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Highly Seasoned Rider!
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pf317 said:
I am getting ready to pull the heads and barrels off 76 shovel. I am taking them down to get the valves checked and the barrels looked at. I know that I have to replace the rings and valve guides. What else would be good to do while having this work done? Oh , I also have to get the spark plug holes redone. What is it that helps the rockers to quieten down? Any suggestions would be appreciated. I don't want to do any high performance work. Just get it back in good condition like the Good old Hog it is.
You say your rockers are noisy....do you mean lifters or rockers? As mentioned just above, shimming the rockers to the proper specification (.004 to .025) is the best way to quiet those down, assuming that the inner rocker arm bushings are not worn loose. Also, take a look at the ends of the rocker arms to see if there is a great deal of wear where they contact the valves. Unless they are in terrible shape, they can be dressed smooth and re-used.

Replacing valve guides and valves to set the proper valve clearance will go a long way towards quieting down the occasional clicking lifter. When the valves are very loose, usually the exhaust, it will be impossible to get a good adjustment on the hydraulic lifters. It really pays to be anal and stop at nothing to bring those heads back to book specs. It will pay off in the long run with a cool-running engine that makes little extra noise. This would include replacing the seats if they are too bad since low seats will change the rocker angle to a disadvantageous one. I'm not sure if the 1976 heads had the stainless low-lead compatible seats but if they don't that would be a good argument for having them changed. The late valve quides use valves stem seals as well and those are a good idea.

As to spark plug holes, I have two sets of heads in my collection. One set has good plug threads and the other set, that is presently on the bike, had a stripped thread on the front head when I got them. I used the Time-Serts (r) on both heads and they worked perfectly. I did them myself by renting the kit from a friendly independent dealer and he only charged me $20 for the rental with the two inserts. They really work great! Much better than welding them up and re-threading. Heli-coils are a disaster on plug threads. You really need a full insert.

If you have the cylinders bored, I would go somewhere that goes by the book and uses the proper torque plate sequence to hold the cylinders while they are bored. The book also shows that pistons are considered loose at .002 to .0025 thousandths clearance. That means that a new rebore, after honing should be less than .002 clearance. Unfortunately the book doesn't give an exact figure. When I had my 1982 80" clyinders bored a few years back, I asked for a "tight fit" so that I could break it in slowly. The local HD dealer did them and they must have done a good job because it's been nice and quiet ever since. I also use 60 wt oil year round since it really doesn't get all that cold where I am. That helps to keep the noise down.

Being a geezer, I tend to stick with stock cast pistons, preferably HD brand. The stock ones are called "low compression" and they are a bit on the south side of 8:1, probably more like 7.5:1. That sounds low, I know, but with the dome that comes on those pistons anyway and with the extreme hemispherical combustion chamber on the Shovelhead, if you bump the compression up too much, you will be getting some detonation. They run beautifully on unleaded 87 with stock compression.

I presume that your engine is a 74 incher. If it is, you can bore those cylinders to about .060 over before they are suitable only for planters. The 80 inchers are paper thin at .030 and anymore that that and forget it.

I'm certain that someone will now come and correct me saying that you can bore the 74's to .090 and the 80's to .050 but you really can't.

Good luck. :)
 

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Highly Seasoned Rider!
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Above comments by Springer and Otto are certainly valid. The rollers in the cam followers often get loose and those rocker covers sometimes wear as well.

It pays to examine the face of the cam lobes also. The cams will sometimes get pitted on the ramps and this will require replacement.

And as mentioned by Springer, you should check the connecting rods for excessive wear and sideplay between the flywheels.

Good luck! :)
 
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