Head vent ports, needed? Options

[yarin]

While pulling my carbs off I noticed that each head has an air vent. One was capped off, the other was open.

Where should these go and why are they needed? Will capping these contribute to oil leaks?

Here is a pic I found: http://www.914world.com/bbs2/uploads/blog-1...-1131214564.jpg

Thanks

[dmenche914]

Oil on the meter vane seems like good enough reason for the factory to add the vent down stream of the vane. Extra oil shouldn't hurt the carb operation. It how my VW's and 356 is set up (factroy set up). My 356 has some valve guide blowby, so the carb does get oily, but it tunes and works just like the other carb that is clean (no vent line on other side carb.)

Guess what it comes down to is how much false air can the L-jet handle before problems in drivability and running, and how much false air extra would be added by head vents.

If head vents were tied into the same line as the case vent, ventalation would decrease over individual hoses, however the ventilation will still be more than a single case vent, and certainly be more even (ie head would recieve direct venting now, verse via the push rod tubes) Over all vent flow would be restricted by going to a single port on the intake manifold, so that should minimize false air, yet still benifit from head venting (with a corresponding decrease in case venting flow) The junction where the hose meet up would be the restirction, down to one hose diameter. same as stock. Additional restriction can be added to the hose to balance the total "false air" flow to the same as that as the stock L jet would see, just is now the same false air flow is from three sources, not just the case.

you could "tune " the restriction with an oxygen sensor to measure and match stock mixture level at the tail pipe (assuming all other engine system are in order).

Make any sense???