Adjustable push rods for 903cc?

Discussion in 'Rear-Engine Fiats' started by Chaostoy, Sep 4, 2018.

  1. Just curious if there exists a form of adjustable push rods, to adjust the length that is. My cousin says I might be able to use some from a Harley.
    I suppose I should explain a bit. I had the block decked and head shaved a small amount when I got the car, along with the cylinders bored out some. It ran great when I got it put together, aside from the 30DICa not wanting to idle.
    A short time after, maybe a month, the rocker studs were pulled from the head some causing the rocker to snap. It was then I realized I neglected to think of the push rod length.
    What options are there to avoid the same happening in the future? I just got a different head, and had new valves, guides and seats and all shined up, ready to install.
    Shims under the rockers, multiple head gaskets, one thick copper gasket...I'm considering it all. :)
     
  2. Jeff Stich

    Jeff Stich True Classic

    Location:
    Norco, CA
    Adjustable pushrods would be overkill (IMO). A decked block & shaved head isn't a huge thickness to make up (especially now that you have a different head). If you're that worried about it, just use a thicker head gasket, or you can make some thin metal shims to go under each rocker stand (don't forget the oiling port!). Multiple head gaskets? Absolutely not. (It would never seal)

    The 850 rocker studs sometimes become loose (ie: the threaded holes in the alloy cylinder head become stripped) due to a previous owner over-tightening the top nuts. This can be repaired using a Heli-coil type insert, or replacing the stud (special stud with a larger bottom threaded shaft & OE size top).
     
    kmead and Chaostoy like this.
  3. Awesome, thanks Jeff!
     
  4. NM850

    NM850 True Classic

    Location:
    Albuquerque NM
    I agree with Jeff, you shouldn’t need them but...I built a decked 903 with a high lift cam. I never liked the geometry so I had Smiths in Oregon custom make push rods. Stronger, lighter than stock, beautifully made and not too expensive if I recall.
    If you are replacing the head make the oil drain drain back modification before you install it.
    I can’t access my parts to provide pictures but Jeff can probably help.
     
    Chaostoy likes this.
  5. Jeff Stich

    Jeff Stich True Classic

    Location:
    Norco, CA
    Here's a photo of the 850 cylinder head pushrod port oil drain mod:

    850pushrodoilportmod.jpg

    (Photo courtesy of John T.)
     
    NM850 and Chaostoy like this.
  6. I did not know about that mod, thanks.
     

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