Weber idle problems

[Shlomi32]

Hi.

I can't get idle on a 1.7 type 4 engine..

I just finished rebuilt IDF's 40.
Idle was 50 but was to lean I think.
I put now 65 and still can't idle.
I have to open the adjustment screw about 6-7 turns to it to begin idle...

Should I get a bigger idle then that?

[mark-s]

What made you think it was too lean with 50 idles? ie what where the symptoms?

65 seems way too large, bit it depends on the engine specs. You'll have to post those along with information such as carb venturi size, distributor type etc. Also you need to be confident that there are no issues elsewhere, so that means timing, compression, valves adjusted, plugs ok.

I'm just telling you this before someone else does.

[Shlomi32]

I saw online a manual that tell that if you should open the adjustment screw more than 1 1/2 - 2 turn that mean the idle jet is too small

I have a svda distributor. Scat c25 cam. Venturi side is 30.

[modok]

What model of 40 idf?

[Shlomi32]

Model??? What do you mean?

Its made in Spain. And the idle jets are on top of the carb

[modok]

here

says "40 IDF 70" this one, 1-2 turns out is normal

model "40 idf 78" 2-5 turns out is normal, (finer thread)

Made in spain? with the idle jets on top? REALLY? That might be something I have not seen. What kind of car did you take them off?

[Shlomi32]

My mistake... Made in Italy...

[modok]

Ah yes, from alfa romeo?
2-5 turns out.

it should idle ok with 65 jet

My charts only go to model 84, I think, I wonder if there is a difference?

[Shlomi32]

I'll do a compression check and update

[modok]

Maybe it could be this problem? worn throttle plates
From another thread:

[Shlomi32]

OK. Problem found. All the cylinder have a compression of 60-70.

The cylinder heads had rebuild before 1000 km.
Piston & cylinders are brand new by KS.


what I miss here?

[mark-s]

From www.ratwell.com/technical/FAQ/FAQContent.html:

According to VW, a heathy Type IV engine is like so:

1700cc: 100-135psi, no lower than 85 psi
1800/2000cc: 85-135psi, no lower than 71 psi

So your compression readings are low. That may not be the sole reason for the idle problem, but it's worth checking that your engine is in good condition before throwing money at jets.

[YDBD]

Are your valves closing all the way? Did you set the valve clearance gap to .006"?

Were the piston rings installed correctly? Unless they are total seal all your piston ring gaps should be set at various gaps. Each engine builder may have their own, but a good start is to have the gaps more than 90 degrees apart.
_________________
'56 pan Dune Buggy since '69
don't live in the past...but when I did:
'67 bug
'64 baja
'60 dune buggy
'73 Personenkraftwagen Type 182 "Thing"

[jason]

Rings spin. Staggering just makes you feel better.

[earthquake]

What Emulsion tubes are in those carbs?

Casey
_________________
74 CLASS 11 LOOK-A-LIKE
69 DUNE BUGGY
79 INTERNATIONAL SCOUT II
05 SCION XB SERIES RELEASE 2[#437]
95 Chevy C3500 dually
98 Ford E150
Link to Kelly J. Nolte 3/20/53 - 11/6/08
https://time-zonelabs.blogspot.com/p/about-kelly.html
DEATH TO CHINGERS!
[From a military recruitment poster in the novel "The Stainless Steel Rat" By Harry Harrison]

[Shlomi32]

[modok]

And they have 3.5 auxiliary venturi instead of 4.5

[ReefKeeper]

Your tubes are wrong should be F11

[ReefKeeper]

Looks like those carbs were set up for something else. I had the same problem with the set of 44's they were set up for a 2332 or some other monster they were not stock. They had the CB performance venturi's in them

[[email protected]]

he's wasting anything he does until he fixes that 65psi compression reading.
_________________
It's just advice, do whatever you want with it!

Please do NOT send me Private Messages through the Samba PM System (I will not see them). Send me an e-mail to john at aircooled dot net

"Like" our Facebook page at
http://www.facebook.com/vwpartsaircoolednet
and get a 5% off code for use on one order for VW Parts ON OUR PARTS STORE WEBSITE, vwparts.aircooled.net