Running really hot! What could cause it?

[resq302]

Ok, I know in NJ yesterday it was pretty hot and humid but I took the car out to a cruise night and got stuck at a couple traffic lights.  On the highway to the show, it was running around 190 which was fine.  I then got off the highway and got stuck at a couple of traffic lights when the temp started rising.  By the time I got to the show, I was running at the 230 mark on my temp gauge.  Way too hot for me!   As the night went on, it got cooler (not much) and on the way home from the show, the temp started rising again.  Now it was going over the 190 mark on the highway!  I have no clue what can be causing this problem.  I just installed a 160 degree thermostat and had the original 053 radiator recored with a high effeciency core.  I have water wetter in the cooling system already also.  The water pump is not leaking that I can see externally and I have all new hoses with even putting a coiled spring in the lower rad hose to prevent it from collapsing.  I have a show coming up on this Sunday and will be driving the car again.  I would prefer it to be running cooler as I know the 230 is way too hot.

Any help would be greatly appreciated.  Oh, the engine in question is a 383 4 bbl bored .030 over and a purple stripe cam with specs of .450/.465.  The engine seems to have plenty of power and no coolant is disappearing, nor is the exhaust making any white smoke.  I have noticed that it is smoking a little black out the driver side but have not thought anything much of it.  The original carb was recently rebuilt/restored by a carb shop and the Carter AFB performer series was removed.  Could it be the carb causing the overheating problems?

Help is desperately needed.

Thanks,

Brian

[Plumcrazy]

What are you running for a radiator fan?
A Mopar clutch fan would be a good choice.

[grouseman]

Do you not have a fan shroud? 

A 160º stat won't reduce overheating. 

Check your timing, and running full manifold vacuum to the dist. may help. 

Maybe check your primary side jetting; give us the rod and jet numbers or dimensions for review.  But if you have 'plenty of power', you'd notice lean jetting. 

[mikepmcs]

stock gauge?

I'm following this one for future ref.

[resq302]

New sending unit, gauge recalibrated along with all the other gauges three years ago by Autoinstruments.com.  Coolant had been around the 12 o clock position until recently (last two weeks).  Everything on the car (with the eception of the electronic ignition conversion kit) is factory stock.  The 22" radiators did not come with a fan shroud for the 383 engines for some STUPID reason.  The fan is a factory (correct) 7 blade fan with out a fan clutch.  Again, something Mopar SHOULD HAVE USED!  Timing is correct as it has not changed.  The only change that I have done recently was to put the factory Carter AVS carb back on after the rebuild.  I just talked to the carb shop and they said to bring the carb down and the will check it as the AVS were notorious for running lean (according to them).  The factory carb seems to have a lack of power, not as much power as the Carter AFB performer series that I had on it prior to the swap.  I am going to try swapping the AFB back onto it and see what the results are now.

[firefighter3931]

With the recent carb install my guess is that it's now running lean. Have a look at the plugs...they should be tan/light brown. If they're white or light grey you'll need to jet up.

Ron

[resq302]

Firefighter,

How does one go about jetting up?  When it comes to carbs and me, it is like a money and the football scenario.  I just brought the carb back to the carb shop and gave them the specs for my engine.  Specs for my engine are...

Block - 383 4 bbl bored .030 over
Cam - hydraulic .450/.465 with a duration of 268/284

[grouseman]

Get the numbers or dimensions of the rods and jets from your AFB and your AVS, and report back.  What's the number stamped on your AVS body? 

In the mean time, you could swap over the primary jets, rods, springs, and cover plates from the AFB to the AVS.  They're almost identical on the primary side, although the primary cluster air bleeds and tube restrictions are almost certainly different. 

To jet up, you use either a larger primary jet (remember, AVS primary jets are different), smaller diameter rod, or combination of the two. 

[resq302]

The AVS number is 4615S.  As for the numbers on the jets, I do not have the carbs with me now as they are at the carb shop who is trying to correct the possible lean problem.

[firefighter3931]

Get the numbers or dimensions of the rods and jets from your AFB and your AVS, and report back.  What's the number stamped on your AVS body? 

In the mean time, you could swap over the primary jets, rods, springs, and cover plates from the AFB to the AVS.  They're almost identical on the primary side, although the primary cluster air bleeds and tube restrictions are almost certainly different. 

To jet up, you use either a larger primary jet (remember, AVS primary jets are different), smaller diameter rod, or combination of the two. 

The primary jetting is probably lean so it needs to be fattened up. I work with Holley carbs but as Grouseman said, a change in jet (larger) or metering rod (smaller) will get you where it should be (richer/fatter). Have a quick look at the plugs to see what the color looks like....that should give you some indication of where to go (for jetting).

Ron

[resq302]

here are the two plugs.  left plug is #8 and right plug is #2

[firefighter3931]

The plugs look white in the pic. That indicates a lean condition. Have the shop fatten up the primary jetting and that should help...a lot !


Ron

[resq302]

Ron, I  just replaced the sending unit for the temp sensor, hoping it was giving a bad reading.  After adding the coolant back in, I was running the engine and notice very tiny bubbles coming up in the filler neck.  What I am hoping is that it was trapped air coming up and out from the block and not the indication of a bad head gasket.  Correct me if I am wrong but when a head gasket goes, doesn't it usually turn the oil a milky color or you get white smoke or steam out of the exhaust?  I have none of that.  I also would not know why my head gasket would go after only about 3000 miles and within 5 years of the engine rebuild.

[dodge freak]

When I change the T-stat I sometimes add some Barr's leak in it, not everytime but once in a while.That stuff really works. Its hard to get everything perfectly seal, yes it can clog rads but if its not too old it be ok. The factory even adds some to the new cars, nothing wrong in using it. Now if they could just make stop leak for oil that works.

[Plumcrazy]

You can have a bad headgasket without getting a milky appearance in the oil.  It just depends on what area of the gasket is leaking.
The bubbles will stop if they're from trapped air in the block.   If not, you could try re-torquing the head bolts.

[Rolling_Thunder]

i am running the same exact engine...    383 with 268-284* cam...     Edelbrock 4bbl however....    750cfm...           my temp gauge was hitting 230* for a while there...     my temp sender(s) were not accurate....   i tried 4 - three gave the same result of 230* - the 4th gave me a reading of 180*...     

[firefighter3931]

Ron, I  just replaced the sending unit for the temp sensor, hoping it was giving a bad reading.  After adding the coolant back in, I was running the engine and notice very tiny bubbles coming up in the filler neck.  What I am hoping is that it was trapped air coming up and out from the block and not the indication of a bad head gasket.  Correct me if I am wrong but when a head gasket goes, doesn't it usually turn the oil a milky color or you get white smoke or steam out of the exhaust?  I have none of that.  I also would not know why my head gasket would go after only about 3000 miles and within 5 years of the engine rebuild.

Brian, it's probably just same air caught in the cooling system. Run the engine with the cap off and bleed the air out of the system. For future reference ; when changing the thermostat, drill a 1/8in hole in the outer band....this helps to eliminate potential air pockets. Don't overfill the rad...leave it 1in from the top to allow for expansion. You can also put the car up on ramps when bleeding the cooling system....this does help.

If the problem persists and you suspect a blown head gasket a pressure test can be done to see if there are other issues. Start by bleeding the cooling system with the cap off and the front end elevated. I'm assuming that the carb has been rejetted as well which will help to keep it running cooler. Ignition timing also has some influence on temps....retarded timing will make it run hot because fuel is burning in the exhaust instead of in the chamber.


Ron

[resq302]

Ron,

so the more advanced (before top dead center) I am, the cooler it will be?  I know that the engine ran great and had excellent throttle response with it REALLY advanced.  The vacuum advance is disconnected all the time and I am just using mechanical advance weights for my advance.  I found with the cam that I have, around 2000-3000 Rpms, the engine would start bucking.  I will try running it some more tomorrow.  The 160 stat already already has a small pin hole that I put into it to relieve any trapped in air in the engine prior to the stat opening up.

I am really hoping that the small bubbles are just air bleeding out and not a head gasket problem.  I should be able to rule out any head gasket problem with pumping up the pressure tester to 16 or 18 psi and checking for the pressure bleeding down right??

[firefighter3931]

Brian, if it holds 14-16 lbs with the pressure tester then it's fine. Leave it pumped up for a few minutes to make sure. Try bleeding the cooling sytem as described and see if that eliminates the problem.

Generally, the engine will run better with the right amount of advance. With the Magnum replacement cam it should have ~16* at idle and 36-38* at 3000 for best performance. You could map out the timing curve in 200 rpm incrementals starting at idle and keep going until it stops advancing. Record the numbers and post them so we can see how much mechanical advance is built into the distributor. The curve can then be tweaked for best performance.


Ron

[resq302]

Ron,

Well.... Good news it seems.  I started up the charger today and put it on  ramps letting it run with the rad cap off and raising the RPMs every now and  then.  I did see bubbles coming up from the fill neck of the rad still, some larger ones and some smaller ones.  The good news is that with the rad cap off, the temp  gauge was about 180 or there abouts.  A little to the right of the 170 mark.  I installed the rad cap and let it idle for about 10 minutes and it went up to 190.  Just shy of the 12 o clock position.  I took it out for a spin around town and it dropped back down to just over 170 where it was when the rad cap was off and idling.  I took it then for a spin on the highway close to me and ended up getting stuck in slow moving traffic and the temp started raising up again to about the 190 mark.  After I got it home, I let it idle for some more and it crept up some more with about 5 mins of idling it was just to the right of 12 o clock position.  Still well within the normal range and still had plenty to go to the 230 mark.  Sooooo..... it looks like there was air hiding in the system somewhere.  Hopefully it is fixed now and when my other carb comes back from the carb shop, it will have just as much power as my AFB does now.

I will keep everyone posted as to what transpires with the show I am going to
this weekend.  Thanks for everyones input and hopefully we got this gremlin out of the engine.

Brian

[firefighter3931]

Great news Brian  ....it appears there was air trapped in the cooling system. It'll be interesting to see if the richer carb helps even more....for sure the current carb setup is lean. Keep an eye on those plugs and shoot for a nice tan color.

Ron

[resq302]

Ron,

I was always under the impression that a whitish tan color on the porcelin meant that the engine was running good.  Black was running rich, etc.  Greenish tint or crust on the porcelin meant there was a head gasket problem, etc.  Also, the thing is with all the additives in the gas today, you always get a tanish tint no matter what.

I also did a pressure test and the needle was falling every so slowly so if there was a leak it is or was a very very small one that might even seal itself.  I think the next time I have the valve covers off I am going to retorque the head bolts also just to be safe.

As for the timing, I wish I had a digital timing light.  All I have is a VERY old one from sears that just has the strobe timing light on it.  Right now I just tuned it by ear and took it for a ride and adjusted as necessary.  I will say that the engine is really responsive now and sounds mean as hell too.

[firefighter3931]

Hi Brian, a tan(ish) light brown is what you should have if the jetting is in the "safe zone" as i like to call it. True, it can make more power if it's on the ragged edge but you risk hurting the engine....not really worth it, inmo.

In the pics, the plugs look white (on my monitor)...what color are they ? If they're closer to tan than white and have some color then you're pretty close. 

As for timing ; you could get some timing tape from your local dealer and install it....then your old Sears gun would work for fine tuning. Fwiw, i have the same timing light and it works well as long as the balancer is marked. 


Ron

[resq302]

Ron,

The one plug that was tan on the side facing the camera was white on the other side, vise versa for the other one.  They were not perfectly white like a brand new plug is but you could tell they are worn.  Also, if I remember correctly, the plugs I installed in April before the show season, so they might have a new look to them still.  Possibly the reason for the white areas still.  I do know that when I "punched it" floored the gas pedal, I got a cloud of grayish black smoke out the exhaust when I was on the highway the other night coming home from the cruise night.  But it only did that when I floored it at first then the smoke went away as I kept accelerating.  I seem to recall most carb cars did that.  If I have a chance tomorrow, I will pull the other plugs since the engine will be cool so I don't add anymore battle scars on my arms and hands.   

Seems to be running really good today.  Hopefully the trend continues.

Brian

[firefighter3931]

Ron,

I do know that when I "punched it" floored the gas pedal, I got a cloud of grayish black smoke out the exhaust when I was on the highway the other night coming home from the cruise night.  But it only did that when I floored it at first then the smoke went away as I kept accelerating. 

Brian, the full throttle black smoke "cloud" is a product of jetting on the secondary side of the carb. Once the primary side is jetted correctly then the back needs to be dialed in. Isn't carb tuning fun 

Honestly, a little black smoke wouldn't concern me too much...a little rich is better than too lean.  As long as the plugs don't foul then it's not really worth losing too much sleep over. Fwiw, i've had good luck with NGK's in BB mopar applications....


Ron