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MG Midget and Sprite Technical - valve adjusting

Hi all
A quick question for once -
On checking the valves - how do people turn the engine over?
On my previous car (Morris Minor) it had a useful implement called a starting handle that one could adjust with one's knee to get the required position for checking the gap on the back of the cam. There seems to be little room to get a spanner on the crank pulley nut.
Cheers!
Dom
Dominic Excell

Pull the plugs. Press on the fan belt to stop it slipping, and turn the engine with the fan blades.

Or pop in gear and roll the car back and forth.

If you adjust them in the right sequence, you won't need to turn the engine that much.
Lawrence Slater

Thanks for that Lawrence I'll have a go at that.
I guess the alternative is to drill a hole through the front, fit a starter dog and use a starting handle.... (joke!) A brilliant invention that should never have fallen by the wayside!
I remember having fun with a starting handle though - winding up the flywheel on the inertia starter flywheel on Martin Shaw's Boeing Stearman - leading edge of lower wing at my back and prop whizzing round a few feet in front of my face...
Dominic Excell

Dom,
If you are pining for the use of your starting handle then its an easy modification on your Spridget. First get a large metal bar (you could probably borrow a scaffold pole from Lawrence) and poke a suitable hole through the bottom of the radiator.
Guy Weller

I guess you have to wear wellies for this task Guy?
Dominic Excell

Only if you have lowered suspension. Otherwise waders are better, or in summer you could try speedos. Just don't post a photo on here!
Guy Weller

there's a JT vid that shows the theory and another JT vid that shows the practice

and here's something I copied from somewhere -

Here is a procedure that basically cuts the time in half to adjust all the valves requires less stops to rotate the engine:

adjust valves 1 & 3 with valves 8 and 6 rocking*
adjust valves 5 & 2 with valves 4 and 7 rocking*
adjust valves 8 & 6 with valves 1 and 3 rocking*
adjust valves 4 & 7 with valves 5 and 2 rocking*

*Rocking - valve 8 just past wide open and valve 6 just approaching wide open

plus of course - set up tappets, points/plugs, timing and mixture in that order

and there a little red covered book
Nigel Atkins

Yep, had that down to a fine art on the Morris Nigel - rule of 9.
Don't worry Guy, I won't even post a pic of me in a mankini (because I wouldn't be seen dead in one!)
Dominic Excell

yepp...rule of nine, I always write it out and check.it off as I go other wise I forget my place

I just stick it in 4 or 5 th gear and grab the front bumper and pull...

it helps if your on a down hill approach, as you learn to adjust quickly and get a good work out before the car reaches the bottom of the hill and any surprises that would follow...hahaha

oh, theres the old me ...I wondered where I was...hahaha

prop
Prop and the Blackhole Midget

adjust valves 1 & 3 with valves 8 and 6 rocking*
adjust valves 5 & 2 with valves 4 and 7 rocking*
adjust valves 8 & 6 with valves 1 and 3 rocking*
adjust valves 4 & 7 with valves 5 and 2 rocking*

Is not the rule of nine gents.
That's;
no8 fully open, adjust no1
no6 fully open, adjust no3
etc. etc.

Be carefull with the rocking method. It was my favorite way of adjusting valves. Untill, with a sporty cam, I checked it with the rule of nine and clearances where all over the place.
Alex G Matla

As an aside, and with reference to Alex's comments, I re-checked and adjusted my valve clearances after fitting a new (Payen) head gasket according to the rule of 9. My 1275 head is fitted with fast road Kent cam and ported slightly. Tech data from the folk/PO who did this work suggests 16 thou, but it seems to run far better - and quieter - closer to the standard 12 thou. I too used the rule of 9 in setting the clearances.

My only concern is not abiding by instructions to set to 16 thou on the modded head, but running about in it seems to be OK.....

That said, I would suspect there is a degree of tolerance in the methodology and in the cam/valves/push rods etc, so when actually running, maybe the valves are actually set closer to 16 thou....



Mark O

Mark, be carefull with tighter clearances. It might run quieter, but exhaust valves may not have time enough to cool down, resulting in burnt valves and all sorts of terrible consequences. Unless you have high lift rockers 14thou or 0,35mm might be better. 16thou 0,4mm is a bit loose for standard lift rockers.
Alex G Matla

There's a knowledgeable chap on the Morris Minor website, some of you may know him - BMCEcosse - who swears by 12thou gaps for inlet valves and 15thou for exhausts on all A-series engines. He used to do a lot of racing with these types, and that was apparently the standard set-up in racing circles.
Dominic Excell

all is explained on the vids I mentioned but does relate to standard cam IIRC

there's also the (I don't know what it's called) using gauges one size up and down of specified

then there's allowing for wear variation, that click thing or extra feeler gauge measurements

then there's do you check cold, hot or running

and I'm sure other variations

I think Dom will just do the rule of nine carefully and be happy with that I just offered up the quick method
Nigel Atkins

sorry Dom you must have posted whilst I was typing

you're not going to be racing your car though - I don't know if that's a good idea for a road not (I mean I've not any knowledge) but what's good for a race car isn't necessarily good for a road car
Nigel Atkins

I also have a Kent "Fast road cam", the same as Mark. When I first fitted mine I set them as standard at 12 thou. All seemed well at first but I then found that regularly on one piece of road which involved a long, 2 mile full throttle hill, the engine would seem to tighten up before I reached the top of the hill.

After some discussion and investigation I worked out that this was actually valve stems binding, caused by overheating. I then discovered that Kent Cams advise using 16 thou gaps with their cams. Resetting to this immediately cured the running problem but they did sound very noisy! I then progressively tried reducing the gaps and eventually ended up with the exhausts at 14 thou and inlets at 12thou at which it works well. So I have now stuck with that for over 10 years now.
Guy Weller

I found on the Morris (Marina 1275 engine) that the 15 thou gap was very clattery, but then I didn't really push it that hard to warrant the extra gap
Dominic Excell

Dom,
O/T but just seen this and thought there could be a couple of points in it for you - http://www.youtube.com/watch?v=82YNx-RkGNI&list=UU40j4KqUJPMVv4FQ29ro-xQ&index=1

Nigel Atkins

You have to set the tappets to what the cam supplier says. Looser can be ok but you can damage valve tips if you 'miss' the opening ramp due to too big clearance. Too tight and you risk burning ex valves out.
A series small bore engines should be as quiet as a sewing machine. 1275 tend to be a little louder but not as loud as MGB engines. Some of the Swiftune grinds are a little more clattery.

If you run non standard rocker ratios you need to increase clearances by the % increase of rocker ratios. If you change from 1.28 to 1.5 rockers you increase the lift and duration by 17%, open the tappets by 17% eg standard setting 16 thou, high lift setting tight 19 thou.

Peter
Peter Burgess Tuning

Gents

Many thanks for all info. I would tend to agree with Guy - I do worry about the exhaust gaps somewhat, and from various motorcycles in the past with good reason. Time for a re-check on these at least I feel.
Mark O

This thread was discussed between 21/03/2013 and 25/03/2013

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