MIK
17-07-10, 06:18 PM
hi people, i have just rebuilt a 1.6 8v running on webbers and thrown it into my nova, i set the carbs up as best as i could but the engine will still not run as smoothly as it should there is a small amount of spitting through the carbs and a hell of a lot of backfiring. so i did the usual simple checks, like ignition timing, state of plugs, leads, dizzy and coil. and all is fine. so i investigated further by checking the cam timing, valve spring condition and just generally doulble checked how well id assembled the head. i then pressure and compression tested the cylinders and all four were fine. then the problem revealed itself, i stuck the vaccum gauge on all four vaccum testing ports on the carbs. the needle was just a blur between normal manifold vaccum to around 2 bar revving the engine makes no real difference however on overrun the needle bounces around in the correct area and doesent read above atmospherric however it still is not steady. has anybody come across this before? what could it be? the valve guides seem ok and the valves seat properly and hold pressure there is also no leaks from the manifold or carbs but even if there was it would only read below atmospheric. please help:( thanks, Mike