Classic Mustangs List Archive

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Mail From: mustang (Brandon Peskin)

Now that I have a thoroughly better understanding of how a carb works (thanks to everyone here + ye old shop manual I received for crimmus last year), I realize I was epically stupid during my exhaust retrofit several years ago.

I installed tri-Y headers in 2006 (thus eliminating the stock exhaust logs + exhaust gas tube connector to the bottom of the choke), and I have an automatic choke.


Questions:

1. Is it terrible for the choke to stay closed longer than it should? Will fuel economy/performance ultimately be degraded the longer its open?

2. Is it possible to convert from an automatic to manual choke? Walt B, help me out here: your Shelby has a manual choke with those Tri-Y headers right? I was pretty sure I read somewhere the K-code cars also had a manual choke. I'd assume I could do this by plugging the hole in the bottom and replacing the thermostatic choke housing with either an electric or manual one. I thought I read somewhere that the electric models still solicited the help of the exhaust gas heat, however.


Not only did I disconnect and remove the steel exhaust gas connector to the choke but somewhere in my travels I also removed the little J-plate that holds the heater hoses against the thermostatic choke housing. For now I've zip-tied the heater hoses to the housing. The heater hoses are stainless steel and get VERY hot. I'm hoping there will be some compensation there.

3. Am I missing anything? Is it possible to get heat from elsewhere? I'd think an excellent source would be attached to the breather cap on the valve covers (I have one in my parts bin with an outlet on the side of it).

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Mail From: walt (Walt Boeninger)



Brandon Peskin wrote:

> 1. Is it terrible for the choke to stay closed longer than it should? Will fuel economy/performance ultimately be degraded the longer its open?

Well, it will affect gas mileage and the plugs will get carbon fouled faster... but you may not
notice that since the
plugs get fouled faster anyway ... unlike EFI cars....

> 2. Is it possible to convert from an automatic to manual choke? Walt B, help me out here: your Shelby has a manual choke with those Tri-Y headers right? I was pretty sure I read somewhere the K-code cars also had a manual choke. I'd assume I could do this by plugging the hole in the bottom and replacing the thermostatic choke housing with either an electric or manual one. I thought I read somewhere that the electric models still solicited the help of the exhaust gas heat, however.

My 67 GT500 has Auto choke, and the 67 Trans Am is a race car so it has no choke.....
I think you could swap the parts needed from a manual choke carb to your Auto choke...
it also seems to me someone makes a kit to provide the necessary heat from the headers....

cal-mustang.com/AUTOMATIC-CHOKE-TUBE-KITS-1964-68-Mustang-260289302-2pcs-P14215C1011.aspx

> 3. Am I missing anything? Is it possible to get heat from elsewhere? I'd think an excellent source would be attached to the breather cap on the valve covers (I have one in my parts bin with an outlet on the side of it).

I don't think so....

--
Regards
--------------
Walt Boeninger
(408) 374-4258
(408) 374-1298 fax
(415) 269-0943 cell
4152690943 at txt.att.net
walt at boeninger.net
webmaster at norcal-saac.org
webmaster at vintagemustang.org
shelbytransam.com

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Mail From: mustang (Brandon Peskin)

Totally forgot the main reason I wanted to write.

There's no piston in my choke assembly. It's missing or removed. I'm totally serious. (I have a 1974 vintage autolite 2100). There's just a hole there and by the looks of things it doesn't APPEAR there's ever been one. Did ford do away with the choke piston in later-year carbs?? I'm pretty sure I felt vacuum coming from the hole at some point.




On Apr 24, 2010, at 7:47 PM, Brandon Peskin wrote:

> 3. Am I missing anything? Is it possible to get heat from elsewhere? I'd think an excellent source would be attached to the breather cap on the valve covers (I have one in my parts bin with an outlet on the side of it).

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Mail From: mahilly (Mike H)

The way I understand it, the piston inside the choke spring housing "pulls"
the choke plate slightly open during idle due to manifold vacuum acting on
the piston. And, if I recall correctly, your 2100 carb has the choke
diaphragm on top of the carb, which serves exactly the same purpose.
Correct? I suppose it's possible that Ford/Autolite replaced the piston
inside the choke housing with the diaphragm on top of the carb sometime
during the mid 70's...just guessing here.

It's been my experience that a well tuned 2100 or 4100 does not
really require the choke except during really cold temperatures (I live in
Kalifornia and only drive my stang from April to October, so for me that
means never). My method for adjusting the choke spring: Start the car up,
and as soon as the engine starts to get just a little warm and is running
smoothly, turn the choke housing until the choke plate is wide open, and
just call it good. That seems to work for me, so unless you live somewhere
where it gets really cold, you might give it a try.

On Sat, Apr 24, 2010 at 10:42 PM, Brandon Peskin <mustang at peskin.org> wrote:

> Totally forgot the main reason I wanted to write.
>
> There's no piston in my choke assembly. It's missing or removed. I'm
> totally serious. (I have a 1974 vintage autolite 2100). There's just a hole
> there and by the looks of things it doesn't APPEAR there's ever been one.
> Did ford do away with the choke piston in later-year carbs?? I'm pretty sure
> I felt vacuum coming from the hole at some point.
>
>
>
>
> On Apr 24, 2010, at 7:47 PM, Brandon Peskin wrote:
>
> > 3. Am I missing anything? Is it possible to get heat from elsewhere? I'd
> think an excellent source would be attached to the breather cap on the valve
> covers (I have one in my parts bin with an outlet on the side of it).
>
> _______________________________________________
> Classic-mustangs mailing list
> Classic-mustangs at lists.twistedpair.ca
> lists.twistedpair.ca/mailman/listinfo.cgi/classic-mustangs
>
> Visit the Classic Mustang Wiki! sauce.donair.org/~cm/
>
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Mail From: mustang (Brandon Peskin)

Yeah I've got the diaphragm on the top. Weird that it's just a hole though and not capped off. I'm in California too and it's generally in a slightly-warmer-than-outside garage in the winter. Maybe I'll try your method.


On Apr 25, 2010, at 12:30 AM, Mike H wrote:

> The way I understand it, the piston inside the choke spring housing "pulls" the choke plate slightly open during idle due to manifold vacuum acting on the piston. And, if I recall correctly, your 2100 carb has the choke diaphragm on top of the carb, which serves exactly the same purpose. Correct? I suppose it's possible that Ford/Autolite replaced the piston inside the choke housing with the diaphragm on top of the carb sometime during the mid 70's...just guessing here.
>
> It's been my experience that a well tuned 2100 or 4100 does not really require the choke except during really cold temperatures (I live in Kalifornia and only drive my stang from April to October, so for me that means never). My method for adjusting the choke spring: Start the car up, and as soon as the engine starts to get just a little warm and is running smoothly, turn the choke housing until the choke plate is wide open, and just call it good. That seems to work for me, so unless you live somewhere where it gets really cold, you might give it a try.

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Mail From: walt (Walt Boeninger)



Mike H wrote:

>
> It's been my experience that a well tuned 2100 or 4100 does not
> really require the choke except during really cold temperatures (I live
> in Kalifornia and only drive my stang from April to October, so for me
> that means never).

Oh, yea......I'm also in Kalifornia....chokes? Who needs 'em!
..... the 427 Contemporary Cobra I'm providing
foster care for has no choke..... I just started it yesterday..... hasn't
run since January... once the fuel system got primed, it starts and idles
on it's own at 600 RPM .... I've never had a car that did that does that
... it usually takes a minute or two to get them to idle without coaxing..

--
Regards
--------------
Walt Boeninger
(408) 374-4258
(408) 374-1298 fax
(415) 269-0943 cell
4152690943 at txt.att.net
walt at boeninger.net
webmaster at norcal-saac.org
webmaster at vintagemustang.org
shelbytransam.com