This has been happening for some time, but has recently manifested itself moreso since I put in the rebuilt engine. The increase in the severity may be due to the fact that I think I still need to advance the ignition timing a bit more due to the hi-po cams that I now have, however, it's pretty much the same problem that I've had for a while.

 

Basically since I installed the weber, although that may not be the single cause, Roxanne has idled a bit rough. For the first few minutes after startup, she will slowly decrease idle speed until she dies. Also, although she seems to start okay when warm (sometimes takes some effort, but fires right up most of the time), cold starting is an issue. Here's what normally happens when I start her up in the morning (keep in mind this is around 25 degrees). Pump the gas a few times, crank, and she fires a bit but can't quite get going. Pump again, then crank, tries again. Then the only way to get her going is to crank at full throttle. She then fires, missing a bunch, then takes off. Still no idle until she warms up though. Then when I go to drive off, she'll try to die sometimes, but I can keep her going with some pumping of the throttle. That has also happened once or twice with the engine warm.

 

Even when warm though, the idle is rough, like there is a miss. If i slowly give it throttle, once she gets above about 1300 rpm, it smooths right out.

 

I'm thinking there are two probable areas to investigate. Either the Weber just isn't set up right or has gummed up idle jets or something, maybe the float level or choke is off, or I've got bad ignition components. Maybe when we took off the intake manifold, the carb got jolted and it screwed up something, or it was damaged by the backfiring when the drivers side cam was off a tooth. It's been two years since I replaced the coil and wires with Accel high voltage stuff, and the cap, rotor, and spark plugs are less than 6,000 miles old.

 

There is also the looming phantom that I screwed up something internally when I rebuilt it. This doesn't seem likely though, as if that were the case, then there would probably be other symptoms like oil burning or lack of power, which I haven't seen any of yet.

 

I'm going to mess with the timing today or tomorrow to see how that affects it. It seems to want some more advance, as it runs a bit smoother with that. I just need to take the time to get that right. It seems to me that the starting problems are related to carburetion though. The only experience I have with webers is what I've done on this one, which is installing it and adjusting the idle speed and mixture, and the choke and high idle, so I don't know how things like float level affect performance. I do have a hitachi in great condition that I could put back on, but I like the way the weber runs when it's going good.

 

Please help!

Is there anyone else near you with a weber that you could swap on to see if the problem goes away?

Not that I know of. I could swap the hitachi back on and see what happens though.

Somebody suggested that maybe the power valve was damaged by a big backfire, and is now dumping fuel. Does this sound possible?

Are you smelling excess fuel or getting black smoke at idle?

It smells a little rich. I've played with the idle mixture adjustment a bunch and that can't get it to run right, so it would appear that it's got something putting fuel in that shouldn't be. (If I remember correctly, I had to lean out the idle mixture noticably, so it's probably getting a decent quantity of poorly atomized fuel from the PV or some other source, hence the bad running until the engine speeds up and can handle that fuel better.)

Ahh, the vagueries of carburation.

 

First I would swap the hitatchi on (if it is known good) and see how it runs. Then if it runs well, just do a full rebuild/clean on the weber.

Thanks for your help SB.

 

Do you know if it's easy to get to the power valve on the weber, and if so is it easy to tell if it's damaged? I just don't want to do another flippin' carb swap on this thing (three different carbs on it within a month and a half last fall), but I will if needed. And since the Weber is brand new as of last fall, there shouldn't be anything else that would need replacement, although it could probably benefit from a good cleaning after 6,000 miles of use.

 

If taking apart the weber is a big project, I may just put the Hitachi back on until this summer when I've got the time to mess about with it some more, because I need a reliable car with decent fuel economy, and the Hitachi was doing great for a Hitachi.

If it is the power valve you can get the kit that includes it for about $32 from http://www.racetep.com/rebuildrejet.html

 

Here is a diagram for component location and a description of the opperation of the valve.

 

 

 

http://www.redlineweber.com/html/Tech/32-36_dgev_parts_breakdown.htm

 

 

http://www.dimequarterly.tierranet.com/articles/tech_carb_tuning_guide.html

Crikey that's cheap for a complete rebuild kit! Carbsunlimited, where I bought the carb from, wants $29 for the power valve assembly alone.

 

That article on theory is some good reading too.