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engine problem



 
 
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  #1  
Old September 4th 05, 03:10 AM
george taylor
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Default engine problem

Ok, I am not sure what is causing this, maybe someone will know. I rebuilt a
1600 single port and went through and adjusted the valves. Everything lined
up correctly (valve wise) starting at #1 at tdc. When I crank the motor
instead of it sucking in air it blows out of the carb. Did I some how put
the cam in wrong? I can not picture it being in wrong if I can get all the
valves in the correct positions at tdc of each cylinder. Any clues?


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  #2  
Old September 4th 05, 03:53 AM
Speedy Jim
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george taylor wrote:

> Ok, I am not sure what is causing this, maybe someone will know. I rebuilt a
> 1600 single port and went through and adjusted the valves. Everything lined
> up correctly (valve wise) starting at #1 at tdc. When I crank the motor
> instead of it sucking in air it blows out of the carb. Did I some how put
> the cam in wrong? I can not picture it being in wrong if I can get all the
> valves in the correct positions at tdc of each cylinder. Any clues?
>
>

Assuming you did get the cam marks lined up,
there is not just ONE TDC for each cylinder, but in fact TWO.

Take #1 cyl as an example.
The first time that the pulley mark comes around,
#1 piston is at its high point and the exhaust valve
is open to let the burned gases out.

The NEXT complete revolution of the pulley brings
the mark up again, but this time #1 piston is
completing the compression stroke and both Intake and Exhaust
valves must be closed.

Go thru it again. Focus on #1 valves. Turn the pulley
and watch for the #1 rockers to "back off" at TDC.
This would be the correct TDC to adjust #1 valves.

Hard to explain; hope that was clear.

--

Speedy Jim
http://www.nls.net/mp/volks/
  #3  
Old September 4th 05, 02:20 PM
george taylor
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Default

Thanks. I did notice that there were 2 point that were at tdc, so I rotated
it to the point that both valves were closed. I will try it again. I just
can not se that if both valves are in the closed position, and the piston is
at the top of the cycle that it would push out air.
Thanks again.
"Speedy Jim" > wrote in message
...
> george taylor wrote:
>
>> Ok, I am not sure what is causing this, maybe someone will know. I
>> rebuilt a 1600 single port and went through and adjusted the valves.
>> Everything lined up correctly (valve wise) starting at #1 at tdc. When I
>> crank the motor instead of it sucking in air it blows out of the carb.
>> Did I some how put the cam in wrong? I can not picture it being in wrong
>> if I can get all the valves in the correct positions at tdc of each
>> cylinder. Any clues?

> Assuming you did get the cam marks lined up,
> there is not just ONE TDC for each cylinder, but in fact TWO.
>
> Take #1 cyl as an example.
> The first time that the pulley mark comes around,
> #1 piston is at its high point and the exhaust valve
> is open to let the burned gases out.
>
> The NEXT complete revolution of the pulley brings
> the mark up again, but this time #1 piston is
> completing the compression stroke and both Intake and Exhaust
> valves must be closed.
>
> Go thru it again. Focus on #1 valves. Turn the pulley
> and watch for the #1 rockers to "back off" at TDC.
> This would be the correct TDC to adjust #1 valves.
>
> Hard to explain; hope that was clear.
>
> --
>
> Speedy Jim
> http://www.nls.net/mp/volks/



  #4  
Old September 4th 05, 06:58 PM
bug '59
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Default


"Speedy Jim" > schreef in bericht
...
> george taylor wrote:
>
>> Ok, I am not sure what is causing this, maybe someone will know. I
>> rebuilt a 1600 single port and went through and adjusted the valves.
>> Everything lined up correctly (valve wise) starting at #1 at tdc. When I
>> crank the motor instead of it sucking in air it blows out of the carb.
>> Did I some how put the cam in wrong? I can not picture it being in wrong
>> if I can get all the valves in the correct positions at tdc of each
>> cylinder. Any clues?

> Assuming you did get the cam marks lined up,
> there is not just ONE TDC for each cylinder, but in fact TWO.
>
> Take #1 cyl as an example.
> The first time that the pulley mark comes around,
> #1 piston is at its high point and the exhaust valve
> is open to let the burned gases out.
>
> The NEXT complete revolution of the pulley brings
> the mark up again, but this time #1 piston is
> completing the compression stroke and both Intake and Exhaust
> valves must be closed.
>
> Go thru it again. Focus on #1 valves. Turn the pulley
> and watch for the #1 rockers to "back off" at TDC.
> This would be the correct TDC to adjust #1 valves.
>
> Hard to explain; hope that was clear.
>
> --
>
> Speedy Jim
> http://www.nls.net/mp/volks/


So if i understand this correct there are 2 TDC positions?
As a novice i'm told to also line up the dizzy at the right mark(cyl 1),
does that automaticly set up the right TDC?

just wondering,
Roger



  #5  
Old September 4th 05, 11:40 PM
Speedy Jim
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Posts: n/a
Default

bug '59 wrote:

<SNIP>
> So if i understand this correct there are 2 TDC positions?
> As a novice i'm told to also line up the dizzy at the right mark(cyl 1),
> does that automaticly set up the right TDC?
>
> just wondering,
> Roger
>
>
> That's no guarantee. If the dizzy drive gear is put in wrong,

the dizzy can just be turned or plug wires swapped around.

You have to follow the motion of the valves to determine
whether TDC is an exhaust stroke or a compression/firing stroke.

--

Speedy Jim
http://www.nls.net/mp/volks/
  #6  
Old September 5th 05, 03:58 PM
bug '59
external usenet poster
 
Posts: n/a
Default


"Speedy Jim" > schreef in bericht
...
> bug '59 wrote:
>
> <SNIP>
>> So if i understand this correct there are 2 TDC positions?
>> As a novice i'm told to also line up the dizzy at the right mark(cyl 1),
>> does that automaticly set up the right TDC?
>>
>> just wondering,
>> Roger
>>
>>
>> That's no guarantee. If the dizzy drive gear is put in wrong,

> the dizzy can just be turned or plug wires swapped around.
>
> You have to follow the motion of the valves to determine
> whether TDC is an exhaust stroke or a compression/firing stroke.
>
> --
>
> Speedy Jim
> http://www.nls.net/mp/volks/


Interesting info, could make a huge difference on my "hesitation" problem
posted earlier. Won't find that one in the books (at least not the one i
have)

Thanks
Roger


 




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