TheSamba.com :: View topic - Weber 36 / 40 IDFs

Mon Jun 29, 2009 8:30 pm

Hi Folks,

Quick question - is there any difference in the 'throat' size of the now discontinued 36 IDF's and the 40's?.

I know that the 40 Webs are the same as the 36 of other brands, and when i measured the throat of the carbs they were 38mm. Hence im wondering if weber just did a name change (i know there are some slight internal differences between the two).

The reason for my questioning is basically can i use different venturi sizes that are readily available for 40's in my 36's?

Pardon my ignorance if something is obvious. I am a beginner to the weber world.

Cheers,

Pete

Tue Jun 30, 2009 5:24 am

I do beleve they interchange 8)

Tue Jun 30, 2009 5:33 am

69AUSSQR wrote: Hi Folks,

Quick question - is there any difference in the 'throat' size of the now discontinued 36 IDF's and the 40's?.

I know that the 40 Webs are the same as the 36 of other brands, and when i measured the throat of the carbs they were 38mm. Hence im wondering if weber just did a name change (i know there are some slight internal differences between the two).

The reason for my questioning is basically can i use different venturi sizes that are readily available for 40's in my 36's?

Pardon my ignorance if something is obvious. I am a beginner to the weber world.

Cheers,

Pete

I've got a set of both at home and could have a bit of a look tonight if I get the time, and if no one chimes in with a definitive answer in the meantime :)

Tue Jun 30, 2009 6:52 am

If you end up with 36 IDF's use the following site (by Mark Harney) as a guide. Lots of useful info there.

http://www.carburetorclinic.com/36_idf.htm

Tue Jun 30, 2009 12:03 pm

damnit, can't find my 36's :(

bet they are in the hole at the bottom of the pile under the stairs...

Not going to look for them, can't be arsed, sorry :oops:

Tue Jun 30, 2009 3:20 pm

Thanks for responding guys,

I emailed a second hand weber seller on ebay and he says that they are unique and need their own venturi and even gasket sets.

Bummer. :(

Tue Jun 30, 2009 4:48 pm

69AUSSQR wrote: Thanks for responding guys,

I emailed a second hand weber seller on ebay and he says that they are unique and need their own venturi and even gasket sets.

Bummer. :(
No the venturi's are the same OD as 40's.A freind of mine bought some off ebay. $250 delivered..Uh ahhh ahhh etc. The gaskets are a little differant.I saw the Harney pics of his.These i have look like a normal 40 idf. See pics.I got these "40 idf" vents in today from Pierce manifold, and are exactly same as the ones in the carb.These carbs here are in great shape but had mismatched parts and some that need replacing.
I am useing a 40 idf kits...Will be here tomorrow so can let ya know if the top gasket is differant.Look at that big step down the barrel, so that the 40 vents fit in it.

Tue Jun 30, 2009 5:10 pm

Yeah, those are different from mine. The ones I have here have internal mixture screws with fine threads, and they have the late spring bar linkage, rather than the wheel and cam, and mine don't have the high speed enrichment tubes (fixed tri-jet setup). Those are pretty cool. If you get drip on those pump squirters, James, let me know, I have a trick for you to make it stop. You may not have it much with those small throttle plates.

I've never paid real close attention, but part of the venturi thing may be where the bottom of the aux vent discharge tube is. If it is significantly higher or lower in the bore, the minor diameter alignment on the venturis for a 40 IDF may be wrong and make transition a little weird. Might look at the std vents against the other ones and make sure the minor diameter is at the same height in the bore.

Tue Jun 30, 2009 6:57 pm

Thanks Mark...i should have the rest of the parts tomorrow...twiddling thumbs while waiting for parts and was nice and cool last two days now will be back to 100 plus...perfect carb working temps...Agh!

Tue Jun 30, 2009 8:20 pm

James i think you just made my day! :lol:

Mark, i emailed you this morning (OZ time) asking the same question so i guess you dont have to worry about repsonding to it anymore!!

Mine are the same as Marks, so i might go home and pull them down and see if i have a 'step' in the barrels like yours James. James if you could do a rough measure up (OD, height etc) i might compare with mine. It would be appreciated.

Thanks for all the help guys. I dont feel like ive bought useless heapas now (although for literally a last minute find on ebay and AU$240 whose complaining :D )

Tue Jun 30, 2009 9:10 pm

OK...I will be out in the shop early and will get some facts to post for ya...James

Tue Jun 30, 2009 11:58 pm

somewhere at home i have 2 sets of 40's and a set of 36's all in need of a serious rebuild, some so much so that the PO had welded a homebrew arm on that i'll need to cut off just to take the plates out, but hey ho, you gets what you pays for ;)

back to topic, If i can find the time, the inclination and my camera, i'll get the screwdriver and calipers out and take some pics of the parts with dims. It's 8am here so about 11 hours or so until i get back from work if people can wait

Wed Jul 01, 2009 3:30 am

Ok folks just got home,

I have measured the venturi I pulled from my 36's with my highly accurate $2 tape measure:

32mm Venturi:
OD: 40mm ish
Height: 38mm

So those with 40 IDFs tell me what you got!!

On a side note, i have the worst jetting combo in the history of planet earth so will have to source a completely new set.. :cry:

Thanks to those who have gone out of their way to help unravel the mystery!

Wed Jul 01, 2009 12:55 pm

i'm working on it but having some technical difficulties with camera and computer deciding they don't like me or eachother

and my caliper battery is kaput

Still, I have a pair of 36 IDF, 2 pairs of 40 IDF's with significant differences and a set of really bad 36 DRLA's for comparison

when I get the photos uploaded and reduced in size, i'll post them straight up :)

Wed Jul 01, 2009 3:02 pm

bollocks

Now they're all corrupted and can't be opened..... trying to fix

Watch this space

Wed Jul 01, 2009 5:06 pm

Ok i got all my parts in and ity is now my opinion that 36 IDF and 40 IDF venturi's are interchangable.The 40 IDF rebuild kits will work as well.
My measurements..they can vary as the vents are not perfectly round.
40.76 plus/minus Dia OD
36.97 plus/minus length
The gaskets from the 40 kit fit find.See pic of carb left and a NOS kit
gasket on right carb top.

Thu Jul 02, 2009 12:03 am

vgajames wrote: Ok i got all my parts in and ity is now my opinion that 36 IDF and 40 IDF venturi's are interchangable.

not in the ones I have :(

the 36 vent is about 1mm smaller in diameter in one set of 40's. These are the ones that have the secondary venturi as a slip in bar rather than a complete ring

The other set of 40's do look about the same but i've not managed to get the vents out of them yet, they are a little bit stuck

My camera has bit the big one and all the photos i took last night are lost so i can't post the pics nor tell you want the dims were but as soon as I get back on track, i'll post them. Not looking likely before the weekend or early next week.

Sorry to dissapoint anyone

Thu Jul 02, 2009 8:31 am

Marv [UK] wrote: vgajames wrote: Ok i got all my parts in and ity is now my opinion that 36 IDF and 40 IDF venturi's are interchangable.

not in the ones I have :(

the 36 vent is about 1mm smaller in diameter in one set of 40's. These are the ones that have the secondary venturi as a slip in bar rather than a complete ring

The other set of 40's do look about the same but i've not managed to get the vents out of them yet, they are a little bit stuck

My camera has bit the big one and all the photos i took last night are lost so i can't post the pics nor tell you want the dims were but as soon as I get back on track, i'll post them. Not looking likely before the weekend or early next week.

Sorry to dissapoint anyone
Well thats interesting...So your 36's have the bar upper vent? Are they Itailian made Webers, with the cam drive accel pump or a spring bar?
Weber must have did some experimenting in the early days.
I know ya don't hear about 36 IDF's much.
The original poster said his were like mark harneys so i think he will be ok and his measurements looked like mine...
For you it should be no big deal to have some 40 vents turned down to fit, Huh? :wink:

Thu Jul 02, 2009 8:51 am

vgajames wrote: Marv [UK] wrote: vgajames wrote: Ok i got all my parts in and ity is now my opinion that 36 IDF and 40 IDF venturi's are interchangable.

not in the ones I have :(

the 36 vent is about 1mm smaller in diameter in one set of 40's. These are the ones that have the secondary venturi as a slip in bar rather than a complete ring

The other set of 40's do look about the same but i've not managed to get the vents out of them yet, they are a little bit stuck

My camera has bit the big one and all the photos i took last night are lost so i can't post the pics nor tell you want the dims were but as soon as I get back on track, i'll post them. Not looking likely before the weekend or early next week.

Sorry to dissapoint anyone
Well thats interesting...So your 36's have the bar upper vent? Are they Itailian made Webers, with the cam drive accel pump or a spring bar?
Weber must have did some experimenting in the early days.
I know ya don't hear about 36 IDF's much.
The original poster said his were like mark harneys so i think he will be ok and his measurements looked like mine...
For you it should be no big deal to have some 40 vents turned down to fit, Huh? :wink:

no, the 36's have a bog standard full circle diameter vent and aux vent at bang on 40mm diameter,

the later 40's without the high speed enrichment circuit and with a lever driven accel pump have the bar aux vent and circular vents of just a hair over 41mm.

The early 40's with the high speed enrichment circuit, cam driven accel pump have full circle aux vents but i haven't managed to extract them from the body yet, they are 'quite' corroded and seem to have been used on a submarine. It looks from first glance that they are compatible with the 36's but I won't know for sure until i get them out.

Basically, not all 40's are the same. same can be said for 36's

What i need is a specialist tool, sort of akin to a slide hammer to tease the aux vents out (they're spring loaded) but with an expandable fitting on the end ....

Thu Jul 02, 2009 2:32 pm

For stuborn aux vents i have had good luck with a real skinny long screw driver handle that i open the butterflys and stick the handle end up against the bottom of the vent and tap it loose with a hammer on the screw drivers tip.Hav'nt broke one yet, ya have to be careful and is beter then useing pliers... :wink:
I got my freinds 36'd done and we hope for cooler weather next week end to put them on his 1600 thats got CB 044 specials (40x35.5) and Engle 110. Thing it will do better then the K-duds.
You can see on the carb on left i put a fuel inlet going the other way and blocked off the other hole where the pressed in inlet was.
Also neither carb had return springs so left got a CB missing link and right got a stock spring.