What is wrong with my weber ?

[Raynald]

Hello All !
i have a small problem with my adjustment of weber ...
at 3200 rpm ,i have pop in my carb. my engine is running great at idle and 3500 rpm and more...it is a 2.7 liter with 60 idles jets and
135 main jets, ventury 34mm, i think my timing is good,
do you think my weber is too lean at the beging of main stage...?
or i mist some other adjustments,
Thanks
Raynald

[hesaputz]

Sounds like partially plugged idle jet; unscrew 'em, blow 'em out, reinstall. Takes 10 minutes. Happens to mine all the time.

[Nitrometano]

May be is a little lean. My webers do the same when they are out of calibration.

[Steve@Rennsport]

I'd agree with David,....its likely a clogged idle jet or two.


David,...........................I must tell you that this doesn't need to be a regular occurrance,... With proper air and fuel filtering, its a VERY rare event.

Here are few suggestion for keeping Weber's (and any other carburetor) trouble free:

1) Make sure the tank is absolutely rust free and the in-tank filters are clear

2) Use a fuel filter that removes debris down to 1 micron. I use a Racor 110A.

3) Throughly clean the air cleaner housing(s) and use a layer of grease on the rubber ends of the air filter element(s). This keeps dust out.

4) Replace or eliminate the sound proofing pad between the cabin & the engine compartment. When they are old, they sluff off tiny particles that always find their way into the flow bowls, and thus into the idle passages.

[joehahn]

nice tip steve on sound pad. when i gave up fussing and handed car over to mechainic he took one look at my crumbling engine sound pad and said "that's the culprit". crap falling off everywhere. removal plus rebuild and i am tight for 1.5 years.

[Raynald]

Thanks
is this possible my carb are not good balance over 3000 rpm ?
Raynald

[A Quiet Boom]

Originally posted by Raynald
Thanks
is this possible my carb are not good balance over 3000 rpm ?
Raynald

Not sure I know what you mean by that. I'm in agreement with the others, check you idle jets. I assume the car runs smoother when you're deeper into the gas pedal. There's been a lot of threads about this lately with both webers and zeniths. Mine had a clogged jet on one cylinder so it was terrible at part throttle but fine at full throttle when you're pulling primaily from the main circuit. I like the adjustment instructions in the Hayne's manual best for sychronizing and adjusting the carbs.

[RoninLB]

Originally posted by Steve@Rennsport

2) Use a fuel filter that removes debris down to .1 micron. I use a Racor 110A.

hmmm.. I bought five 2 micron spin on filters for the 120 model. I guess I'll be ok. I didn't know 1 micron was available? meanwhile I have it in my head that the routine is 10 microns...

[A Quiet Boom]

I'd say 10 microns would be sufficent since that's about 0.0004 inches or 0.01 mm. My idle jets for example are 0.62mm or 620 microns! I'd think a 0.1 micron filter is a little extreme. Having said that however my tank probably has a little rust, the internal filter has never been changed and I use a generic filter. Still I think my clogged idle jet was caused by varnished gas due to winter storage or debris left from rebuilding the carbs. Heck it could have even been something in the fuel line after the filter for all I know.

[Raynald]

Hello All
today i do your recommendations, i removed all idles jets and check all no problem there... i do a mixture ajustment and all have reaction of turn and all is Ok at 3 turns and haft out, my idle is stable...
my problem is at 3200 rpm i have a pop on high-way in carb...
at this RPM it running on the main circuit ?

Raynald

[Raynald]

hello
i check my plugs all is the same color cofee-moka...
what is the next step...?

[A Quiet Boom]

The pop on the highway, how far down is the gas pedal? Also how did you check the jets? I usually check them with the appropriate sized pin drill but a thin piece of wire also works. My guess is you're still mostly using the idle circuit on the highway, how does it do at full throttle, any pops then?

[Raynald]

Christian
it is hapening only in highway at around 100 KM./H. when i try to accelarate i hear a pop in weber, my pedal is in meedle and after the pop i have a good accelaration, in city i don't saw the problem,
i saw the springs around the mixtures screws is not very tight my screws is moving by side after 3 turns and a hafts out !!! is this normal ?
can this afect my adjusment ?
Thanks

[RoninLB]

maybe check the accelerator pump flow.

[A Quiet Boom]

Yep, check those accelerator pumps. It should squirt fuel even with small movements of the butterflies. Those screws do seem a little loose, but without seeing them I can't say for sure. I'd be tempted to try a 61-63 idle jet and turn those screws in a little. Take one of the screws out and check the o-ring on it, if they are missing or broken you'll pull air past them and cause the car to run lean and the screws to be loose. Have you adjusted the accelerator pump linkage?

[Raynald]

Thanks,
i rebult my weber 2 years ago and i have adjust my pump ,if i remenber i have 6 cc of gas on each bank,
but i think my mixture screws is too out , it will be a good idea to orders bigger idles jets and turn more in my screws i can move it side by side.
and i will check for the carb balance at 3200 rpm,
Raynald

[Raynald]

Good news !!
i make progress ! i have check the carb balance at 3000 rpm and everything is fine ! i have old mains jets of 105 and i drill it a little more of my new 135 (estimation of 145 or 150) and i try it to night and no popping at 3200 rpm...
i will try it tomorrow with a long run !
i hope i will have resolve my problem...
Thanks
Raynald

[1974carrera]

Raynald, please do report your findings after you drive it. Based on the description that the engine pulls well at higher revs and greater throttle openings, I wouldn't necessarily think that the main jets need to be larger. Your description sounds like the pop occurs when the throttles are transitioning more into the main jets which does seem like an accelerator pump issue. Might be worth it to check their discharge again just to be sure...? Did this popping issue just occur or has it been doing it all along?

By the way, I was looking at the pics of your car on your link and it looks incredible. You did a really nice job restoring it! Are the black paddle Fuchs in some of the pics 7" & 8" X 16's? and what's up with that exhaust...what is it?

[Raynald]

Hello Bob,
i will recheck my accelerator pump again to be sure ! but my english is not perfect i can not explain perfectly my problem,when i stay at 3200 rpm on hightway it is poping some time, not when i do acceleration
it is like my weber are too lean at the begin of the main stage...
my fuchs are 7 and 8 X 15 inchs i restaured ... a lot of sand-paper... and time and the muffler is Dansk i brought it from jasper a pelican member

[A Quiet Boom]

Originally posted by Raynald
Hello Bob,
i will recheck my accelerator pump again to be sure ! but my english is not perfect i can not explain perfectly my problem,when i stay at 3200 rpm on hightway it is poping some time, not when i do acceleration
it is like my weber are too lean at the begin of the main stage...
my fuchs are 7 and 8 X 15 inchs i restaured ... a lot of sand-paper... and time and the muffler is Dansk i brought it from jasper a pelican member

That sound a lot like the idle jets to me, try one or two sizes bigger and see what happens. I really don't know why they call them idle jets, they should correctly be called part throttle jets.