Help needed with the Mitchville mk1 tina

[deluxemk1]

Hey everyone I need help for a change ,rather than lecturing about paintwork I need help with carbs.Twin 40s to be exact Right heres the drama ,I have a set of holbay (yeah I know they arnt the best ones!) 40s .The carbs are rebuilt and serviced mated onto Ian Walker inlet manifolds.When I fired these carbs up a year ago they poured petrol out the back carb.Since then the engine was left for a while .I orignally thought I had a dodgy o ring seal and replaced it.No joy still chucking it out.Then thought fuel over pressuring and surging because it had the mechanical ac pump on them.So scrapped that for a electric pump,filter king regulator etc from rally design so I got a steady even flow at 3psi to them.Checked the bowls inside were full of fuel by removing the top of each carb and running pump and moving float to check fuel flow and cut off.These seem fine .So when I put it all back together and cranked it on the push button soleloid and worked the throttle linkage to my disgust the poxy back carb started chucking fuel out again in the same place.Got the raving ump with it now cos I hoped all the money sorting the fuel system and new o rings would sort the pig out.Dont think the float height is excessive either.If I cant sort it Im gonna offer a reward to anyone who can sort it on our open day this saturday at the workshop.Please help Im a helpless car painter I dont understand such things Whose clever with 40s then ?

[Twinkle]

sounds silly but have you overtightened them to the manifold and squashed the o-rings?

[Twinkle]

pics of the damage the over tightening can cause

 

[J Elvy]

If you turn on the fuel pump with the top off the carb and push up the floats does the petrol stop coming out or do you have to lift them hard to stop it?? Should only have to lift them gently to stop the fuel, if not then the needle jets are probably shagged!!

[deluxemk1]

Thanks er sadly the o rings are not overtightened I feared that and replaced em again with new ones .The lock nuts on the carbs have been tightened just enough to leave that 1mm gap or so they say to leave between the two brass cup washer with the rubber sandwiched between them so thats okay.The float cuts off the fuel flow easily and quickly so I think thats okay as well. God knows wots wrong! One other thing for initial start up the mixture screws should be wound right in and then wound out exactly one full turn on each screw am I right?

[Guest MK1gaz]

Are you sure the fuel pressure is low enough and are the carbs level so they're not sticking up in the air ?

[w p e]

take the float of you might find that one side has filled with fuel has the solder on early carbs brass floats went poruse if not then its deffo a float level. 15mm open 7.5 closed including the gasket. these carbs might not work very well as the progression hole and other internal drillings are different

[deluxemk1]

Thanks for the help guys Il go to the workshop and check today