1275 Tappet clearances

Post by **iwsmithy** » Wed Apr 02, 2008 7:11 pm

Hello all,
I need to reset the tappet clearances on the truck. It has a Midget 1275cc engine with a fast road cam.
I once had a photocopy of a Midget workshop manual which told me what to set them to but can't find it anywhere so now do not know what clearances the tappets should be. Can anyone help?
Points gap and Timing figures would be great as well for future use if you had them handy? Cheers.

Post by **bmcecosse** » Wed Apr 02, 2008 8:52 pm

Because of the cam - set them to 15 thou inlet and exhaust. If you find the exhaust clearances have closed up - then valve seat recession is setting in - so keep a close eye on them in the future! And of course - if any gaps have opened up by more than a very few thou it means something (usually the cam) is wearing away. points gap is always 15 thou - and timing is best set by advancing till you get pinking when pulling hard in top gear - then retard it slightly until no pinking. If this causes a poor idle - then you need to consider having the dizzy advance curve reset to suit your engine.

Post by **Matt** » Wed Apr 02, 2008 10:38 pm

The spec for a standard engine is 12 thou, however it should really be set according to the cam... do you know what it is?

Post by **bmcecosse** » Thu Apr 03, 2008 12:31 am

Stnadard when leaded petrol was availabel! To prevent exhaust valve recession the exhausts should always be opened up to 15 thou even on a standard cam. Later A+ engines were specified with larger valve clearances - for a good reason!

Post by **Kevin** » Thu Apr 03, 2008 4:40 pm

I think Roy is correct as the hotter cams usually have a little more clearance, if you know what make of cam was used you can contact the manufacturer and they will tell you the correct spec.

Post by **bmcecosse** » Thu Apr 03, 2008 4:43 pm

In fact The Wizard claims MORE bhp from running with slightly increased valve clearances (more than the 15 thou) - to do with the valve being 'snapped' off it's seat - but of course it will also be slightly noisy.

Post by **Kevin** » Thu Apr 03, 2008 4:48 pm

Been reading the yellow bible have we

Post by **bmcecosse** » Thu Apr 03, 2008 5:10 pm

Know it inside out - from a few years back. Mine is blue!

Post by **MoggyTech** » Thu Apr 03, 2008 5:30 pm

I think what puts people off opening up the valve gaps is the BMC factory manual, which states they must not be anything other than 12 thou. Petrol and oils have come a long way since they wrote that, and while you may get a slight tappet noise increase, at least you know they are closing fully. Better a bit wide than too tight.

Post by **bmcecosse** » Thu Apr 03, 2008 7:48 pm

Exactly - if the gaps ever close up, perhaps due to hot exhaust valve expanding - then the seats are instantly ruined ! Which is why I suggest 15 thou on a standard engine for the exhaust valves.

Post by **iwsmithy** » Sun Apr 06, 2008 9:02 pm

Thanks guys, all set at 15 thou and sounds great!