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> Carburetor jetting, Recommended base line jets for Weber 40s
Slanski62
post Jan 10 2017, 11:14 PM
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Hello. I'm new to the forums here but have been reading and learning a lot. Thank you.

I have a pair of Weber 40s I plan to use on a 2056 I'm building. The carbs are used, and I don't know how they're jetted. Can anyone recommend a base line? I'm at an altitude of 486 feet. I appreciate any suggestions!

Steve
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jmill
post Jan 13 2017, 04:40 PM
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You'll know if it has ethanol in it. There'll be a sticker on the pump that says something like "up to 10% Ethanol added".

Carb pops are usually caused by a lean condition. That means vacuum leak, clogged jets or jets too small. They can even be caused by an improper linkage or bad linkage setup (not synced).

Assuming you have mixture screws properly adjusted
1- check for vacuum leaks
2- check out linkage
3- clean idle jets
4- step up idle jets (as said, 47's are on the small side)

Exhaust pops have a few causes.

Again assuming mixture screws properly adjusted
1- check for exhaust leaks
2- adjust valves
3- idle jet too small

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amfab
post Jan 13 2017, 06:28 PM
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Great! Sorry for the thread hijack, I saw this thread and had to ask.
You guys gave me great notes on this. As soon as I finish my longs and floorpans and the car is back on the ground Ill get on this. In the meantime Ill order some bigger jets so I'm ready to go, maybe just replace the gaskets while I'm at it.
Carbs were synced and idles set when I had it tuned up and valves adjusted a few months ago. It runs pretty well aside from the popping, i have experienced partially clogged jets before and its not that bad.
Is there a best place to order jets?
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Posts in this topic
Slanski62   Carburetor jetting   Jan 10 2017, 11:14 PM
stugray   First question: What venturis does it have? If you...   Jan 11 2017, 07:58 AM
maf914   Here is a jetting guide from the Weber Tech Manual...   Jan 11 2017, 08:12 AM
jmill   The chart above doesn't include the IDF. My b...   Jan 11 2017, 01:59 PM
john77   If all else fails, you can email a guy called Bud ...   Jan 11 2017, 02:09 PM
Slanski62   If all else fails, you can email a guy called Bud...   Jan 11 2017, 08:03 PM
Steve Pratel   From my notes Dell 36's (flow similar to Weber...   Jan 11 2017, 10:26 PM
amfab   I have a set of IDF 36s with 32 venturis It has 4...   Jan 12 2017, 10:37 AM
stugray   I have a set of IDF 36s with 32 venturis It has ...   Jan 12 2017, 11:03 AM
porschetub   I have a set of IDF 36s with 32 venturis It has...   Jan 12 2017, 03:58 PM
jmill   145 isn't out of the ballpark if he's usin...   Jan 12 2017, 05:57 PM
amfab   145 isn't out of the ballpark if he's usi...   Jan 13 2017, 01:04 PM
jmill   You'll know if it has ethanol in it. There...   Jan 13 2017, 04:40 PM
amfab   Great! Sorry for the thread hijack, I saw this...   Jan 13 2017, 06:28 PM
jmill   It's been awhile since I've ordered jets. ...   Jan 13 2017, 06:41 PM
michael7810   I like Pierce for Weber parts and advice Pierce   Jan 13 2017, 09:37 PM
stugray   I have used this place recently with good service:...   Jan 14 2017, 10:56 AM
jmill   I like Pierce for Weber parts and advice Pierce ...   Jan 14 2017, 06:54 PM
michael7810   [quote name='michael7810' post='2443690' date='Ja...   Jan 15 2017, 06:05 AM
Tedman5   Aircooled.net is a great source for Weber parts al...   Jan 15 2017, 03:05 AM


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