lack of choke on carb

B

burt and faye curtis

New member
Jun 3, 2012
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Last year when the rebuilt Pattersen carb was installed on my coach, a
choke wasn't installed as the mechanic felt it was dropping down the idle
just fine. Bert had connected up a manual choke on the first one. Now a
friend insists that I need a choke or it will never run right and will
always be idling too high and killing the fuel mileage. So, if it is in
fact dropping the idle after a while, do I really need the choke? Coach
starts up just fine as it is.

Thanks again in advance,

Fay Curtis
'76 Glenbrook
Kneeland, CA
 
Does it idle to high now ? if so get it up to operating temperature and set the idle to 650 rpm or so in drive, if it is hard to start when cold after
you have adjusted the idle it should not take more than a light foot on the accelerator for a couple of minutes until the engine get a little hot.
So to your question, do you need the choke in CA ? nah not really, it will not do anything after the engine reaches it operating temperature, in
colder climates I think that you will need it just as it will make everything easier for you when it comes to start up and driving the first couple of
miles
--
1973 26'-3 # 1460 Parrot green Seqouia Known as the Big Mean Green Machine,
And just sold my 1973 26'-2 # 581 White Canyon lands under the name Dobbelt trøbbel
in Norway
 
Espen,

Thanks for your help. Felt that it was probably good as I trust the guy
that installed it, but now I have to get the other fellow to keep his paws
off of it!

Fay

> Does it idle to high now ? if so get it up to operating temperature and
> set the idle to 650 rpm or so in drive, if it is hard to start when cold
> after
> you have adjusted the idle it should not take more than a light foot on
> the accelerator for a couple of minutes until the engine get a little hot.
> So to your question, do you need the choke in CA ? nah not really, it will
> not do anything after the engine reaches it operating temperature, in
> colder climates I think that you will need it just as it will make
> everything easier for you when it comes to start up and driving the first
> couple of
> miles
> --
> 1973 26'-3 # 1460 Parrot green Seqouia Known as the Big Mean Green Machine,
> And just sold my 1973 26'-2 # 581 White Canyon lands under the name
> Dobbelt trøbbel
> in Norway
>
>
> _______________________________________________
> GMCnet mailing list
> Unsubscribe or Change List Options:
> http://list.gmcnet.org/mailman/listinfo/gmclist_list.gmcnet.org
>
 
You do need the choke to start and be able to drive off in a minute.
I'm i Northern CA, and even in Southern CA it is never warm enough to not
need a choke unless the carb is running extra rich.
We do work on several a month, so I know for sure on this.

> Does it idle to high now ? if so get it up to operating temperature and
> set the idle to 650 rpm or so in drive, if it is hard to start when cold
> after
> you have adjusted the idle it should not take more than a light foot on
> the accelerator for a couple of minutes until the engine get a little hot.
> So to your question, do you need the choke in CA ? nah not really, it will
> not do anything after the engine reaches it operating temperature, in
> colder climates I think that you will need it just as it will make
> everything easier for you when it comes to start up and driving the first
> couple of
> miles
> --
> 1973 26'-3 # 1460 Parrot green Seqouia Known as the Big Mean Green Machine,
> And just sold my 1973 26'-2 # 581 White Canyon lands under the name
> Dobbelt trøbbel
> in Norway
>
>
> _______________________________________________
> GMCnet mailing list
> Unsubscribe or Change List Options:
> http://list.gmcnet.org/mailman/listinfo/gmclist_list.gmcnet.org
>

--
Jim Kanomata
Applied/GMC, Fremont,CA
jimk
http://www.appliedgmc.com
1-800-752-7502
 
> Last year when the rebuilt Pattersen carb was installed on my coach, a choke wasn't installed as the mechanic felt it was dropping down the idle
> just fine. Bert had connected up a manual choke on the first one. Now a friend insists that I need a choke or it will never run right and will
> always be idling too high and killing the fuel mileage. So, if it is in fact dropping the idle after a while, do I really need the choke? Coach
> starts up just fine as it is.
>
> Thanks again in advance,
>
> Fay Curtis

Fay,

I have to wonder what is going on here.
When you say no choke was installed?
Do you mean no choke plates? (The double butterfly that is right at the top of the carburetor?)
Or
Do you mean no thermal choke operator? (The device that opens and closes the choke as you might do with a manual cable.)

If it is the former, then you will indeed have a hard time starting cold and there is a lot else that will be difficult, but as you say this is not an
issue, lets go on.

If the thermal operator heater is what is missing, then I am going to assume that you mean the connection to the manifold heater (often referred to as
a cross-over) has not been installed. Without these parts, the choke will probably function as intended but the pull off time will be longer than it
should. This will cause the engine to stay at a high idle longer than desired. But, again, you say that this is not an issue. If the parts are
available, this is no big deal to install. If they are not, it is even simpler because you can change it to an electric version for a small price.

If the situation is causing you some concern, you might have someone check into it, but again, it sounds as though it is not. Unless you plan to go
someplace that is much colder than you are accustom to, just enjoy the coach.

There are lots of carburetor fueled engines out in the world with no choke system at all. The operators just have to be aware of the situation.

Matt - the engine lab refugee
--
Matt & Mary Colie - Members GMCMI, GMCGL, GMCES
'73 Glacier 23 - Still Loving OE Rear Drum Brake with Applied Control Arms
Now with both true Keyless and remote entry
SE Michigan - Twixt A2 and Detroit
 
> Last year when the rebuilt Pattersen carb was installed on my coach, a
> choke wasn't installed as the mechanic felt it was dropping down the idle
> just fine.

If on cold start there is a high idle and it drops to a lower idle after a short warmup, it sounds like there is something activating the high idle
cam. It is independent from the throttle.
Quote:
> Bert had connected up a manual choke on the first one. Now a
> friend insists that I need a choke or it will never run right and will
> always be idling too high and killing the fuel mileage.

What is your warmed idle RPM.
Quote:
> So, if it is in fact dropping the idle after a while, do I really need the choke? Coach starts up just fine as it is.

I believe you do have a choke. It may not be hooked up but you are in Cal, so... You are just fine as you are. If it becomes a problem in the winter,
just give it a little more gas to start,if needed, and let it idle a little longer at warmup. The idle cam will drop as it warms up when you blip the
accelerator, if you don't get crazy revving it up.
Thanks again in advance,

Fay Curtis
'76 Glenbrook
Kneeland, CA
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--
Patti & Jerry Burt
73 Gmc 26' Canyon Lands -
Photos - http://jburt.smugmug.com/GMC-Motorhome
Lots of upgrades but lots to do to make it ours.
Members: FMCA - GMCMI - GMCWS - Pacific Cruisers
Click to expand...
Click to expand...
 
I really can't imagine why one would not want an operating choke. With outside temps warm or cold the engine starts much better with a choke and
improves driveability when you first start, just like JimK says. So I say get the choke fixed as it is there for a reason.

Jon
--
Jon Payne
76 Palm Beach
Westfield,IN
 
I talked on the phone with Faye yesterday. She has an adjustment problem,
not a part missing. She has it under control.
Jim Hupy
Salem, Or
78 GMC ROYALE 403

> I really can't imagine why one would not want an operating choke. With
> outside temps warm or cold the engine starts much better with a choke and
> improves driveability when you first start, just like JimK says. So I say
> get the choke fixed as it is there for a reason.
>
> Jon
> --
> Jon Payne
> 76 Palm Beach
> Westfield,IN
>
> _______________________________________________
> GMCnet mailing list
> Unsubscribe or Change List Options:
> http://list.gmcnet.org/mailman/listinfo/gmclist_list.gmcnet.org
>
 
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