V-Twin Forum banner

1 - 11 of 11 Posts

·
Registered
Joined
·
365 Posts
Discussion Starter #1
http://groups.msn.com/harleytechtal...=0&ID_TopParent=796738&ID_Parent=797228&pps=k

Mike Roland Sent: 11/23/2005 1:20 PM
I have run up to .700" lift with 250 lbs of seat pressure on record setting gas and fuel race motors using bone stock Harley rocker arms. Beyond that lift and seat pressure we found them to be a necessity. The loads and the amount of travel across the tip of the valve cause the stock rockers to start to pull and push the end of the valve stems, but we are talking lifts and pressures way beyond street motors will ever see.
At the lifts and sping pressures street engines run with, I have not found them to be needed at all. I also have not found that they add any performance, nor have I found them to extend valve stem and guide life.
I would save my money and use it somewhere else.
Mike Roland
 

·
Registered
Joined
·
2,300 Posts
I would agree, at the lifts that one usually runs on the street the roller rockers are not necessary.

What is not mentioned is that someone as meticulous and experienced as MR would be working with heads where the valve geometry is properly set.
This can often not be the case with reworked heads, in fact I only know of a few head guys that specifically set this correctly.
 

·
Registered
Joined
·
365 Posts
Discussion Starter #4
I don't know Hippo, I think most Head Porters set
rocker arms perpindicular at 1/2 valve lift. The greater the
lift from stock, the more important the length of the valve stem.
The valve stem length is the easiest variable to ensure
the valve and rocker are 90 degrees at one half valve lift.
The rocker tip should also be centred so that loads will be centred in the
middle of the valve stem to reduce side loads.
This would also be a problem that roller rockers couldn't fix


joepenoso
 

·
Nice to ride again :-)
Joined
·
1,802 Posts
I know this is a guy with a lot of knowledge but how can he make a statement like that? The TW-6hg just exploded a rocker support plate and although the cause is still undetermined, if I would have had stock rocker arms in there I am sure it would have been trashed also.

I wonder what he considers street?

I guess as was said, if all was perfect, and was getting tore down every mile or so who would care?

I can say I will be getting rid of the rest of the cast parts soon. Both rocker support plates, cam plate and I am going to a fueling pump.

Also a good porter does check spring packs, seat pressure, valve stem height and related geometry. I mean even the composition of the valve guides is a consideration in this.

I don't know this guy at all but I will spend the extra and have forged where I can after my experience.
 

·
Registered
Joined
·
1,460 Posts
Hello LAF, so you have just had another bad experience in a rocker support plate going south???

Ozzie
 

·
Nice to ride again :-)
Joined
·
1,802 Posts
Ozzie In Arabia said:
Hello LAF, so you have just had another bad experience in a rocker support plate going south???

Ozzie
Hey Ozzie.
No just threw it back together with one OEM rocker support, 4 push rods and 4 lifters to survive the winter riding I get in here. Trying to save the $900 or so I need for support plates, cam plate, fueling pump, and gear install kit, and then wait for car port weather of 50 or so, which will be April or so here, and then put them in.

Hopefully I can get one of those GP gizmo's and do it with the cam chest since new cam bearings and support plate will go in I think it would be a good time to put that in the other side at the same time.

On topic:
On a Twin Cam lifter, oiling holes can face either way:)
 

·
Registered
Joined
·
1,460 Posts
LAF said:
Hey Ozzie.


On topic:
On a Twin Cam lifter, oiling holes can face either way:)

EVO`s used to have the oil holes facing each other..........but it really did not matter.

Twinkies oil holes face toward you but again I dont think it matters.......disclaimer: this is my opinion.

All the best, Ozzie
 

·
Registered
Joined
·
1,460 Posts
LAF said:
Hey Ozzie.


On topic:
On a Twin Cam lifter, oiling holes can face either way:)
Oooppps, sorry LAF, I thought you were asking a question.

All the best, Ozzie
 

·
Registered
Joined
·
365 Posts
Discussion Starter #10
LAF

I reread your thread regarding the rocker support tragedy. Although no expert I think it would have happened with any cam. As to roller rockers helping or hindering in that situation I think it would make no difference.
:dunno:

joepenoso
 

·
Nice to ride again :-)
Joined
·
1,802 Posts
joepenoso said:
LAF

I reread your thread regarding the rocker support tragedy. Although no expert I think it would have happened with any cam. As to roller rockers helping or hindering in that situation I think it would make no difference.
:dunno:

joepenoso
I don't think the roller rockers contributed anything to whatever failed.

I do think that they stopped any further damage, and got me home with the grace of god for sure. I think a cast rocker arm would have had the cup completely broken off.

I do think if you are going to the compression, and lift, and the spring pressures I am running for my cam you should.

No other reason then I was advised by numerous people to use them including the designer of my cam.

I in no way suggest this guy doesn't know what he is talking about, and I don't really like to spend money if I don't have to.

If you lay a stock, and a S&S roller rocker together, and asked 100 people what looks like it will do its job better, I would say 90-95% would say the S&S.
 
1 - 11 of 11 Posts
Top