TheSamba.com :: View topic - Are ALL Webber IDF 40's Hard to Start When Cold?

Thu Jan 19, 2012 8:09 am

I have a set of webber idf 40's and they suck when it comes to starting the car when its cold outside.. Is this just hwo they are? I usually pump it a few times and then it will kinda start and then die and then It usually takes 3-4 minutes to actually get it to keep running and then I cant press on the gas any untill it warms up or it dies. A few minutes after things warm up they are fine.. Im used to a 30 pict 1 carb (what i came from) and i dont care if its -10 degrees outside i would pump it a few times and boom its on, done deal. What do you think? Its on my 1776 110cam cw crank 044 heads and everything is jetted right according to aircooled.net and it does run great when finally warmed but is a bastard to start cold.

Thu Jan 19, 2012 8:13 am

Yep, it is nature of the beast when it comes to performance carbs, also, big engines with no chokes or EFI to compensate.....

Just Grin and Bear it and do what we all do, the morning dance which allows your heat to get going too.... RB

Thu Jan 19, 2012 8:29 am

Every engine is different. My engines start right up and idle even in freezing weather, may need to idle a minute to run good. but I run high compression and race fuel.
Is the engine tuned great? retarded timing can make it tougher to idle cold. Carb jetting. If you run chromealloy pushrods and they are adjusted too tight cold idle will be tough. ( if you set them at 0 lash when it was 90 degrees outside they may be too tight at 10 degrees)

With no choke you can expect the engine to take a little to run on it's own, maybe 2-3 throttle blips when its 30 degrees F. 4 minutes sounds like you may have a tuneing issue.

Thu Jan 19, 2012 10:19 am

this problem is usually due to one or both of a couple things.

If the carbs are jetted too rich (VERY COMMON), the plugs get fouled over time and then won't fire when cold.

The other cause is the accel pumps not working. See if they are working.

We need to know WHICH webers you have to help with jetting.

Thu Jan 19, 2012 12:28 pm

My 40 IDF's start my 2027cc OK in cold weather (< 40 F). I do have an electric fuel pump and I do turn the key and let it pump for 10-15 seconds to prime the carbs before I engage the starter. That's only if I have not driven the bus for a week or two. When it is cold weather, it will take a good 10 to 20 seconds with the engine turing over under the starter while I pump the gas peddle a few times. But that does not seem too bad for carbs.

Thu Jan 19, 2012 1:04 pm

One pump and crank it over is all it takes here! 8)

Thu Jan 19, 2012 1:09 pm

I have started a cold soaked beetle engine at -40F with dual 2bbls. Started right up, but cranked SLOW, and took about a minute before it would idle on it's own.

Thu Jan 19, 2012 2:29 pm

mine starts just fine,oops, I have the china shit hpmx 44's sorry.
I use thin synthetic oil and it spins just fine also.much better than deno oil.

Thu Jan 19, 2012 4:18 pm

they are Italy Webber IDF 40's do you think they are jetted to rich? they are 50 jets on my 1776 110cam cwcrank 019 distributor at 28 degrees. When i pump it i see gas squirt in the carbs, wouldnt that indicate the accelerator pump works?

Thu Jan 19, 2012 4:44 pm

what plugs do you have? plug gap? Venturi, main jet, emulsion tube? 50 idles are close to correct IF they are actually 50s, many have been redrilled to larger sizes.

Thu Jan 19, 2012 4:54 pm

Also whats you initial timing?

Thu Jan 19, 2012 5:44 pm

40 pump , f11, 50 idle jets,28 vents,115 main and 170 airs .plugs are bosch wr8cc+ plugs. Set at .28

Thu Jan 19, 2012 6:05 pm

As for the thread title....heck no

First off, the carbs need to be setup right, acc pumps working good, 40 is too small for all my engines, but then again my engines are all about 2 litres :wink:
anyway, I'd drill it out to 45 or 50, but your results may vary

then you have to know how to DO it
pump a few times then start cranking, holding the throttle 1/8 to 1/4 open. After a few sec it starts to fire then pump gently every few seconds to keep it running. THere is no choke so you feed it fuel with the Acc pump. But since each cylinder has a squirter it works great once you learn how

I had 36 idfs with 40 or 45 squirters on my old junk bus engine, when I lent it to my brother for awhile he'd go out in the morning to start it and I'd literally see the front of the bus going up and down from him pumping the throttle hard as he could :lol: THe acc pumps were crusty and the jets too small, also the throttle cable would return in slow motion when it froze, so starting did not work very well, but it worked good enough I never bothered to fix it

A lot of motorcycles and stuff that have IR carbs are the same way, you want to start with the throttle cracked just a little.

I'm pretty sure your acc pumps aren't working, so you didn't need to know all that, heck I'm just rambling now, oh well no law against it

Thu Jan 19, 2012 6:33 pm

I'm running 40 Dells on my 1915 (34 vents, 60 idles) and at 30 degrees I just give it a couple quick pumps, crack the throttle open just a bit, and fire it up. If I pump it again real quick a couple times, it will settle down and idle at about 5-10 seconds run time. I may be running a bit rich though. I haven't had a chance to tune the thing up since I got it on the road. I just barely had it going and a rod in my truck started knocking, so its been my primary transportation while I get my truck back on the road. I'm about to get a wideband and tune it up properly though.

Thu Jan 19, 2012 8:03 pm

[email protected] wrote: this problem is usually due to one or both of a couple things.

If the carbs are jetted too rich (VERY COMMON), the plugs get fouled over time and then won't fire when cold.

.
Similar prob with mine too going to try this.Now that i think of it its been a while since i have swapped plugs and do know it use to be rich til i rejetted mainly at lower rpms.

Thu Jan 19, 2012 8:28 pm

this all looks almost perfect, assuming the jets are sized as marked. I'd look to make sure the squirters are squirting.

vwoki wrote: 40 pump , f11, 50 idle jets,28 vents,115 main and 170 airs .plugs are bosch wr8cc+ plugs. Set at .28

Thu Jan 19, 2012 10:22 pm

Too Rich

Thu Jan 19, 2012 10:39 pm

beetlebug69 wrote: I noticed my plugs are ALWAYS black. And im barely at 1 turn out on all of them. I clean them off and play with the mixture screws and STILL black! Doesn't smoke though maybe just a little at the start but thats it.

I would suggest you need to go down a size or two on your idles

Fri Jan 20, 2012 1:27 am

fuel pressure too high? wrong float levels?