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312 reverse rotation firing order

R

Relay

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I am rebuilding a 312 and learned it is reverse rotation. I have no manual so I was using the wealth of information on the web and local shops support. Unfortunately there is no info on reverse..... Can anyone point me to a resource or tell me the firing order? Thanks
 
Reverse firing order is the regular firing order , backwards. Normal is 1.5.4.8.6.3.7.2. Reverse is 1,2,7,3,6,8,4,5. Just be sure you understand Ford numbers are right bank 1,2,3,4 from the front and left bank 5,6,7,8 from the front. Left bank is port side and right bank is starboard side unless is is a flywheel forward or V-drive.
 
Thanks for the reply.. The firing order you provided matched the one I determined by rolling the engine in watching the valves. Your response confirms I am correct
 
Ricardo. The cam is direct drive off the crank so that it rotates opposite to the crank unlike a standard Y block. The std firing order for car or truck wont work anx the firing order offered up. I am not sure at this point what to think. Thanks
 
Relay said:
Ricardo. The cam is direct drive off the crank so that it rotates opposite to the crank unlike a standard Y block. The std firing order for car or truck wont work anx the firing order offered up. I am not sure at this point what to think. Thanks
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Ooops..... my bad!
Correction: If the engine rotates RH or CW (if viewed from the flywheel end), then you do have a RH/Reverse Rotation engine, according to industry standard.
I am sorry about that misinformation earlier. I hope that I have not lost credibility with you here!

Back when the 312 was being marinized, who knows what they were doing for camshaft drive. Some were gear driven (two gears) which rotated the camshaft in a standard LH Rotation direction. This was likely due to the oil pump and distributor rotation direction..... assuming this is a two gear drive.... (not two w/ idler gears, w/ a total of four)

One sure fired method to determine firing order, would be to follow the camshaft profile. If the camshaft is correct for this RH Reverse Rotation engine, then the Camshaft profile will determine the cylinder firing order!

  • Temporarily mark your harmonic balancer @ 90* intervals from # 1 TDC.
  • Now locate #1 TDC Compression Stroke.
  • The last valve to have closed (for this #1 cylinder), would have been an intake valve.
  • Place this # 1 cylinder spark plug wire in the correct corresponding distributor cap location.
  • While watching all of your intake valves, rotate the crankshaft 90* in this RH rotation direction.
  • Look for the next-in-line intake valve that has cycled and "closed" just prior to TDC C/S.
  • Now continue rotating until this cylinder is at TDC (of which will be C/S)
  • This should be your next in line cylinder to fire!
  • Taking a lead from "Engineguy68", it would appear to be # 2 cylinder (Normal is 1.5.4.8.6.3.7.2. Reverse is 1,2,7,3,6,8,4,5) (I cannot verify this)
  • That cylinder's spark plug wire would effectively follow the #1 spark plug wire's location in the distributor cap and in the normal direction (since the distributor is NOT being reverse rotated).
  • Repeat this process at 90* rotation intervals, until the engine has made two full revolutions, and you are back to #1!
This is certainly not the only method to use, but it should be fairly goof-proof for you!

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