Shim values

[KA1J]

I'd appreciate some help, I just measured my valve clearance on my XJ11 & the normal ranges in inches are:

Exhaust: .008 ~ .010

Intake: .004 ~ .006

My measurements (No, not my chubby gut...):

Intake #1 = .003 shim is 285
Intake #2 = .005 shim is 280 (is OK)
intake #3 = .004 shim is 280
Intake #4 = .004 shim is 280

Exhaust #1 = .009 shim unchecked (is OK)
Exhaust #2 = .008 shim is 275
Exhaust #3 = .008 shim is 290
Exhaust #4 = .010 shim is unchecked (is OK)

I'd like to replace the shims on intake 1,3,4 and exhaust 2,3.

I have them out and would like to exchange them for the proper ones
but I'm not sure which values would be the best to put in at
this time but probably the next size or two sizes lower.

What would be my best choices for shim values with these measurements?

Thanks!

[petejw]

hi KA1J,

each .5mm shim is equal to 2 thou,

personally id change the intake 1 to 280 that would make it 5 thou,

and even tho the ex valve 4 is in spec id drop it down to 8 thou
with the next size shim up.

u want the gaps to be as close as possible with each other,

i know this probably conflicts with some but
i also like the gaps to be on the smaller side of the specs for better
performance, as long as the valves havent been lapped recently
then they shouldnt close up any time soon.

[KA1J]

One other thing, I've discovered is the short side of the lobes are not exactly what I expected. I thought the point opposite from the tip of the lobe was the widest point to measure but I get my widest measurements a bit off to the side from that.

For instance, I just exchanged the shim in #1 exhaust with the shim from #4 and I find it indeed now measures .008 but not at 180 degrees from the tip. I get this measurement when the cam is rotated ~10-40 degrees off the line following the path the shim travels. This is where I get my .008 reading. If I point the tip the farthest from the shim I read .005.

I've been taking my measurements from wherever I find the widest gap, do I need to take them from where the tip is pointed the farthest from the shim or have I been measuring correctly by finding the widest point?

Don't tell me I have bad cams... Do I?

[DGXSER]

I would say you have worn cams not bad ones. The gap from the factory should be consistent for the until you see the lobe start being formed. So the side opposite the lobe should be the widest gap, if yours is not, then your cams have some wear on them. The part I would be interested in, is how much difference do you get between the opposite point and your widest gap?

[jetmechmarty]

I just checked mine again.

Intake:

#1 = .004
#2 = .004
#3 = .004
#4 = .003

Exhaust:

#1 = .009
#2 = .008
#3 = .008
#4 = .007

Do I simply reshim #4, or do all but #1 exhaust. I'm replacing the cam chain, too.

[trbig]

i know this probably conflicts with some but
i also like the gaps to be on the smaller side of the specs for better
performance

I'm on the other side of the fence. I'm betting that 99 (or 100) out of 100 people will never be able to notice any performance difference in a valve shimmed to the max vs the minimum clearance spec. I'm also betting that there's very few that just really love to get back inside that valve cover once they ever get it good and leak-free.

I like to set 'em and forget about 'em for 50k+ miles, so I set them as close to max as possible without going over. I don't want to be 10 or 20k miles down the road.. wondering if that gap is getting too close and worrying about burning a valve.. etc. I ride to get away from hassles and worry.

Just my 2 cents. Not saying Pete is wrong in any way.. it's just our train of thoughts are on a different track.

[jetmechmarty]

OK Tod, I'm not having fun doing this, so I'm going to break the chain, pull the cams, and shim all of them out to the max.

[crazy steve]

OK Tod, I'm not having fun doing this, so I'm going to break the chain, pull the cams, and shim all of them out to the max.

That would be my choice too; as much hassle as it is to adjust these, the longer the time between the better. I also use the 'early' intake spec (.006-.008") across the board, regardless of the year. The little extra noise tells me everything is happy...