Motorhome 2 headset tubes glowing red

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Motorhome 2 headset tubes glowing red

Post  mach1charlie on January 24th 2017, 9:22 pm

Second tubes back from the front, both sides. Do 460s in heavy duty use burn exhaust valves in those cylinders? About 1 minite after startup trying to run in new RV cam, ran it 5 min. and got scared, shut it down.
Thanks

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Re: Motorhome 2 headset tubes glowing red

Post  68formalGT on January 24th 2017, 10:45 pm

If your timing is still at 0 you need to advance it some.
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Re: Motorhome 2 headset tubes glowing red

Post  BBFTorino on January 25th 2017, 1:28 am

Carb or EFI??

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Re: Motorhome 2 headset tubes glowing red

Post  mach1charlie on January 25th 2017, 12:32 pm

Carb... I'll look for a vacuum leak that feeds those cylinders? Maybe a vacuum tee.
Don't think it's timming only 2 tubes glowing

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Re: Motorhome 2 headset tubes glowing red

Post  hookin78 on January 25th 2017, 1:17 pm

Ive seen that happen when the valve isnt completely closing due to too much lifter preload causing the lifter to pump up and have the valve open a touch. was any machining done to the engine that could cause it to have to much lifter preload...?

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Re: Motorhome 2 headset tubes glowing red

Post  dfree383 on January 25th 2017, 1:21 pm

Or a burnt exhaust valve could be the issue
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Re: Motorhome 2 headset tubes glowing red

Post  mach1charlie on January 25th 2017, 2:56 pm

Motor is a rebuild...not mine, 7k miles and ate two cam lobes ant the bottom of one lifter, had a slight clatter to it. Then it bent push rod and threw a lifter out of the bore, lost oil pressure. I r&r cam and lifters and on start up got the 2 glowing header tubes.

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Re: Motorhome 2 headset tubes glowing red

Post  mach1charlie on January 25th 2017, 3:02 pm

Oh it had long push rods in it...like 8.62, I figured that was done to get it off warranty! I put in stock 8.55, preload seemed right. I'm working on a class a with no front access...broke down in a dirt parking lot, mostly mud here in raining CA.

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Re: Motorhome 2 headset tubes glowing red

Post  The Mad Porter on January 27th 2017, 4:44 pm

X2 on ignition timing. When breaking in camshaft we typically try to run 30 or more degrees timing while the cam is breaking in. In some cases while on dyno I have had to hook up the vacuum advance to cool the headers down. This even when air fuel ratios are in the high 13's akin to cruise mode. A factory carb will likely be even leaner.

Double check timing and for any potential vacuum leaks.

What is your initial timing set at? Total timing less vacuum advance?




S
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Re: Motorhome 2 headset tubes glowing red

Post  mach1charlie on January 27th 2017, 6:25 pm

Yes, next day I kicked timing ahead, cranked down intake bolts, ran her for 25 minutes to finish cam break in. Every thing looked good.

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Re: Motorhome 2 headset tubes glowing red

Post  Doug Rahn on January 28th 2017, 10:38 am

Since your initial startup only lasted 5 minutes, I would keep a close eye on the lifter preload. Typically cam break in should last 20- 30 minutes of continuous run time.
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