Weber selection and initial jet tuning

[blodi]

Yes. This is the same valve as last time. (#4 intake.). 

These are aftermarket pads that are flat on the bottom. Seems the factory ones would stay put better, no?  

I just pulled the #3 intake pad out. It measures .19-.20 (with my junk Harbor Freight calipers). I’ll take it into work tomorrow for a accurate measurement. But it is certainly thicker even by eye.  The wear pattern on that rocker isn’t as centered as the #4/ .017 valve.  Is that normal for the pads to be different sizes for each valve? Also are they different between intake/exhaust valves?   Can I still get factory ones?  I’d be willing to replace them all with factory ones that are a consistent thickness if that is what it takes. 

[blodi]

Yes. This is the same valve as last time. (#4 intake.). 

These are aftermarket pads that are flat on the bottom. Seems the factory ones would stay put better, no?  

I just pulled the #3 intake pad out. It measures .19-.20 (with my junk Harbor Freight calipers). I’ll take it into work tomorrow for a accurate measurement. But it is certainly thicker even by eye.  The wear pattern on that rocker isn’t as centered as the #4/ .017 valve.  Is that normal for the pads to be different sizes for each valve? Also are they different between intake/exhaust valves?   Can I still get factory ones?  I’d be willing to replace them all with factory ones that are a consistent thickness if that is what it takes. 

[Captain Obvious]

If the stock lash pads have a recessed area for the valve stem tip on the underside, then simply measuring the overall thickness is not a suitable measurement to compare against one that does not have a recess. The important part is the distance between the valve tip and the follower face. If there is a recess on the underside, you have to subtract the depth of the recess.

So I don't know exactly how you're measuring the pads, but if you're just putting the two of them next to each other on the table and saying "one is thicker than the other", you may not getting the full story.

I also don't know if you are including the height of the locator "wings" on the top of the pads either. The height of those side wings are not really important. You only care about the location of the grooved out face between those two wings.

Kinda hard to describe with just words... If this doesn't make sense, let me know and I can whip up some sketches.

[blodi]

Measuring just the flat bottom to the flat top using calipers.  None of mine have the recessed part on the bottom. Not measuring the “wings” on the sides.  

Edited March 1, 2018 by blodi

[Captain Obvious]

I misunderstood then. I thought this was a mix of some that had the recess and some that did not. Mix of stock and aftermarket.

As you were!    

 

[240260280]

If valve seats were cut to same depth then all lash pads should be same.

[gundee]

I read that you got a new lash pad before and machined it down to .170in.

Is that what the broken one measured? I would pull all rockers to check wipe pattern.

Then make note of thickness of each corresponding lash pad.

Start checking everything as if you were assembling a new head.

[blodi]

7 hours ago, Lumens said:

I read that you got a new lash pad before and machined it down to .170in.

Is that what the broken one measured? I would pull all rockers to check wipe pattern.

Then make note of thickness of each corresponding lash pad.

Start checking everything as if you were assembling a new head.

Yes, the broken one was .170....MSA (who I guess gets their pads from Rebello) only now stocks .175 and greater. So I got a couple 175's and had them machined down to 170.  

I think you are right...I'll just pull them all and document the size and wipe pattern and we'll go from there.  3-5 inches of snow here tonight....I guess I got time

 

[blodi]

I just found this on lash pad sizing...the last line is interesting. 

"
Having the correct cam-lobe wipe pattern is extremely important to ensure the longevity of your cam. This is accomplished by using the procedure below.

Coat the contact surface area of the rocker arms with lay-out fluid or black magic marker. Install one rocker arm and set the clearance to the cold specifications. (Intake .008 Exhaust .010) Using the cam sprocket bolt, rotate the cam one complete revolution. Compress the valve spring and remove the rocker, check the wipe pattern to see if it is centered and does not extend off the rocker arm pad. Adjustments are made by using different-thickness lash pads. These are available in 0.010 in. increments and range from 0.150 in. to 0.330 in. Stock lash pads are 0.118 in. (3mm). If the pattern is towards the valve end of the rocker, a thinner lash pad is needed. If the pattern is closer to the pivot end, a thicker lash pad is required. Continue this procedure until all the rockers have been checked. It is not unusual to have as many as five or more different size lash pads to achieve a correct setup.
"

So maybe it's not odd that i have different sized pads? I'd like to believe Larry knew what he was doing when it built this since he had build "hundreds" of L engine over the years. 

 

 

[gundee]

Always good to check rather than assume. But we still don't know why that pad came out.

Also as long as your doing this check to see if you are getting coil spring bind at full lift. That would be a problem right there.

[moelk]

5 hours ago, blodi said:

I just found this on lash pad sizing...the last line is interesting. 

"
Having the correct cam-lobe wipe pattern is extremely important to ensure the longevity of your cam. This is accomplished by using the procedure below.

Coat the contact surface area of the rocker arms with lay-out fluid or black magic marker. Install one rocker arm and set the clearance to the cold specifications. (Intake .008 Exhaust .010) Using the cam sprocket bolt, rotate the cam one complete revolution. Compress the valve spring and remove the rocker, check the wipe pattern to see if it is centered and does not extend off the rocker arm pad. Adjustments are made by using different-thickness lash pads. These are available in 0.010 in. increments and range from 0.150 in. to 0.330 in. Stock lash pads are 0.118 in. (3mm). If the pattern is towards the valve end of the rocker, a thinner lash pad is needed. If the pattern is closer to the pivot end, a thicker lash pad is required. Continue this procedure until all the rockers have been checked. It is not unusual to have as many as five or more different size lash pads to achieve a correct setup.
"

So maybe it's not odd that i have different sized pads? I'd like to believe Larry knew what he was doing when it built this since he had build "hundreds" of L engine over the years. 

 

 

I had to install different size lash pads to get the correct wipe. Nothing strange with that.

//Andreas

[blodi]

I can probably just check the wipe patterns first. If they all look good...no need to take everything apart and measure everything, right?