Help diagnosing why my engine runs/sounds wrong

[Dean]

Thanks for reading everyone.

Firstly after finally getting my moggie started I noticed that there is a miss in the exhaust sound. It is more obvious when it is revved, the miss is every half a second or so. I have checked the compression and all four cylinders are good, all four plugs spark, I have run neat redex through the air intake to try and clear it, but it's still there.

So does anyone have any ideas? I think it could be a valve, but can this be so if the compression is good? Could it be the carb? Tuning? My dad told me it had this problem before he stored it 21 years ago, so it has nothing to do with it standing for so long.

Any thoughts are greatly appreciated.

Dean

[MoggyTech]

Could be a sticking valve than only sticks sometimes. Exhaust manifold leak will cause it, as will inlet air leak. Set timing to 2 degrees BTDC static and go from there. Set mixture using the carb lifting pin and jet adjuster nut. Engine revs should increase slightly or stay the same with the pin lifted 0.8mm

[Dean]

Thank you Moggytech, a leak is something I hadn't thought of.

[bmcecosse]

It maybe just needs a good hammering to clear all the gunk out. Otherwise - check over the ignition system for bad connections and maybe fit new points/condenser/rotor arm and dizzy cap - and maybe new HT leads too. At least you then have all new ignition on the car!

[beechford]

you didnt say which engine,my sidevalve had a loose connection with the bakelite knurled nut on the side of distributer replaced with little brass nut problem gone

[MoggyTech]

Forgot to say it might be early signs of a condenser failing. Starting with fresh ignition parts eg a service kit, may well cure the problem, and avoid time consuming engine diagnostics.

[Dean]

Apologies, it's an 803 OHV Goldseal.

Thanks guys, I was a bit worried it could be something expensive. At least now I have something to go on.

[bmcecosse]

If the compressions are good (relative term on an 803!!) then it won't be anything expensive.

[Dean]

This is old, but just updating and bringing my threads to a conclusion. It was a dodgy plug that was causing the slight misfire. Replaced with a new one and it runs lovely now. Oh! and it's a 948cc goldseal not an 803cc as mentioned earlier. Thanks for the help all the same.

[bmcecosse]

[frame][/frame]

Glad to hear it was just a plug............