Advice wanted - rebuild or just change con rod bearings?

[Ozdunc]

Here's the current situation.
1969 2.25 petrol - zenith carb - runs well, bit heavy on fuel, slight ticking on the lifters, lower compression on no4 cylinder that seems to be piston rings, no smoke at all. Starts first time, but knocks under load. No leaks from main bearings, leaks a bit around the oil filter housing but doesn't seem to be using much oil. Seems to run around 70-75degC and uses no coolant. Power seems OK I can do over 90kmh.
No idea of actual mileage, but pretty sure its original.

Talking to the local mechanic, whilst filling up the other day, he seems to think the low compression in no4 might just be sticking rings esp as it doesn't blow smoke, and maybe it just needs some upper cylinder lube to de-gunk the rings and maybe a bit of 'Italian tuning'

Now knowing this, I'd like some advice.
Should I pull the engine to change the knocking bearing, and do a complete strip and rebuild? Facing and reboring as necessary.

Or since its running pretty well right now apart from the knock, just drop the sump and replace the con-rod bearings, and service the Zenith.

Whatever I decide to do I won't start work until its though its next rego at the end of April, and until then I was thinking of running a litre of Morey Oil Stabiliser just quieten the knock. I know I'm just masking an issue, but I'd like to make it a little quieter for the next couple of months. Im running 20W50 Castrol atm.

Cheers

[russellrovers]

Here's the current situation.
1969 2.25 petrol - zenith carb - runs well, bit heavy on fuel, slight ticking on the lifters, lower compression on no4 cylinder that seems to be piston rings, no smoke at all. Starts first time, but knocks under load. No leaks from main bearings, leaks a bit around the oil filter housing but doesn't seem to be using much oil. Seems to run around 70-75degC and uses no coolant. Power seems OK I can do over 90kmh.
No idea of actual mileage, but pretty sure its original.

Talking to the local mechanic, whilst filling up the other day, he seems to think the low compression in no4 might just be sticking rings esp as it doesn't blow smoke, and maybe it just needs some upper cylinder lube to de-gunk the rings and maybe a bit of 'Italian tuning'

Now knowing this, I'd like some advice.
Should I pull the engine to change the knocking bearing, and do a complete strip and rebuild? Facing and reboring as necessary.

Or since its running pretty well right now apart from the knock, just drop the sump and replace the con-rod bearings, and service the Zenith.

Whatever I decide to do I won't start work until its though its next rego at the end of April, and until then I was thinking of running a litre of Morey Oil Stabiliser just quieten the knock. I know I'm just masking an issue, but I'd like to make it a little quieter for the next couple of months. Im running 20W50 Castrol atm.

Cheers
hi keep running until it realy noisey the 214 motor was the best motor it depends on your milage just round town no proplem

[Blknight.aus]

pull it drop the crank and pistons out, bottle brush hone the bores and delip as appropriate, measure it up and decide from there.

mains should be ok but the crank if its been running with a knocker would probably like a regrind and a new set of rods and big end bearings, but you might get lucky and be able to sort it with some new shells.

[chazza]

Try some sludge remover first; Cost Effective Maintenance make a good one, have a look at their website.

The bearings will need replacing but until you get the sump off, you won't be able to tell whether the crank needs grinding; if it does do the whole motor,

Cheers Charlie