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  1. #1
    Registered East Coast B's Avatar
    Join Date
    Jun 2001
    Lehigh Valley, Pennsylvania

    1998 454EFI Throttlebody butterfly opening??

    When I take off the flame arrestor and have the throttle to WOT, the butter fly(is there another name for this) isn't perfectly horizontal with the air flow through the throttle body... if I look to the left where the throttle cable connects I can see the throttle is about 1/2" from the back stop... seems to me that I'm missing some extra throttle. I rechecked the throttle cable alignment and after adjusting, it's right back to where I started. If I try to tighten up on the cable, I can see the butterfly opened just a little which increases my rpm's when in nuetral. I took the top mount mercruiser 3000 apart, but I don't see any adjustment in there at all. I'm satisfied that I can't do anything in the area of the throttle body..... bottom line is I need extra throw in the throttle.... problem is that at WOT, the handle is 90 degrees forward an onto the fiberglass.... it just ain't going any further... I took the handle off of nuetral which is perfectly up and down and put it back on however on one notch back... Now neutral is abot 35-40 degrees back which isn't conducive to driving, just don't like it in that position.... even in that position, at the engine, I'm still not against the backstop... Anyway of adjusting the throttle throw at the helm.... I could just add another cable and pull on it for that last little top end!!!! Any ideas?

  2. #2
    Platinum Member Platinum Member mcollinstn's Avatar
    My Boats:
    1991 F311SR1
    Join Date
    Sep 2001
    drill a new hole closer to the shaft on the butterfly link plate. hook the cable to the new hole.
    I see London, I see France...

  3. #3
    Registered East Coast B's Avatar
    Join Date
    Jun 2001
    Lehigh Valley, Pennsylvania
    Thanks for the idea mcollinstn!!! Easy enough! I'll give that a look!!! Excellent!!!

  4. #4
    I had the same problem when I replaced my cable. I bought a teleflex cable and I ended up trimming a little extra off of the hard plastic that links to the carb (opposite end of linkage). There was about 1/4" too much plastic and I could not get enough throttle, now I get a little extra pull but it didn't give me anymore RPM.

  5. #5
    Registered robyw1's Avatar
    My Boats:
    1998 Wellcraft 22' Scarab
    Join Date
    Jul 2003
    Spring, TX
    I have had the same problems on many of my hot cars. On a carburetor it probably won't gain you anything but if you are using fuel injection keep in mind that the TPS sensor needs to see true WOT so that it's maximum voltage can be attained for proper operation.


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