When i used to remove the dipstick when the car was running the revs would die and the engine stop ( I have been told this is normal).
Unfortunatly the car has started to be a real bugger and wont keep its idle, so i have changed the dizzy cap, plugs and leads and was fiddleing around when i thought i would see if removing the dipstick did anything this time.
Well no, if i remove the dispstick now the revs dont die.!!!
What should i now be looking at, being of limited mechanical knowledge i am stumped as to why it would at one time effect it and now doesn’t.
removing the dipstick means that you are letting in more air in the system. try to see if the car runs better without an air filter, which would mean it is clogged
Air goes in through the oil filler cap & out via the breathers. I’d take it as a good sign if the revs went up without the filler cap or dipstick. Checking the air filter is good advice, check the breather hoses too.
The engine needs fuel & air to run and there’s a throttle to restrict the supply of both so you can control how fast it does run. If you add an extra air supply that bypasses the throttle the revs will increase, but there’ll be less fuel in the air which could slow it down or stop it.
A well set up engine would briefly run faster then stall or struggle. An engine that was over fuelled might run better.
No difference would suggest it was already leaking in lots of air.
> I fail to see what air fuel mix has to do with air in the crank case…
On standard engines theres crank case recirculation to burn fumes in the combustion cycle, so the crank case ventilation is connected into the carburettor, if you remove the pipe off the carb its after throttle as such will alter the mixture
Air coming through the crankcase breather into the inlet manifold doesn’t go past the carb jet: it doesn’t pick up any fuel, but it fills the cylinders in place of air that has run over the jet.
