Another valve shimming question. Please help

[mikeroy420]

Today I measured my valve shim sizes using the feeler gauge method. I'm using Tomei Procomp cams, Tomei solid pivots, and Tomei test shims and guides. I used the Tomei formula to calculate the sizes.

The formula is:

Measured Size - Desired Clearance = The difference you record

Nissan Recommended Clearance is 0.14 to 0.17mm. I used 0.13 because of new cams, etc.

Difference X Constant (1.43) = Adjustment Value

Adjustment Value + Test Shim Size ( IN 2.8mm, EX 2.7mm) = Shim/Guide size
needed

But some of the values I got seem a bit high to me. Here is what I got for values:

Intake:

Guide Shim

1) 2.96mm 1) 2.96mm
2) 3.05mm 2) 3.01mm
3) 3.11mm 3) 3.11mm
4) 3.12mm 4) 3.13mm

Exhaust:

Guide Shim

1)2.99mm 1) 3.02mm
2)3.06mm 2) 3.02mm
3)3.02mm 3) 2.99mm
4)2.99mm 4) 2.95mm


The thing that alarms me is that some those sizes dont show up on the Tomei website. I know the oversize shims or guides can be ground down, but what about the bigger sizes? Do these numbers make sense?

Is there any way to check out the clearances before I order the shims and guides.

Any help would be appreciated.

[greenman100]

Yeah, that can be right if the rocker arms/cams are a bit worn.

You can get shims up to 3.20mm, but the guides are limited to 3.0mm from nissan. Smaller sizes can be had from tomei. Actually, larges sizes can be special ordered, iirc.

MyNismo.com - NISSAN SR20 Valve shims/shim guides (http://www.mynismo.com/products/?id=5834)

Your guides are pretty close to 3.0mm. Even the 3.06mm case, you're looking at being 0.06mm/1.43 = 0.04mm loose

which is nothing.

So go 3mm on all your guides, and get the closest shims you can find. if you can't get the same size, get one that matches what you had to do on the guide.

So on cyl #2, you'd want to get a shim that's on the looser side, because you're running that valve pair loose. You want the rocker arm to sit flat on the cam lobe, so if the guide is looser, you need a looser shim.

Make sense?

[greenman100]

also that's the cheapest place i've seen for shims/guides. lmk if you find somewhere cheaper

[mikeroy420]

Yeah, that can be right if the rocker arms/cams are a bit worn.

You can get shims up to 3.20mm, but the guides are limited to 3.0mm from nissan. Smaller sizes can be had from tomei. Actually, larges sizes can be special ordered, iirc.

MyNismo.com - NISSAN SR20 Valve shims/shim guides (http://www.mynismo.com/products/?id=5834)

Your guides are pretty close to 3.0mm. Even the 3.06mm case, you're looking at being 0.06mm/1.43 = 0.04mm loose

which is nothing.

So go 3mm on all your guides, and get the closest shims you can find. if you can't get the same size, get one that matches what you had to do on the guide.

So on cyl #2, you'd want to get a shim that's on the looser side, because you're running that valve pair loose. You want the rocker arm to sit flat on the cam lobe, so if the guide is looser, you need a looser shim.

Make sense?

They are brand new cams, rockers, valves, valve springs, retainers. What about the 3.12mm guides? Instead of adding to the 2.8mm, should have subtracted?

Thanks

[mikeroy420]

I'm positive I'm doing this correctly and I keep getting the same results, out of spec guides. Do I need shims for under the solid pivots?

[greenman100]

Didn't see the 3.11/3.12 guides, sorry.

Anyway, I wouldn't sweat it. I'd get 3.0s and install them. If you really want the tighter clearances, then contact Tomei and special order what you need.

[mikeroy420]

Didn't see the 3.11/3.12 guides, sorry.

Anyway, I wouldn't sweat it. I'd get 3.0s and install them. If you really want the tighter clearances, then contact Tomei and special order what you need.

I understand what your saying, but when the cams and rockers start to wear I'm gonna have to have shims custom made. I'm leaning towards installing a shim under the solid pivot. I thinking installing 0.006" shims under the pivots so I can have adjustment on the other side. That way I can as it wears I can adjust as needed without having shims custom made.

I was talking to Tomei and they said they dont make guides any bigger then listed. But they also told me that the formula and rocker lever ratio and have been calculated with use of Tomei and oem valvetrain, not ferrea and bc.