70duster 360 gets hotter the faster i go

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CurtDawg510

CurtDawg510

Well-Known Member
Joined
Nov 18, 2013
Messages
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Location
Hayward, ca
This is what i got
70 duster
The engine
360 punched .060 over with kb-107 pistons, comp thumpr cam .497/.483lift, 235/249 duration @.050, 107 lobe separation...comp cams pro magnum hyd lifters, and ultra pro rockers set at zero to 1/8 turn lifter perload....oil mods to block, stock 360 heads with 1.88/1.60 valves and open chambers, air gap intake with holley 750 dbl pumper (mechanical secondary) MSD 6a box with MSD pro billet dizzy, MSD blaster2 coil, MSD wires to champion copper plugs gaped at .040.... Headman headders to 2.5 exhaust to the bumper
Timing is set at 22deg idle/36deg all in about 2000rpm, no vacuum advance

The tranny
727 with a mild shift kit and a b&m 2400 holeshot converter

Rearend is 8 3/4 with 3.55s and a eaton tru track with moser axles

The cooling

Right now im runnin a 26" 3row radiator out of a 77 powerwagon... Its new, last brass one my local auto store had...a stock style 8 blade pump (mayb gmb makes it?) dual 12" spal fans (3100 or 3600cfm, i forget), and a high flow mr gasket 160 stat..and it has a good spring in lower hose...in front of my radiator i have a big tranny cooler off to drivers side (no name, it was in my parts pile), and a b&m supercooler engine oil cooler (the biggest one i could buy)
I can blow compressed air threw the grill and it makes it to the engine threw the radiator no prob

Ok i think i covered it all... Hood has a rubber seal in front and in back both in good shape... 1st off, im running my fans 100% whenever it hits operating temp (toggle switch inside, ill put sensor in after it runs cool)will idle all day right on 160..... So in town driveing it will start to warm up a lil 180-190, and thats perfect, if it had a 180 stat...but whatever, keep cruzin along, mayb around 40-50, temp starts gettin up to 210-220... I hit the highway jus for one exit, 235deg! As soon as rpms drop, give it 5min and temp will b down too

I have tested my thermostat in a pot of water, it opens wide and starts opening at 160, i have tryed a standard flow fail safe stat, and it got hotter quicker... B4 my electric fans, i had that low profile clutch fan, electric fans cool it down alot quicker (no shroud on clutch fan), but this seems to be a high speed problem... Also, the spal fan i have has flappers on the shroud, so when it gets airflow threw the grill, they all flap open and it gets good airflow

So only other things u can think of is a flow kooler pump, and if that dont work then mayb a cc374 radiator??.... Mayb an air dam under the bumper??

What do u guys think?? Am i missing something?? I tryed to put as much detail in as i cud think of, if i missed something, please let me kno

Thanks guys!
 
I had a problem with my 73 duster get hot like that...and went i was changing out the radiator, I found the lower hose was kinked where it made the turn to go up into the water pump...

something to look at and check off the list
 
Oh, i have an infered gun, i jumped out and did a test when idleing at 200deg (it cools down fast)

All headder tubes were right around 370-410 deg
Heads in front 210-215 both sides
Block 210-215
Intake runners 205
Thermostat housing 195
Top of radiator tank 200
Radiator core 135-150
Bottom radiator hose 185
Water pump 195

I didnt write any of thez numbers, i jus pulled over and was tryin to get a ball park figure to see whats gettin hott b4 it all cooled down! Lol

And its only like 75-80 deg out so this sux!

I also ran straight water when i broke in the engine, and now its about 50/50mix with the green stuff

I also forgot to mention, this is a fresh 360 build, and rebuilt 727.... But it had a 318 with same cooling setup b4 i swaped to a 360...the only thing that i swaped was the radiator hoses (with a good spring in lower hose)... Everything else i bought new
 
70aarcuda said:
I had a problem with my 73 duster get hot like that...and went i was changing out the radiator, I found the lower hose was kinked where it made the turn to go up into the water pump...

something to look at and check off the list
Click to expand...

Ill see if i can swap it out with another hose i have layin around the garage... The one on my car has one 90deg bend, the one i stole the spring from had two 45deg bends... And it came off a small block too!! Good idea, i hope its something lil like this!
 
I just needed to trim part of the hose off to get rid of the kink.
 
I have a very similar combo.Its impossible to overheat,mine. You have one problem. maybe two.The first is insufficient fresh airflow through the rad.The rad is unable to shed the heat. The second is the creation of the heat in the first place.
At cruising speed,say 2600rpm your engine wants in excess of 44* advance,probably closer to 50*.So if you dont have a working vacuum advance unit, thats the first thing you will need.-----------------Street cars need V-cans.Period.---------------- Once you get it on there you will likely need to slow the mechanical down to all in by 3200ish.
-When cruising,if you dont start the fire early enough, the fuel continues to burn while the piston is traveling down the cylinder. This means the cooling system is exposed to all that heat.And the loss of pressure at the top translates into less work performed and therefore more than necessary throttle opening.It may even be still burning as the piston comes up on the exhaust stroke. That means the piston has to push the hot expanding gasses out. Thats extra work for it and ergo more heat.Late cam timing can give a similar problem.
To see if Im on the right track,do this;A) remove the oil coolers that are in front of the rad and roadtest.B) remove one of the fans,and roadtest. C) crank the timing up to 40* and roadtest.Be very aware of, too much throttle, inducing detonation.Put the timing back at the conclusion of the test. Conversely you could retard the timing 20* and see how much easier it is to overheat.
My money is on the timing making the biggest improvement.If it was me Id go straight to the timing.

Dont blow it up!!!
 
OH boy. I have got to learn to type faster.
Before you get started on anything from my previous post, you need to repeat a test.
I see you posted some temps while I was banging keys.
You see where you posted rad core temp of 135* to 150*. But the lower rad hose is at 185*. If thats accurate, there is a problem, hence the request for a repeat test. And the pump at 195* that may also be a problem.
Either the pump is not circulating properly, or .................The belt is slipping, or the ratios are wrong, or there is a restriction in the rad at the outlet spout, or in the hose.
The rad is working. a temp drop of 65* is pretty good(200-135)
So repeat the tests. If results are the same, then check the belt, and the wp drive ratio(pulley sizes). if those are good, drop the lower hose and check the rad and the hose for restrictions. If none its pump time. My Milodon hi-flo is 15 years old.
Now having said all that, I stand 100% behind my previous timing statements.
BTW, you done good with posting a ton of info.
 
AJ/FormS said:
OH boy. I have got to learn to type faster.
Before you get started on anything from my previous post, you need to repeat a test.
I see you posted some temps while I was banging keys
Click to expand...

I had the stock mopar dizzy in their for the first month of runnin around...it had to much advance swing, and it didnt like the vacuum can hooked up, it wud advance at idle up and down...
I have played with timing alot with msd dizzy... Locked out at 32, 22idle/36max, even up to 30idle/44max (starts and runs good, but id rater be at 36)... None of thez timing numbers heated it up or cooled it down... Altho, first start up machine shop said 12 at idle is fine, and it was runnin way hott quick, turning headders colors other than black! Lol

Im leaning on airflow or not enuf volume or even capacity with factory radiator? Even tho its 26x18 core 3row?
U think the oil cooler and tranny cooler can block that much air flow??
Compressed air blows threw it all super easy, and the flash lite shines bright to the other side?

Im open to ideas?? I kno your good!!
 
Ill take it for a spin and let the heat soak up, then do another temp test and write it down... I jus gotta b quick cuz it cools down quick idleing...pullys are stock, the larger ones, i seen pix of the smaller pullys for ac, and i kno belt is tight and new belt...
Im leaning on the pump isnt working right... I have blasted the radiator with the garden hose, and it dumps water out the bottom hose.... I kno that stock pumps have a pretty big gap behind the impellers, wich wud let the water go wherever it wants to i guess... But then why isnt everyone having this problem?

Im with u on a dizzy with vacuum advance for a street car... But i jus dumped like 450 bux on this dizzy and the 2 sets of diff wires i need to clear my wounderful headmen headders...so im tryin to run it if i can
 
You gotta have one of the all time crappiest converters in it ever made. That thing probably never locks up as much as it should. That could be a lot of heat right there.
 
RustyRatRod said:
You gotta have one of the all time crappiest converters in it ever made. That thing probably never locks up as much as it should. That could be a lot of heat right there.
Click to expand...

Really? Its alot better then what i had b4, but that was a stock low stall, i got it cuz it said it cud handle a big block too, so i figured it wud b fine behind a small block gettin romped on all the time! Lol
 
One thing you didn't mention is whether the core support was modified to uncover the 26" radiator. A '70 should have only had a 22" opening if I recall correctly.

It doesn't seem like much but that's 4" blocked off unless it's been modified. Also, you need to keep in mind that with two oil coolers mounted in front of the radiator, all that heat shed by those coolers is going through the radiator, adding to it's job. I know you got fans in there but you may rethink your set-up. Possibly have the fans on the front pushing and the coolers on the engine side of the radiator.
 
It's not the lack of vacuum advance.

I've been running the 318 in my Challenger without the vacuum advance pretty much since I got it, over 50k miles ago. I run it at 20* advanced at idle, 36* all in mechanical at around 3k. It has a stock 26" 2 core with a straight mechanical fan (no clutch), 180* thermostat. Stock 904, stock convertor. Hooker headers, eddy streetmaster 318 intake, 600 cfm eddy carb. I've never had a problem with it overheating, even when its 110* F out. I pulled the vacuum advance because it would ping each and every single time I accelerated. I went with less advance, which it hated, I went with heavier springs, which it hated, and I dialed back the vacuum advance, which wasn't enough. Don't know. I'm sure I'm losing fuel mileage, even though I typically get 16-17 mpg highway. But overheat? Nope. Never.

The 340 in my Duster sounds more like the 360 in question, 9.8:1 compression, KB 143's, .060" over, ported iron heads with 2.02/1.60's, Lunati 60404 .513/.533, 234/242 @ .050", 110* lobe separation. Doug's headers to 2.5" exhaust, Eddy rpm air gap, now has a holley 750 DP. 4 speed. Has a Mallory unilite electronic dizzy I picked up from another member, which doesn't have the provision for vacuum advance. I run it at 22* advanced, 35* all in at 2,800. It has a 26" 3 core Champion aluminum radiator with a Ford Contour dual electric fan set up. 180* thermostat. Stock 22" radiator support. Never runs hot, fans don't even run constantly when its 110* F out. It does have a high volume water pump.

I'm not saying that running it without the vacuum advance can't be a contributing factor, but it's definitely not the whole problem.
 
"I had the stock mopar dizzy in their for the first month of runnin around...it had to much advance swing, and it didnt like the vacuum can hooked up, it wud advance at idle up and down..."
-That dizzy might have needed a bit of work all right,but the V-can hunt part of it was probably in the tune, or the hook-up.It almost sounds like the throttle blades are too far open.Which, with 22*initial, shouldnt be.

"and the flash lite shines bright to the other side? "
-If thats true that three row should be fine, and your temp readings already proved it.

"I have blasted the radiator with the garden hose, and it dumps water out the bottom hose.."
-No better test.

"I kno that stock pumps have a pretty big gap behind the impellers, wich wud let the water go wherever it wants to i guess."
-The hi-flos have a plate behind there.

-Im still leaning on the restricted lower hose. Go out and squeeze it. Every inch or so, looking for the hose to collapse. I know you said theres a spring in there but maybe its NDG. Start it up, warm it up til the stat opens, and rev it to 3000 to 3500, and watch the hose, to see what it does.If it does not collapse, shut the engine off.When its cool enough, remove the radcap,and check the fluid level. It should be about 1 inch below the bottom of the lower cap-seat.Start er up again, and wait til the stat opens. With your safety glasses on, and eyes glued to the water in the top of the tank, which should be roiling pretty good, blip the throttle a bit.You should see the water move through there pretty good. Blip it a few more times and ever a little higher.At no time should the water try to climb out the spout.Finally rev it up to 3000 or so. The water should be rushing through there, maybe with little whitecaps even, but never climb over the side. While doing this keep one eye on the lower hose.You may have to turn the fans on if the temp gets up to 200ish at the stat.But dont let it fall far enough to close the stat.
This is how it should function.
If the water wants to climb over the side, there is a restriction.
If the water does not fly through past the lower cap-seat, the pump is lazy, or theres a restriction on the suction side.
If the water stops and starts, the stat is faulty.
If the belt squeals, there is foreign material on it, and it needs to be cleaned or replaced.

BTW1, Your temp sender. Where exactly is it located?
BTW2 manual control of the fans, is inviting disaster at the worst, and premature engine wear at the least.The engine needs to get up to temp as quickly as possible and stay there. Not shuttling between too hot and too cold. I would change that to automatic control asap.
BTW3 Have you heard the expression "cutting off your nose to spite your face"? If you are going to spend a very significant amount of time on the street, you absolutely need the V-can. Once its tuned,your engine will have more driveaway,and lowspeed torque,run smoother,quieter, cooler, and get waaay better fuel mileage. The gentle tip in will be much more responsive.
And do you recall what the Mopar dizzy specs were?Typically they are a 20* sweep and all in by 3000 to 3600, and with a 20*can on it. This is more or less what I run.But then Im tuned for 87E10, and rely very heavily on the V-can.
BTW4 did you catch Tylers post#13?
Yeah I know youre almost married to what you got now. But one day you will begin to wonder.And Ill be here for you. Unless Im dead. Or they boot me off.
 
AJ/FormS said:
"BTW1, Your temp sender. Where exactly is it located?
BTW2 manual control of the fans, is inviting disaster at the worst, and premature engine wear at the least.The engine needs to get up to temp as quickly as possible and stay there. Not shuttling between too hot and too cold. I would change that to automatic control asap.
BTW3 Have you heard the expression "cutting off your nose to spite your face"? If you are going to spend a very significant amount of time on the street, you absolutely need the V-can. Once its tuned,your engine will have more driveaway,and lowspeed torque,run smoother,quieter, cooler, and get waaay better fuel mileage. The gentle tip in will be much more responsive.
And do you recall what the Mopar dizzy specs were?Typically they are a 20* sweep and all in by 3000 to 3600, and with a 20*can on it. This is more or less what I run.But then Im tuned for 87E10, and rely very heavily on the V-can.
BTW4 did you catch Tylers post#13?
Yeah I know youre almost married to what you got now. But one day you will begin to wonder.And Ill be here for you. Unless Im dead. Or they boot me off.
Click to expand...

I hope im replying to all this right... With cap off rater runs threw radiator pretty good, no white caps or nuffin, but its flowin (mayb like garden hose half on)...

The temp sensors are right by thermostat, drivers side has aftermarket mechanical gauge, pass side has stock sender for gauge in dash...
As soon as i get it to run cool, im gunna put in the temp sender so fans are on at 180, off at 170
Core support is not cut open, its only about 1.5" on both sides id have to cut out
Im about to take it for a spin and see what the temps read
 
Well good on Tyler. Those 3 inches add up to 15%. Get out the jigsaw. Do not pass go. Go straight to jail.What were you thinking?Whats the point of a 26 inch rad in a 22 inch core support? I could be mad if it wasnt at least a bit funny.You will joke about this for years.Now go push Tylers thank button.
As to cutting the core support; I think I cut the top and bottom, and then folded the metal over to 90* on mine. I thought it might force a bit more air through the core at speed.Kinda like a funnel.Since I never ran it as a 22, I cant say if it works or doesnt.But mine has shown no tendency to overheat.

So what about the lower hose?
 
Oh, and the holly has ben modified by me so its on idle circut... I drilled small holes in primary side, then closed primary all the way (off set screw) then slowley closed secondarys untill it was bairly runnin, then jus cracked open primary jus a lil to set idle... That idle screw is like 1/2 turn in... It has super crispy throttle now...cuz it was runnin on main ciruct all the time b4 and ran like crap.... I think i kno what im doin with the car... Lol
74s up front, 80s in back, 28 shooter up front, 31shooter in back... Its got 50cc pumps, but it runs better on the 30cc cams (orange), so i guess thoz big pumps jus "look cool" now... Lol
Oh and a 2.5 power valve, its about 5-6" of vacuum in gear
 
AJ/FormS said:
Well good on Tyler. Those 3 inches add up to 15%. Get out the jigsaw. Do not pass go. Go straight to jail.What were you thinking?Whats the point of a 26 inch rad in a 22 inch core support? I could be mad if it wasnt at least a bit funny.You will joke about this for years.Now go push Tylers thank button.
As to cutting the core support; I think I cut the top and bottom, and then folded the metal over to 90* on mine. I thought it might force a bit more air through the core at speed.Kinda like a funnel.Since I never ran it as a 22, I cant say if it works or doesnt.But mine has shown no tendency to overheat.

So what about the lower hose?
Click to expand...

The 26" radiator works JUST FINE in front of a 22" opening. Mine does. Yes, you are losing some efficiency because some of the core isn't exposed directly to flowing air. But, it's still exposed to air. Which means that part of the core is still exchanging heat to the air around it. On the backside it's still exposed to all of the same air regardless. Water still circulates through that part of the core, all of that extra metal is still exposed to air, and the radiator still has a larger surface area. So, it still works quite a bit better than a 22" radiator.

Not only that, but the stock opening is 22 5/8". Splitting hairs? Absolutely. But so is tearing into someone for not cutting their 22" radiator support for their 26" radiator.

And of course, the car doesn't overheat all the time. Just at speed. So, is it really an airflow problem? It would overheat at idle if the radiator was insufficient. The fact that the temperature climbs when the cooling system is receiving the most airflow tells me it's not a radiator problem. You have a water circulation problem at higher RPM's. Since you can see through the core and the radiator flushes clean, I would suspect the water pump or a collapsing hose.

And you don't need a vacuum can for the street. Might be helpful, but if it were mandatory I couldn't have put 50k+ miles on my Challenger without one. And I'm definitely not the only one.
 
Blu
If you drove 50,000 miles without a v-can, never had one, how is it you have a basis of comparison? Lets see; 50,000 miles saving just 2mpg , that would be what $600bucks at the pump? and represents what $900 at the time clock. And that would be more than a weeks wages up here. Then theres the wear and tear aspect.You know ring wear, cylinder wall wear. Bearings, etc.
And I guess youre quite a bit smarter than every factory engineer ever to design an ignition system. They are certainly a lot smarter than me.
One day you will wonder, and then you will install and tune one, and then you can come back and tell us all about it. In the mean time every dollar I save at the pumps is a dollar and a half I didnt have to earn. And I like saving $250 to $350 a year, with nothing more complicated then the v-can,especially when the taxman doesnt get 30%. That covers my annual cost of insurance.
I dont know how your car is built, but in mine the rad is behind the core, and the edges would be totally shrouded,had I not cut the sides back, rendering those 15% nothing more than heat sinks.And as to exchanging heat under a closed hood with 8 header pipes breathing fire within inches of them, Im sorry, splain it to me.
And finally, I didnt say v-cans were mandatory. I said ; street car needs v-cans.Period. post#6. Did you get that? N-E-E-D.
And how is your Challenger combo even pertinent? Its a teener/904, with a mechanical fan, and a stock TC. But if you cant tune a v-can then I guess you should rip it out.
Now as to tearing into Curt; We are now into post 19ish. By now I felt we had a good rapport going on, and felt a bit of humor was not out of line.So Curt If you were offended, I am truly sorry. The"tearing" was supposed to be a light-hearted poke.
 
I think you're chasin your tail blaming the radiator core opening, but that's just my opinion.
 
I do too. Here's something "I always post" because this happened to me. OLDMANMOPAR used to be on here posted that he thinks that "use" thermal cycling, expansion, contraction, CAN eventually break the bonds between the rad tubes and the fins.

I saw this on at least one rad shop tech page, also.

I had my original 67 rad, allowed my 360 to run hot at speed, even though a shop told me it should "be enough."

One week I threw a later /6 rad in the car--same 2 core except newer tanks off a 73. INSTANTLY the temp gauge dropped a sizeable amount, and the engine ran noticeably cooler.

WHAT IS NEEDED in the auto industry is a legitimate, repeatable, test setup to equate rad heat exchange, IE a set water flow, airflow, and BTU exchange.
 
Well, I was stuck on circulation. Somehow this devolved to 15%.
Curt dont cut the core support. Theres at least three fellas here that poo-poo that idea.Now where were we? Oh yeah.

So what about the lower hose?
 
In post 3 you stated the radiator core was 135-150? But everything else is 185 plus? Hell you answered your own question. The coolant is not getting to the radiator to to exchange heat. It's either a restriction problem or a flow problem.
 
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