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91 Civic Si D16A6 head replacement - D15xx?

Discussion in 'Engine Building' started by Dual-500, Jun 13, 2010.

  1. Dual-500

    Dual-500 Well-Known Member VIP

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    Recently replaced head on D16A6 in a 91 Civic Si. Can't get timing right. Did some research on this site and it appears it probably has a D15XX cam in it and I'm not sure of the head. Casting number is PM3-11. Reading another thread on this topic, it was stated that the stock A6 cam in the D16A6 motor is retarded reference the keyway by 4.75 degrees compared to the D15 cams.

    Can I see the cam markings by simply removing the valve cover? I'd like to know exactly what's in it. What about the PM3-11 head?

    This saga started when I initially cranked it up after the head change - dist is full retard against the stop and it's still ~4-5 degrees advanced according to my timing light. The same timing light and cam sprocket as well as distro are being used.

    Can't get it past emissions testing, fails NOx in the low speed part. Also, have a adjustable timing sprocket for it - need 4mm key for it - ordered today.

    I'm thinking put the adjustable sprocket on it and dial it in to get passed on emissions as sticker expired last month. Then find an A6 cam for it.

    BTW - I changed injectors, temp sensors, thermostat, water pump, belts, hoses, head bolts, & total exhaust system when doing head work.
     
    Last edited: Jun 13, 2010
  2. K2e2vin

    K2e2vin Senior Member

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    non-VTEC D15Bs have the same head casting as D16A6s. As far as the cam, I've never heard of any markings on them to identify them so having the lobes measured and compared with the manual would probably be your best bet.
     
  3. Dual-500

    Dual-500 Well-Known Member VIP

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    How could it be that the camshaft would not have any part number or configuration numbers on it? Mind blowing. ;)

    Oh and thanks for the reply bro. I was hoping that to be the case and suspected as such. And, if I changing the cam, it ain't no big thang.
     
  4. K2e2vin

    K2e2vin Senior Member

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    You'd be surprised at what Honda does. There was a whole confusion about D16Z6 vs. JDM D15B VTEC cams; and the serials on them were "mixed" so you couldn't use that to decipher if there was a difference without measuring. Same goes for Honda's D-series transmission; 88-91=PL3, 92-95=S20, 96-00=S40. You wouldn't know if it was DX, Si, EX, etc.

    As far as the head casting, this post from HT shows how the codes are just all over the place, though I found in a thread on HT where someone's D16A6 had a PM3-11 head casting code:
     
  5. Dual-500

    Dual-500 Well-Known Member VIP

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    You got any idea on the cam lift for the D16A6 cam - the A6? I can measure that with a dial indicator pretty easily.

    Now I can see how the rebuild shop could have problems keeping track of these - especially since they are interchangeable within the head castings.
     
  6. K2e2vin

    K2e2vin Senior Member

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    I just checked the manual, and it says the D15B2 and the A6 have the same lobe height, so duration and/or lobe separation must be different.

    According to the Helms manual; 36.603(IN), 36.747(EX)...I'll see if I can find more info.
     
  7. K2e2vin

    K2e2vin Senior Member

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    D15B2 & D16A6 cam specs - D-series.org

    According to that thread(Bone is very knowledgeable in D-series engines, as so is jlicrx on here), the A6 has more lift than what is listed in the Helms.
     
  8. Dual-500

    Dual-500 Well-Known Member VIP

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    That's what I saw on another thread - maybe on a different site HT possibly. A guy with a D15 motor wanting to put a D16 cam in it.

    I appreciate any info you can get. I have the sprocket to time it - but, if it's still a performance loss then I will get the right cam for it. Have a header and 2.5" exhaust - all stainless on it so I ain't goin for a limp cam.

    Don't want a race cam - just what it's supposed to have in it.
     
    Last edited: Jun 16, 2010
  9. Dual-500

    Dual-500 Well-Known Member VIP

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    Found a D16A6 cam for $50 shipped to my house. I'll install when it gets here. Meanwhile, will probably put adjustable pulley on it this weekend when the 4mm key stock arrives and get it past emissions.

    Thanks for the assist dude!!!! I'll post results for anyone interested.
     
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