19 replies to this topic

[Paulryanmini]

Hi all .

I have a 1275 engine that bellows smoke when revved and more so under acceleration.

Bit of a background. Brought a 90% restored mini with a bad 998cc engine. (I have a previous thread on this )
I acquired a second hand ("known good" by seller) 1275 engine from a late carb mini.

I've since completed the swap.

Engine is fitted with
Refurb Hs4 carb with stage 1 needle and red sprin on a alloy inlet manifold.
It came fitted with a distributor with electronic ignition so I've left this in place.

It starts first turn of the key and idles nicley.
Pulls very well. (I'd be inclined to believe it's more than a standard 1275 )

Compression figures PSI (not leak down )

185
175
180
180

Attached is a short video. Sound might be a bit funny as there is a VW air-cooled idling in the background.

As you can hear it also backfires if you blip the accelerator hard.

I'd appreciate any thoughts on what it could be.


https://imgur.com/gallery/5VepLj9


Thanks
Paul

[cal844]

Sounds like its burning oil, repeat your compression test with a small amount of oil down the bore, post the result.

Generally if the compression value increases when oiled it will be the rings, if not, the valves. I'd be inclined to say the valve guides or stem seals by the description you've given.

I had a 1275 that would give a puff of smoke when first started(I couldn't see for smoke, but once the engine was running for a few seconds it would clear) that hadn't been used in years, it cleared within 100 miles.

I hope this helps

Cal

[Paulryanmini]

Cheers for the reply.
I'll try that next time I have some free time.

I also meant to mention it has a vacuum line from dizzy to the carb and seems to run better with it disconnected.

When I first fitted the 1275 I was hoping it would be oil in the exhaust system.
The previous 998 engine had worn rings and was smoking so bad you couldn't see behind you.

But I've driven it maybe 2-3miles now and left it idling and the smoke is not reducing.

[cal844]

What is the CO emissions set to? you'll need to do a fair few miles to get the exhaust system clear. As I say try another compression test, repeat it with the oil down the bores.

I'd say the engine is running rich, what colour is the plugs? My plugs are a grey sooty colour but the carb is fuelling perfect for the cars they are on.

[cal844]

What is the CO emissions set to? you'll need to do a fair few miles to get the exhaust system clear. As I say try another compression test, repeat it with the oil down the bores.

I'd say the engine is running rich, what colour is the plugs? My plugs are a grey sooty colour but the carb is fuelling perfect for the cars they are on.

Dont adjust the carb, or timing just yet, I'd do that as a last resort only.

[Paulryanmini]

To be honest I've no idea what the co emissions are set to.
Plugs are black if I recall correctly from doing the compression test a few weeks back.
I think I'll remove the exhaust tomorrow and try and clean it out. I'll also run the engine with the exhaust off to see if it smokes.

[Paulryanmini]

I should say that the engine is now in a early 80's shell so passing emissions testing for the Irish MOT should be a easy exercise

[Paulryanmini]

Ill whip off the exhaust tomorrow (hopefully) if that doesnt work I'll redo the compression test with oil in the bores and check the condition of the plugs.
Thanks again for your help

[cal844]

If it's in an 80s reg car, set the CO to 4.0% CO once you get it fixed. When was the engine last given a full service? You might just need to replace an air filter or a dizzy service

[Paulryanmini]

When I fitted the engine I did oil , oil filter , plugs , air filter.
Has electronic dizzy and cap looks ok.

Thanks for the tip. Once it's running properly I'll get the CO set up.
Thanks again

[cal844]

What I'd do is check the vacuum advance pipe for splits or perishing then go from there, check that the carb is set right and that the oil in the dashpot is filled correctly

[Paulryanmini]

Perfect thanks , I'll hopefully get some free time tomorrow to have a look at everything you mentioned.

[cal844]

If you cant work things out just post again with things you have checked and I will try to give you more pointers

[Paulryanmini]

Will do, thanks again

[Paulryanmini]

Had a spare half hour today

Vacuum pipe is good
Plugs are slightly black.
Started first turn of the key and idiled with half choke from cold.

Removed the exhaust from the manifold back. Gave it a few revs and there was no visible smoke. Took it for a short drive and apart from now being deaf I couldn't see any smoke.

The exhaust has a thick layer of oil , almost like tar on the inside of it.

I tried washing it out with a hose pipe and degreaser but had no luck. Next week I'll use the power hose and refit it