Glowing exhaust and high temps

[The_Handier_Man1]

From: knuckleheadpower  (Original Message)
Sent: 1/3/2007 11:21 PM

I am ready to bring my 76 Brave from arizona to chicago. I have gone over it and made several long trips over the holidays. My rig does pretty good in the big mountains here in arizona, but it seems that open road high RPM cruising (like over 60 mph) it overheats. We went through the cooling system and everything is OK. I stopped on the highway at night on the way to Yuma and noticed the exhaust manifolds were glowing orange in the center. It is a 360, and has that two into one exhaust with a big muffler. I think it is an exhaust restriction. The two into one pipe setup is totally retarded. The right side pipe kind of goes straight into the muffler and the left pipe intersects it at like a 60 degree angle. I am pretty sure it is original. Any body have a similar problem ? I am going to put 2 1/2 inch duals on it tomorrow. I just hope thats the problem. I have to solve this issue and get back  Please help!!!

   

From: Elandan2
Sent: 1/4/2007 8:52 AM

These engines are working hard and it is common for the manifolds to be glowing from the heat of combustion.  Some things to check are, ignition timing (advanced too far will cause a hotter running engine),  mixture, ( running at over 60 you are probably into the secondaries on the carb and could be running rich).  If your cooling system is keeping up, i.e. no actual overheating there is no problem there.  The new exhaust will definitely help the performance, the factory exhaust was a trade-off between cost and performance (most likely cost was the most important factor).  Good luck, it sounds like you have a strong runner there.   Rick

   

From: knuckleheadpower
Sent: 1/4/2007 9:29 AM

The timing is fine, the plugs are burning perfect, and the cooling system seems OK. the temperature just steadily rises at steady highway speed. it seems like at high rpm, the exhaust cant flow enough. I just hope thats what it is, otherwise it will take forever to get back. having to go so slow and always stop to let it cool down.I was just hoping someone had a similar problem.

   

From: Elandan2
Sent: 1/4/2007 10:10 AM

Does your engine have a skirted thermostat?  It may be that there is enough coolant bypassing the radiator that the temperature rises.  The skirted thermostat forces the coolant through the radiator and eliminates the bypass when it is fully open.  Rick

   

From: knuckleheadpower
Sent: 1/4/2007 1:20 PM

I have tried both types. I usually use the skirted marine style. The fan is perfect in the shroud. the radiator is in good shape with no fin corrosion. I wonder if the water pump impeller could be rotted, or cavitating for some reason. 

   

From: bluebird5750
Sent: 1/4/2007 3:21 PM

If it is running lean, it'll do that too. Not enough fuel to cool the cyclinders.  Have you changed the fuel filter? If you have, do you have any spark knock? You might try to decrease the timming 1 degree at a time to see if it help.

   

From: bluebird5750
Sent: 1/4/2007 3:28 PM

My rig did that when I bought it. Mine was a raditor that didn't flow well enough. Sometimes you can't tell by looking in them. I took mine to a raditor shop and had a flow test done on it. But only after I tried everything else. It only flowed about 1/3 what it was supposed to.

 

From: millertimewinne
Sent: 1/4/2007 4:09 PM

One thing to look at would be the heat riser flap in the exhaust manifold. If the flap has become rusted in the closed position, it won't let the exhaust out and it will start to glow red. Squirting some PB Blaster on the valve spring and weight should free it up. Good luck!

   

From: knuckleheadpower
Sent: 1/4/2007 5:13 PM

Engine is running at good stoich (14.5). There is no butterfly in the manifold. Radiator flow/dwell is a suspicion but it doesent run hot when the engine is loaded and working at a low rpm, only at high speed. Does anyone have the two into one exhaust ?  If so, has the exhaust been a problem ? 

   

From: bluebird5750
Sent: 1/4/2007 6:37 PM

Mine ran ok unless I was pulling. One reason why I bought it. OK at 50/55 but anything over it started heating. Now I can run what I want, no overheating. Usally pull 4500# trailer @65 mph.

   

From: knuckleheadpower
Sent: 1/5/2007 12:03 AM

what size motor do you have, and did you change to duals? did you have that two into one exhaust ?

   

From: bluebird5750
Sent: 1/5/2007 2:55 PM

I have a 454 engine, had duals on it when I bought it.

   

From: DaveB_D27CU
Sent: 1/6/2007 5:50 AM

Elandan2, Bluebird, Millertimewinne, good sugestion. Always look at the basics first.

But I think our friend has conviced himself that the problem is his "Y" pipe (the common name for what was called 2 into 1 exhaust). "Y" pipes have been used on everything from car to heavy truck over the years and although it is more restrictive in flow than dual exhaust I have never heard of it being the cause of over heating a vehical.

Will going to dual exhaust take some heat out of the engine? Yes and make a couple of HP's to boot.

Will this help his problem? I don't think so. Right now I'm thinking it can be one of 2 things.Heres why:

     1) You have a 360 engine in a large vehical with the areo dinamics of a brick. Glowing manifolds could be the result of just pushing this vehical to hard with such a small motor. Solution, "SSSLLLOOOWWW" down, It's a Winnebago not a Porche.

     2) I alway look at the caruretor last. but since you already ruled out a problem
with the cooling system I think Bluebird hit it on the head when he said you might be running lean.
         a -You said it ran good in the mountains, but not when on the high way. In
         the mounting the air is thinner so your fuel air (F/A) mix is richer, Out on the
         arizona high way (Lower alt.) with high heat, Leaner F/A mix.
         b - You said that the manifold were starting to glow, again either an over
         worked motor or a lean F/A mix.
         c - Lastly you said that the F/A mix is "Stoich 14.5" Sorry but this term drives
         me nuts, first Stoich is 14.7:1 - second when is it Stoich? Idle, 35mph, 55mph,
         65mph or WOT? the F/A mix is different at all different speed. And for the
         record unless you have a feed back carburetor(carb.) or a fuel injection system
         14.5 is to LEAN.

         The ideal of running a car at Stoich came about in the late 70's early 80's when
         the big 3 started running "Feed Back" carburetors on car. A feed back carb
         with the help of an O2 secncer and a computer can adjust the fuel mix any
         were from a .05 to 1.0 #/hr of fuel. This HUGE range gave the computer all
         room it needed to compensate for change in temp, alt., throttle position etc.
         but I digress.

You might want to look at the fuel pump. Using an electric fuel pressure gauge see what your fuel pressure is on the open road, if it drops below 3psi you will really start running lean. At about 2psi the vehical will start surging and you could start doing damage to your motor.

If you change to dual exhaust you will need to jet your carb richer 1 jet size, If you add headers you will have to jet up 2 to 3 jet sizes total.

If you have a F/A meter in your rig, best jet your carb to what ever speed you want to run at with a F/A ratio of  between 14.2 and 13.8 with 14.0 being about the best all round.

I hope I did not up set anyone with my long winded message.  If you need some help stepping through debuging you carb. or want clarifiction on the terms just e-mail me and I will be more than happy to help.

 

From: knuckleheadpower
Sent: 1/6/2007 3:51 PM

Sorry if there is some confusion, when I said Stoich, I ment the reading on my "RSR Stoich F/A gauge, which I borrowed of my drag bike to check the mixture at WOT. It has been a indespensible tool, ecpecially when running 28 lbs of boost. I would like it running fatter,but I think the mixture is OK. I have seen the same temperature problem when catalytics get clogged. I have not totally ruled out the cooling system, it might be some obscure problem. I will keep you guys posted after I put the duals on today. I cant wait to get home and drop this 360 in the junk pile. Thank you Dave for you correction on my  improper nomenclature, history lesson, ond the offer for Carb lessons 101.
I hope I did not upset anyone with my long winded reply.

 

From: bluebird5750
Sent: 1/6/2007 7:26 PM

How long would your drag bike run at wot at that mixture?  That might be where it make its best power, but how long would you be able to run it like that? I'm a drag racer too, and I run my cars on the lean side to get the most power out of them. But I don't think you can run a carburated motorhome like that. I went through the entire cooling system. I would have bet there was nothing wrong with the raditor by looking at it. Only the flow test proved differant. Good luck.

   

From: knuckleheadpower
Sent: 1/7/2007 12:02 AM

bluebird, I think you are right, and I am dealing with multiple problems. I know what your saying about the mixture, I would like it fatter. I think they have it running on the brink to make enough power. Was your radiator partially plugged ? I also noticed the core on a 440-3 was the same size, but actually had larger tubes. I am in a small town here they really dont have much for services. I am trying not to do to much since I have a  comlete 75 indian with a 440-3 at home for a donor. Thanks !  I will keep you guys posted



From: dougs23rb
Sent: 1/7/2007 6:08 AM

I had exactly the same problem on an early 80's Z28. I could sit in city traffic in Phoenix with the AC on...no problem. Go to Prescott and some fairly steep grades at slow speed and again no problem. Get up to 50 MPH or higher even on level roads and watch the temp slowly increase. It was fuel injected and no codes sent to the computer. Plugs had good color.
I too suspected the exhuast especially the converter but no change after replacing it. I even pulled the thermostat. Everything was working. I partially drained the radiator enough to see substantial flow so both the pump and rad core seemed OK. After I decided to replace the radiator thinking it was restricted at the bottom half of the core and started to remove it I discovered that the area between the radiator and condenser was packed full of dried grass. I really waswn't convinced that was it until I cleaned it out. I had to put the thermostat back in.
I'm with DaveB on this one. Too lean and or to many RPM's and load. Put a vac guage on it and drive. But it's down around 5 to 7 inches when she's cooking. If it was an exhuast restriction it just wouldn't run. Can't get air in if you can't get air out.
 
   

From: bluebird5750
Sent: 1/7/2007 7:29 PM

Yea, my raditor looked fine. But when I took it to the shop they put it on a flow station. Only flowed about 1/3 of what it was supposed to. Heck I changed the fuel pump, replaced all the rubber line going to the tank, changed carbs, water pump, flexflight fan blade. Then the raditor shop. And now I went back to the original fan with a new clutch. At least I know what I have now. And I pull my race car to the track 3 times a month with it. No problems. I had a minnie winnie with the 360 Dodge  many years ago. And didn't have any problems with it, but I was in a camp ground some where in Penn, on a trip out east and a felow came in with one that had the manifolds burned off right above the joints on the Y pipe. Good luck on your journey back east.

   

From: uglydukwling
Sent: 1/8/2007 9:14 AM

I wouldn't want to lull you into a false sense of security, but for some vehicles it's normal for the exhaust manifold to glow in the dark. The operator's manual for my GMC DUKW says not to worry about it; press on regardless. (Bear in mind, though, that the DUKW is a military vehicle, so it was also normal to have people shooting at you.) I haven't had time to check any other manuals to see if other manufacturers considered it normal in more conventional service.

   

From: knuckleheadpower
Sent: 1/13/2007 1:26 PM

Went for a test run from Cottonwood to Chandler to visit the Rotorway factory yesterday. Temp was steady, with a little more power as well. It did climb alot on some of the big grades though. However, on a flat out run the problem seems to be solved. Pulled over when the temp was up after climbing the hills to check the manifolds. It was dark out and they did have a little glow to them in the center where the two ports are next to each other, but nothing like before. I have to figure out the mileage, I hope it has improved as well. When we were in the junkyard, we looked at alot of motorhome exhausts, and noticed almost all of them had cracked manifolds. I think I will ceramic coat the inside, as well as the outside of the 440 manifolds when I drop in the new motor. Waiting for this ice storm to pass so we can leave monday.