Why are carbs so freaking hard to start in cold weather ?
How do you fire 'em up on a cold morning? How long to get 'em hot and drivable? Is your gas pedal jitterbug a happy dance? OK how about a heating pad on the intakes?
Will the magician reveal his secrets please? Thanks. Bill

Bill, I have dual 40mm Del Ortos and I pump them twice, turn one the key and they fire right up. I sold early 911's and 914-6s and they came with a throttle positioner. I hold my car at 2000 rpm for a minute and then it idles fine. What are you running? Al.

I just give the pedal a couple pumps and turn the key and it starts right up. Then I reach for the hand throttle and it holds it there at a fast idle for a few minutes to warm it up.

Did you make that yourself Craig?

Yes and its very easy to do

On chilly mornings (~30 is the coldest that I have yet started my car) a quick start depends more on when the last time I drove it was. If it has been a few weeks, the gas in the bowls has either evaporated or started to separate and go stale, and it takes a while to get started.

When I have driven the car recently, I let the pump run for a few seconds, pump 2 or 3 times and crank it till it fires. Usually comes up pretty quick. At that point, I hold idle at about 1500 rpm for 60 seconds, or until the head temp gage reads 100 (what ever happens last). At that point, I can usually take my foot off and the car will *just* idle on its own so I can start gently driving.

Either way, it is a slower start up sequence then an FI car. Just the nature of the beast.

Zach

+1 on what Zach said. If it's been only a day or so, mine starts right up with a couple of pumps. If it's been longer, I let the pump run for 3 or 4 seconds, then two pumps and it starts right up. It only takes driving out to the main road, maybe 1/4 mile, before it's running smooth.

I'm running a single Weber Progressive. It's actually a very good setup in warm weather... and in cold, it has the advantage of having an electric choke. I pump once just as I'm starting to crank and it usually turns over within 3-4 seconds. The choke keeps it running at around 1800-2000 rpm until I pump again to cancel it. When it's cold out, I let it run choked for 30 seconds or so. It doesn't idle perfectly smooth until it warms up, but it doesn't stall either.

The big problem is that it takes a very long time to really warm up (5-10 minutes of driving) and during that time, any acceleration in first gear is prone to flood the engine as the fuel vapor recondenses. Takes a very gentle touch not to flood it, or a lot of revving and clutch slipping.

This thread has me somewhat less optimistic about improvements if/when I switch to dual 40mm HPMX.

Has anyone actually tried a pre-heating element?

can you post how you installed the hand throttle? my carbs (dual weber 40's) are almost impossible to start in the N.E. cold

Why would you go to HPMX carbs?

The improvements between a single carb and duals is quite dramatic.

Duals on a T4 are essentially individual throttle bodies. Throttle response is instantaneous. You never have to worry about flooding the engine due to the gas vapor resolidifying.

I let the engine warm up for a minute as it is supposed to be easier on the engine and increase its life span. Remember, these engines when carbed were state of the art 40 years ago, you can't just turn them on and drive (if you want them to last, that is).

Zach

If I buy new, I'm planning to get Raby's kit. He currently sells HPMX. The kit includes all the induction hardware for a TIV and will soon include his new cable linkage. Reasonable deal for $700...

Yes, please post pictures. If one were to use Jake's new cable linkage, I would imagine this would be even easier. I have an extra heater lever. Hmmmmm.

Get him back...
We want pics of the hand throttle...come on...

Rich

The HPMX is basically a Weber made by Empi.

craig we need to see that hand throttle! don't make me take my 914 off it's jack stands and come out there

An empty threat...

Rich

Just copy the 914-6 system, it's nothing more than a rod that pushes against the pedal cluster close to where the cable attaches.

I don't bother with the hand throttle on my conversion car, but I do have to keep pumping the gas pedal for quite a while to get it running in the cold. The original 914-6 is easier as your leg doesn't get as tired from all the pumping!

BTW, the hand throttle can also be used as a poor man's cruise control if you have it set to provide a high enough throttle position when fully engaged!

An empty threat...

Rich
[/quote]

sadly this is true

I drove my white car to work yesterday and today in low 40s temps. Dual Dellorto 40s - started on the second try both days. After only a few seconds maintaining a higher idle with my foot on the gas pedal it idled without stalling when I got out to close the garage door.
Since I don't have heat I probably won't drive it when the temps get a little colder.

If your fuel mixture is on the lean side to begin with it will be harder to keep running when cold.

Hand throttle can be adapted to any 914. The cut out is there in the shifter base, and the threaded hole for the rod support is in ALL 914's. All you need is the hand throttle parts. I kept many of the six parts from my factory six when I sold the body. I put the hand throttle on my '74 conversion. Although I have a red knob, the factory used a black one. The first pic shows the hand throttle knob/lever. The second pic shows the difference between the six and four acc. lever. The six is number 22 with the "wing" on the side of the lever for the hand throttle rod to contact. The four lever has no "wing" and is number 19.

Click to view attachment

Click to view attachment

is there a cable that goes thru the center tunnel and out the fire wall to the carbs? does it then connect to the manual choke on the side of the carb? are these parts still available? sorry bout all the ?'s

The hand throttle in the pic has a rod that goes FORWARD to contact the lever connected to the acc. pedal.....

Sounds like the real secret is to start the car every couple of days to keep the carbs from drying out.

Would a heating coil from the plumbing shop wrapped around the carbs make any difference in cold startup? What part is actually effected? The gas, the intakes, the motor, etc?

A pic of the hand throttle from the Porsche Pet......The rod # 43 goes through the bracket # 47 and pushes on the "wing" of the acc. pedal lever.
Click to view attachment

What is your problem.

90% of carbs problems can be traced to the ignition.

Rich

Here is the way I did my hand throttle. I got a heater lever with a straight shaft, a 1/4" rod about 18" long (will have to be cut to length), a clevis, a small piece of angle iron for the front guide, and a small piece of flat stock welded on the throttle lever on the pedal cluster.

Click to view attachment

A pic of the clevis. The hole at the bottom of the heater lever had to be drilled larger for the pin of the clevis the fit.
Click to view attachment

The bolt to the left of the access cover is where the guide is and the hole is already there on top of the tunnel. The piece of angle has a nut welded on for the mounting bolt and a hole drilled for the rod
Click to view attachment

thanks for the pics
rich

No problem other than not driving enough. The car sits for a week and then startup usually takes 3-5 pumps and 2 trys to fire it up. Then it takes a couple of minutes to idle without me holding the gas pedal. One above comment on letting the carb bowl dry up is probably what's going on.
I also like the hand throttle info here.

If I haven't driven for a while I always let the pump run for a few seconds until I hear it change pitch, indicating it is no longer flowing fuel, and is pushing against closed needle valves.
Then I pump the throttle a couple times to prime the intakes right before cranking it over.

I added a "primer switch" that runs the pump when the engine is off. I hold that switch down for a few seconds to build pressure and fill the bowls then release it, pump the pedal a couple of times, and start her up. It might take a couple of tries to get the engine to catch, but that's it. Before I put in the switch, it was a real PITA.

I also let it warm up for a minute or so...the fumes trapped in the garage then kill any critters left in the garage while I'm out driving

Craig,

Good write-up and pics. Thanks,

Nate

Looked up some parts on Stoddard's this morning.

914-6 accelerator cable, 914.423.066.00, $87.14
Heater handle knob, 914.424.792.01, $16.50

Stoddards has all the accelerator cable parts from the pedals to the bellcrank on the transmission. Didn't check Pelican but they probably have them as well.

Nate