Engine Running Hot on One Side

[AZCOWBO]

Hi Guys, I have been traveling extensively on business, so I haven't had the opportunity to play with the "Billet-T", much lately or chat with you guys.

I decided to polish the billet fenders, instead of painting them. They turned out unbelievable, except everyone wants to touch them, and it takes about an hour each time to polish the prints out each time it happens.

My issue now is, I recently had the carbs dialed in and the master mechanic advanced the timing considerably. The problem now is it overheats on one side. When I take a laser reading, the driver's side head is 176.6 degrees and the passenger side head reads 225 degrees. The dash gauge reads 280 degrees. I have the same 180 degree thermostat, which it ran perfect, temperature wise, prior to the tuneup.

What could be causing this?

 

[putz]

Sound like the timing is causing your problem.

 

[der Spieler]

My guess is there is too much timing and/or the passenger side of the carb is running too lean.

 

[Mike]

When one side is running hot, it's talking to you and telling you it is leaner than the other side. If the intake has been modified, it isn't right. How's the engine idling? If idle RPM is hunting and seeking, you've an intake gasket leaking on that side. If all else fails, stick another number of jet on that side and see what happens. The jet will be a crutch, so try to sort the problem by other means first.

 

[Ted Brown]

You can also find a vac. leak with WD40, spray all the gaskets, slowly, and when the engine speeds up, wolla there is the problem. retarded timing will cause over heating.

 

[AZCOWBO]

Temp. was fine until timing and carbs were leaned. I have a closed chamber Wieand Ram, how could one side be running to lean, when I have both carbs set the same, unless both are too lean for one side, keeping in mind that temp was not an issue before. I moved the timing all over the map to see if that would help. I am over carbed for the cam with the Demon Jr.525s and was told to drop them to 390s. Also, when I called Demon and Holley, the told me you can't down jet the Demons. I thought you could down jet and carb.

 

[AZCOWBO]

Temp. was fine until timing and carbs were leaned. I have a closed chamber Wieand Ram, how could one side be running to lean, when I have both carbs set the same, unless both are too lean for one side, keeping in mind that temp was not an issue before. I moved the timing all over the map to see if that would help. I am over carbed for the cam with the Demon Jr.525s and was told to drop them to 390s. Also, when I called Demon and Holley, the told me you can't down jet the Demons. I thought you could down jet and carb.

TED, WILL A VACUUM LEAK ON THE VACUUM LINE ON THE CARBS CAUSE THIS?

 

[one finger john]

TED, WILL A VACUUM LEAK ON THE VACUUM LINE ON THE CARBS CAUSE THIS?

A vacuum leak at the intake gasket is probably it. Could be blown head gasket or a blocked water passageway. You never said what the actual timing specs were and what they were changed to.
36* total, 12-14 initial, full advance by 3000 rpms. It ain't rocket science.

 

[GAB]

Any possibility that you might have an air pocket in the water jacket on the one head? If you do, it might be creating steam and a higher temperature would result. Is the sending unit for the temp gauge on the same side as the higher reading head? Have you done anything relating to the cooling system lately?

Just some random thoughts.

 

[one finger john]

TED, WILL A VACUUM LEAK ON THE VACUUM LINE ON THE CARBS CAUSE THIS?

I'm not Ted but I slept at (insert motel chain of choice) ..... Let's establish a base line.
1 No the leaky vacuum line will not cause ONE side of the engine to run hotter.
2 The engine is in good running condition, right? Good compression straight across?
3 You had problems with the ignition and changed it out, right? Did it run properly after that?
4 "Closed chamber" Weiand = tunnel ram, right? Got two 525 cfm deamons for 1050 cfm. right? Is the set up back carb provides idle mixture for all cylinders or both carbs provide idle mixture for all cylinders? Deamons are not Hollys. Go back to baseline on the carbs and call Deamon. Set it up so that BOTH carbs are used for idle mixture control. Right now the total cfm is irrelevant. I can get it to idle and perform properly with 600 cfm Hollys on it.
5 Again, what were the timing specs before/after? Was the advance as pulled from the shipping box or was the advance checked and set ON A DISTRIBUTER MACHINE?
6 What changes were made to the carbs? Be specific. From what to what.
7 When the engine is warming up, feel the cylinder heads. Does the PASS side warm up faster?
8 Is the water temp taken from the head or the thermostat?
9 Where are the infrared temps being taken?
10 If the "tune up" made it run worse, it wasn't much of a "tune up", was it?
11 Go back to original tune and supply ALL info on what was done and what was the original set up.

The more information YOU supply, the more information WE have to help you. John

 

[Ted Brown]

Sounds like you are getting some very good info, for things to check... Have you taken the thermostat out? Plug all vac. inlets to test.. try it and see if any difference is noticed... also check to see that you have no restrictions in the hot side exhaust system... Like they say, we need to know what real changes you made to get this problem... Good Luck with finding it... :thumb:

 

[72442conv]

Seems quite obvious that the changes done to the engine caused the problem. Try to go back to the old tune. Lean carbs will overheat the engine and can cause serious pinging, detonation, increased cylinder temperatures and some nice holes in the pistons. It is possible that the mixture is quite leaner on one side of the carburetors and not the other side, that can cause one side of the engine to run hotter. Check the idle mixture screws to make sure that they are not overly closed. Idle mixture screws should be about 1 1/2 turns out, and on a tunnel ram they should be about the same amount out. A very common thing that happens with carburetors that have rubber lines running to them, is that when people take the bowls off to change the jets and put them back on, inevitably a small piece of rubber breaks off and jams inside one of the jets. That will cause a major lean mixture. Normally you should never have to go higher or lower than 3-4 jet sizes. Carbs are real close out of the box. If you went less than 3-4 jet numbers you certainly leaned it out way too much. Having one primary jet jammed with a piece of rubber will cause that side of the engine to run hotter.
I hate to say this, as I may be totally off base, but just because someone is a master mechanic does not mean that they can tune an engine. Most younger mechanics have no clue as to how a carb works. you tell them that the carbs are too big and that you have too much fuel and they immediately think that putting smaller jets will fix the problem. As if smaller jets can cure and over carburetion problem. Your tunnel ram should work fine with the 525's. The factory jetting should have been very close. If someone just said lets lower the jets X amount of numbers without seriously looking at a whole bunch of things they may just have leaned the engine out. Take a timing light and put the timing at about 35-38 degrees total timing, let the idle timing fall where it will for now.
If I was you I would 1st check for vacuum leaks, if there are none I would start undoing what was done to the carbs and setting myself the timing. You can check for a plugged jet by taking the air cleaner off and accelerating the engine while looking down the bores of the carb (be careful about backfires!). Accelerate the engine to 3-4,000 rpm and you will see when fuel starts coming out of the boosters. Fuel volume coming out of the booster should look identical. If one looks weak you have a plugged jet.

 

[AZCOWBO]

I'm not Ted but I slept at (insert motel chain of choice) ..... Let's establish a base line.
1 No the leaky vacuum line will not cause ONE side of the engine to run hotter.
2 The engine is in good running condition, right? Good compression straight across?
3 You had problems with the ignition and changed it out, right? Did it run properly after that?
4 "Closed chamber" Weiand = tunnel ram, right? Got two 525 cfm deamons for 1050 cfm. right? Is the set up back carb provides idle mixture for all cylinders or both carbs provide idle mixture for all cylinders? Deamons are not Hollys. Go back to baseline on the carbs and call Deamon. Set it up so that BOTH carbs are used for idle mixture control. Right now the total cfm is irrelevant. I can get it to idle and perform properly with 600 cfm Hollys on it.
5 Again, what were the timing specs before/after? Was the advance as pulled from the shipping box or was the advance checked and set ON A DISTRIBUTER MACHINE?
6 What changes were made to the carbs? Be specific. From what to what.
7 When the engine is warming up, feel the cylinder heads. Does the PASS side warm up faster?
8 Is the water temp taken from the head or the thermostat?
9 Where are the infrared temps being taken?
10 If the "tune up" made it run worse, it wasn't much of a "tune up", was it?
11 Go back to original tune and supply ALL info on what was done and what was the original set up.

The more information YOU supply, the more information WE have to help you. John

1. Idle is from both carbs and idles perfect. Idle adjustment on DR. Performance on Pass. side.
2. Performs and runs better than ever.
3. Temp. sending unit is on intake hot pass. side at front
4. New thermostat, 180 degrees, same as other one prior to heating
5. Infrared temps were taken at the front of each head. 176.6 on DR and 226 on Pass. side.
6. Don't know what timing specs are or were.
7. Intake and head gaskets show no sign of leakage.

 

[one finger john]

1. Idle is from both carbs and idles perfect. Idle adjustment on DR. Performance on Pass. side.
2. Performs and runs better than ever.
3. Temp. sending unit is on intake hot pass. side at front
4. New thermostat, 180 degrees, same as other one prior to heating
5. Infrared temps were taken at the front of each head. 176.6 on DR and 226 on Pass. side.
6. Don't know what timing specs are or were.
7. Intake and head gaskets show no sign of leakage.

Thank you AZCOWBO, this info helps a lot.
1. At idle with the large shared plenum the engine is idleing on 4 venturies, essentially 2 2 barrels. If you have a vacuum guage hooked into the manifold then adjusting the idle is easy. Look for a vacuum drop when adjusting one carburetor to the other and then slowly adjust the idle (and vacuum) up til smooth. Or close the primary blades until a .040 in feeler guage just slips thru and then make very minute adjustments to the blade opening and mixture screws. Remember that screwing the mixture screws in does not always lean the mixture out.
I am not clear on what "Idle adjustment on DR. Performance on Pass. side" means. Can you help me?
2. Great, glad to hear it. But the Pass. side appears to be 50* hotter at idle and the temp has risen 100* when fully warmed up. Why did you replace the old thermostst? Do you still have It? If you do, put it back in. First put it into a pan with water and bring the water to a boil. See where the thermostat opens. It helps to have a stick thermometer to watch the temp rise. Or your temp gun. If it doesn't pass the test, do the same with the new one.
3. Find out what the timing is in the distributer and write it down. Make this your timing mantra. "12* initial, 36* trotal, timing all in by 2500 rpms" DISCONNECT THE VACUUM ADVANCE UNTIL THE ALL THE OTHER PROBLEMS ARE SOLVED. Then find out how much advance is in the vacuum advance cannister (should be no more than 10*) ON A DISTRIBUTER MACHINE and then hook it up for better mpg on the highway. When you hook it into the carbs, hook it into the vacuum port ABOVE the throttle blades.
4. Put the car on an incline so that the rad cap is the highest point in the cooling system. Start the engine and bring it up to temp. I would do this with the rad cap off. and I would watch the coolent flow to see when thermostat opens. Check for bubbles in the coolent flow, possible indication of a blown head gasket.
5. Check the exhaust pipe on the hot side (passenger side) for any rust or odd coloration that might indicate water in the combustion chambers. Blown head gasket. Check for water in the oil. Think chocolate milk shake. If so, blown head gasket. IF AT ALL POSSIBLE, DO A CYLINDER LEAK DOWN TEST OR HAVE THE COOLENT ANALYZED FOR THE PRESENCE OF CARBON BYPRODUCTS. All this can be done quickly at your master mechanic's shop. One hour max.
6. Check the intake gasket by Ted's method or use any flammable compressed substance (starter fluid or brake clean works well). Don't forget the leak might be in the lifter valley and wouldn't evidence itself.

The more you can eliminate the POSSIBLE problems the more you can concentrate on the other problems. The more I think about it the more I'm feelin' a blown head gasket. Prove me wrong, do a leak down test.

John

P.S. Don't forget that once it is fixed, the whole tune may have to be changed. Having fun yet?

 

[RPM]

Have you tried shooting the individual header pipes with the temp gun? We used to diagnose diesel engines this way, you could tell which injector was rich or lean. You can tell the same thing in a gas engine.

Also does this engine have a mechanical fan on it? If it does take the belt off and recheck. The fan blowing on the front of the heads will give you false readings.

 

[GizmoJoe]

I'm not a real mechanic and I didn't sleep anywhere special last night.....
I think you have had some great advice here (undo the work since everything started after the work) but I really want to re-state the air pocket issue just so you can eliminate it. You never know.

I can't tell you (it hurts too much to talk about it) how much grief I went through with an air pocket in one side of a V engine.
You can either jack up the car so the filler point is way higher that the engine or have someone vacuum-fill the rad. They pull a vacuum through the rad and suck in the coolant and suck out the air.

Like I say... it's probably not that but if you have drained the rad during the work.. it's an easy thing to eliminate. Better than the rad, pump, fan... etc that I changed before I.. grrrrrr

 

[Mike]

The hotter (leaner) you run a motor, the more power it makes. Step on it until it lifts the ring lands and when you re-assemble it, be sure to pull 1/2° out of it. (Yes, that was a joke.)

36° total can be a ton of timing, so be careful about trying to live and die at that number. If you're running a piston with a .250" dome, then you will need some timing in that range. On the other hand, that much timing with a flat top piston can cause detonation.

If the motor wants to idle down to a steady RPM, I think you can safely eliminate a vacuum leak as being the culprit. A vacuum leak will fool a Holley/BG power valve and have it opening and closing, causing an erratic idle and a real heavy gasoline smell at the exhaust. If you want to check for leaks anyway, I still recommend using carb cleaner. Anything will work, but WD-40's oil base will leave an oily residue and the ether in starting fluid is so light it can drift upwards and get pulled into the carb, which will really have you chasing your tail. In most instances, if an intake gasket is leaking into the lifter galley, it will try pulling oil at idle or when the throttle is closed, same as a bad valve guide.

Whoever told you a BG Demon cannot be jetted has his/her head in a dark place. The BG carbs use a Holley jet, located in the very same place in the metering block as a Holley carb.

Don't be surprised at having a need to jet each corner of a carb differently. Particularly on a stock big block Chevy head. The siamesed intake ports do not share the same air flow figures, which is why you will note the good BBC race heads are symmetrical port heads. In addition, #'s 2, 3, 6 and 7 intake runners direct air/fuel flow to the side of the chamber. #'s 1, 4, 5, 8 direct air/fuel flow more to the center of the chamber. A BBC with a open plenum, dual-plane intake would use 4 different jet numbers to be right. The odd-fire V-6 we raced used split Dominators, to align the carbs over the intake runners. Each corner was jetted individually, we ran 4 different spark plugs and ignition timing was tailored to each individual cylinder.

Always be careful when making jet changes. The jet number does not always correspond to actual orifice size. Look at these numbers

#60 - .060 #65 - .065 #70 - .073
#61 - .060 #66 - .066 #71 - .076
#62 - .061 #67 - .068 #72 - .079
#63 - .062 #68 - .069 #73 - .079
#64 - .064 #69 - .070 #74 - .081

Stepping from a #60 to a #61 isn't bringing you much in a percentage of flow volume, whereas stepping from a #69 to a #70 is much more volume. Never step more than 2 numbers at a time, or you risk getting lost. A lean cylinder is always going to be hotter, but if it goes too lean it will become a cold cylinder, as there is not enough gasoline introduced to the chamber to support combustion.

Take baby steps. And carefully record your changes and the results they bring. It will make life much easier on you.

 

[Leakers]

1. Idle is from both carbs and idles perfect. Idle adjustment on DR. Performance on Pass. side.
2. Performs and runs better than ever.
3. Temp. sending unit is on intake hot pass. side at front
4. New thermostat, 180 degrees, same as other one prior to heating
5. Infrared temps were taken at the front of each head. 176.6 on DR and 226 on Pass. side.
6. Don't know what timing specs are or were.
7. Intake and head gaskets show no sign of leakage.

Presuming this is the big block Chev motor in your profile/intro ????
You may not have a problem at all, we notice the same thing on the KB Olds /BBC in our funny car during warmup...... the engine/cylinder head configuration on a BBC is the cause .
Try taking the temp at other places on the heads...the ports on a BBC are asymmetric when fitted to the engine...... front port on one side is an exhaust and the front port on the other side is an inlet........... if this is the reason for your readings when you go check the back of the heads in the same place the problem will change sides and sometimes the back will read hotter overall than the front.
It is hard to find a place on BBC heads where the temps will read even side to side, usually nearer the middle of each head and on the intake side. All this only happens when it is running or soon afterward , and the whole lot will even out somewhat if you leave it to sit for a while.......

 

[one finger john]

Presuming this is the big block Chev motor in your profile/intro ????
You may not have a problem at all, we notice the same thing on the KB Olds /BBC in our funny car during warmup...... the engine/cylinder head configuration on a BBC is the cause .
Try taking the temp at other places on the heads...the ports on a BBC are asymmetric when fitted to the engine...... front port on one side is an exhaust and the front port on the other side is an inlet........... if this is the reason for your readings when you go check the back of the heads in the same place the problem will change sides and sometimes the back will read hotter overall than the front.
It is hard to find a place on BBC heads where the temps will read even side to side, usually nearer the middle of each head and on the intake side. All this only happens when it is running or soon afterward , and the whole lot will even out somewhat if you leave it to sit for a while.......

Hey guys AZCOWBO's car has a small block Chevy. Not a BBC.
Mike, 36* can be run on a flat top sml. blk. comfortably. Just tryin' to get AZCOWBO in the ball park. Also, when I said that a Demon is not a Holley, I ment that there are differences and the tuner should be aware of them.
As for AZCOWBO's problem, something is physically wrong in an engine that has a 50* difference in cylinder head temp and a 100* hotter overall engine temp than last reported. Something is happening here that we are not being made aware of. There is more to this story.
I will rerfrain from any more comments untill the whole story comes out.

John

 

[Mike]

Hey guys AZCOWBO's car has a small block Chevy. Not a BBC.

And so it is. I picked up on his 'closed chamber' comment and got BBC in mind, before looking for images. Mea culpa. :blush:

As for AZCOWBO's problem, something is physically wrong in an engine that has a 50* difference in cylinder head temp and a 100* hotter overall engine temp than last reported.

Absolutely. AZCOWBO, what cylinder head casting are you using? And do you have the same casting on both sides?