mph when I nailed it. The speedo is set for larger tires which you know we are trying to get lined up...so yes we were driving slow and hit many stop lights with only about 3min of steady running time at 50mph according to the speedo....which is fast right now.

I think 45mph on my speedo = 38mph actual because the correct speedo gear for my tires, ring gear, trans is 45 tooth but I have a 38 tooth.

Blueprint engine manufacture said to use a 160 thermostat but he said, "I think we run the 160 on that motor". I know that the Chrysler Service Tech Training manuals say 180 for all Chrysler durring the early 1970s.

Why is a little hotter than 160...say 180....better for oil and so forth?....just trying to understand for which this is not explained in the service training manual....except they say, "it works better".

I have looked everywhere for a shroud but can only find two that I would need to modify (I have the radiator off center of motor over on the passenger side about 2.5 inch). If I have to modify where I buy metal, cut, bend, weld, rivit and so forth I might as well make my own shroud. And I thought I was done cutn, weldn, grindin, filen, drilln, bendn.......and measuren.

The easiest thing to start with would be the pully and I had not even come close to thinking of that. I'll change that first and then see what happens.

I sure am glad I joined this chat page....you guys are great.

Thanks for reading my long posts and for the advise which I am positive will make a difference.

Kur

[cudabob496]

I have a 72 service manual for my Cuda. It lists possible causes of overheating: blocked radiator air passages, incorrect timing, low engine oil, incorrect valve timing, bad temp gauge, restricted overflow tube, faulty rad cap, frozen heat control valve, dragging brakes, excessive engine idle, frozen coolant, faulty fan drive, faulty temp sending unit, faulty vacuum bypass valve, overfilling, insufficient corrosion inhibiter, blown head gasket, broken or shifted lower hose spring, low coolant level, collapsed rad hose, fan belt lose, glazed, or oily, air leak through bottom hose, bad thermostat, water pump impeller broken or lose, restricted rad water passages or restricted engine water jacket.

[KMS]

Trashed Charger,

I have both electric and pully driven.....and I agree I should not have this issue especialy with the three row giant all copper Bel Air radiator.
I even cut out 2 inch of the core wall on the passenger side to get all the rows in the ram air flow and the electric fan 16" dia is a pusher (3000cfm) which is off center (passenger side) where the pully fan 6 blade 17" dia(no clutch) is off set on the dirvers side.

I have several friends with the pully flex fans 6 blade and no shroud and they run cool too, with no electric fan.

My electric fan is on a toggle switch....I only wanted to use it after a race at idle but I need it for idle all the time to hold 195 with the 160 thermostat.

I agree with your enegy consumption logic for electric vs machanical.....actualy.....if the blades are made correctly on the mechanical fan it will out do the best electric fan by about 15% less power consumption for the same amount of air flow. This is due to loss of energy through the resitance in the wires and windings and bearings of the armature. The mecanical fan is just piggy backing on the water pump which has to turn no mater what......so you can't count the firction loss at the belt/pully or bearing friction in the pump for the mecahincal fan....the only friction for the mechnical fan is the friction of air....which we also have the same air friction with an electric fan so the air friction cancles out as an "even steven" in the comparison of energy consumption.

I'll try changing the pully first and let every know how that goes....I'm sure it will make difference with all the radiator I got on the core wall.

Thank you,

Kurt

[KMS]

Originally Posted by cudabob496

I have a 72 service manual for my Cuda. It lists possible causes of overheating: blocked radiator air passages, incorrect timing, low engine oil, incorrect valve timing, bad temp gauge, restricted overflow tube, faulty rad cap, frozen heat control valve, dragging brakes, excessive engine idle, frozen coolant, faulty fan drive, faulty temp sending unit, faulty vacuum bypass valve, overfilling, insufficient corrosion inhibiter, blown head gasket, broken or shifted lower hose spring, low coolant level, collapsed rad hose, fan belt lose, glazed, or oily, air leak through bottom hose, bad thermostat, water pump impeller broken or lose, restricted rad water passages or restricted engine water jacket.

Some of those items are possible most should not be as the radiator is brand new, ....everything is brand new and I ran it all for about three hours running time and flushed the entire system before this 70F nice day we had today.

I was running 160F when it was 30F outside...no problems at all.

But I did add fluid one quart....I'm using prestone.

Overfilling? How would I do that?

Air passages in the radiator? Where are those at?

Thanks for your training manual tips.....I guess I need to get a book...it might have saved me on some other things already down the drain.

Kurt

[TrashedCharger]

To answer your question about increased efficiency at higher running temperatures than 160F, it's just basic fluid physics and thermodynamics.

On the fuel end, your fuel atomizes into a gas vapor inside your intake manifold at 195F. If it doesn't get to this temperature, the engine is simply wasting fuel. Full fuel atomization needs this temperature along with air and liquid mixture to complete the formula to change fuel from liquid into vapor. Keeping the engine at 195 helps performance for economy, torque and horsepower.

On the oil end, the viscosity reaches it's rated numbers at 212F. This is the average temperature of your oil that comes from it's hottest points (bearing journals and cylinder walls) to the coldest points (inside your pan and filter). This does not reflect the temperature of the coolant, but your engine's coolant temperature should be at least 180F to acheve 212F average oil temp.This temperature gives the oil's viscosity the perfect combination of strength and flow.

When the oil temperature increases to 212F average, your oil pressure will drop, because the viscosity becomes thinner. This will cause flow to increase between the bearing and journal surfaces, flowing more oil between the contacting surfaces of your engine, making it run cooler in it's hot spots and gives better lubrication and less friction and drag.

It all adds up to getting more efficiency (not to mention more life) out of your engine.

Make sure you are not using a flex fan for your pulley driven fan. Those are worthless. A friend of mine ran one on a '67 Plymouth Sport Fury with a Chrysler 3 row radiator with a non clutch pulley drive and it caused his car to overheat. He went with a seven blade without a clutch and it ran too cold. Then he used the same fan with a clutch and it runs perfect and has WAY less fan noise.

Your two fans are fighting eachother, even if they aren't creating turbulence from being out of center from one another. Running two fans in trijectory of eachother, even if perfectly centered and creating no turbulence actually doesn't benefit flow. In fact, it detracts from it.

If you think about one fan blade spinning in front of another, the fan blade that is behind the other in the direction of the air flow is just being blocked and deprived of it's air flow, while at the same time, the one in the rear is blocking the pressure being created from the fan in front.

Think about what happens when you put a piece of paper in front of a box fan. Or better yet, a toy windmill in front of a fan. Even though the windmill is spinning, it does decrease flow, increases drag and will slow the fan down.

The only time the two fans in the same trijectory, pushing air in the same direction will not fight eachother (one decreasing the other's flow, either from in front or from behind) is when both fans are going the exact same speed. And at that point, you might as well just be running one fan with more blades. It will likely be more efficient than the two fans going the exact same speed, regardless of the other electrical drag factors with running an electric motor.

Personally, I would ditch the electric fan and get the system running par without it. Redundancy is usually the equation of a problem that could be solved easier.

I think the manual is suggesting that overfilling the oil could cause it to overheat, due to the crankshaft whipping air into the oil, then feeding the foamed oil into the bearings, which won't cool or lubricate the bearings as needed.

Is your block new? That edelbrock water pump may be the problem. I know that some water pumps are designed to spin in the opposite direction. They will flow in the wrong direction, but rather poorly.

The stock Chrysler aluminum water pump works good enough on cars set up correctly that you usually have to take some measure of increasing the temperature on a small block. That was done at the factory by running a 195 thermostat and a clutch fan.

When my friend went to that 3 row big block radiator, he had problems with his heater not working, or working poorly when it did. These engines usually run too cold, unless something is in need of attention, like fouled cooling passages in heads or a block or calcium deposits in a radiator, blocking rows.

When you start to hot rod a small block chrysler, they can get hot easier, due to the added stroke and/or bore, increase in BTU's from running higher octane fuel and running more advance. This is probably why they suggest to run a thermostat that opens up at 160 to get it to run at 195-200.

Remember that the rating of a thermostat is only where it opens. This doesn't mean that it will get the engine to run at the openning temperature or was even designed to. It's number is only the temperature rate that it needs to open in order to get the engine to run at whatever temperature the system is designed for and that's all that it means.

You may want to double check your ignition advance. If it's getting too much, it can increase the temp of your engine significantly.

I would also check that radiator out a little closer and maybe have it tanked, or get another radiator that you know is good without a doubt. You could have just swapped one set of problems for another there.

[KMS]

Trashed Charger,

Thanks for the detailed explinations.

Yes it is new block....this engine is manufactured as a full dress engine by Blueprint Inc and came with the Edelbrock water pump.

Fan clutch will not fit...no enough clearence between pump and radiator.

I thought...160 was my target temp....but now I understand that is not the case.....this helps a lot.

I understand what you mean about two fans push and pull, but it runs cooler with both fans in operation at idel, and it runs cooler with just the mechanical fan while the car is in motion.

I only have the electric fan to get coverage of all the rows due to no shroud at idel, and that seems to work.

Everything worked OK except tooling around at very slow speed....less than 40 mph.....temperature kept rising and got up to 210 quickly and was still on the rise.

there is one other item I did not mention;

I have an over flow tank on the over flow tube where the radiator remains full all the time, with a 16 psi cap. I wonder if that could be part of the problem as the training service manuals state the radioator to be filled to about 2-inches down from the cap to keep air in the top tank.

gota go to work,

thanks

kurt

[drag duster]

Hi Kms--didn't Know About Your O-heat Problem Til Now,read Over This Thread Rather Quickly,may Have Missed Something,but---as You Know Our Cars Are Somewhat Similar,so Let Me Share Our Exp.
We Have A Stock 340 W/a Larger Cam Than Yours,in Our Never Ending Quest For Quicker E/t We Have Progressively Increased Carb. Size,finally Maxing Out At 930 Cfm,along With Better E/t We Also Noticed Each Time We Changed Carb/engine Temp Decreased--i Think That Like Many Folks Ive Found On This Site Your Big Stroker Is Undercarburated. Other Thought Is Ign. Timing,how Much Total?how Much At Idle? & What Type Advance??

[dwc43]

I finaly found your overheating thread we talked about in your other post. I agree with drag duster. I skimmed over the posts quickly too. And drags right, your way under carbed and that edel is not that good to sart with anyway. Even if it was not undercarbed you would be giving up quite a bit of throttle response using that carb.

Get rid of that gm rad cause it will be prone to air loc the way you mounted it in that car. Get you a standard two core rad to fit the car. Very seldom do you need more than that. Stock 3 and 4 cores tend to block the air flow through the rad cause the fins are too close together and all of the aluminum rads we use in our race carsw are two cores. And the few aluminum race rads that are 3 and 4 cores have much wider fin spacing to increase air flow.

Set you timing to 36* total and get an 850 TQ and make sure it's jetted correctly and you'll cure the problem and add some more hp and throttle response to it as well. Timing anad carb jetting and size can effect the cooling system. And running it at 160 is too cold. 195 is perfect as long as it's maintained. It helps atomize the fuel and keep cylinder pressures at the right levels as well. Too cold is just as bad as too hot.

[drag duster]

I Agree With Dwc,except----we Use An After-market Alum. Radiator From Summit,very Pleased. Forget The Tq Since Youre Going For Performance,double Pump Holley--at Least 850 Cfm.--& Finally I Perfer 180 Degr.,but 195 Is Better Than 160--still Curious What Type Of Advance Your Ign. Has

[dwc43]

Originally Posted by drag duster

I Agree With Dwc,except----we Use An After-market Alum. Radiator

We have them in our race cars too. I think it's a two row 1.25 inch wide tube. Use it for weight reduction more than anything else since the stock 2 row kept it at about the same temp as this one. Also use that 6 blade 8000 rpm rated plastic flex fan. Talk about a weight savings over a steel one or an electric one. Wont let us run the electric ones in our class anyways.

And one mroe think if it was not mentioned about your car KMS. That pusher fan on the front of your rad blocks the air flow from the grill at highway speeds. The grill area is not that large on these cars so flow is limited from the start. Simply pulling that fan may solve the problem if everything else is correct.

[KMS]

bummer........but glad to get the advise.

Drag duster, dwc43.....you guys are saying some things that I had thought about but had no way to verify and would cost money...delay the project...more work.

I have a stock 340 radiator....brand new...and it did not do so good but that was back when all I had was a crappy 1500cfm fan as a pusher....no mechanical fan.....I have been working on the overheating problem since October......I kept the 340 ratiator however. That radiator would allow room for fan clutch too.

A bigger carb? Boy will my wife shit when she hears that.

If I could sell the 750 it might help ease the bichin.

I'm glad I cut out around the factoy radiator mount holes when I widened the opening in the core wall...at least I can still use that as a mount. But now I would need to add metal back to block the extra open back up....right?....maybe not...maybe the 340 radiator frame will still cover.

Yep...I wondered about the ram air being blocked by the pusher electric fan.

I also notice that the 750 Edelbrock doesn't open up until the last 3/8 inch of throtle cable travel which is kind of hard to hit unless I mash the pedal to the floor.

This still might be easier than fabricating my own shroud.

I already orded the smaller pully.....$25....not sure what I will do with it.


The timimng issue.....I got a PM from a guy today about that same issue but I can not answer his PM because I do not have enough posts yet.

How do I set the angle on the timing?

I have a MSD ready to run distributor with spring advance.....the vacume advance is not connected.

I don't know what the advance is off hand but I have it on a spec sheet somewhere. I will post it later....man I got alot of responce today from this fantastic group of folks. I got a PM today that I cannot reply too yet due to my junior status. I realy like this forum and the people are great....kind of like Arron's Stomp Box forum for do-it-yourself audio giutar effects electronics.....old style FX from the 60s and 70s rock era, which I posted there for several years and learned so much from that group of guys too. Most of my metal fabrication experience came from making guitar stomp boxes.


I need some time here to read all that posted today and then some to reflect on this and figure out how to break the news to my family members.

Thanks,

Kurt