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ohiowesty
Samba Member
Joined: March 26, 2016
Posts: 42
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 Posted: Mon May 29, 2017 6:39 pm Post subject: Weber shenanigans |
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Late bay westy with single progressive Weber here.
I would appreciate some advice regarding three issues:
1. With choke on, it starts pretty high at 2100rpm and then, within a few minutes, it steadily creeps up to 2800, at which point I get nervous and blip the throttle to turn the choke off.
I located the fast idle screw, what would be the proper rpm limit to set?
2. I have a hard time going over 55-60mph.
Any suggestions? Maybe messing with the secondary progression?
3. I am paranoid about pre ignition and running too lean. When listening to the exhaust, with the choke on, I hear one slight popping in the exhaust every 10-15 seconds or so. So far I adjusted the valves, dialed in the timing really good, adjusted the idle screw and mixture screw - and they fall within baseline specs (1 3/4 turns). It idles great, drives pretty smooth, no dead spot. Svda pertronix dizzy. Ported vacuum reading is pretty high (19) measured with a crappy vintage fuel saver gauge.
How can I check for lean condition without running the bus until spark plugs change color and maybe blow a hole in a piston?
Thank you |
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busdaddy
Samba Member
Joined: February 12, 2004
Posts: 51112
Location: Surrey B.C. Canada, but thinking of Ukraine
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| Posted: Mon May 29, 2017 6:55 pm Post subject: Re: Weber shenanigans |
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Back that high idle screw out, you want it to end up at a speed where it won't die but doesn't sound like it's ready for launch, maybe shoot for 1500 to start with and see how it does?.
Top speed can be many things, throttle cable adjustment is first, running on all 4 cylinders (valves, compression and plug wires) is next and mixture is 3rd. If it's too lean it usually craps out and coughs or misses, a 10 mile highway run followed by a shut down and coast to the side of the road for a plug pull once it cools a little is the best way to tell if you dont have an AFR meter.
(BTW AFR meters are now ~$100, you'll save that in a few tanks of gas if it's rich and what's new heads worth if it's lean??
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mnskmobi
Samba Member
Joined: February 28, 2005
Posts: 536
Location: Melbourne, Australia
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| Posted: Mon May 29, 2017 7:18 pm Post subject: Re: Weber shenanigans |
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I agree with busdaddy's suggestion about the AFR meter. Extremely useful for dialling in a carb. 
Have you had a look here?
https://www.thesamba.com/vw/forum/viewtopic.php?t=217070&highlight=weber+suck
Unless you live somewhere that's warm all year round or only drive when it's warm you will need manifold heat with a single weber progressive to avoid icing. |
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ohiowesty
Samba Member
Joined: March 26, 2016
Posts: 42
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| Posted: Mon May 29, 2017 10:19 pm Post subject: Re: Weber shenanigans |
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Yes I am well aware of the general consensus that single webers suck, and I read that entire thread a while ago. I have another Westy with FI, and that's my main ride. My goal with the carbureted one is to make it run good enough until I can convert it to FI. |
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ohiowesty
Samba Member
Joined: March 26, 2016
Posts: 42
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| Posted: Mon May 29, 2017 10:33 pm Post subject: Re: Weber shenanigans |
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| busdaddy wrote: |
Back that high idle screw out, you want it to end up at a speed where it won't die but doesn't sound like it's ready for launch, maybe shoot for 1500 to start with and see how it does?.
Top speed can be many things, throttle cable adjustment is first, running on all 4 cylinders (valves, compression and plug wires) is next and mixture is 3rd. If it's too lean it usually craps out and coughs or misses, a 10 mile highway run followed by a shut down and coast to the side of the road for a plug pull once it cools a little is the best way to tell if you dont have an AFR meter.
(BTW AFR meters are now ~$100, you'll save that in a few tanks of gas if it's rich and what's new heads worth if it's lean?? |
Thank you Busdaddy. Truth be told, the throttle cable is on the loose side. As for AFR meters, for $100 I can only get a narrow band AFR setup. I'm actually very close to pulling the trigger on a PLX wideband with the newer Bosch 4.9 sensor. It monitors sensor health and has a touch screen multi gauge. https://www.plxdevices.com/Wideband-O2-Touch-Screen-Multi-Guage-p/897346002719.htm. I was initially looking at the AEM and Innovate LC2, but there seems to be a high rate of sensor failure lately. |
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Wildthings
Samba Member
Joined: March 13, 2005
Posts: 50332
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| Posted: Tue May 30, 2017 4:41 am Post subject: Re: Weber shenanigans |
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If your engine doesn't bog coming off idle then the carb is probably running very rich at highway speeds.
What distributor are you running and what are you setting the timing at? |
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ohiowesty
Samba Member
Joined: March 26, 2016
Posts: 42
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| Posted: Tue May 30, 2017 7:05 am Post subject: Re: Weber shenanigans |
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| Wildthings wrote: |
If your engine doesn't bog coming off idle then the carb is probably running very rich at highway speeds.
What distributor are you running and what are you setting the timing at? |
Pertronix Flamethrower SVDA.
Timing set two days ago:
Hose off: 28 degrees all in
Hose on:
7.5@850rpm
10@1000rpm
22@1500rpm
36@2000rpm
38@2500
39@3000
40@3500rpm
40@4000rpm
dwell 52
Carb settings are within baseline:
Idle speed screw 1 3/4 turns in
Idle mixture screw 1 3/4 turns out.
Today I noticed that my idle dropped from 850 to 750 so I turned out the idle mixture screw another 1/4 turn to bring it back to 850. So I guess I made it even richer. |
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Wildthings
Samba Member
Joined: March 13, 2005
Posts: 50332
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| Posted: Tue May 30, 2017 9:11 am Post subject: Re: Weber shenanigans |
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| ohiowesty wrote: |
Today I noticed that my idle dropped from 850 to 750 so I turned out the idle mixture screw another 1/4 turn to bring it back to 850. So I guess I made it even richer. |
That doesn't have anything to do with the mixture when running down the road though. In general with these carbs they run lean coming off idle and still run a bit rich at cruise, so if the carb has been jetted to get rid of the off idle bog then it is probably quite rich at cruise. However if someone has jetted the secondaries off to the lean side you can still end up lean near full throttle.
Have someone hold the throttle to the floor while you watch the carb linkage. The butterflies should be just shy of being fully open.
You also might want to dump a bottle of carb/fuel injection cleaner into your tank and let it do its thing. |
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