I'm hoping its not terminal. She's covered 189,000 kms and started misbehaving on the way home. Power dropped off, felt gutless and bogging down as if on 2/3 cylinders. Although still running It is backfiring continually. Hoped it was just plugs oiling up but a fresh set made no difference. No evidence of an air leak anywhere as all carbs are seated ,manifolds intact. I have checked the valve clearances on the rear pots (1 and 3) and they range from 0.08 to 0.13 inlet , 0.15 to 0.23 exhaust. I know they are way out of sync and admit I should have been a bit more sympathetic but ......... I havent had the clearances done since 24.000kms
Also did a compression test No 3 was 170 , No 1 was 0.... Haven't got round to the front ones yet as its too tight to get the tester in.- adapter being sourced as we speak.
Has anyone has a similar experience and how did they deal with it?
Admittedly this was with a rubber bung tester so I may not have been making a good seal. If the 0 reading is correct then I'm thinking that the head will need to come off . Given these readings I have worked out that the shims I need are smaller than those in use ( most were 2.25mm).
Ever Hopeful.
Rob

Hmm, personally I'd get a proper adapter for the compression tester to get 4 true readings.

If no good then a leak down tester, should determine between compression being lost either through rings or valves.

If valves then do the shims and see what happens.

If rings then I'd buy a new engine.

Thanks for the reply.
I've asked Phil Denton Engineering about the compression adapter and have bought some M10 X 1.00mm taps to do the spark plug mod as an alternative. Hopefully as you say I will know which direction to take once I have the readings.

Too small valve clearance will result in little compression and poor running. They also need to be correct before a compression check.

189000 km is pretty impressive, especially if it lives to fight another day..

vaccum pipe split?

this can cause the symptoms above, fuel flow gets restricted and carbs only partially filll up running lean and spluttering etc.

would be my first check as it is the easiest too.

Thanks Neosophist. Already ruled that out as I checked yesterday. Went back and checked the valve clearances and retried to get a compression reading. Same result unfortunately, 0 on No.1 ,170 on No.3. Lookin like its rings or valves. Is there an easy way to check either?

0 psi?

even if rings were shot it'd be putting out 60-70 psi.

that soudns like the adapter isnt seating properly in that cylinder.

only reason itll be 0 is if there is a hole in the piston or valves have broken off, and then that is bad news.

http://www.ebay.co.uk/itm/3-5M-5-5mm-LE ... SwKtlWilzX

something like this will let you see inside the cylinder without having to take the engine to bits.. might not get a good look at the vavles but you will be able to check piston and cylinder walls for obviosu signs of buggary

Looks neat and ideal.probably take nearer a 10-14 days shipping if past experience is anything to go by. How difficult is taking the head off? At least , this would give me a better picture of the issue. I just worry about getting the cams and gear train back in the right way.

It's very easy to do,But the head gasket will cost you £50.