SJ410 - Exhaust pipe outlet is always black

[Pugsley]

I sort of know the answer to my question - go and get the exhaust emissions checked and then professionally set up, but I would appreciate comments on other owners experience. The engine is basically new, I've had a rebore (100 miles ago) and obviously new pistons, new oil pump, four new exhaust valve guides and valves, (all valve seats recut and ground in) new cam belt and tensioner, head and block skimmed and crank reground with new bearings. The block was also chemically cleaned. I have no doubt that this was professionally and competently carried out by a local racing car- engine company.

I've fitted a new (reconditioned) 38 HIF SU carb which came with an AEM needle - the engine breathing is good and the engine runs very smoothly with an amazing gain in power from when it was kicking out lots of blue smoke and using 1 pint of oil every 100 miles or so. My concern is that the exhaust pipe outlet is always sooty black (but no obvious black smoke when it's running) - it never turns that nice shade of ash grey.

The air filter looks clean, the plugs and points are new with the ignition correctly set up. The vehicle does a job of work and does go off road as it's my shooting hack but does a fair road mileage also to get to the farm. Is this condition normal for the technology of a 1988 engine or do you think that the carburation may need looking at? The only thing I can add is that since the engine rebuild, it's slightly tricky in starting the engine from cold (not sure if I'm giving it too much choke or it needs more) and when it's hot, even though it runs well, it smoothly increases in revs without faultering if I pull out the choke. I would have thought that when hot, the use of the choke would have made the engine protest if the carburation was correct.

[Henry]

If its pumping out black smoke then its too rich. I would get it checked out.
Henry

[Pugsley]

As mentioned, it isn't putting out any black smoke.

[ScottieJ]

how far have you driven it since the new engine was fitted and are you still using the the old exhaust? it could just be all the crap in the exhaust from the old engine!
It can take quite a while to blow it all through sometimes; espiecially if it was burning a lot of oil.

[Pugsley]

Hi scottiej410

I think you may have put your finger on it (I was wondering the same thing myself) - yes it is the original exhaust system, the front section is new and the rear whilst old, is in good condition. I am going to replace the air filter anyway and I'll play around with the carb settings afterwards as I suspect they may require adjustment now that the engine is rebuilt.

Thanks

Ian

[ScottieJ]

No worries, I had a similar thing the other week when i rebuilt and fitted a 410 engine for a guy from bristol! we fired it up and it was smoking like a trooper it cleared up after a few days though!