|
Sponsored Links (Register now to hide all advertisements) |
|
|
Thread Tools | Display Modes |
02-22-2018, 12:07 PM | #1 |
Senior Member
Join Date: Oct 2011
Location: elmira,ny
Posts: 1,517
|
automatic choke operation
Decided to hook up the auto choke on my carb (SBF 2 brl). I cleaned out the hole in the exhaust manifold so the heat tube would slide in and noticed that it appears to be a blind hole. how can heat travel up the heat tube to the choke housing to open the choke if the hole in the manifold is a blind hole. I assume there is some sort of vacuum assist from the choke housing but with a blind hole how does the heat travel?
|
02-22-2018, 12:39 PM | #2 |
Senior Member
Join Date: Jun 2010
Location: San Antonio, Texas
Posts: 16,436
|
Re: automatic choke operation
I agree. Most all heat riser tubes have at least some circulation through the hot manifold (it just needs heat, not exhaust) but it won't work well without the ability to flow hot air with a carb vacuum port to aid the flow. What is the origin of the engine/manifold sbf combination? Maybe the manifold pathway is crusted up with corrosion of something.
|
Sponsored Links (Register now to hide all advertisements) |
|
02-22-2018, 01:45 PM | #3 |
Senior Member
Join Date: Jun 2010
Location: Detroit suburb, MI
Posts: 3,706
|
Re: automatic choke operation
If it becomes an major issue and a lot of work to correct it, you can always buy a Holley electric heated choke thermostat cap for $15 all day long. Supply it with 12V when the ignition is on, then a short ground wire, and your all set. There should be a vacuum pulled through the choke housing on the carb which keeps it from overheating and pulls the air through.
Sal |
02-22-2018, 05:10 PM | #4 |
Senior Member
Join Date: May 2010
Location: now Kuna, Idaho
Posts: 3,779
|
Re: automatic choke operation
What year carb and manifold? Most shop manuals for whatever year you have will show the heat tube setup. It varies between years and engine models.
Definitely you do not want exhaust gasses in the heat tube! It will clog and corrode the choke mechanism in no time. This was common back in the day and parts houses had various repair kits to bypass the clogged/burned out factory tubes. |
02-22-2018, 06:37 PM | #5 |
Senior Member
Join Date: Jun 2010
Location: San Antonio, Texas
Posts: 16,436
|
Re: automatic choke operation
I think the old mustangs and similar cars with 289 & 302 engines had a kind of steel wool inside the stove to act as a filter for the air being drawn in from down on the bottom of the stove part. A person may have to take the manifold off and see what can be done to restore proper function. PITA for sure but working on it in the confines of an engine compartment is a PITA too.
|
02-22-2018, 11:17 PM | #6 |
Senior Member
Join Date: Oct 2011
Location: elmira,ny
Posts: 1,517
|
Re: automatic choke operation
Sponsored Links (Register now to hide all advertisements)
went thru'59-'65 Motors manual and a '81 Ford manual. they show the heat tube/choke and manifold but nothing as to how it works. I've had a lot of '60's-'80's fords but never thought of how it should operate. As I remember the heat tubes were a tight fit in the manifold |
02-23-2018, 12:53 AM | #7 | |
Senior Member
Join Date: May 2010
Location: now Kuna, Idaho
Posts: 3,779
|
Re: automatic choke operation
Quote:
Another thought: By the '70's at least some Fords were using hot air pipes from the exhaust manifold to the air cleaner with doors that let in heated air when cold and then opened to let in cool air after the engine warmed up, and also electric chokes. So your manifold and original carb may not have had a heat tube for the choke! Do you the exact year of the carb and manifold? There should be a metal tag on top of the carb with a date code such as 'E4' which would be 1974. |
|
02-23-2018, 08:46 AM | #8 |
Senior Member
Join Date: Jun 2010
Location: San Antonio, Texas
Posts: 16,436
|
Re: automatic choke operation
If it looks like the one in the link, then it has a similar stove to the ones made in the 60s. https://www.ebay.com/i/182743884683?chn=ps
I'm not sure if the bottom part of the stove can be removed or not if it's too crusty. Some folks just get a long drill bit and drill though but it needs to have filtered air passing through the system. The thermally controlled induction air heating system is a separate system. PCV and EFE (early fuel evaporation) systems started showing up around 1962 and were the first of the emission controls. Last edited by rotorwrench; 02-23-2018 at 09:16 AM. |
02-23-2018, 11:03 PM | #9 | |
Senior Member
Join Date: Oct 2011
Location: elmira,ny
Posts: 1,517
|
Re: automatic choke operation
Quote:
|
|
02-23-2018, 11:17 PM | #10 | |
Senior Member
Join Date: Oct 2011
Location: elmira,ny
Posts: 1,517
|
Re: automatic choke operation
Quote:
|
|
|
|
Sponsored Links (Register now to hide all advertisements) |
|