cam.in.head Posted September 30 Share Posted September 30 (edited) in aid of an upcoming experiment ! am i right innassuming that if you bought an identical size webber for a 1.6 vs a2.0 it would be jetted differently ?. not that im going to buy one ! if so how would that cross reference to modding a 1.6 solex 32/32 didta to run a 2.0. from memory i think the main jet for barrel 1 is a X35 and an X45 on barrel 2 ? ( cannot remember to top air mix ones ?) seeing as its the same physical engine and inlet system would it not be much variation ?? Edited September 30 by cam.in.head Quote Link to comment Share on other sites More sharing options...
Jessopia74 Posted September 30 Share Posted September 30 Jetting for sure would be different, idle and main, plus iirc Emulsion tube this might give you an idea ? https://www.carbparts.eu/jetting_table Quote Link to comment Share on other sites More sharing options...
cam.in.head Posted October 1 Author Share Posted October 1 thankyou for that .i had a quick nosy . bit confusing in parts BUT personally lwould you say these following statements are true? a larger cc version of the same engine will require slightly larger main jets ? e5 fuel 99 ron also requires larger jet ( richening) over std old 4 star leaded ? reason im asking / thinking is that my slight running issues nowadays could be all down to modern fuel . obviously i wont use e10 but even using e5 marked esso synergy i do get a bit of surging at a constant throttle once warm . replacing rotor,cap,leads,plugs makes no difference and running the factory timing marks is worse . im on an extra 5 deg of static advance and half vacuum range .this seems the best settings after months / years of experimenting . only change not tried yet is jetting . difficult on a varijet ( hence the solex idea, jets easily replaceable) 1 Quote Link to comment Share on other sites More sharing options...
Jessopia74 Posted October 1 Share Posted October 1 When increasing the Ethanol content, the management is adjusted as slightly more fuel is required due to the Ethanol lower BTU so leaner without change. ofc this is on a fully mapped ECU, but the same would be true for carb engines. If your carb jets are already on the low side for your engines demand, then even E5 will lean it even more, especially noticeable more under load when engine is usually at its richest. But you can increase timing with it as it suppresses detonation, however if it’s already lean then the flame front ans it tries to burn through the cylinder will be erratic. Now we are into territory that is outside of my knowledge somewhat. But, 5% ethanol would only mean a jet size increase of around 2-3% . 1 Quote Link to comment Share on other sites More sharing options...
cam.in.head Posted October 1 Author Share Posted October 1 so .on a varijet its not easy finding alternative needles and jets so that may be why the slight surging is once the car is fully warm rather than with any choke. so theoretically ( to try at least) blocking off part of the air filter inlet MIGHT richen it a bit ? or would it only affect it at full throttle ? there might be another way by playing with the jet ?. il try some more googling or make an adapter and fit a solex, at least i can easily play with the jets on that . timing is definately at its best position after much experimenting so im happy with that . Quote Link to comment Share on other sites More sharing options...
Jessopia74 Posted October 1 Share Posted October 1 Well, back in the old Webber days, when I was skint, we drilled them out 🤣 Tbh it was more reaming, but sure you get the idea. Sadly this is only mains. Anyway back on topic, sort of. My point really is that it should not make that much of a difference with only E5 to even need the carb adjusted, however you have something funky going on that is messing your ‘burn’ for sure. Fancy buying a Lambda & gauge kit and installing it? Quote Link to comment Share on other sites More sharing options...
cam.in.head Posted October 2 Author Share Posted October 2 i had heard that e10 would run lean and need adjusting / jetting so figured that e5 would make SOME difference too. it would be nice to find some proper leaded 4 star to put in ! engine is low mileage ( under 80000)with good compressions,correct cam and good stem seals . was rebuilt by me a few years back so i know what everythings like inside. tried arm,cap,leads,plugs and modified the vacuum advance limit .which improved it 99% so not that far off now it may actually be a fault with the current varijet but i keep disregarding it due to being new ( or new a few years back with low mileage on now !) so trying another varijet on may prove this first . i do have another couple of useable ones before trying the solex on . last case i could go jetronic as i have all the bits and it has an injection tank on anyway but as i have 2 jetronic cars it would be nice to keep this on carb. 1 Quote Link to comment Share on other sites More sharing options...
Jessopia74 Posted October 2 Share Posted October 2 So do you think the one you have now is for a smaller capacity? If so then definitely try a good other carb first before drastically swapping to Jetronic as that has its own issues now they are getting old 😬 Quote Link to comment Share on other sites More sharing options...
cam.in.head Posted October 2 Author Share Posted October 2 no the carb i have on now is the correct one for the 2 litre and ran fine until all this new fangled fuel came along a few years back. will keep you posted . jetronic is fine on the other cars and the only issue there is the intermittent idle control due to the ecu. 1 Quote Link to comment Share on other sites More sharing options...
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