Pan head rocker blocks

Post Reply
Pooka
Inactive member
Member
Posts: 56
Joined: Sat Nov 24, 2007 2:22 pm
Bikes: *
Location: Lebanon, Missouri

Pan head rocker blocks

#1

Post by Pooka »

Can any one tell me why the block tops have to be made of brass ?
Guest

#2

Post by Guest »

Pooka, It was a lousy design. It‘s beyond me why any engineer would design a pivot point that has to take the constant load of push rod to valve spring and make the load carrier out of brass. There is a USA company that I’ve seen that makes them out of tool steel. Bob
Pooka
Inactive member
Member
Posts: 56
Joined: Sat Nov 24, 2007 2:22 pm
Bikes: *
Location: Lebanon, Missouri

#3

Post by Pooka »

Yeah, that was my point. Why should they have to be ?
They are under a continuous load, made from a soft material(brass),
with a hardened shaft running inside them, and only turning a quarter of a turn, not a full revolution.
So all the pressure is on the upper block,the softer material.
Four times the movement. Eventually egg shaping the upper half.
The you end up with an low oil pressure problem, in an engine that has an oil pump that doesn't push a lot of pressure to begin with.
I've always thought that volume was more important then pressure,
you still have to get it from one place to another.
Now, about the all steel blocks. I've also looked into them.
They are made here in the good old U.S. of A. !
And price is comparable to after market from who knows where.
I contacted the company, they are are honed to spec and ready to bolt on.
I have found a place to get rebuild stock Pan blocks,but, to me it just makes sense to use the steel block.
panpered
Inactive member
Member
Posts: 20
Joined: Sat Dec 22, 2007 4:32 pm
Location: Las Cruces, NM
Contact:

#4

Post by panpered »

Who makes the steel replacement blocks? I (and others) might want to look into them.
Pooka
Inactive member
Member
Posts: 56
Joined: Sat Nov 24, 2007 2:22 pm
Bikes: *
Location: Lebanon, Missouri

#5

Post by Pooka »

This is who is selling them.
AAOK---1533 N Milwaukee #200---Boise, IDAHO 83714---(email) orders@aaok.com ---(tel) 702-988-0952---(fax) 702-988-0954
You can also find them on E-Bay by using this:
Item number: 270121265582
Cotten
Senior Member
Posts: 6937
Joined: Sun Feb 10, 2002 2:30 am
Bikes: -
Location: Central Illinois
Has thanked: 112 times
Been thanked: 310 times

#6

Post by Cotten »

Excuse me, but....

Although it is certainly worth questioning, I am not quick to agree that Panhead rocker blocks were a "bad design". After all, they are damn near bullet-proof.

Comparing their durability to Chubblehead's rockerarms makes them seem like lifetime units!

If anything goes wrong with the bronze caps, some abuse occurred that was never intended.
And they are rebuildable beyond our lifetimes.

I have witnessed where they were beaten tight again with a ballpeen, and then run ruthlessly.

My own experience was to plug up my entire motor with decomposing silicone in the 80's, blowing the oilfilter off into the wind on an out of state run one hot July. After returning home to bar-hopping, the rockers squeeked for two weeks. At least.
Upon inspection a decade or more later: they looked just like any other panhead rocker blocks.

Obviously they were expensive to produce, and that was their demise. Other than that they lasted too long.

Where in the hell did the legendary durability of the Panhead arise, if not from its heads?
(After all, the chassis design was generally the same as a Knuck or a BTSV, even after the swingarm changeover)

You can pick at the valve geometry, or quibble with the bizarre ramps on the arms,... but overall the rockers are the dinosaur overkill that has kept the species alive.

Just...my...humble opinion........

...Cotten
Pooka
Inactive member
Member
Posts: 56
Joined: Sat Nov 24, 2007 2:22 pm
Bikes: *
Location: Lebanon, Missouri

#7

Post by Pooka »

Hey Cotton,
" Just...my...humble opinion...Cotten "
As always, your input is respected and welcomed.
And I have to agree with you on the longevity of Pans to Shovels.
But it just always seamed to me, in my humble opinion,
that the design, was just wrong.
But based on the K.I.S.S. or basic H.D. thought process of the time.
" If it ain't broke, don't fix it "
Then they built the Shovel(?)
:roll:
108
Member
Posts: 184
Joined: Sun Aug 29, 2004 2:31 pm
Bikes: 1948 FL 74in Panhead Chopper , 1958 Zundapp Citation 500
Location: Indianapolis

rocker blocks

#8

Post by 108 »

I stopped to eat supper and Cotton beat me to it. I agree with him- its not a bad design at all. The surface contact area of rocker shaft is huge compared with a car rocker with about the same spring pressure. And if the oil was poor or the flow failed the brass could go a long time with out scoring. I had the heads off my '48 2 years ago to reseal the pans and check everything. The original brass blocks were a little too loose so I just ground them down on an emery sheet on glass, torque checking the full width clearance with plasti-gage until the fit was good as new. Cost = near zero, and saved a lot of time. Also ground down the head gasket surface to flat again the same way,where the head bolt inserts were trying to pull down out of the aluminum.
wantapanrealbad
Inactive member
Member
Posts: 36
Joined: Wed Jan 11, 2006 2:21 am
Bikes: -
Location: Eastern Tennessee

#9

Post by wantapanrealbad »

I would be concerned that the hardness and composition of the steel bearing blocks may be too similar to that of the shafts. You will get better wear performance with a hard material next to soft one. Hard next to hard will gall, old automotive main bearings are a good example.

Joe
fourthgear
Inactive member
Senior Member
Posts: 1400
Joined: Sat Apr 03, 2004 5:54 am
Bikes: -
Location: north florida
Been thanked: 7 times

#10

Post by fourthgear »

Cotten hit the nail on the head as usual. That Bronze cap takes a lot of abuse at each end of it , both up and down against the bottom half too.( spring pressure one way and cam lift the other ) That bronze cap will give a little I'm sure , softer more forgiving material for flexibility. Bronze is used on a lot of things for a lot of reasons , but I think the big one is its durability.It may not be the best material for this application if you wanted to get a full blown drag motor , but the length of service in an every day rider is obvious.

Now oil pumps are a diff. bag of worms . I 'm no longer a follower of the saying that they are adequate for the application and I also believe that pressure does have an effect on lubricating components. Who knows maybe the oil pump and or the way the oil was distributed to the various components does not have some thing to do with premature failure of the upper ends of these motors . Of course if you change to a new type of pump , you lose the ability to rebuild it if its in rebuild-able condition, but I will take the loss for a better oiling system. If that upper end is not getting adequate ,moderate temperature ,oil , it will fail.
Cotten
Senior Member
Posts: 6937
Joined: Sun Feb 10, 2002 2:30 am
Bikes: -
Location: Central Illinois
Has thanked: 112 times
Been thanked: 310 times

#11

Post by Cotten »

FourthGear!

I feel that the oilpumps also fall into the blessed dinosaur overkill catagory, but we really aught to address that in a separate thread.

Back to rocker blocks,
My personal misgiving is their weight.
I have some magnesium printer's plate stashed for nearly two decades towards a remedy project: to replace the cast-iron bottom halves, of course.
But somehow my priorities changed.

....Cotten
daddywags
Inactive member
Member
Posts: 12
Joined: Thu Dec 30, 2004 6:38 pm
Been thanked: 1 time

roller arm rockers

#12

Post by daddywags »

Yeah, seems the pan rockers last forever and are very forgiving, not like that troubleheads or blockheads. Heck, a lot better than the new twin cam setup. Heard a lot of fixing and aftermarket stuff for the twin cams are out.
I heard someone is making roller arm rockers for them. That sounds like a good idea, anyone else hear or know who does it?
fourthgear
Inactive member
Senior Member
Posts: 1400
Joined: Sat Apr 03, 2004 5:54 am
Bikes: -
Location: north florida
Been thanked: 7 times

#13

Post by fourthgear »

Cotten
Why weight ? that lower block is not part of any reciprocating mass . Unless you want to bring the weight down for racing. Magnesium is some lite stuff though, is it a better bearing material ? Just curious .
Guest

Re: rocker blocks

#14

Post by Guest »

108 wrote:I stopped to eat supper and Cotton beat me to it. I agree with him- its not a bad design at all. The surface contact area of rocker shaft is huge compared with a car rocker with about the same spring pressure. And if the oil was poor or the flow failed the brass could go a long time with out scoring. I had the heads off my '48 2 years ago to reseal the pans and check everything. The original brass blocks were a little too loose so I just ground them down on an emery sheet on glass, torque checking the full width clearance with plasti-gage until the fit was good as new. Cost = near zero, and saved a lot of time. Also ground down the head gasket surface to flat again the same way,where the head bolt inserts were trying to pull down out of the aluminum.
Looks like I really opened a can of worms.
Just a couple of questions here.
I understand the glass and emery cloth method of keeping a flat suface.
But what about the inturnal shaft diamiter of the block.
By removeing material from the top block, with out honeing the top and bottom blocks, as a set, to match the rocker arm, doesen't that set up a
wear pattern, that could be worse in the long run ?
Second. And this could be for another thread. Why do the bolt inserts pull out ? And is there any way to fix them ?
Pooka
Inactive member
Member
Posts: 56
Joined: Sat Nov 24, 2007 2:22 pm
Bikes: *
Location: Lebanon, Missouri

Re: rocker blocks

#15

Post by Pooka »

Anonymous wrote:
108 wrote:I stopped to eat supper and Cotton beat me to it. I agree with him- its not a bad design at all. The surface contact area of rocker shaft is huge compared with a car rocker with about the same spring pressure. And if the oil was poor or the flow failed the brass could go a long time with out scoring. I had the heads off my '48 2 years ago to reseal the pans and check everything. The original brass blocks were a little too loose so I just ground them down on an emery sheet on glass, torque checking the full width clearance with plasti-gage until the fit was good as new. Cost = near zero, and saved a lot of time. Also ground down the head gasket surface to flat again the same way,where the head bolt inserts were trying to pull down out of the aluminum.
Looks like I really opened a can of worms.
Just a couple of questions here.
I understand the glass and emery cloth method of keeping a flat suface.
But what about the inturnal shaft diamiter of the block.
By removeing material from the top block, with out honeing the top and bottom blocks, as a set, to match the rocker arm, doesen't that set up a
wear pattern, that could be worse in the long run ?
Second. And this could be for another thread. Why do the bolt inserts pull out ? And is there any way to fix them ?
Don't know why but I was signed in as guest.
Post Reply

Return to “Cylinderheads”