Rough Idle, Cold Only

[The_Handier_Man1]

From: OldEdBrady  (Original Message)
Sent: 5/21/2005 12:30 AM

If it's a bit chilly, the old Whiny Beggar idles like a tank.  On occasion, I even have to keep my foot on the gas just to keep her going.  Once she's warmed up, there are no problems.  She purrs.

What can I do?

'76 chassis, 440-3, thermoquad.

New plugs, rotor, wires, etc.



From: HeavyHaulTrucker
Sent: 5/21/2005 1:47 AM

Sounds like time for either a carburetor rebuild or a tune-up.  If your thermoquad is original, I would bank on the rebuild (replacement is better, but rebuild is cheaper).

John



From: OldEdBrady
Sent: 5/21/2005 8:46 AM

I'll give the rebuild a shot.  Hope that does it.  Thanks.



From: ClydesdaleKevin
Sent: 5/21/2005 10:10 AM

I had the same problem when we first brought the Ark home.  I'd start her, she'd idle VERY roughly, and sometimes stall during the first couple of minutes of idling.  It would take almost 20 minutes for it to warm up, and if I tried to move her before she was warm, she'd run like a Sherman tank and sometimes stall out.

I discovered that the PO had removed the thermostat altogether, so I bought one from Summit Racing and installed it. 

The Ark now starts right up (it was starting right up to being with), and doesn't stall.  She also warms up VERY quickly, idles smooth as butter, and can be driven within minutes.

This may or may not be your problem, but installing the thermostat solved the problems the Ark was having.

Kev and Patti Smith.



From: SeaRaySRV16O
Sent: 5/21/2005 10:33 AM

You have most likely checked this, however, I was going nutz tryn' to make my 413 idle smooth on a cold start up. After a new coil & cap & rotor, I finally got down to the plugs which showed almost zero signs of wear. The P.O. had replaced them just before I bought the rig.

Turns out the Autolite #86 plug only is threaded 3/8" and never extended down into the combustion chamber. At the suggestion of several board menbers, I replaced those 3/8" Autolites with 3/4" Champions (RN14YC) that also has an extended tip and my cold start/rough idle vanished. So ya' may wanna verify you have the correct heat range plug for your engine application. Good luck.

Regards,

Robert Donley
Jenison, MI



From: denison
Sent: 5/21/2005 1:07 PM

     A choke sticking open is a good likeliehood.  I dont assume they work properly unless I am looking at them with the air cleaner off. 
    All the suggestions have been good.  A very long-shot would be if you were using 20w50 oil, and the weather was cool, (like under 45f-50f in the mornings?  There might be a couple of lifters that would not bleed down fast enough to let the valves fully seat - until the oil was warm.
    This would also be the case if you had a broken valve spring.  All of the valves have double springs, and if either the inner or outer one is broken, it wont make the lifter bleed down as fast as it should.   Though its rare, valve springs do break.



From: ClydesdaleKevin
Sent: 5/21/2005 6:35 PM

Denison's suggestion about a sticky choke makes me think that might have been part of the Ark's problems as well.  I didn't think about it until I read this, but at the same time I changed the thermostat, I also thoroughly cleaned the carb with carb cleaner, including the choke linkages and butterflies.  Now it makes more sense to me why "just changing the thermostat" made such a dramatic difference...lol.

Kev and Patti Smith.



From: OldEdBrady
Sent: 5/22/2005 7:07 PM

Thermostat.  Never occurred to me.  And, with some the the idiotic things I've found from the PO, that might just be it.  And even cheaper than a carb rebuild.  I'll try it.  If it doesn't work, then I can always go to the rebuild.



From: ClydesdaleKevin
Sent: 5/22/2005 8:06 PM

I'm not sure about a 440, but with a 413 in a motorhome, you have to use the skirted thermostat...something about the way it directs water into the heads.  Somewhere on here Denison gives a website to Summit Racing, with the right part numbers.  Like I said, I'm not sure about the 440, but with the 413 the skirt is a must.

Kev



From: HeavyHaulTrucker
Sent: 5/22/2005 10:11 PM

I use the regular thermostat in my 440, and I have never had a problem... temp guage never goes above 185, even on a steep hill.

John