Incorrect Lifter Clearance - Vacuum issues?

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Hi guys,

I am about the adjust lifter clearances on my car for the first time.

I have done a fair amount of research on how to do this correctly in terms of how much resistance the feeler gauges should have.
I need to set the intake at 0.01mm and the exhaust at 0.013mm.
My test for whether I did this correct or not shall be that a +0.001mm gauge will not fit, and a -0.001mm gauge will fit easily.

I understand that if the gaps are too large the engine will tick.
But what will be a symptom of too little gap, ie, the valve is not closing completely?

This is what I am thinking:
1. Compression test - This should come lower than expected?
2. Perhaps the vacuum reading will be jumpy if intake valves are incorrectly set - Is this an accurate assumption?
 
Originally Posted By: Spetz
I need to set the intake at 0.01mm and the exhaust at 0.013mm.
My test for whether I did this correct or not shall be that a +0.001mm gauge will not fit, and a -0.001mm gauge will fit easily.

times 10?
 
Originally Posted By: Spetz
... a -0.001mm gauge will fit easily. ...
I can imagine that a 0.001mm gauge would be extremely thin, but am having trouble picturing a -0.001 one.

The last time I adjusted valve clearances, the numbers were 0.010 and 0.012 INCH (about 0.25mm and 0.30mm), intake and exhaust, respectively.
 
They make go, no-go feeler gauges. Thin, then thicker and that is what they are trying to discuss.

But, you need to read up on this motor. Does it exhibit valve seat regression over time, or simple wear?

In all cases, I'd set them to 0.001~2" (thousanths of inch) more than spec and live with the slight tick. Very likely the engine will run better and will make more torque off idle and around town where it is noticeable. What you give up is a little bit at 4,000 RPM and above and lots of folks spend very little time there ...
 
You won't get any symptoms of too tight while the engine is cold. Unless they're way too tight and you lose compression...

But lifters that are a little too tight will prevent the valves from seating when the engine is hot and everything has expanded. The exhaust valve in particular needs good contact with the seat for heat transfer or it will get too hot and be burned. Then you will lose compression. Permanently.

As others have said, a whisker too loose is OK. when I've checked valves on older engines, they're generally within spec - or they're too tight (valve seat recession). So, a check and adjust keeps the valve burning from happening.

Just be glad you're not changing shims to correct valve clearance. That involves special tools, arithmetic, and buying parts to get proper clearance...
 
Originally Posted By: BrocLuno
They make go, no-go feeler gauges. Thin, then thicker and that is what they are trying to discuss.

But, you need to read up on this motor. Does it exhibit valve seat regression over time, or simple wear?

In all cases, I'd set them to 0.001~2" (thousanths of inch) more than spec and live with the slight tick. Very likely the engine will run better and will make more torque off idle and around town where it is noticeable. What you give up is a little bit at 4,000 RPM and above and lots of folks spend very little time there ...

Changing clearance from manufacturers spec in an attempt to simulate different cam lobe size and duration (increasing clearance simulates a slightly smaller cam) is pretty much a worthless exercise with OE cams and not worth the additional valve train noise which is what most people want to get rid of by adjusting the valves in the first place plus peak HP drops in the mid/higher RPM range where this V6 likes to live.
Most OE cam profiles on US model engines are already cammed and geared for lower end performance anyway.

This aluminum head engine uses stellite seats so valve seat recession isn't a big issue.
Yes they make go no go feeler gauges but you cant get a good pull through with them, if it feels like dragging the feeler over a weak magnet that's the feel your looking for. Personally I use regular feel gauges or a dial indicator for valve adjustment.
 
I'm not sure if Mitsubishi uses hydraulic lifters - the general rule of thumb says it's better to have valves that are a little loose than a little tight.
 
Originally Posted By: HosteenJorje
Use a Go-No Go feeler gauge.


Why? Just wondering why many people like them, personally I don't but that preference.
 
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What I do is use two feelers, in this case one at 0.10 and one at 0.013.
I get it to where the 013 is very tight or won't go and the 010 goes in freely.
 
Thanks everyone for your responses.

Yes the clearances are 0.10mm and 0.13mm.

The way the workshop manual said to adjust the lifters is by tightening them until I feel the turning torque change.
I did this however the feeler gauge was difficult to pull out so this seemed a bit too tight.

I'll give it another shot tomorrow.

I want to get them just right where they aren't too loud, I'm not losing any lift from them being too loose but of course not too tight where I am losing compression to due valves not closing completely not to mention burning the valves.

Also another thing to note is that the engine will be used in a circuit car which will be at high temps. I don't assume I need to compensate for higher than average temperatures and add more clearance?
 
Not with an aluminum head(s), unlike an iron head valve clearances increase when hot not decrease. No compensation required unless its a full on race engine with thin stems.
If you want to practice getting the "feel" take a weal magnet like a fridge magnet and drag the feeler accross it, that is the feel your looking for. I always try and get a good long swipe at it, it makes a difference.

If the oil film is causing you problems and it can just clean the oil away with a little brake cleaner, don't blast it just a short spray will do then try it.
when done lube the contact area with engine oil, a pump oil can works good.
 
Setting clearances to a high level of accuracy is probably not as important as you think in terms of it's affect on noise level. I'm sure you will set them good enough to satisfy that criteria.

What's more important than the absolute accuracy is that as far as possible you get them the same on all cylinders. Consider that when you change valve clearances you also change the valve timing and lift. Not by much perhaps but the effect is real enough to be noticed in the smoothness of the engine if you have one cylinder a few thou different to the others. It's not relevant with modern vehicles but in the days of carburettors any tuning was always done after the valves had been set because of the impact that small changes in valve timing can have on idle mixture and speed.
 
True, Honda for example give a range eg 0.10-0.12mm on some engines so when checking if any of those feelers go in but 0.13 wont your good to go, it just has within range.
 
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