803 cc timing chain

[philip jones 51]

Hi ,
I have 1955 803cc four door saloon morris minor and the timing chain has started to rattle very loudly .
Are all the timing chains the same on all OHV engines and is it better to fit a duplex chain rather than a single chain.
Regards,
PHILIP JONES

[bmcecosse]

Certainly not needing a duplex on an 803 - but you WILL be needing new sprockets (and rubber rings) with the new chain.

[moggalot]

New simplex sprockets, chain and rings will almost certainly cost more than the £29 odd for the duplex kit which will make a better job of it as well.

[philthehill]

Whilst there is very little difference in price between a simplex kit (B/M Pt No: GSK108A @ £24) and the duplex kit (ESM Pt No: 10M820 @ £23.99) my preference every time would be to fit the duplex as it is virtually fit and forget. The rubber tensioning rings soon loose their tensioning capacity and it is back to a rattling timing chain again.
There is also very little difference in the work involved whether fitting simplex or duplex; and unless you strip the timing cover off you cannot tell whether it is simplex or duplex so keeps it looking original. The side valve engine, type U.S.H.M had a duplex fitted as original equipment and the change to simplex with the 803cc engine to me was a retrograde step. So if it was good enough for the side valve engine it must be good enough for the 803cc engine.
Fitting the later timing chain cover (Pt No: 12A1419 (MOSS)) with the neoprene seal would be a good move as the old felt type seal whilst new is good it soon compacts and then weeps oil. You will need the flat type oil thrower plate (Pt No: 12A1148 (MOSS)) if fitting a duplex set up.
Phil

[IslipMinor]

I agree with Phil - a duplex is definitely fit and forget.

We fitted one to the original 948 when it was modified and ran with it for ~50,000 miles, then after the restoration we now have a 1380 that has duplex as standard. Another 50,000+ miles (the chain was changed at the same time as the cam, so 3 chains) on the 1380, which has large valves, high lift cam and 1.5:1 rockers, so the chain is having to do some real work and never a hint of a rattle.

Don't forget to countersink the bottom 2 holes in the front engine plate and fit countersink screws to give clearance with the wider chain.

[bmcecosse]

If the duplex is cheaper than new simplex parts - by all means fit it! The BEST solution is the simplex with tensioner as fitted to all later A+ engines - but the need to buy/fit the later timing cover with bulge makes it an expensive option.