Hi peeps,would i be correct in thinking that two twin 40's webbers are two big for a 1641 ?engine has only done 100 mile and the left bank isnt firing at plug end.I have been told that 34/36 carbs are the way forward as the 40's are "drowning" the engine and mpg and performance will never be at its peak thanks :roll:
twin 40 webbers on a 1641
- Thread starter dub68bay
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Geeze
Well-known member
40s can be made to run fine on a 1641, it's all in the size of the vents (venturis).
Do you know what size your current vents are?
Even with too big vents though, it shouldn't 'drown' the engine like that. Have you been through the usual suspects (fuel pressure, spark is good, etc).
Do you know what size your current vents are?
Even with too big vents though, it shouldn't 'drown' the engine like that. Have you been through the usual suspects (fuel pressure, spark is good, etc).
Humpty
Well-known member
Agreed.... I ran 40mm DRLA's (Dellortos) on a 1641 back in the 90's..... Ran sweet.... I'm sure the Webers can be tuned to do the same.
i will be checking fuel this afternoon as soon as it stops raining,it ticks over on two on its own so think fuel is ok.I will put a spare plug on the lead and test it at the other end cheers.Humpty i have been told bout "reducing" kits or something for the carbs but was told cheaper to flog these brand new ones and buy correct ones from the off.bodywork is my bag not engines reallt and im completely lost with carbs lol :lol:Humpty said:
40 is the size of the butterfly in mm ,so 36 idf have 36mm butterflys.4mm ant going to make a lot of differance unless you have ported/bigvalve heads or big cam.the venturi size can be changed as they slip in so you can have a 36 set up to flow more air than a 40 if it has smaller venturi.is this a new setup or has it run before?could be carb flooding ,to much fuel pressure will cause this as will incorrect float level,idfs are sensitive to this.have you set carb linkage up correctly ,could be its only pulling on on carb on idle.disconect one carb from link ,unscrew idle stops and set them both the same then check idle mixture on each cly (fastest idle then turn in 1/4 turn)basic set up procedior.
Brand new IDF's, are these EMPI copies? the quality of them seems to be a little hit and miss from what I've read on here.
Most wouldn't recommend the 34/36 Weber Progressive either, I ran one on a 1641 with no trouble, but 1641 on twin 40's was much better
Until your sure the fundimentals are tip top, tappets, timing, fuel delivery, ignition, compression etc, then it's hard to troubleshoot.
Most wouldn't recommend the 34/36 Weber Progressive either, I ran one on a 1641 with no trouble, but 1641 on twin 40's was much better
Until your sure the fundimentals are tip top, tappets, timing, fuel delivery, ignition, compression etc, then it's hard to troubleshoot.
Geeze
Well-known member
Sounds like a good plan. Need to start with making sure the carbs are in sync and that the fuel pressure is right.
Especially the fuel pressure - webers and dells are both very sensitive to too much pressure
Especially the fuel pressure - webers and dells are both very sensitive to too much pressure
what do you mean by drowning? they flooding? have you set the mixture screws? if they still flood then jets/vents and pressure need a looky see.
idf 40s are good, on your motor, cant remember the jetting but i think mine had 28mm vents. ran well good mpg. again just watch the fuel pressure, 3.5psi is what you want, look for signs of leaking fuels that could indicate high psi etc and/or get a fuel pressure guage
idf 40s are good, on your motor, cant remember the jetting but i think mine had 28mm vents. ran well good mpg. again just watch the fuel pressure, 3.5psi is what you want, look for signs of leaking fuels that could indicate high psi etc and/or get a fuel pressure guage
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