S&S instructions state the same .003 runout spec they originally noted for their TC3 Twin Cam plate & pump, however their technical dept states they will work up to .005". For reference all of the M8 cranks we have measured have been well within .003", the bike in this thread was just over .002"

 

Thanks Jamie. I just ordered the S&S pump and plate, along with a bunch of other goodies from FM, and your timing with this thread is perfect.

 

hi jamie,
thanks for the write up! 👍
at the point in this picture, can you install a new cam without removing issue pushrods etc... or is that a whole nother job?
i was just thinking while I'm in there...

 

No, cam swap = would need stock pushrods to be cut & replaced with adjustable

 

 

Could someone be kind enough to explain the "Dual Scavenger" pick up system on this S&S set up that I her about that make it better than the Fueling set up? It's probably apparent to most, but I'm not so familiar with that aspect of these two pumps. TIA.........

 

Wouldn't it be nice to have some type of tool that could be installed to hold the lifters up so that the cam could be pulled with out touching the push rods? Something that like rotates in over the cam and then bolts to the case then allowing you to pull the cam out. Hum....I wonder if that is possible. That would save a lot of time and money.

 

 

The stock pump has two scavenging pickups, one for the cam case and one for the sump in the crankcase. It only has one scavenging gerotor which is the pump pulling on both pickups. So if the cam case gets pumped dry the pump will suck air on that side which can cause it to lose prime on the crankcase side which will result in sumping. Try putting two soda straws in your mouth, one shorter than the other. When the liquid gets below the short straw it will be harder or impossible to suck liquid through the other straw as long as you are pulling through both.

The S&S pump has a gerotor or pump for each pickup which makes it more unlikely the sump side will lose its prime. The money invested in it when doing any upgrades or even if it is your only upgrade is well spent in my opinion.

On the TwinCam they managed to counter this by making the sump pickup longer and smaller which also helped counter the variances in crankcase pressure caused by the pistons going up and down. The M8 just has a big hole on the right case where the oil pump connects. Harley has tried making the oil pump pickup smaller, whether that is working I can't say. Also, that's why if you idle it on the side stand there may be some extra oil collect in the sump. The S&S won't keep that from happening, but it should clear it soon after you stand the bike up straight.