Hard starting with webers

[BK911]

I just pulled the CIS off of a 3.0 and installed webers. They run pretty well, but are a PITA to get started. Any tips or tricks?

Pump 5 times, WOT and turn the key?
Pump once, closed throttle and turn the key?

For those with webers, what is you cold starting ritual? Starting fluid?

[lindy 911]

3 pumps, partial throttle (1/4) turn the key. Hold the revs with your foot until it will idle on it's own. Might take a few minutes depending on the temperature.

Lindy

[KTL]

Originally Posted by lindy 911

3 pumps, partial throttle (1/4) turn the key. Hold the revs with your foot until it will idle on it's own. Might take a few minutes depending on the temperature.

Lindy

That's how my 3.0L with Weber 46s and lumpy cams starts. Same went for a friend's 3.0L with Weber 40s and stock stuff CIS mechanicals in the engine.

[Steve@Rennsport]

Its critically important to understand how these things (Webers & PMO's) work so you know how to operate them.

Weber downdraft carbs, unlike Holley, Carter, Rochester, and some others, do not have a choke or other cold-starting aids. Weber & PMO carbs rely on manual activation of the accelerator pumps to push some fuel into the engine when starting from cold.

If the car has been sitting for a few weeks, or long enough that the fuel has evaporated from the float chambers, one may need to intially pump the pedal several times to get sufficient fuel in there to help it run for a minute or so.

The precise number of "foot pumps" varies with temperature, carburetor configuration, adjustment, and camshaft profile.

The trick is to pump just enough fuel in there to light off the engine and keep it running, without flooding the thing or washing the oil off the cylinder walls. Practice makes Perfect to find that combination, but its really easy.

[RWebb]

if it's been sitting a week or more, let it sit a couple of minutes with the key on so the fuel pump can fill the float bowl up, then pump

you can also install a heating pad under the motor to warm it up...

[john walker's workshop]

a 3.0 would need 0.60 idle jets to run well and minimize the spitting and popping after it starts, so it starts to run well after a couple of 2500rpm revs. what do you have? stock 40s may have 0.45, 0.50, maybe been changed to 0.55. minimum 0.55 , but that's usually a bit small still.

[RoninLB]

winter cold after sitting for a few days = waiting for bowls to fill, pump a few times and keep whacking the pedal while it's turning over till it fires and then step 2 comes into play keeping it alive for that 1st minute

ps: my carbs and acelerator pumps adjusted relatively lean compared to most for nice EGTs

[1QuickS]

After I finish my reassembly on a set of Webers I routinely start a cold (60 degrees) engine with this procedure:

• turn on ignition and let fuel bowls fill
• actuate throttle to get two squirts
• turn ignition key
• engine starts and idles

If everything is right with ignition, compression and carbs then you shouldn't need too much foot jockeying to get'er to run. The above procedure routinely works using rough bench settings only, not after detail tuning is accomplished.

[RoninLB]

that works with me with carbs set rich

[BK911]

Thanks for the help. BTW, it was also 20F here when I tried to start her! Once started she runs awesome. I think I flooded her intially.

I am using:
36 vents
160 mains
60 idles

@Paul - your website was a huge help in setting up the carbs.
A big shout out to Richard Parr for his help too.

[RoninLB]

wild thought is that i don't think there's much difference in firing cold Webers or PMOs. I figure using either one for cold winter starts isn't much different than using 6 tin cans to pour gas into the cylinders. I can see a difference using different camshafts in cold firing, but other than that if cold starting is an issue install new spark plugs in November. Tune for power not cold starting


it was also 20F here when I tried to start her
---- did that last week around 1am. I could have awoke the dead in those 5 minutes

[James Brown]

Works for Zeniths also, 1. pump on to fill bowls, 2. pump several times, 3. 1/8-1/4 throttle, 4. crank engine and if it starts, keep idle around 1200, after 45-73 seconds, good to go! having a hand throttle would help.

[RoninLB]

i paid $40 for hand throttle 5 years ago from one of the 911 junk yards

it's a home run when cold starting and can be reckless when used as a cruise control