OS FS .91 Surpass

Michael Keeven

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Feb 12, 2000, 3:00:00 AM2/12/00

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I have a couple of simple questions for an engine expert. I have this
OS FS .91 Surpass engine in which I want to replace the bearings. The
piston liner does not just slide out like other OS engines I have
disassembled. In those the liner was a slip fit and slid right out. Is
it normal for this engine to have to heat the crankcase to remove the
liner. In Harry Higley's book 'All About Engines' he says to turn the
crankcase upside down at an angle on a pad of paper and take a wood
dowel and a hammer to the bottom lip of the liner.
My second question concerns the timing mark on the camshaft. It's too
late now to observe where it was when it was first removed. According
to Higgley "The camshaft's punch mark must point directly under the
pushrods with the crankshaft at TDC (649)." Picture 649 does in fact
show the camshaft in the 12 o'clock position. But, in 'A complete guide
to O.S. Model 4/Strokes' by Graham C. Rice he says "Hold the Crankshaft
timing mark steady at the 12 o'clock position (A) and spirally rotate
the Camshaft into its housing until the Camshaft timing mark comes to
rest at the 6 o'clock position (B)." Illustration 'B' does in fact show
the timing mark in the 6 o'clock position.
These two references diametrically contradict each other. Which one is
correct?
T.I.A.

--
Michael Keeven
Pacifica, CA
http://www.geocities.com/CapeCanaveral/Campus/8059/index.html
<mailto:m_ke...@pacbell.net>

Bill Fulmer

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Feb 12, 2000, 3:00:00 AM2/12/00

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Bofe of um....
Michael Keeven <m_ke...@postoffice.pacbell.net> wrote in message
news:38A568D3...@postoffice.pacbell.net...

Paul McIntosh

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Feb 12, 2000, 3:00:00 AM2/12/00

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Yes, they are both correct. Since the camshaft rotates once for each
crankshaft revolution, one turn of the crank will bring the cam mark to
the top. You want to assemble the head and valves with the cam lobes
pointing down to make it easier to get everything lined up. There will
be no pressure on the rocker arms or valves like that.

--
Paul McIntosh
Desert Sky Model Aviation
(877) 311-3759 (toll free)
(602) 780-9005 (in AZ)
http://www.tcfb.com/desertsky

Chad

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Feb 12, 2000, 3:00:00 AM2/12/00

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Yep just heat the case in the oven at 375 . Try and get the liner out after
5 min, If it still doesn't want to come out bake it for another couple of
min. I put gloves on and hold the engine upside down and hit my two palms
together. Should slide right out. As for the second question I have no Idea.
I myself am putting new bearing is a surpass 48 and I need to know the cam
alignment to TDC.

Michael Keeven wrote in message
<38A568D3...@postoffice.pacbell.net>...

Dno1939

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Feb 13, 2000, 3:00:00 AM2/13/00

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Heat the case and the sleeve will loosen up. Start the cam in one tooth to the
left of pointing at the push rod tubes and it will rotate in to the correct
alignment. Be sure to hold the crank at TDC when you do this. Good Luck!!

>I have a couple of simple questions for an engine expert. I have this
>OS FS .91 Surpass engine in which I want to replace the bearings. The
>piston liner does not just slide out like other OS engines I have
>disassembled. In those the liner was a slip fit and slid right out. Is
>it normal for this engine to have to heat the crankcase to remove the
>liner. In Harry Higley's book 'All About Engines' he says to turn the
>crankcase upside down at an angle on a pad of paper and take a wood
>dowel and a hammer to the bottom lip of the liner.
> My second question concerns the timing mark on the camshaft. It's too
>late now to observe where it was when it was first removed. According
>to Higgley "The camshaft's punch mark must point directly under the
>pushrods with the crankshaft at TDC (649)." Picture 649 does in fact
>show the camshaft in the 12 o'clock position. But, in 'A complete guide
>to O.S. Model 4/Strokes' by Graham C. Rice he says "Hold the Crankshaft
>timing mark steady at the 12 o'clock position (A) and spirally rotate
>the Camshaft into its housing until the Camshaft timing mark comes to
>rest at the 6 o'clock position (B)." Illustration 'B' does in fact show
>the timing mark in the 6 o'clock position.
> These two references diametrically contradict each other. Which one is
>correct?

>ampus/8059/index.html

Michael Keeven

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Feb 13, 2000, 3:00:00 AM2/13/00

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Thanks Paul, I understand now. But, doesn't the camshaft rotate once
for every two rotations of the crankshaft. Therefore, with the piston
at TDC, you could insert the camshaft in either the 6 o'clock or 12
o'clock position. I understand about installing the the cam followers
and pushrods with the timing mark (and lobes) in the 6 o'clock
position. That is where you would want to adjust the valves also.

Paul McIntosh wrote:
>
> Yes, they are both correct. Since the camshaft rotates once for each
> crankshaft revolution, one turn of the crank will bring the cam mark to
> the top. You want to assemble the head and valves with the cam lobes
> pointing down to make it easier to get everything lined up. There will
> be no pressure on the rocker arms or valves like that.
>
> Bill Fulmer wrote:
> >
> > Bofe of um....
> > Michael Keeven <m_ke...@postoffice.pacbell.net> wrote in message
> > news:38A568D3...@postoffice.pacbell.net...

> > > I have a couple of simple questions for an engine expert. I have this
> > > OS FS .91 Surpass engine in which I want to replace the bearings. The
> > > piston liner does not just slide out like other OS engines I have
> > > disassembled. In those the liner was a slip fit and slid right out. Is
> > > it normal for this engine to have to heat the crankcase to remove the
> > > liner. In Harry Higley's book 'All About Engines' he says to turn the
> > > crankcase upside down at an angle on a pad of paper and take a wood
> > > dowel and a hammer to the bottom lip of the liner.
> > > My second question concerns the timing mark on the camshaft. It's too
> > > late now to observe where it was when it was first removed. According
> > > to Higgley "The camshaft's punch mark must point directly under the
> > > pushrods with the crankshaft at TDC (649)." Picture 649 does in fact
> > > show the camshaft in the 12 o'clock position. But, in 'A complete guide
> > > to O.S. Model 4/Strokes' by Graham C. Rice he says "Hold the Crankshaft
> > > timing mark steady at the 12 o'clock position (A) and spirally rotate
> > > the Camshaft into its housing until the Camshaft timing mark comes to
> > > rest at the 6 o'clock position (B)." Illustration 'B' does in fact show
> > > the timing mark in the 6 o'clock position.
> > > These two references diametrically contradict each other. Which one is
> > > correct?

> > > T.I.A.
> > >
> > > --
> > > Michael Keeven
> > > Pacifica, CA
> > > http://www.geocities.com/CapeCanaveral/Campus/8059/index.html
> > > <mailto:m_ke...@pacbell.net>
> > >
>

> --
> Paul McIntosh
> Desert Sky Model Aviation
> (877) 311-3759 (toll free)
> (602) 780-9005 (in AZ)
> http://www.tcfb.com/desertsky

--

Anthony

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Feb 13, 2000, 3:00:00 AM2/13/00

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the cam turns two times to every 1 rev of crankshaft thus tdc[top dead
center] at firing[compression] and tdc at overlap[both valves open] with
piston at tdc and set cam so mark is pointing up. has to be in line with
push rod tube using a straight edge of sort ck to see if mark on cam shaft
lines up with center of push rod tubes, Drawing a fake line through cam
[line should go through middle of cam to mark to center of push rod tube as
seen from side] timing mark on prop drive washer should line up at center
off case on top by push rod tubes, should be it I hope this helps

Michael Keeven wrote in message

<38A680EA...@postoffice.pacbell.net>...

Jim White

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Feb 13, 2000, 3:00:00 AM2/13/00

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"Anthony" <col...@pe.net> wrote in message
news:K_Ap4.42096$ox5.10...@tw11.nn.bcandid.com...

> the cam turns two times to every 1 rev of crankshaft

ummmm.... reverse that.....