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Weber Idling issues


alfamatt

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Just put a weber DFEV on the 71 504, and I can't seem to get it to idle smoothly when warm. (when cold, too,but I'll tackle that next) Timing is set to 10 degrees BTDC, plugs are good, Also idles a bit high, and I can't back out the idle speed screw enough to get it much below 1000 rpm. Suggestions where/how to look for a vacuum leak? Any other suggestins?

Thanks,

Matt

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Hi Rabin,

The carb is pretty generic. That's how they're sold these days, then you're meant to tune them if you want to. Actually, it runs just fine--progression is good, no flat spots, etc. I just think it could idle a bit smoother. The plugs look good, but I don;t know how old they are, so I'm going to go back to the basics--plugs, points, cap,etc even though they all look good. Which NGK plugs do you use? Some people use the BPREY, and some people use the BPR7EY. Which are you using?

And, re the electronic ignition you're using, what parts does it include?

Thanks,

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Actually carbs are usually set up for a certain flow rate usually based on displacement. Mine was new as well, bought it because the motor it was set up for was a 2L. I found jet specs on the Aussifrog's site just to make sure, disassembled the new carb to find the recommended jets and emulsion tubes already installed. Fired it up and it was perfect.

Electronic ignition is the set up from a newer 505 with the XN6 engine. Distributor drops right in so you just need the coil and ignition module and you wire it in.

Can't remember off hand what plug code, but easy enough to cross reference.

Have you checked timing?

Rabin

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Mine is set up for a 2 liter as well, so it's probably pretty close. Timing is good. Plugs and wires are the next thing. Wires are the original, and I found a set to try. Maybe my expectations are too high, but I think it ought to tick over very smoothly at idle. I'll keep you in the loop.

Matt

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  • 3 weeks later...
  • 4 weeks later...

OK, I figured out the problem, but not the long-term solution. The previous owner had disconnected the PCV valve and was venting the crankcase to the atmosphere. As I've done with some of my previous Alfa's, I vented it directly to the air filter. Apparently, this upset the mixture, so that the car would not idle correctly. (There is a fair amount of blowby, so this makes sense.) In any case, venting the crankcase to atmosphere solved the problem--the car now idles as it should.

My long-term solution is to reconnect the PCV system, but I can't seem to find a PCV valve. Anybody have a suggestion for a substitute?

Thanks!

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here's an interesting thread from aussiefrogs, which discusses the pcv system on these cars -- the subject of the thread is actually a 505gr, but that engine is a 1971cc carbureted engine like yours so there is some commonality, i think. lots of good info, also an argument (as you would expect from an australian forum :) )

andré

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Lots of good info there - Here's what I got for my 505 Turbo:

http://store.034motorsport.com/catch-can-air-oil-separator-provent-200.html

Might be overkill, but it should work well. Hard to believe there would be that much blow by that it would affect idle though... That's a LOT of blowby.

Rabin

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  • 1 month later...

You probably need some kind of air/oil separator, a place where oil vapor can condense and go back to the sump so that only the minimum is ending on the intake.

Someting like that:

5F11C70A.gif

You can see that the cam cover gases have a long path to the intake, also there is some kind of metal mesh inside item n°2.

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  • 6 months later...

Here's a manual that has info on setting up both a Solex and Webber carb on a 2.2 L, 8V Douvrin engine used in both early '80's Renaults and Peugeot 505's.  I hope this helps someone.  I find removing the carb and getting a rebuild kit, soaking it overnight in a gallon of liquid carb and throttle body cleaner (NAPA has it) works wonders before rebuilding and re-installation.  

f3n-j7r-j7t-z7u-z7w-engines.pdf

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