78' Camaro LT1 Conversion Cali Smog Legal

Discussion in 'High Tech Retrofits' started by supwicha, Feb 26, 2014.

  1. sbca96

    sbca96 Veteran Member

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    Yes, the stock shifter gives a nice stealth feel, I do not blame you. I made the
    mistake of NOT telling a friend of mine I had one, and he went and bought one
    like a month ago. Oh well.

    I used a 1994 Firebird Formula, so I had to stay with single exhaust/single CAT.
    This was a blessing and a curse, the blessing is I ran the factory fuel lines down
    the drivers side (safely distanced from the CAT), the curse is I am left with the
    single exhaust setup. To make matters worse I made an reducer/adapter to go
    from the CAT to the stock exhaust (until after smog) but couldnt make the rear
    sway bar work. The reducer is still on (3 inch down to 2-1/4 inch) but I have
    the Magnaflow now. For the record, I figured out tonight that is a 43% drop in
    area right out of the 3 inch high flow CAT. Oops.

    Yes, I had to use the air pump, not a big deal, until its a problem. My 1995 SS
    clone recently failed smog at the smog station that has passed it for a decade
    as a new tech looked at the little filter on the smog pump intake hose and felt it
    didnt pass visual.

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    So I had to find the old air box that came with the car, but I didnt have all the
    pieces, I at least had the cover. He tried to tell me that the hose went into the
    chrome pipe, but that would draw air AFTER the MAF. The original cover shows
    the hose barb on the side. I mimiced that on the filter with a hole and a double
    barb from Home Depot.

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    On the car :

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    Yes, they are THAT picky folks. I brought up that the B-bodys you could remove
    the air pump, but he said "where is the sticker". Apparently, you need to have a
    Dealership affix the sticker - which isnt free.;)

    Tom
     
  2. supwicha

    supwicha Veteran Member

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    Ok, time for another update. This weekend I managed to get a fair amount finished. I notched the frame to clear the AC compressor, cut/modify exhaust for cats, and modified the crossmember for the trans.

    AC COMPRESSOR: I introduced Mr. Plasma Cutter to Mr. Subframe and provided sufficient clearance for the compressor and hi/low side manifold. I still need to pocket the frame which is next on the to-do list.

    EXHAUST: Because I must pass smog, i cut the existing welds on the piping and separated the cats and set my angles to accommodate my cross member. No permanent welding, I'll wait until it's back in the car and tack weld everything and remove for good welds.

    CROSS MEMBER: I struggled as to what to do on this. I entertained the aftermarket solution but since I'm trying to spend money where it is really needed and because I have equipment (chop saw, Mig, Plasma), I decided to modify as needed. My biggest concern was to maintain the original pinion angle to drive line relationship. First I took a string and spanned it between the top of the frame rails on another stock camaro I have ('79). I then measured the distance from the string to the trans yoke where it enters the transmission. This distance is exactly 2.07". I then put string on the new frame rail and adjusted the elevation of the tailshaft to 2.07". Simply setting the cross member further back on the frame set the tailshaft to 3.4", too much for me. I clamped some 3/16" stock between the frame rails and bolted the member to the trans and set it on top of the frame. I then scribed the member where the cuts where needed. I then cut the ends of the member and dis some minor grinding to get a fit that did not require force to install. Lastly I tack welded, removed, and permanently welded. I'll do some additional reinforcement later. Then I set the newly modified member between the frame rails, reset my elevation to 2.07", drilled and bolted up. I needed to use a hole saw on the opposite sides to have access to install lock washers and nuts. Hole cutting on a piece such as this is a common structural process anyway and distributes stress so I have no concerns there. I have some final cleanup to do on the flat stock as I made it oversize until final fit was obtained. That's all for now!

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    Last edited: Jul 13, 2017
  3. sbca96

    sbca96 Veteran Member

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    If I might suggest. You bolted the rear crossmember in shear, with no backup if a
    bolt were to somehow break. I would weld a secondary flange over the frame on
    each side, wasnt the original crossmember bolted on from above? That puts the
    load on the crossmember and the bolts are there only to hold it in place. The way
    you have it, the bolts are taking the entire load.

    You could use some 90 degree iron and bolt from above. I would be one better
    and also make the steel support from below the original crossmember. So is is on
    the bottom and then goes over the frame.

    Tom
     
  4. supwicha

    supwicha Veteran Member

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    Your exactly right thus my comment for additional reinforcement later, this holds my setup for now so I can finish mocking up the other necessary mods. I'll be adding some additional stock below the member to the new plate as well as an additional plate that spans the top of the subframe. If I had some 4" x 2" angle, that would have served me better but I'll make it work :) Thanks for your kind suggestions.
     
  5. sbca96

    sbca96 Veteran Member

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    Funny thing, I posted that as I am removing the 4L60E from the wifes 99 Camaro
    SS and that crossmember is bolted from the bottom. Granted that puts the load
    on the head of the bolt, not side loaded, but the bolts in effect carry the load. I
    can say they are decent sided bolts, but still.

    Tom
     
  6. bigdav160

    bigdav160 Veteran Member

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    What load? The transmission is connected there by a piece of rubber.

    I guess, being bolted from the side would have subframe twisting acting on them.
     
  7. hot72rod

    hot72rod Veteran Member Gold Member

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    It's hard to tell from the pic, but those look like grade 2 bolts?

    I'm with sbca96 on this. But if you decide not go over the frame rail at least use grade 8.
     
  8. Fbird

    Fbird Veteran Member Lifetime Gold Member

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    he will be going over the frame. Bolts are for holding something together...not for supporting wieght. But they work wonderfully for mock up ;)
     
  9. sbca96

    sbca96 Veteran Member

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    The weight of the engine/trans assembly, vibration, engine torque, etc. I am for
    matching the original design for piece of mind is all.

    I'm not sure about grade 8, perhaps grade 5. This is a common misconception in
    graded bolts, they are rated differently. Grade 8 is "stronger" but in the direction
    of the shaft, like head to thread force. Grade 5 is stronger in shear in most cases
    usually a grade 8 bolt can be broken with side load, where as a grade 5 will bend.

    I would match what the manufacturer used and the orientation its used in.

    Tom
     
  10. hot72rod

    hot72rod Veteran Member Gold Member

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    I agree. But I was thinking more bolt stretch then side load. Yes there is going to be side load and the grade 5 bolt has more of a shear strength than the grade 8, but with the twist from the trans. Now if the bolt is being dropped in from the top like the factory did it grade 2 is more than enough.
     

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