the usual weber stuff, need help

dlampe · #1 (**permalink**) 10-31-2010, 04:32 PM

Ok, I think I have this sorted but let me see what you guys think. I was having some popping from the right side pipe. I went from 65 to 60 idle jets with a 100 holder. I was 3/4 turns out. The popping got worse. The plugs were pretty black but the car idled around for a long time. I went back to the 65's and it got a little better. A/F is 12.5 - 13 to 1. I screwed the idle mixture screw out to 1 turn. Still had a little popping but not bad. I screwed the idles out to 1.5 and the a/f is now around 12 to 1 and the popping is gone but black smoke is massive at idle. My though is to go to a 70 idle jet and screw the idles back in to 3/4. Does that make sense?

My timing is set at around 35 degrees max at 3000. I was wondering if the timing could be a factor. I have a duraspark dizzy with vacuum advance.

BT SNAKE · #2 (**permalink**) 10-31-2010, 05:24 PM

Them Webers can run good with the mixture screws a 1/2 turn to 3 screwed out. Just because it's a 1/2 turn out doesn't mean you need smaller jets.You need to know which size is right for your motor. If you have a high vacuum it will suck more fuel in with less turns on the screw.If you have a lower vacuum it will need more turns. You can't go by a set number of turns on the screw. I always went by the plugs. I used to take the car out on the road and run it at 45mph then shut it down and coast into my drive. Pull a plug. Chocolate means you're good and white is lean. Black is not good.

As always you need to sycrometer them first. They all need to be sucking the same amount of air. Dean, I know you know a lot of this stuff but it's for other reading this that may not know.
I still hate webers though.

I been bent over the fender way too many times because of those pop snappin pieces of ahuuu... well you know what I mean or you will know soon.

Good luck I hope it helps.

Hersh

ENTDOC · #3 (**permalink**) 10-31-2010, 06:05 PM

most of the research I did led me to conclude that anything over 3/4 turn out meant that your idle jet was too small. I would agree that going to the 70 jet is the right idea, assuming you have 2 progression holes. With 3 holes you can get by with a smaller jet. You need to be concerned about cylinder washdown with the idle screw turned so far out I would think

BT SNAKE · #4 (**permalink**) 10-31-2010, 06:58 PM

Dean,
A 70 idle jet sound big to me. Maybe not. It sounds like you are running rich all the time. If this is true then maybe your choke tubes are to small.
Also you might want to invest in one of these. I wish I
still had mine, I'd send the darn thing to you.

http://www.jegs.com/i/Innovate-Motor...ductId=1294324

Hersh

dlampe · #5 (**permalink**) 10-31-2010, 07:58 PM

I'm running 40 mm chokes now. I had 45mm chokes and couldn't get them to work. I have been thinking about this and I'm wondering if I should go with the MSD dizzy to get the timing in sooner or just lock out the duraspark and set the time at 36, no advance. If I had more advance under 3000 rpms would it lean it out? According to my a/f meter I am pretty rich with the idle screws turned out. Also my screws are the old ones with less taper so more than 1.5 doesn't really change anything. You are all in at that point. I feel like the car runs best at 1/2 to 3/4 turns so maybe the bigger idle jet is the way to go. I'm still not sure about the timing and the role that it plays in all this. My other weber cars all had the timing advance locked out and were more track oriented.

BT SNAKE · #6 (**permalink**) 10-31-2010, 08:47 PM

Dean,
I think you may have a vacuum leak because you have to screw out the Idle jet so far. I think you should leave the timing alone unless the motor falls on it's face on acceleration from about 30mph.

One more thing, your stoichiometric mixture should be between 13 and 14.5.

Hersh

BT SNAKE · #7 (**permalink**) 11-01-2010, 07:57 AM

Dean,
Now that you have got me thinking about this, I
went and tried to find my old Weber setup manual.
I didn't find it. It's still buried somewhere deep in the storage unit. Anyway I saw that you run vacuum advance. I never did. If you run vacuum advance you cannot use the vacuum from the
manifold as it will be advanced at idle. Then when you hit throttle it retards and fall off on a flat spot.
If you have it plumbed for vacuum under the manifold then it should be OK.
You have a good ignition box and dizzy. That's not
your problem I'm sure.

Hersh

dlampe · #8 (**permalink**) 11-01-2010, 08:54 AM

I have looked and looked for a vacuum leak and I just can't see anywhere it could be. The manifold is plumbed for vacuum. I hope there isn't a leak under there somewhere!

I took the dizzy apart last night and it has 26 mechanical built in. I am going to sften the springs and reduce the mechanical to around 15 total so I'm all in by 2000 to 2300 and I can set initial at 20. I don't think that is the problem either but I wanted to change this anyway.

Back to the issue. The webers should be able to run at 12.5/13 to 1 a/f without popping and it is only popping on one side. If it leaks where the header meets the sidepipe, would that cause this or is it to far down stream? If the header is tight on the head and there is no sign of black sought, where else can I look?

bobcowan · #9 (**permalink**) 11-01-2010, 09:45 AM

Sounds like the balance is off just a tad. It doesn't take much to create drivability and performance problems. Set that exactly right befor changing anything else.

Snakebit · #10 (**permalink**) 11-01-2010, 11:24 AM

If it is only on the one side, then the balance is off or the linkage needs to be adjusted so both banks are opening the same amount. If they are sync'd at idle, then check the sync at 2000 rpm and see if both sides are the same.

priobe · #11 (**permalink**) 11-01-2010, 12:07 PM

I would have to agree with the balance being off. I would resync your carb and try to turn down the idle screw as far as you can go.

I would also check for a vacuum leak as well, unless you know for sure you do not have one.

my .03

dlampe · #12 (**permalink**) 11-01-2010, 01:58 PM

Thanks guys. That gives me a few things to try. We should all get together and write a book about all the silly questions that come up with these Webers. It seems like I am able to offer advice about problems when it is someone else's car but my brain shuts down when I step into my own garage! I really appreciate the fact that here are still a few Weber guys around to bounce ideas off of.

Thanks,
Dean

BT SNAKE · #13 (**permalink**) 11-01-2010, 08:06 PM

Dean,
I know you have a 482 Pond. Do you have a dyno sheet?

If you take it to a dyno shop that is familiar with webers
they will generally do the jetting for you. They will charge
for the time but usually no charge for the jetting. Try a shop that does a lot of Porsches with webers. I believe
this is the right way to get the most out of that motor.

I wish I could be more helpful but I have been away from Webers for so long I forgot a lot. This sure brings back memories though.

Hersh

*13* · #14 (**permalink**) 11-02-2010, 07:28 AM

I'm just catching up on this thread, Sorry. Sounds like you guys are on the right track, so my input isn't needed....Isn't there a "Webers for Dummies" book?

ACademic · #15 (**permalink**) 11-02-2010, 07:48 AM

Quote:

Originally Posted by *13*

Isn't there a "Webers for Dummies" book?

Build it and they will come. I'd pay good money just to read it and understand them better.

bobcowan · #16 (**permalink**) 11-02-2010, 10:15 AM

Quote:

Originally Posted by *13*

I'm just catching up on this thread, Sorry. Sounds like you guys are on the right track, so my input isn't needed....Isn't there a "Webers for Dummies" book?

http://www.carburetion.com/books.asp About halfway down the page

A little cheaper on Amazon
http://www.amazon.com/Weber-Carburet.../dp/0895863774