Replacing rocker arm springs with shims?

[sp838]

I am going to be torquing the head bolts, checking/adjusting valve lash, replacing rocker cover gaskets next week. I've found couple great threads here in the forum, as well as nice step by step here:

 

http://www.geocities.ws/motoguzzi1064/GuzziFiles/V11ValvesTorque.htm

 

What I haven't found is any mention of replacing the rocker arm springs (part number 94 32 22 15 - http://www.gutsibits.co.uk/prod_img/lrg/IMG_1634.jpg) with shims, in order to all but eliminate side to side play in the rocker arms. This is standard practice in BMW airheads, I was wondering if anyone here had any experience with this.

[luhbo]

Good question. It's standard on Beemers ever since, same as the springs are standard ever since on the Guzzi Vee. I don't know anything about tolerances up there or how much the parts shrink or grow with changing temperatures, but these springs at least make sure that the rockerarms will rock, regardless whatever circumstances might come together. Imagine that for the effect you think of you'd need to take out the play between arms and base more or less completely.

 

Hubert

[gstallons]

 

 

I don't think you will benefit yourself or the bike from replacing the springs w/shims. If it will make you feel better doing it , go ahead and do it.

[sp838]

Thanks luhbo. I am looking in the BMW forums now for more information about how they go about it. I will also look through Guzziology to see if there's any mention there.

 

gstallons - you're not being very helpful these days...

[guzzimeister]

Hi

 

the reason you don't hear about it, is that it's not necessary to do it usually. I've seen engines with six figure mileages on them without any significant top end maintenance. All Guzzis have a very healthy top end oil supply; I take my oil pressure readings from the banjo double union feed to the rockers and it never indicates less than 80psi in normal temperatures.

 

Cheers

 

Guzz

[sp838]

From Michael Rich at Mike Rich Motorsports:

 

"Typically shimming the rocker arms is done by custom making bronze spacers to fit--you must have .004" side clearance to allow for oil  to escape and the growth of the spacer--use 630 bronze--Be sure the ends of your rocker arms a smooth."

 

And from Charley at Zydeco Racing:

 

"I'm not sure how much play would be removed by replacing the springs with solid spacers. I ran solid spacers on my race bike, but that was more to help with oil pressure. If you do go to solid spacers, they need .004" clearance between the rocker stand and the rocker arm.....measured at either end of the spacer. Be sure that both ends of the rocker arm are square and machined smooth, as well as the area on the rocker stands where the spacers will contact them. If they need to be cleaned up or machined, do this before measuring for your spacer which must be .004" shorter than that distance. If the oil has no where to go, very little will ever reach the rockers.

 

If you have a lot of side to side movement, you probably need new rocker arm bushings and spindles. Also, if you have sacked springs, worn copper thrust washers (that are pushed on by the springs) and worn bushings and spindles, you can bleed off excessive amounts of oil, which will lower your overall oil pressure. If you ever change the small bolts which attach the spindles to the rocker stands, make sure they are no longer than the stock bolts or they will block off the oil coming up through the stand, which then is directed down through the center of the spindles and lubricates the rocker arms. Make sure that the rocker stands have not warped and the bosses in the heads where the rockers mount are still flat and square. Since there is no gasket there, you can bleed off a lot of oil pressure, if things don't mate well."

 

Not a quickie job, but good to know how to do it if the interest ever arises. I plan on taking my bike to the track next season, so it's not out of the realm of possibility.  

[gstallons]

If you do go forward with this................There are o-rings under the rocker arm stands that need to be replaced . If you see oil that is between the head/cylinder mating surface that is where the leak is coming from .