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which opens first???????

  • Thread starter Thread starter snailpower302
  • Start date Start date Feb 17, 2009
S

snailpower302

New Member
Feb 15, 2009
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0
Feb 17, 2009
#1
  • Feb 17, 2009
  • #1
At tdc and you turn the motor over clockwise ( on the compression stroke) which valve opens first is it the intake valve or the exhaust valve? Trying to figure out if the cam is 180 out!!
 

nmcgrawj

Advanced Member
Sep 28, 2003
3,651
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Indianapolis, IN
Feb 17, 2009
#2
  • Feb 17, 2009
  • #2
The intake has to open to let fuel/air in to then compress it (both valves closed) then the exhaust opens to push it out with the intake following very close behind.
 

joel5.0

Member
Jun 15, 2004
429
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Puerto Rico
Feb 17, 2009
#3
  • Feb 17, 2009
  • #3
snailpower302 said:
At tdc and you turn the motor over clockwise ( on the compression stroke) which valve opens first is it the intake valve or the exhaust valve? Trying to figure out if the cam is 180 out!!
Click to expand...

If in compression stroke TDC, you would have to turn crankshaft CW close to 180° for the exhaust valve to start opening..... if you are in the exhaust/intake changeover cycle TDC, the intake would start opening immediately after you start rotating the crankshaft.

BTW... don't you mean the distributor? If you install the cam 180° off, using the cam sprocket as the reference, it would be the same as installing it "dot-to-dot".
 
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