Valve stem seal replacement without removing head?

[2002dude]

Good to know on the cam. 
 

This is the engine. 

[2002iii]

1 hour ago, 2002dude said:

Good to know on the cam. 
 

This is the engine. 

That looks like its ready for a rebuild, someone didn't change the oil enough.

[2002dude]

So now im collecting parts for a top end rebuild. 292° cam from IE, IE HD springs, is it important do do their rocker arms?  Also, are the 1mm larger valves worth the time?

[kbmb02]

2 hours ago, 2002dude said:

So now im collecting parts for a top end rebuild. 292° cam from IE, IE HD springs, is it important do do their rocker arms?  Also, are the 1mm larger valves worth the time?

 

Suggest measuring the valve springs - on the seat at your installed height, and then what they will be on the nose.

In my opinion, +1mm valves won't provide any advantage for the build as you describe it. -KB

[TobyB]

If you change the cam, it's wise to use new or refaced rockers.

Febi rockers are fine, as long as you inspect for gross visual flaws.

 

+1 for stock springs, measured, unless you're planning to spin past 6700.

 

Valve size isn't a restriction until you get to higher revs, too.

 

t

 

[Son of Marty]

+1 on new rockers on a new cam. The lowest rate of matched valve springs that will do the job are the ones you want IMO, Stock valve size are fine up to 304' cam then maybe. Do have your machinist or yourself port match the head to the intake manifold.

[2002dude]

On 2/5/2023 at 7:54 AM, kbmb02 said:

 

Suggest measuring the valve springs - on the seat at your installed height, and then what they will be on the nose.

In my opinion, +1mm valves won't provide any advantage for the build as you describe it. -KB

Im not sure i follow?  Measure the length of the current valve springs?  If they are all the same height, run them?

[kbmb02]

3 hours ago, 2002dude said:

Im not sure i follow?  Measure the length of the current valve springs?  If they are all the same height, run them?

 

There is solid general information in the replies above; you can review those and likely be okay.

 

However, if you wanted to educate yourself, there’s a rabbit-hole of information to be learned. Descriptions like “HD” and “dual springs” tell us nothing about the rates, and whether those are best for your build goals. As @Son of Marty and @TobyB said/alluded to, more is not always better. -KB

[TobyB]

TLDR:  yes, measure the height, uncompressed, of all 8 valve springs, and if they're

within factory tolerance, they are a very good starting place.

 

...and now, because I don't want to face my own demons:

 

more valve spring pressure = more wear.  Always.  And it's not linear.

 

The valve springs are there to close the valves- the cam and rocker open them,

the springs close them.  So as long as the springs can do that as fast as the cam

drops away underneath them, they're strong enough.  A more- aggressive cam will set

them down quicker, relative to a mild cam, and a higher- lift cam will set them down faster, again relatively.

The stock springs can manage a stock- ish cam up to 6800 or so very safely.  Much over that,

and the springs can't close the valves as fast as the cam tries to. 

A '292' or less is a pretty stock- ish cam.

 

On many engines, this was used as a rev limiter,

but on the 2002, it tends to break rockers.

 

For metallurgical reasons, springs almost NEVER lose their rate- as in, the amount of force it takes

to displace the spring a mm stays constant, as long as the spring isn't physically damaged, or compressed

to the point where the coils touch.

 

However, it's not uncommon for springs in general to compress over time.  This reduces the force they

apply at a particular height. Cheap springs are notorious for this.

M10 valve springs are NOT.  I've taken apart a few dozen parts heads from junk engines, and I've never found

a stock spring that didn't measure within limits.  I've had one or 2 that were marginal, out of at least a hundred.

 

So measure the height of the springs.  If it matches what the factory engine specifications say for 

'valve spring, uncompressed' your springs will be fine up to 6500 or so.

 

If you plan on spinning faster, then you'll want more pressure open, compressed at lift, but

not much more closed on the seat, so off you go on a hunt for the right spring.  

As Ken says, this rabbit hole goes almost straight down.

I've seen 'HD' springs that were no stronger than stock, had more seat pressure but no more nose

pressure, were uneven, that failed in use, coil bound, and wore grooves into each other.

 

t

 

 

 

[2002dude]

20 hours ago, TobyB said:

TLDR:  yes, measure the height, uncompressed, of all 8 valve springs, and if they're

within factory tolerance, they are a very good starting place.

 

...and now, because I don't want to face my own demons:

 

t

 

 

 

Thank you for taking the time!