Benefits of getting valve clearance done

[Vyse]

My car is getting close to 25k miles. Ive not noticed any tapping sounds from the engine bay, but there is a tiny bit of hesitation when accelerating I noticed. I was wondering if its worth getting valve clearance done anyway? I heard it could improve economy and a bit of extra power.

Thanks

[DVandrews]

Most modern engines have hydraulic followers so there is no valve clearance to set. If the engine has mechanical followers then having the follower clearances checked and set is worth doing after 25,000 miles, if they are too narrow then the exhaust valves can burn a little and it will cost you some power, if they are too wide then cam and follower wear will result as well as a reduction in power.

Dave

[stevieturbo]

Really depends what engine. But even a modern engine shouldnt need them looked at at such low mileage.

My van has simple mechanical lifters and still runs fine at 370k....too much of a pain to get at the damn things to check them ! LOL

[Vyse]

Its a Honda K20 engine, I think they use mechanical followers.

[Sheepshanks]

Vyse said:

My car is getting close to 25k miles. Ive not noticed any tapping sounds from the engine bay,

Don't they tend to close up on Honda engines? So you wouldn't get any tapping.

[stevesingo]

OP, the tapping sound may be a high voltage spark jumping. Check you coils for damp and arcing marks.

[TheRealFingers99]

Certainly won't do any harm. Is DIYable -- see here.

Honda use a very old school method, no shims, just a feeler gauge required.

Honda specify huge mileages, even for such an antique design in a high revving engine.

Advantages of doing it are that the engine won't burn or drop a valve and should run better.

[andyiley]

stevesingo said:

OP, the tapping sound may be a high voltage spark jumping. Check you coils for damp and arcing marks.

He said he has NOT noticed any tapping.

[otolith]

I seem to remember from owning a Civic Type-R that it was a scheduled service item. Can't remember which one, but I had the car from zero to fifty odd thousand miles.

[Pumaracing]

Oh for god's sake you big girl's blouses. The valve clearances won't budge a thou on a modern engine for 100,000 miles. Find something else to whitter about or I'll have to start kicking arse and taking names.

[Vyse]

I thought that they actually moved quite a bit on Honda engines, especially the high revving ones.

[TheRealFingers99]

Pumaracing said:

Oh for god's sake you big girl's blouses. The valve clearances won't budge a thou on a modern engine for 100,000 miles. Find something else to whitter about or I'll have to start kicking arse and taking names.

Well, that's what Honda say. Ferrari, FIAT, Ducati and Toyota (to name but a few) say different.

There are posts on the Honda forums where the exhaust clearances have changed fairly dramatically, to the point where (apparently) both vacuum and fuel trim were out of spec at well below 100k.

[DVandrews]

They certainly budge more than a thou on the K series VHPD and R500 spec. engines and in fairly short order. These are high revving engines with quite rapid valve acceleration.

Dave

[Vyse]

If I can get it done for a decent price, I think am going to get them done. Doubt it will make things worse anyway only better.

[TheRealFingers99]

Get some dirt under your fingernails, it's fun!

[Old Merc]

Pumaracing said:

Oh for god's sake you big girl's blouses. The valve clearances won't budge a thou on a modern engine for 100,000 miles. Find something else to whitter about or I'll have to start kicking arse and taking names.

Nice one,I agree. The only time I ever adjust valve clearances is when rebuilding a head after cam belt failure.
I have only adjusted my 50 year old classics once.
The saying is, "don't fix what ain't broke"

[TheRealFingers99]

Old Merc said:

The saying is, "don't fix what ain't broke"

As in "there's oil in it, why bother changing it?"

[Sheepshanks]

There are certainly threads on US forums where Honda has pushed the interval to (I think) 100K miles where people have checked them early and found all the exhaust valve clearances have closed up.

[DVandrews]

I'm willing to bet that the valvetrain on the 50 yr old classic isn't under much duress, certainly the valve acceleration will be modest as will the overall lift and spring poundage. In these circumstances follower clearances tend to remain close to spec. over higher mileages. Seat recession on the exhaust valves may well be much lower.

Dave

[Mr2Mike]

It's such an easy and straightforward job to check and adjust the clearances on the K20 that if you have any doubt at all then just do it. The official service interval is every 110,000 miles or whenever they get noisy. Mine got noisy at around 90k.