Removing / refitting Webers

[Cadence]

Further to my recent post, I’m going to have a go at removing the type 31 carbs to drill a hole the rear inspection plates. (As used on later models)

This will hopefully cure the vacuum effect that’s likely causing fuel to drip when the engine is shut down after a spirited drive.

Both rear inspection plates have clear evidence of fuel leakage around their edges.

I’m no mechanic so have read the manual several times before starting the work

I had imagined that I’d remove and refit the carbs individually to get better access to the mounting cups / washers to ensure correct tightness.

The manual says remove the carbs ‘As an assembly, ensuring that the synchronising linkage between the two isn’t distorted’

Is that really necessary or am I creating new issues by attempting to split them on removal and refitting?

Thanks

[Craven]

No, you need to take them off as a pair, linkage gets in the way. The mod now is as pic, pretty standard now. In my experience with the 31 it will never perform as you would like over stumble issue. Fundamental position of progression drillings simply wrong for a 1558 TwinCam, try by all means but not waste £££ on them.

[Cadence]

Thank you for the feedback - I agree on further investment and figured drilling a couple of holes was FOC, so worth a shot.

Cheers

[types26/36]

Just a couple of tips:
1. DISCONNECT the battery BEFORE STARTING ON THE JOB.
2. Keep a FIRE EXTINGUISHER handy.

[rgh0]

I always pull the webers and airbox back plate off as an assembly. Using a 1/4 flexible extension drive shaft and socket it is quick and easy to access the mounting nuts to remove and refit. Doing it this way also retains to the carb balance though I do always check it after reassembly.

cheers
Rohan

[Cadence]

Just a couple of tips:
1. DISCONNECT the battery BEFORE STARTING
2. Keep a FIRE EXTINGUISHER handy.

Very good point - I was planning to disconnect the battery but will now have the extinguisher to hand as well.

Thank you

[Cadence]

I always pull the webers and airbox back plate off as an assembly. Using a 1/4 flexible extension drive shaft and socket it is quick and easy to access the mounting nuts to remove and refit. Doing it this way also retains to the carb balance though I do always check it after reassembly.

cheers
Rohan

Thanks for the tips Rohan. Confidence levels are rising

[elans3]

Agree with Rohan, the only way to keep the carb balance something like, but I also check mine as soon as it's back together and fired up, with a carb balancing tool, (synchrometer.).

[Cadence]

Another dumb Weber fitment question incoming………

Decided to shelve fixing the 31’s for the time being and have bought a new pair of 151’s jetted for a Sprint.

Presumably the good advice about taking the old ones off as a pair is now out the window as the new carbs will need to be set up from scratch?

I’m thinking that bolting them on individually should make it easier to achieve the correct thackery washer clearance?

Any tips about where to start with setting up the throttle lever balance on the new carbs?

Thanks again

[steve lyle]

Another dumb Weber fitment question incoming………

Decided to shelve fixing the 31’s for the time being and have bought a new pair of 151’s jetted for a Sprint.

Presumably the good advice about taking the old ones off as a pair is now out the window as the new carbs will need to be set up from scratch?

I’m thinking that bolting them on individually should make it easier to achieve the correct thackery washer clearance?

Any tips about where to start with setting up the throttle lever balance on the new carbs?

Thanks again

Since you won't be putting them back on, it doesn't make any difference at all how you take them off. The backplate is coming off of them at some point, anyway.

If they're new 151's, you might find like I did that you have to 'fettle' the mounting holes a bit with a file to get them to fit over the mounting studs. So I had to fit them individually. Then synch up the throttle linkage thingies and put them on as a pair.

Eyeball the throttle lever balance so both carbs seem to close at the same point. Get the engine started and balance them from there with your synchrometer.

[Craven]

Position of the butterfly edge seen through the progression holes, set equal on both.

Prog Holes.jpg (64.68 KiB) Viewed 174 times

[Cadence]

Thanks for tips - I’ll crack on with it this afternoon

[SENC]

Position of the butterfly edge seen through the progression holes, set equal on both.

Prog Holes.jpg

Agree with this as easiest way to get close. I find that sticking a small flashlight in a throat on each carb makes seeing where the butterflies are simplest. Be sure to check this on each carb (throat to throat), too - you wouldn't expect a twisted throttle rod on a new carb, but I'd go ahead and eliminate the question while off.

[Cadence]

Thanks for the tip - makes sense to do that whilst they’re on the bench.

Not sure whether there should be sealant between the back of the airbox and the carb bodies, however it’s surrounding all 4 trumpets and they’re now refusing to budge.

I’ll buy some Plusgas today and try that.

Is it feasible to gently tap the choke and trumpet out as a unit from the butterfly side?

[tonyabacus]

It sounds like someone has used sealant to prevent air leaks around rge airbox/carb joint, so beware trying to knock them apat through from the butterfly end.

Try one of the craft knives or single sided razor blades to cut through the sealant instead. You could also try some fine cheese wire which may cut through the sealant. When reassembling make sure the airbox face is as flat as possible and instal with the proper gaskets. I seem to recall these can be obtained in different thicknesses to take up some slight distortion in the plate, but depends where you buy them from, so ask for thickness before purchase.
Tony