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Thread: Ok, cpk sensor ??/timing

  1. #1
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    Ok, cpk sensor ??/timing

    Alright, back again-On the 1996-1998 5.7 motors, what is the tolerance for placement of the sensor?
    Im fed up with 300$ timing covers and about to break down and make one if i don't get a little cooler..
    Is there ckp learn on these systems similar to the Lsx systems?

    To touch up on setup, I have a gen1 400sbc trying to go roller and use 96-98 ecu/pcm and using flex fuel injectors for added gpm, mounted on the manifold.

    Can i simply use centerline angle offset and copy angle from a timing cover with the sensor? Will it be close enough?

  2. #2
    Super Moderator dave w's Avatar
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    Quote Originally Posted by 405cubes View Post
    Alright, back again-On the 1996-1998 5.7 motors, what is the tolerance for placement of the sensor?
    Im fed up with 300$ timing covers and about to break down and make one if i don't get a little cooler..
    Is there ckp learn on these systems similar to the Lsx systems?

    To touch up on setup, I have a gen1 400sbc trying to go roller and use 96-98 ecu/pcm and using flex fuel injectors for added gpm, mounted on the manifold.

    Can i simply use centerline angle offset and copy angle from a timing cover with the sensor? Will it be close enough?
    To my knowledge, the 96 ~ 98 PCM do not have a crank learn. Below are a couple pics I have from my crank position research. The trigger wheel is position EXACTLY half way across the sensor when #1 cylinder is at TDC. I think this is the only crank trigger alignment that works.

    Maybe the $100 timing cover from EFI Connections is an option?

    http://www.eficonnection.com/eficonn...spx?ItemId=885

    dave w
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    Last edited by dave w; 01-07-2014 at 07:36 AM.

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    If the size of the teeth are the same, and the size of the notches are the same, then the crank sensor can be placed anywhere around the wheel that puts the sensor in the same position relative to the wheel as pictured above.

    Injector timing is synched off the cam sensor when present, or off the crank sensor when cam signal not present.

    I would look at the disassembly that's floating around to see if there's a variable for a timing reference angle or crank sensor offset value.

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    Good info...suggestions?

    Good stuff guys. As far as the 100$ cover, i have a non-roller block, which lacks cam retainer plate provisions-meaning i must use cam button and rely on timing cover to keep the cam in the block.

    That leaves me needing a rigid cover, at least aluminum etc.

    Another problem i see is space for double roller chain & ckp reluctor beneath...
    anyone have any ideas?
    Possibly the gm severe duty single chain? Guess I fail at finding a cover so far...

  5. #5
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    Quote Originally Posted by 405cubes View Post
    Another problem i see is space for double roller chain & ckp reluctor beneath...
    anyone have any ideas?
    Possibly the gm severe duty single chain?
    Personally I think the single roller is a better unit, larger pins and rollers. I pulled one out of a 2500 series truck with nearly 200k miles and it showed almost no sign of stretching. Cloyes makes that single roller for GM and the one you buy from them has an adjustable crank gear for timing the cam -4* 0* or +4* Just find one of the used plastic covers and use it as a template for welding a tube to tin cover for the sensor.
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  6. #6
    Super Moderator dave w's Avatar
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    I build my own external 4x crank position sensor. The machined timing cover from EFI Connection is likely less expensive than building your own external 4x crank position sensor? Maybe you have access to free CAD and free CNC time?

    Maybe the $100 EFI Connection timing cover could be reinforced on the inside with a piece of metal. The reinforced metal would be for the cam button to thrust against. I'm thinking the L31 Vortec plastic cover, once reinforced, can withstand nearly the same lateral force as a factory sheet metal timing cover.

    dave w


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    Re: the diy external- im assuming it is larger diameter than balancer? What did you shave to fit? Balancer?

    ....Im assuming it locks on the woodruff....

    Quote Originally Posted by dave w View Post
    I build my own external 4x crank position sensor. The machined timing cover from EFI Connection is likely less expensive than building your own external 4x crank position sensor? Maybe you have access to free CAD and free CNC time?

    Maybe the $100 EFI Connection timing cover could be reinforced on the inside with a piece of metal. The reinforced metal would be for the cam button to thrust against. I'm thinking the L31 Vortec plastic cover, once reinforced, can withstand nearly the same lateral force as a factory sheet metal timing cover.

    dave w



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    Super Moderator dave w's Avatar
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    Here are few more pics. I have it bolted to the harmonic balancer. CAD is an AWESOME tool! CNC machining is also AWESOME. The geometry is identical to the factory trigger wheel, only larger diameter. I'm using the L31 Harmonic Balancer, to offset the thickness of the trigger wheel. All the accessory pulleys line up.

    dave w
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    Thats really nice. I work in a "dark ages" old school machine shop, cad and cnc arent available lol. Im looking at a scrap bin a bridgeport and a 1/10 degree rotary table. In the time it takes me to prep and setup, cnc could have spit it out!

    Thats an awesome install, i contacted efi about the topic and they talked me out of it a while back. After seeing yours....makes me want to go for it.

    Thats just flawless clean man!

    Minor ???- tooth centerline relative to woodruff, clockwise-remember what it was?
    Thickness etc-any numbers would get it started. I may just do it.

    Quote Originally Posted by dave w View Post
    Here are few more pics. I have it bolted to the harmonic balancer. CAD is an AWESOME tool! CNC machining is also AWESOME. The geometry is identical to the factory trigger wheel, only larger diameter. I'm using the L31 Harmonic Balancer, to offset the thickness of the trigger wheel. All the accessory pulleys line up.

    dave w

  10. #10
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    Basically 30 degrees on, 60 degrees off then, according to
    the cad drawing. With TDC to occur at midpoint. Thats easy enough.

    That solves it! I knew someone had to
    be doing this thanks for sharing!!!

  11. #11
    Super Moderator dave w's Avatar
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    Quote Originally Posted by 405cubes View Post
    Basically 30 degrees on, 60 degrees off then, according to
    the cad drawing. With TDC to occur at midpoint. Thats easy enough.

    That solves it! I knew someone had to
    be doing this thanks for sharing!!!
    30 degrees / 60 degrees Yes.

    The attached pic is designed to mounted to the harmonic balancer also. With the revised design the harmonic balancer will need to have the outer ring of holes drilled and tapped with threads. The advantage of the revised design is it does not interfere with the crankshaft pulley and is very simple / low cost to make!

    CAD and / or CNC maching is available, send me a PM for pricing.

    dave w
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    Last edited by dave w; 01-09-2014 at 11:49 PM.

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