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Author Topic: manifold temps  (Read 401 times)
rcbeam
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« on: July 21, 2013, 12:40:30 PM »

Hi.  Today I took my MC8 out for a bus run down I-75 south, from Lexington, Ky to Williamsburg Ky and back.  Again the bus ran flawlessly as it always has but at the turn around point and again when I got parked back in Lexington I checked my exhaust manifold temps.  The bus seems to be a little weak on hills but maybe my expectations are out of line.  Also even at full throttle on a hill I never see any dark exhaust.  About the most I think I see in my left mirror is maybe a little haziness but nothing of any substance.

I used my infrared thermometer and scanned the middle of the manifold on both sides. It read 270 or so on the curb side and 200 on the street side.  I got the same reading both times, mid trip and once back home.  Both checks were made with the engine idling.  I am concerned of the difference between the two manifolds and it makes me think once bank of cylinders are doing more work than the other.  Maybe the rack needs adjusting?

My bus is  86' MC8, 8V71 natural, with HT740.

I appreciate any feedback.

Russell
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Russell
1976 MC8
Lexington KY
www.sweeteveningbreeze.blogspot.com
Utahclaimjumper
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« Reply #1 on: July 21, 2013, 12:44:43 PM »

 There are a lot of variables here, and yours aren't enough to worry over.>>>Dan
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bevans6
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« Reply #2 on: July 21, 2013, 01:17:15 PM »

The manifolds will cool off considerably in just the amount of time it takes to get stopped, out and back to the rear of the bus.  If you can, downshift the trans and run up the hill on the governor.  Don't try to pull a hill in fourth with a natural 8V-71 in a 40 foot bus.  It would be interesting to know what injectors you have in there.

Brian
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1980 MCI MC-5C, 8V-71T from a M-110 self propelled howitzer
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luvrbus
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« Reply #3 on: July 21, 2013, 01:40:35 PM »

Exhaust temperature the reading is at 1800 rpm and 2100 rpm a reading at idle means nothing plus a infrared gun unless you have one of the high $$$ guns are not that accurate 800 to 850 F is what you are after exhaust gas temperature not a manifold reading

good luck 
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rcbeam
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« Reply #4 on: July 21, 2013, 03:55:46 PM »

Thanks guys.  On the interstate I try to drive somewhere between 62-65.  I'm not in a hurry and I'm more concerned with fuel cost than time.  I don't ever do hills with my foot in it.  I try to maybe be no more than 3/4 throttle and when my speed gets close to 50 or if it is a long hill I'll drop to 50 and downshift to 3rd and run 49 the rest of the way up.  So far I've not had a grade that I needed to go any lower. 

One of my goals is to go over Jerrico Mtn in Tn to see how she does.  I've not had any overheating problems yet but do get some temp rise at the dash gauge on longer climbs but comes back down once I go over the top.  I'm very watchful of engine temp.  I think I need to tighten up the air flow through the radiators though just by looking at it.

I don't want to get too hot climbing Jellico and have no place to pull over out of the way.  I can't remember how much shoulder they have on I-75 up Jellico.

I've seen in a lot of posts people talk about smoking at full throttle and I don't seem to have any smoke that I can really see in my left mirror.

Thanks for the replies.
Russell
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Russell
1976 MC8
Lexington KY
www.sweeteveningbreeze.blogspot.com
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