Need help quick!

[Quick Draw]

Hey, I'm trying to get up to FoCo tonight, but having a hell of a time...

So Doris all the sudden won't idle... and generally runs like shit below 2500 RPM. It really seems like a vacuum leak, but I have checked EVERYTHING.... I cannot find a leak anywhere. The strange thing is that when I have the idle screw boosted up, it goes back and forth between running fast and almost dying on about a 5 second cycle. Then as its winding down, it makes a high pitched whining noise, and if you listen carefully, its there even when its running. I know...it REALLY sounds like a vacuum leak. I'm going out to the garage to check this out more. If you have ever heard or seen anything like this, let me know...

[ike]

Sounds like a vaccume issue to me as well. dont know that there is much i can offer though without seeing her in person.

[Quick Draw]

I'm really stumped as of now. For good measure, I started checking some other things. Compression seems fine and oil only has oil in it. So I think its safe to say the HG is fine, which I expected. All of the valve clearances are within spec. The timing is perfect. The spark plugs look good, and are a nice light brown color. There are no exhaust leaks at the head. The motor runs good at high RPM, so I can hopefully rule out any head or valve issues, though they may not be in the best shape for how long it was ran without exhaust. So, not really any progress yet. I'm still thinking its either a carburetion/vacuum issue or an electrical issue. Which is what I thought to begin with. I'll put it back together and run it so that I can rule out the electrical issue and screw around with the carburetor...

[Quick Draw]

I think I have it figured out. I wish I would have checked this sooner. While they seemed tight, I pulled the Weber and the Redline adapter plates. I resealed and torqued them down. Instantly, after starting it up, the idle shot up to where it should be with the idle screw so cranked. Then I adjusted it up, and she's purring and running smooth at 1100 RPM again.


SO YES....IT WAS A VACUUM LEAK....DUHH...

Off to FoCo, as soon as I clean up my mess..

[Quick Draw]

P.S. My brain really begins to rot this time of night...maybe you can tell...

[ike]

Glad to hear you got it figured out. it is always the little shit it seems.

[Quick Draw]

So interestingly enough, with the vacuum leak Doris packed a little more punch at WOT, which is where I drive 99% of the time. Just shows how rich it is usually. And it definitely smells that way too. I was getting used to that nice power up top. So I might have to buy some jets from LCE to finally correct for the altitude. I used to do this all the time on motorcycles, so it should be cake.

[RedRunnertc]

If it's a Weber, you should be able to lean it out enough ... very unusual to swap jets on a Weber.

[Quick Draw]

It's tuned about as good as it can get right now. I think a couple steps down on the mains would really be perfect. The rest of the range feels good. That's often the case with bikes too. Also, I have my mixture screw backed out beyond their recommended range, to the point that they suggest some rejetting. According to the Redline manual, the jetting is sufficient up to some level slightly below us. I don't quite remember. 4500 or something.

[fast7mtoys]

wish i or russ would have read this earlier........we both had a bunch of problems on his truck with my old webber...........(i never had a problem with it on my celica) oil filter boxes, or even better felpro gasket boxes(paper board) and a ball peen hammer.......it makes the best gasket i have ever used for a webber..........even better than cut to fit gasket material..........shouldn't have to use silicone on the carb gaskets......

[vwfastg60]

Originally Posted by fast7mtoys

wish i or russ would have read this earlier........we both had a bunch of problems on his truck with my old webber...........(i never had a problem with it on my celica) oil filter boxes, or even better felpro gasket boxes(paper board) and a ball peen hammer.......it makes the best gasket i have ever used for a webber..........even better than cut to fit gasket material..........shouldn't have to use silicone on the carb gaskets......

That was the issue...the gasket paper is crap! i had never even seen someone use that stuff before you did it that way and i will never use it on anything again....If you want i have like 3 rolls of it that are about new from all that carb mess.

I took it all off and cleaned the plates and roughed them up i used a thin coat of copper RTV and let it dry over night. I also used locktite on the bolts and cranked them down evenly and it never leaked again. As for tuning it i have a wideband and will be around this weekend if you wanna tune it.