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  1. #1
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    Default Splined opti spun slightly

    After removing my MSD splined opti, the shaft spun slightly before I could mark it. I turned it back to where I thought it was at and marked it. There isn't any type of notch on the splines and now there's a chance I may have to resort to drastic measures when I re-install it to make sure I don't have timing/firing issues. I'm pulling the cover off to remove the water pump drive gear so I am thinking I may have to turn the crank to #1 TDC and open the opti and align it to correspond to fire #1 cylinder. Since this is my 1st rodeo dealing with this opti removal/install, I just wonder if I'm overthinking this issue. I don't know if the tolerances inside the opti are that critical or if the PCM will compensate for any slight variance in the shaft positioning once it is bolted back on. The time to fix any issues will be while the front cover is off if I have to do anything. Any feedback would be appreciated.
    '94 Z28 Red, SLP Ultra Z hood/air box/spoiler, LT1 w/deletions & mods, 4L60e, Pacesetter LTs/ORY, LS1 front brakes, Kenny Brown Double Diamond SFCs.
    '94 Z28 Arctic White, T-tops, retired.

  2. #2
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    Default

    Quote Originally Posted by Ardent_Z28 View Post
    After removing my MSD splined opti, the shaft spun slightly before I could mark it. I turned it back to where I thought it was at and marked it. There isn't any type of notch on the splines and now there's a chance I may have to resort to drastic measures when I re-install it to make sure I don't have timing/firing issues. I'm pulling the cover off to remove the water pump drive gear so I am thinking I may have to turn the crank to #1 TDC and open the opti and align it to correspond to fire #1 cylinder. Since this is my 1st rodeo dealing with this opti removal/install, I just wonder if I'm overthinking this issue. I don't know if the tolerances inside the opti are that critical or if the PCM will compensate for any slight variance in the shaft positioning once it is bolted back on. The time to fix any issues will be while the front cover is off if I have to do anything. Any feedback would be appreciated.
    I had the same issue with my 94. Save yourself some antifreeze and turn the motor to TDC and make sure the rotor is positioned toward number one.

    Sent from my SM-G955U using Tapatalk
    Same as everybody else...350 small block, double hump heads, 3/4 cam

  3. #3
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    Default

    https://www.nookandtranny.com/Info_LT1.html

    From I remember I thought the spline driven distributors could only go on one way. One of the splines is wider or gapped differently. Itís been awhile since I had one apart. Check out the link above and scroll down to the distributor section.


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    Stock bottom end, Impala head gaskets, Stock heads w/stage 2 port polish Comp beehive springs, Crane 1.6 RR's, Thunder Racing cam, Cloyes Billet True Roller TC, Long tubes, custom true dual 3" w/X-pipe, Ported intake with 58mm TB, 36lb injectors, PCMforless chip, Tick Performance stage 3 M6, Strange S60 4:10's True Trac 35 spline axles, MSD complete Ignition system, Summit electric water pump and a ton of other upgrades.

  4. #4
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    Default

    Quote Originally Posted by 1QUICKZ28 View Post
    https://www.nookandtranny.com/Info_LT1.html

    From I remember I thought the spline driven distributors could only go on one way. One of the splines is wider or gapped differently. It’s been awhile since I had one apart. Check out the link above and scroll down to the distributor section.


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    I was under the same impression. However upon closer inspection, I can see a notch on the cam (it appears a spline is missing on it) but all the splines on the shaft of my opti are evenly spaced. If there were 3 splines connected to each other on the opti shaft then it would fit only one way, which is what I understood. The GM service manual advises to mark the shaft for re-installation, and now I see why.
    '94 Z28 Red, SLP Ultra Z hood/air box/spoiler, LT1 w/deletions & mods, 4L60e, Pacesetter LTs/ORY, LS1 front brakes, Kenny Brown Double Diamond SFCs.
    '94 Z28 Arctic White, T-tops, retired.

  5. #5
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    Default

    In theory, the splined shaft only fits into the splines in the cam sprocket one way, and if you are careful, and donít force anything, you will not have a problem. Things get messed up when someone doesnít align the splines correctly, finds the Opti doesnít seat all the way, and use the mounting bolts to pull the Opti down so it sits flush with the timing cover, forcing the shaft into the wrong position.

    Courtesy of Shoebox


    94 Formula A3+1: 381ci forged stroker - Callies Stealth, Oliver 5.85 billet rods, BME nitrous pistons / CNC LT4 heads / Comp Cams solid roller / TH400+GearVendors OD / 4.11's/Strange 12-bolt / 300-shot (dry) N2O / Spohn Suspension / 6-pt roll bar /AutoMeter instrumentation / MoTeC M48 Pro engine management system /a few other odds 'n ends.

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  7. #6
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    Default

    I just wanted to add to the comments. I did an opti replacement near 2 yrs. ago on my wife's '94. The MSD replacement opti was giving me a hard time slipping into the splines. I found that the black coating on the MSD opti was causing a real tight fit into the camshaft sprocket splines. I took a wire wheel to the splines on the opti and buffed a bit of the coating off. The keyed portion of the splines is kinda tough to see(old eyes), but exercising patience and just a thin coat of grease it will slip fit without forcing it on. As said, it will only go on one way. In fact, it seems I made a small paint dot with a paint pencil on the shaft and on the timing cover to indicate where the keyed portions were to make sure I had it positioned correctly. If it doesn't slip right in, you don't have it positioned correctly.
    '94 Z28 Bone stock,4l60e
    '97 SS SLP,T56,385 stroker,AFR210,XFI292,NO traction til top of 3rd gear.
    '57 Chevy 3100 p/u LT1/T56

  8. #7
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    Default

    msd definitely has a messed up spline that is the one to go in the notch in the timing gear.
    2016 Camaro 1SS - Gotta stay LTJuan

    1996 Impala SS T56 - Le2 H/C, SBE, T56 swap

    The wrench for LTConvert's 94 Z28- Ellwein 383/LE Trickflows/ P600B/ CPT Pro Race/Pro Torque 3200

  9. #8
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    Default

    I followed everyone's advice and got 'r done. I didn't have to remove the opti cover, but I followed behind @JOATMON and found the key. It resembles the valley between 2 splines being filled 90 percent. The key on my non-vented opti on a shelf in my barn looks like the ones in the pics by shoebox and nookandtranny. I got the key into the slot some 8 or 10 times, but there was 1/16" left until it was flush with the block. I finally pushed it with one finger and it snapped in like a button snap on a western shirt and was flush. It slid right in the slot and no force was needed, as advised by @Injuneer. When I got it to TDC the slot in the cam gear was at 6 o'clock, making it easy to do this on my back...LOL. I installed my electric water pump and now I'm moving on to the oil pump swap. I'm glad this is a hobby and not a necessity on a DD. I'm able to back off when frustration sets in to go at it another day. Thanks for all the feedback.
    Last edited by Ardent_Z28; 12-31-2018 at 06:37 PM.
    '94 Z28 Red, SLP Ultra Z hood/air box/spoiler, LT1 w/deletions & mods, 4L60e, Pacesetter LTs/ORY, LS1 front brakes, Kenny Brown Double Diamond SFCs.
    '94 Z28 Arctic White, T-tops, retired.

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