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914World.com _ 914World Garage _ hand throttle vs cold start circuit

Posted by: bbrock Nov 13 2017, 03:50 PM

My Webers have the cold start circuits installed. While I'm replacing the floor pan and have easy access to the tunnel, I am thinking about adding a couple tubes to run cables from a hand throttle lever to the carbs to operate the chokes. Wondering if anyone has done this and whether it would provide superior cold starting to the traditional hand throttle. I live in the frigid north where it can freeze any day of the year, so I want the best cold start operation I can get. Thoughts?

Posted by: GeorgeRud Nov 13 2017, 04:12 PM

The original hand throttle just provided another way to depress the accelerator cable on the -6s. Please post pics of your Weber carbs with the chokes - I assume they’re not for a -6 as I’ve never seen chokes on the 40IDA or IDT carbs.

Posted by: bbrock Nov 13 2017, 04:40 PM

QUOTE(GeorgeRud @ Nov 13 2017, 03:12 PM) *

The original hand throttle just provided another way to depress the accelerator cable on the -6s. Please post pics of your Weber carbs with the chokes - I assume they’re not for a -6 as I’ve never seen chokes on the 40IDA or IDT carbs.


Oh yeah, I should have added those details. These are 40IDFs for a 4 banger. Seems everyone using these with air cooled engines either ignore them, or block them off because engines start cold without using it. But 95% of those people live in Cali so.....

Here's a pic of the cold start on one of my carbs. The circuit adds a little extra fuel to richen the mix rather than reduce air like a traditional choke. Seems like this would be better than than just bumping up revs with a hand throttle until the engine warms. confused24.gif

Attached Image

Posted by: porschetub Nov 13 2017, 05:32 PM

No not really needed a handthrottle is a better solution,getting the cables setup correct would be a hard task,last thing you need is one to stay open a bit and fuel wash your motor.
I remember an old article on the Porsche 356/ 912 about why they had no chokes on the these cars the reply from Porsche was something like ''parts you don't need'' .
On my six its 3-4 pumps on the accelerator hand throttle full on and it starts right up,not long before you pull the hand throttle back to idle,if your carbs are dialed in you will have the same result with a 4.
Good luck beer.gif

Posted by: DaveO90s4 Nov 13 2017, 05:44 PM

My 914 as purchased with its single centre mounted carb was very hard to start. That carb had a choke arrangement that was disconnected.

To connect it I simply ran a cable from engine, through centre of firewall low down about where the other cables , fuel line etc go through, horzontally out the small access hatch between the seats near the firewall, along the right hand slider of the driver's seat and made a small bracket to mount the cable pull lever on to the front R H seat, down close to the floor.

Worked perfectly, no horrible cable kinks, unobtrusive, easy to manipulate, no dashboard modifications, etc

I know you obviously have different carbs, but if you do decide to connect a cable you might find the above the easiest way to do it.

Regards

DaveO
Oz

Posted by: nditiz1 Nov 13 2017, 06:09 PM

Mine did have the CSC hooked up on both carbs. I will most likely not use it as I am trying to clean up the engine bay.

The PO was into bicycles and used a hand lever hooked to a central mount point. There was a bracket mounted at the rear of the engine on the top. The cable inside would pull both levers open all via bicycle brake/gear cables. It was a pretty neat setup. PM if interested in having my old setup. The lever was mounted just behind the E-brake, but could be mounted anywhere really.

Posted by: bbrock Nov 13 2017, 06:45 PM

QUOTE(porschetub @ Nov 13 2017, 04:32 PM) *

No not really needed a handthrottle is a better solution,getting the cables setup correct would be a hard task,last thing you need is one to stay open a bit and fuel wash your motor.
I remember an old article on the Porsche 356/ 912 about why they had no chokes on the these cars the reply from Porsche was something like ''parts you don't need'' .
On my six its 3-4 pumps on the accelerator hand throttle full on and it starts right up,not long before you pull the hand throttle back to idle,if your carbs are dialed in you will have the same result with a 4.
Good luck beer.gif


This seems to be the consensus and helps answer the first questions of whether it is needed. What would be a typical "cold start" air temp for you? I won't be driving the car much during winter so starting in our -35F/-37C temps isn't much of a concern, but there will be plenty of days starting the car as low as 0F/-17C. Part of my challenge is figuring out if no-choke starting experiences of others translate to Montana weather.

QUOTE(DaveO90s4 @ Nov 13 2017, 04:44 PM) *

My 914 as purchased with its single centre mounted carb was very hard to start. That carb had a choke arrangement that was disconnected.

To connect it I simply ran a cable from engine, through centre of firewall low down about where the other cables , fuel line etc go through, horzontally out the small access hatch between the seats near the firewall, along the right hand slider of the driver's seat and made a small bracket to mount the cable pull lever on to the front R H seat, down close to the floor.

Worked perfectly, no horrible cable kinks, unobtrusive, easy to manipulate, no dashboard modifications, etc

I know you obviously have different carbs, but if you do decide to connect a cable you might find the above the easiest way to do it.

Regards

DaveO
Oz
QUOTE(nditiz1 @ Nov 13 2017, 05:09 PM) *

Mine did have the CSC hooked up on both carbs. I will most likely not use it as I am trying to clean up the engine bay.

The PO was into bicycles and used a hand lever hooked to a central mount point. There was a bracket mounted at the rear of the engine on the top. The cable inside would pull both levers open all via bicycle brake/gear cables. It was a pretty neat setup. PM if interested in having my old setup. The lever was mounted just behind the E-brake, but could be mounted anywhere really.


Whoa! Two guys who have chokes/CSC hooked up! I've done a lot of searching on this subject and you guys are the first. Nice to hear it can actually work. Bicycle cable (or frunk cable) is exactly what I have in mind. Difference is that I'd run the cable to a 914rubber repop lever mounted in front of the gear shift for a factory appearance. I think it would be simple and reliable. Actually, I think it would be easier than retrofitting a hand throttle since it wouldn't require a mod of the peddle cluster. The bigger questions is whether it is necessary.

Posted by: theer Nov 13 2017, 07:07 PM

I had a hard time starting my 1.9l w/ dual 40 webers this weekend. Temps were in the low 40's (F). It finally started, but it took a few minutes.. maybe 7 -10 crank attempts?

Choke would have been very helpful.

So - do I have this circuit already, or is it an add-on? Is there an electric choke available, like on the old VW's?

Posted by: Tbrown4x4 Nov 13 2017, 07:07 PM

None of my 40 IDF castings are not even machined for the enrichment circuits.
It gets cold here, (not Montana cold) but a few pumps and off she goes. I hold the idle speed up with the pedal long enough to start defrosting the windshield and I take off.

Posted by: Tbrown4x4 Nov 13 2017, 07:10 PM

The IDF's don't have choke plates or a mechanism for fast idle speed. The enrichment circuit just supplies extra raw fuel for a cold engine. Much like a lot of older motorcycle carbs. (I'm thinking Mikuni's, I believe a lot of Keihins have choke plates.)

Posted by: bbrock Nov 13 2017, 08:09 PM

QUOTE(theer @ Nov 13 2017, 06:07 PM) *

So - do I have this circuit already, or is it an add-on? Is there an electric choke available, like on the old VW's?


Like Tbrown4x4 said, it depends. Some have them, and some don't. If yours have a mechanism like in the picture above that has a little lever a cable would attach to and a brass screened intake on the bottom, then you have it. If you have a solid plate screwed on there, then you could probably easily add it. Since most people who have them, take them off, I'd think they'd be easy enough to source. But I still have no idea how well they work.

Posted by: Tbrown4x4 Nov 13 2017, 08:33 PM

Most people disable them by tapping the casting for screws to hold the plungers down. The problem with them is they can stick and dump raw fuel into the intakes. I always wanted to have the enrichment circuits, but honestly never really needed them.

In reality, fuel injection is your best bet for all situations, but it sounds like you're already set with the carbs.

Posted by: bbrock Nov 13 2017, 08:59 PM

QUOTE(Tbrown4x4 @ Nov 13 2017, 07:33 PM) *

Most people disable them by tapping the casting for screws to hold the plungers down. The problem with them is they can stick and dump raw fuel into the intakes. I always wanted to have the enrichment circuits, but honestly never really needed them.


Hadn't seen that trick. But I've seen https://www.amazon.com/WEBER-CHOKE-BLOCK-PLATE-99005-135/dp/B01AKCI8X8.

QUOTE
In reality, fuel injection is your best bet for all situations, but it sounds like you're already set with the carbs.


Well, that's a story I just wrote about on another thread. I tore this engine down for rebuild in 1989. A large reason was because the FI had become an unreliable POS and I had no idea how to fix it. Everyone was putting carbs on back then, so I rebuilt the bottom end with a carb cam and bought the IDFs. Twenty-eight years later and I'm finally finishing the project. Eventually, I'll likely go back to the FI but for now, it will be these carbs.

Posted by: porschetub Nov 15 2017, 01:01 PM

No its not really that cold in winter @ my part of the world,I think your best option is test them once you have your engine together on a cold day ...if it starts better set them up with a 2 way cable,I would be worried about forgetting to close them after warmup however sad.gif .
IMO a well tuned (jetting,ignition and cooling system ) aircooled engine will start up easily in most conditions without a choke.

Posted by: Spoke Nov 15 2017, 02:58 PM

My 2056 has dual carbs and starting it is not too much trouble. Got to pump the throttle a bit to get fuel in the chambers first. The first attempt doesn't start the car as the carb bowls fill with fuel (after sitting for a week +) before it will start.

I do find that the engine hesitates off the line quite a bit before it is warm w/o a choke with carbs. Much more obvious in the cold weather as opposed to summer temps.

Posted by: Tbrown4x4 Nov 15 2017, 08:54 PM

My car doesn't sit very much, but I put a fuel pump controller in that runs the pump for 3 seconds and then waits for a tach signal. (I have a CB performance 3.5psi pump near the 75-76 location.)

Posted by: Elliot Cannon Nov 15 2017, 11:25 PM

My fuel pump (CB Peformance 3.5psi) comes on as soon as the key is turned. When it's cold I turn on the key, pump the throttle a few times and squirt some fuel in and it starts up great. I don't too often operate in below freezing temps but when I do, I use the same procedure. Works great for me. smile.gif I never felt the need to hook them up.

Posted by: bbrock Nov 16 2017, 01:12 PM

This is all great feedback. Still would love to hear about starting a carbed engine at zero degrees F, but this has been great. I'm liking the idea of just waiting until the car is back together and testing the cold start circuit. I was thinking that the time to prep for cables to the carbs would be when I had the floor off and tunnel opened up. But in reality, it's just a couple holes with grommets that would be needed to pass the cables through the firewall.

As for forgetting to put the lever down after the engine warms, I wouldn't think it would be much different from a manual choke. It happens, but becomes obvious pretty quickly. In this case, I would assume the engine would idle fast due to the rich mixture.

One other thing. In addition to starting ease, I've read elsewhere of some people warning about fuel washing the oil off the cylinders when you pump the accelerator just prior to starting. That might just be crazy "Internet lore" but wonder what you think. It is true that the cold start circuit would be spraying atomized mix into the intake and only when there is vacuum to pull it in during a combustion cycle.

Posted by: jd74914 Nov 16 2017, 01:31 PM

QUOTE(bbrock @ Nov 16 2017, 02:12 PM) *

As for forgetting to put the lever down after the engine warms, I wouldn't think it would be much different from a manual choke. It happens, but becomes obvious pretty quickly. In this case, I would assume the engine would idle fast due to the rich mixture.

Yeah, you'd hit a high idle. As a note, my dad drives his carbed 911 when it's well below freezing and I don't think has ever forgotten that lever so once you get acclaimed it's really a non-issue IMHO.

QUOTE(bbrock @ Nov 16 2017, 02:12 PM) *

One other thing. In addition to starting ease, I've read elsewhere of some people warning about fuel washing the oil off the cylinders when you pump the accelerator just prior to starting. That might just be crazy "Internet lore" but wonder what you think. It is true that the cold start circuit would be spraying atomized mix into the intake and only when there is vacuum to pull it in during a combustion cycle.

Ehh, really no different than a cold start value or the increased fuel pulse on a FI car. You know, in a really cold start on a modern car they actually can inject 100-1000 times more fuel per pulse then needed at idle and don't have washing issues. At those temperatures your fuel is condensing on the intake manifold and almost dripping into the cylinders at low engine speeds to I really don't see much different. You'll get pooling no matter what.

Posted by: bbrock Nov 16 2017, 06:01 PM

QUOTE(jd74914 @ Nov 16 2017, 12:31 PM) *

Ehh, really no different than a cold start value or the increased fuel pulse on a FI car. You know, in a really cold start on a modern car they actually can inject 100-1000 times more fuel per pulse then needed at idle and don't have washing issues. At those temperatures your fuel is condensing on the intake manifold and almost dripping into the cylinders at low engine speeds to I really don't see much different. You'll get pooling no matter what.


Wait... what? Are you saying that people on the Internet make stromberg.gif up? This changes everything! blink.gif

Posted by: Mark Henry Nov 17 2017, 01:43 PM

Cold start circuit I would disable, shit design. It will stick open, not if, but when.

Get your engine built by me and then tell me you're going to use the cold start circuit I'll write "warranty VOID" across your invoice.

Even from my igloo I've never had a problem starting a weber car in the winter. That said any moisture will freeze in these carbs, in the real cold I've seen floats stick open and fuel spill out the tops, etc.
Also single carb's I've seen them turn into a block of ice.
My Gene Berg 42 DCNF's the plungers are tapped and screwed shut right from Berg, one winter I drove it every nice (but cold -20C) day, never had a problem with starting.

BTW the /6 weber warm up lever isn't a choke, it just holds the throttle open so you have fast idle till warm.

Posted by: bbrock Nov 17 2017, 03:00 PM

QUOTE(Mark Henry @ Nov 17 2017, 12:43 PM) *

Cold start circuit I would disable, shit design. It will stick open, not if, but when.

Get your engine built by me and then tell me you're going to use the cold start circuit I'll write "warranty VOID" across your invoice.

Even from my igloo I've never had a problem starting a weber car in the winter. That said any moisture will freeze in these carbs, in the real cold I've seen floats stick open and fuel spill out the tops, etc.
Also single carb's I've seen them turn into a block of ice.
My Gene Berg 42 DCNF's the plungers are tapped and screwed shut right from Berg, one winter I drove it every nice (but cold -20C) day, never had a problem with starting.

BTW the /6 weber warm up lever isn't a choke, it just holds the throttle open so you have fast idle till warm.


I've been waiting for a Canadian to chime in on this thread. This is great info all around - that I should have no problem starting even in real cold, and the cold start circuit is a POS. I'll block it off and forget about. And yeah, I had a VW bus with a single carb, and later 34ICTs that would all turn to blocks of ice. Difference was that the ICTs would stop icing up once the engine got warmed up.

I did know how the handle thottle works. But I was curious about whether the CSC works better than cracking the butterflies during warmup. Sounds like I don't need either. thumb3d.gif

Posted by: brant Nov 17 2017, 03:20 PM

my current motor is FI
but I daily drove a 2.0/4 for years back in the 80's
it had 40mm IDF carbs and was living in boulder Colorado at the time
never failed to start

I remember near Christmas in about 1990, it was 17 below F
started up
a little cold until it idled for a few minutes

just pump the acc pedal a few times and then turn the key
KISS... its plenty easy to start without more complications.
brant



QUOTE(bbrock @ Nov 16 2017, 12:12 PM) *

This is all great feedback. Still would love to hear about starting a carbed engine at zero degrees F, but this has been great. I'm liking the idea of just waiting until the car is back together and testing the cold start circuit. I was thinking that the time to prep for cables to the carbs would be when I had the floor off and tunnel opened up. But in reality, it's just a couple holes with grommets that would be needed to pass the cables through the firewall.

As for forgetting to put the lever down after the engine warms, I wouldn't think it would be much different from a manual choke. It happens, but becomes obvious pretty quickly. In this case, I would assume the engine would idle fast due to the rich mixture.

One other thing. In addition to starting ease, I've read elsewhere of some people warning about fuel washing the oil off the cylinders when you pump the accelerator just prior to starting. That might just be crazy "Internet lore" but wonder what you think. It is true that the cold start circuit would be spraying atomized mix into the intake and only when there is vacuum to pull it in during a combustion cycle.


Posted by: Mark Henry Nov 17 2017, 05:05 PM

Only time you would run into issues with the IDF would be running without a rain tray and parking outside. Like I said moisture and freezing temps will cause issues. BTDT

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