Thanks for the advice and suggestions. Head was vaccum checked and decked both sides before fitting with the BK460 head gasket. Cam timing set and checked with DTI - all ok. No play in jack shaft bearings. Dizy fine.
Reason we know there's no power on 2 & 3 - removing the plug lead makes no drop in RPM.
Remove No 1 plug lead and engine almost stops - so its the cylinder that's doing all the work.
Remove No 4 plug lead and engine RPM drops - so this cylinder is doing some work.
Looked at it last night and the light came on
You can get very badly burnt doing this, on only do it on a stone cold engine Started up and quickly felt the GTM 3-branch manifold tracts.
No 1 was hot, as was No 4, but the center pairing of 2 and 3 virtually stone cold.
Then looked and realised that the length of the tracts compared to the problem.
No 1 tract is the longest, and thats the cylinder thats doing all the work.
No 4 is the next longest, and thats also working - but not at full capacity.
Center tract is not only the shortest, but it also has to carry the exhaust pressure of 2 cylinders, and they are the 2 that are not working.
Identical engine works fine in a mini that is fitted with an LCB.
So, we needed to reduce the exhast gas, and not having a spare LCB, we removed the roller rockers and refitted standard rockers.
Fired it up, and hey presto, now sounds like it should, all cylinders performing ok, center exhaust tract gets hot.
So, the problem lies in the standard GTM 3-branch manifold, as it cannot flow sufficient exhaust gas.
Now going to modify and fit an LCB manifold, then re-fit the roller rockers, and I'll let you know how well it works.
), then going to change diff and fit propper big-bore LCB etc.