MG-Cars.info

Welcome to our Site for MG, Triumph and Austin-Healey Car Information.

Parts

MG parts spares and accessories are available for MG T Series (TA, MG TB, MG TC, MG TD, MG TF), Magnette, MGA, Twin cam, MGB, MGBGT, MGC, MGC GT, MG Midget, Sprite and other MG models from British car spares company LBCarCo.

MG MGB Technical - Valve question

I'd really appreciate help on setting the valve clearances on my 1980 UK spec "B". No time to trawl the archive before doing the job tomorrow.
Have fitted new head and rocker shaft today so all valves closed and rockers loose. Engine at TDC on No. 1 piston. Presumably valves 1& 2 can be set.When the crank has gone through one complete 360 deg. rotation what valves should be open closed? Could someone talk me through the setting sequence when working from scratch. Many thanks.
ph barton

Use the Rule of 9 ( if No.2 is closed you adjust No.7/ No.3 closed you adjust No.6 but always they add up to 9 ) 15 thou should be about right depending on what Cam you have (my Piper is set inlet 16 thou exhaust 17 IIRC)
K Harris

Yep thanks i'm happy with the general principal of the 9 rule..so I can sort 1&2 7&8 I'm thinking of how to get the sequence for the valves on the middle cylinders. How can I judge TDC for cylinders 2 &3 ?
ph barton

That is not the case you need to see when the rockers are angled down towards the valves then adjust the valve which equals rule of 9. The first 2 open will not be 1 and 2 but will be 1 and 3 and you can then adjust 6 and 8. So valves 1 and 2 will NOT be FULLY open together!
Robert (Bob) Midget Turbo

But both valves of a cylinder will be closed as it's about reaches the top of it's compression stroke? So you can set both valves of each cylinder at this position in the cycle?
ph barton

ph! It's called the rule of 9 because it's a handy rule.

You set one valve at a time. You can be sure that the valve (valve N) you want to adjust has its cam at the opposite side of the camshaft when its corresponding number (valve 9-N) is fully open.

It allows for a bit of inaccuracy with the fully open valve. You can probably adjust the two valves when the piston is EXACTLY at TDC but you would probably need a dial gauge for that.
Mike Standring

ph
Bob Turbo's got it correct
If you are using the 9 method, TDC will not be needed or wanted for the job
Simply turn your engine clockwise from the front until the front valve is fully down, at this point no.3 valve (cyl.no.2inlet valve)will be down as well. Count these from the front as 1 and 3 and then using the 9 method adjust nos. 8 and 6 (which will be the last and 3rd last valves) Then turn the engine half a turn untill the next two valves are fully open and adjust their opposites by the nine method as well then another half turn till two more are down and so on untill all eight are done
Willy
WilliamRevit

This thread was discussed between 09/02/2010 and 10/02/2010

MG MGB Technical index

This thread is from the archives. Join the live MG MGB Technical BBS now