Weber Conversion Project

[Bert]

If I could unplug all the electronics and bolt on a simple carburetor, and still pass Ontario emissions tests, I'd be in auto heaven. I've never tangled with a Weber setup but their reputation is legendary. 40 years ago everyone on the performance circuits with small cars lusted over these things.

[denguy]

I ended up making a 1/2" thick micarta[that's what I had on hand] spacer to go under the Holley-Weber Escort carb to insulate it from engine heat. Before I did that the gas was bubbling in the carb, could hear it.

[Festy46]

I wish that someone would come up with a simple little hand held air-fuel ratio meter gizmo that you could stick up your exhaust.

This doesn't go up the exhaust but instead screws into the O2 sensor hole. I had one of these on our car to make sure the engine wasn't running lean, but the tech guys threw a fit. Seems they thought I had some super secret power booster installed.

http://borla.com/products/induction/Halmeter/Halmeter.imgs/Halmeter_AF30_Brochure.pdf

[denguy]

Here's another A-F ratio gauge.

http://www.racetep.com/aemuego.html

[MasterTec]

UPDATE: Just finished the adapter plate today. I filled in the holes with an epoxy and then drilled and beveled new holes so the screws will sit flat and even with the adapter plate to accommodate the gasket:



I also removed and checked the jets that came with the carb and they are going to be way too big. The main jets are 140 and 150 and the idle jets are 50 and 60. The idle jets may be ok so I scored a pair of 130 jets and a pair of 135 jets off of ebay cheap. I'll start with a 130 and a 135 for the mains and then tweak things from there.

I haven't actually installed the new carb yet (otherwise I'd have pictures) but I have to ask.. think I should use the heater or not? I think I'll leave it on there and see what happens.

[zoe60]

That's a smart way to do your adapter plate. Well played sir. If I remember correctly, I think my idle jets are both 50's and worked well on my B3 as well as my B6. I'd try the 135 as the primary main and the 130 as the secondary main. Every engine is different so good luck!

[sketchman]

This doesn't go up the exhaust but instead screws into the O2 sensor hole. I had one of these on our car to make sure the engine wasn't running lean, but the tech guys threw a fit. Seems they thought I had some super secret power booster installed.
http://borla.com/products/induction/...0_Brochure.pdf

Seems you can't get one anymore. They've gone to a wide band system. Kinda stupid since they already existed much cheaper than their product.

[MasterTec]

OK I have it installed. The person I bought the jets from accidentally send me air corrector jets instead of main jets. I should have the right ones in a couple of days but I decided to just go ahead and install it for now and see how it runs.

And the verdict it in.. I LIKE IT! The car is a lot snappier and I just LOVE the throaty Quadra-jet type of noise it makes under full acceleration! I still have some adjustments to make but it's definitely driveable! I think once I get the smaller mains it will actually help and when I get the dashpot reinstalled it will help with stalling out. Enjoy the pictures below.

I do have a few questions though. I may be a certified master technician but to be perfectly honest I've almost never touched a carburetor. They had just about all but been replaced with FI when I started working on cars in the mid 90's and I just never really ran into enough of them to learn.

Anyway here's my problem. The idle is very high. Even fully warmed up with no choke and the idle speed adjust all the way backed up it still wants to idle high. I've verified no vacuum leaks and the throttle is all loosey goosey. It seems to run smoothest with the idle mixture screw right at 2 full turns out but I had to tighten it half a turn (to 1 1/2 turns out) to force the idle down to a reasonable level.. about 900-1000RPM.

I have a feeling new jets will help with this but I'm not quite sure what to change them to. Here's what I have now:

PRIMARY IDLE 60
SECONDARY IDLE 50
PRIMARY MAIN 140
SECONDARY MAIN 150
PRIMARY AIR CORRECTOR 170
SECONDARY AIR CORRECTOR 180

I know my mains are too big (I have 2 130's and 2 135's coming to play with the two different sizes) and I have a feeling I need to go 50/50 or maybe even 45/50 on the idle jets. Can someone explain what the air corrector jets do and if I should go bigger or smaller with them?

While driving the car seems to have full power. It doesn't bog down and it doesn't smoke or ping - showing no signs of running rich or lean. My only real driveability (aside from it trying to idle high) problem is it tends to want to lurch a bit when first starting out making it hard to get going without slipping the clutch more than normal. This could be related to me having to adjust the idle mixture down to force the idle down.

I'm half tempted to buy a Weber tuning manual just to learn about this if nothing else!

My next steps are to clean up the vacuum hoses a bit. I'm going to leave the EGR and EVAP systems intact. My Weber air cleaner even came with a fitting for the engine vent hose to attach. I need to tape off the old base heater wires and make more permanent brackets for the throttle cable and the return spring. I also need to reinstall the fast idle dashpot and its solenoids.

I also have to figure out the best place to install the distributor vacuum hoses. I left them installed to the intake just like stock. I'm still not quite sure about what the two hoses do. The top one controls timing advance.. but what does the bottom one do?

I should also note that the CHECK ENGINE light did not come on. The electrical connectors for the carburetor and the base heater are not plugged in however all the other solenoids (even if not being used right now) are still connected electrically. Once I get things tweaked properly I'll start unplugging the unused solenoids one at a time to see if any make the light come on.

Click on the picture to see my album (and full size pics):

[Bert]

Congratulations! Just like having a stick shift, now you control the engine and not some inflexible electrical demon that is more liability-conscious than performance-oriented.

[MasterTec]

OK today I built a bracket for the throttle cable and throttle return spring. I also hooked up the evap hose to the air cleaner and straightened out the vacuum hoses some more.

I'll have an updated pic soon. All I have left to do is install the idle actuator and to put in smaller main jets and tune!

I also have to check the timing to see what I can get by with and I see a new cap/rotor/plugs in my future as well.

[bravekozak]

Keep the MAP sensor hooked up with vacuum feeding it and leave your o2 sensor intact. I think that's all it takes to keep your cel light off.

You can remove the MAP sensor and O2 sensor, if you remove the CEL bulb from the cluster. I promise you the CEL light will stay off forever.

[MasterTec]

Why though? What's the harm in leaving them hooked up?

[zoe60]

I left mine there. Doesn't hurt a thing. My EGR valve and o2 sensor are intact as well. Your installation looks great. Amazing how much more get up and go it has, isn't it? High idle thing is weird, I would still suspect a vacuum leak. What is your timing set at? I keep mine at about 12 advanced, but I have an aftermarket ignition system. I don't know if you would set the timing differently for the original system or not. Good luck!

[MasterTec]

OK Another update.. I did in fact find a vacuum leak. It was a vacuum hose I missed. The idle dropped down some but I still have to adjust the idle speed screw all the way down and turn the idle mixture screw about 1/2 turn in from it's best running point to bring the idle down to what I consider "normal".. about 800-900 or so. The engine idles smoothest (but highest) with the mixture screw about 2 1/2 turns out from its stop. Going out further than that doesn't seem to make much of a difference but going in brings the idle down and makes it idle rougher.

I'm convinced my idle jets aren't right but I don't know whether to go bigger or smaller with them. Based on what I've been reading about the adjustments they are too small however based on what I've been reading about what people are using on their festys.. mine might actually be a bit too big. What do you guys think?

I installed 130/130 mains and it seems to have full power under light and heavy acceleration.. nice and smooth once warmed up but a little bit "boggy" when cold but it gets over that real quick. I haven't run into a carb yet that ran "normal" under load when cold. There's no pinging at all and no signs of it being too lean or too rich.

I also checked my timing. The sticker on the hood ways 0 degrees but it was set to about 8 degrees advanced. I bumped it up a little further still to 12 degrees and we'll see how that does. I also relocated the top vacuum hose for the distributor to the back of the carb.

[bravekozak]

You have to have an exhaust gas analyzer to determine if you have the right jet size. Here is an interesting article.