330 rocker arm axial clearances

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IslandGuy
Posts: 19
Joined: Sun Mar 22, 2015 5:06 pm

330 rocker arm axial clearances

Post by IslandGuy » Tue Feb 16, 2016 11:28 am

Per the WSM, less than 0.002" is ideal, with 0.006" being the wear limit. Although I don't doubt the viability of the spec, how it's achieved seems to be another matter. The newly provided copper-like spacer washers are .001-.002" thinner than the worn ones I'm replacing. The aluminum spacers are all of the lot with regards to thickness which compounds the problem. They range from 0.3665 to .03745". Unless each rocker box/rocker is fettered to fit, I'm just not seeing how else this can be done, if a quality overhaul is to be achieved.

My current plan is simply to manufacturer spacers at the thick end of the calculated spec and hone plate them to the precise clearance desired. Unless, of course...I'm missing something.
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Dogdish
Posts: 11
Joined: Thu Mar 16, 2006 9:06 pm
Location: Denver, CO

Re: 330 rocker arm axial clearances

Post by Dogdish » Sat Feb 20, 2016 1:12 am

IG,

I think we had to machine those aluminum spacers to each specific rocker arm to get the required clearance. Took awhile, but we made 24 of the spacers.

My old Queen ate a camshaft many years ago, as it had the older style hardened wafer valves and "broke through" the top of the valve stems. I assume that put some side (or different) loads to the rocker and the camshaft lost. I'm sure others that are a lot smarter than I will chime in soon.

Bill
365GTB/4 14097

IslandGuy
Posts: 19
Joined: Sun Mar 22, 2015 5:06 pm

Re: 330 rocker arm axial clearances

Post by IslandGuy » Sat Feb 20, 2016 12:55 pm

Bill,

Thanks for your reply. All of the original (?) spacers are of varying thicknesses, despite all having the same Ferrari part number. The variation in thickness is greater than 0.007" form thinnest to thickest. The best plan I've come up with is to simply machine precision spacers for each rocker box. Time consuming yes, but seeing the sub-standard job that has been done in the past and resulting high valve train wear, I see no other way.

I'm finding, that despite little to no evidence of wear, that both the rocker arm widths and rocker box widths also vary considerably. Even with two brand new "thrust washers", some rocker have axial clearance x2.

Just another fun project...

Thank you.

dana
Posts: 4
Joined: Wed May 23, 2012 5:58 pm
Location: Seattle

Re: 330 rocker arm axial clearances

Post by dana » Fri Mar 25, 2016 12:53 pm

The way to do this is to have a local waterjet shop cut out shims from bronze shim stock from McMaster Carr. Will be low cost and all you have to do is a light hand lap when you get them from the shop. Small job shops with abrasive-waterjet cutting machines are available in most cities now.

I've had all kinds of shims and metal or paper seals made this way.

IslandGuy
Posts: 19
Joined: Sun Mar 22, 2015 5:06 pm

Re: 330 rocker arm axial clearances

Post by IslandGuy » Sat Mar 26, 2016 10:34 am

Follow-up:
I had new aluminum spacers inexpensively made. Now, with the stock 1 mm thrust washers, axial clearances are now well within factory tolerances. This made more sense than having wear parts of different thicknesses. I'm somewhat skeptical that the factory paid much attention to this detail. Perhaps this help to explain the excessive valve train wear these cars seem to have.

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