Shovelhead Top End Rebuild

[noodlum]

What's up everybody, I figured since I have my bike apart for paint that I might as well go through the motor. Before I tore it down I was getting some oil out of the exhaust and was fouling plugs. I thought it might be valve seals, what do you guys think? I was told when I bought the bike that it had a mild Sifton cam, and when I pulled the rocker boxes I noticed aftermarket valve spring retainers. How do the cylinders look? Do I need to bore them? Hone them? Re-ring? This is my first time getting into a motor and wanted to get the advice of of people who actually know that the fuck they are doing.

[JBinNC]

Oil in a shovelhead combustion chamber most often comes from a head gasket leaking from the oil return passage to the chamber. That is very common. Second most common cause is worn valve guides and valve stem wear. The shovelheads did not use valve stem seals until '80 or '81, but of course they can and should be retrofitted to the earlier models. Last cause on the list is rings and cylinder wall wear, but all of this should be addressed when doing a top end rebuild.

Measuring the bore for taper and roundness, and checking the skirt clearance, as well as checking the bore for scratches will determine whether a rebore is needed.

For the heads, new guides and valves (black nitrided are by far the best) and a decent 3 or 4 angle seat and a skim of the gasket surface will put them right. Careful set-up of the spring pack and all the clearances is essential, and that is the most fucked up part of doing a shovel top end that I see. You need a well equipped shop to do good valve work on shovel heads, short cutting it will result in a poor job.

Jim

[Dragstews]

You need a well equipped shop to do good valve work on shovel heads, short cutting it will result in a poor job.

Jim

Words of wisdom right there .. !!

[Guest]

If you are going to the bother of stripping the top end, it makes sense to freshen it all up whilst you have it apart. It would save a lot of time and further expense later down the road and winter is a perfect time to do it.

You dont need to go spending fortunes on heavy duty parts if your bike is stock displacement with only a mild cam.

Get the heads blasted and cleaned, some new valves, bores inspected and cleaned up with a mild hone and throw some basic replacement pistons in there. Put back together with some fresh rings and and new gaskets and you are good for many more miles.

[confab]

Addressing everything Jim said about the heads after 40 years and a lot of miles, and having it addressed correctly, was going to cost so much it was almost the price of a new set of S&S heads... So, I just went that route. Very happy with them.

Dunno what machine work is like there, but it is another option if things start to get expensive.

They're cleared for higher cams and have slightly re-designed ports, too..

[JBinNC]

Addressing everything Jim said about the heads after 40 years and a lot of miles, and having it addressed correctly, was going to cost so much it was almost the price of a new set of S&S heads... So, I just went that route. Very happy with them.

Dunno what machine work is like there, but it is another option if things start to get expensive.

They're cleared for higher cams and have slightly re-designed ports, too..

I can do a set of shovel heads for a little more than half the S&S new price. But the Ultima heads are much cheaper, and reportedly pretty good.

Jim