Before dropping that nut into my engine I was trying to solve my starting issue. Slow, smoky and splutters. I had previously set the tappets to 0.15 cold as the directions say on here but it did not solve the issue. In chatting to MitsiArt he was ADAMANT that 0.15 cold does NOT equate to the same thing as the old setting of 0.25 hot. I found it hard to see any flaw in his reasoning so I decided before I strip the front end off to check the timing marks that I would try the tappets at 0.25 hot. That's what I did yesterday and tomorrow I should have it started up. Any thoughts on this? 0.25 hot and 0.15 cold seem to me to be so fundamentally different to each other that I can only assume one is right? In short surely the 0.15 cold setting would become smaller when hot? Meaning valves are open too much and hence causing slow start on both hot and cold?

As far as I know you should always adjust the valve clearance when it is hot, don't know why.

At 0.15 cold, when everything has expanded the clearance would have been around zero, if not touching.
Imagine a 1 to 2 thou extra on the cam, 10 to 20 on the tappet, also the length of the valve, increasing by around 5 or 6.....
0.25 hot would be the running clearance when at less than normal, Luke you of all people should be understanding just how hot an engine gets, why set them smaller cold, than the hot setting.?

Well I would assume because you are then dealing with the smallest the gap will ever be. Ergo you don't risk pushing your valves too far open on a tight engine. The how to on here says that the latest update is 0.15 cold because it can take a while (not THAT long to be honest) to get access to the valves on a hot engine. But looked at from that point of view one would assume 0.15 cold is being given to be the same thing as 0.25 hot. As far as my brain can work out the gap shrinks when hot so a cold setting should be more like 0.35 or something. Unless I am missing something?

Totally right, a bigger gap cold than hot..

Quote: LezT wrote in post #3

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At 0.15 cold, when everything has expanded the clearance would have been around zero, if not touching.
Imagine a 1 to 2 thou extra on the cam, 10 to 20 on the tappet, also the length of the valve, increasing by around 5 or 6.....
0.25 hot would be the running clearance when at less than normal, Luke you of all people should be understanding just how hot an engine gets, why set them smaller cold, than the hot setting.?

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Will do mate, I have only ever set 25 thou hot, or at worst for a new build / early setting of a 'loose' 25, when the feeler is an easy fit. This gives a rough setting for the engine to run and get hot for final setting to the correct gap.

We'll soon have a conclusive on this one when I start mine up. But due to yesterday's donkey moment I may have to redo them one last time as you say because the last 4 were delayed in resetting while I wandered around aimlessly trying to work out what to do about the nut inside my engine!

Well just dont drop your nuts this time Luke

so the answer is when doing your tappets use one hand to hold your nuts, are you going to do them hot, then allow it to cool and recheck to post your findings ??

Will do mate.

Just to clear one thing up.
The setting IS 0.15mm when COLD.
Ask a mitsubishi garage if you don't believe me.

Also, That is 0.15 MILLIMETERS.

25 THOU is not the same thing and a feeler gauge marked 25 THOU or 25T or 25/1K or 25/1000 is actually about 0.6MM thick.
So 25 Thou is not the same as either 0.15mm or 0.25mm

Get a feeler gauge marked 0.15MM.

What was the old setting Billy? 0.25mm or thou?

I had 25 thou in mind and did say thou in the post, which is around .10mm I think.. never realised we were taliking cross puposes with the values here, well spotted Billy, now I am seeing the reasons for the 0.15 measurement.

ps, a bigger gap when hot than cold is because although the cam, tappet and valve all expand slightly as they get warm they are all made from steel.
The head is made from alloy (and alloy expands a lot more than steel when heated) so will expand more than the valve does, this pushes the valve seat down so the valve gap actually increases.
The head expanding also lifts the rocker rail & rocker arms away from the valves.
The rocker arm is also made from alloy and is not even so expands away from the valve.

The clearance needs to be almost nothing or the little feet on the bottom of the tapped will get smacked about and fall off.

There is no old setting.
The original engine manual specs 0.25mm on a HOT engine.
Later versions (ie current spec) state 0.15mm on a COLD engine.

So, all you need to decide is if you are going to set them when hot or when cold and choose the gap accordingly.

Billy, in the how to you could be forgiven for thinking that the 0.15 cold setting is to achieve the same thing a 0.25 hot but without worrying about running it etc and rushing to get the cover off. With this in mind how should we view 0.25 hot? Is it wrong? Ie 0.15 cold is and never was meant to equate to the same thing? But rather 0.15 cold has been introduced because of the explanation you give above about expansion of different materials?

Quote: billymadbiker wrote in post #17

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There is no old setting.
The original engine manual specs 0.25mm on a HOT engine.
Later versions (ie current spec) state 0.15mm on a COLD engine.

So, all you need to decide is if you are going to set them when hot or when cold and choose the gap accordingly.

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Quote: billymadbiker wrote in post #17

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There is no old setting.
The original engine manual specs 0.25mm on a HOT engine.
Later versions (ie current spec) state 0.15mm on a COLD engine.

So, all you need to decide is if you are going to set them when hot or when cold and choose the gap accordingly.

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Yes, my explanation about expansion of different materials was just to point out that as the engine gets hotter the gap between the tappet and the top of the valve gets bigger. not smaller.

So, in theory (but I have never actually checked it) If you set the gap to 0.15mm when cold, then warmed the engine up, then mesured it at hot you would have a gap of 0.25mm.

This will be interesting to see then if that is the case. Will test that this week. Certainly would explain the confusion.

so is the order to adjust!1-2-4-5 rotate 360 3-6-7-8