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Thread: Engine Miss developed

  1. 05-22-2016, 06:51 PM #1
    thilmes
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    Engine Miss developed

    Hello Friends,

    I would love to hear your thoughts on this. Car is a 1970T with carburetors. Motor is basically stock. Motor has had a hard life. I bought car a few years ago, replaced Pistons and cylinders (motor was locked up due to long time sitting with water in cylinder, that is how i bought it). I have put a couple thousand miles on it since getting it running. I recently refurbished the dash so it was out of action for a few months (dash looks great!). finally got windshield in and took it for a drive. Vehicle seems to have a pronounced miss especially at lower RPMs. at full throttle, car performed well. cylinder 3 does not seem to be performing. pulling plug wire did little. I use old my old unisyn (floating ball type). all throats balanced. timing good. dwell good. tested compression on #3. ~125 lbs.

    Reving motor with unisys on stack #3 did not cause float to do much, although it acted like it should have at idle. Exploring a little deeper, one "trick" i used to do on VW's with dual two barrels was to rev up motor and place hand on velocity stack to clear clogged idle jets. tried that. the stack for #3 cylinder pulled on my hand hardly at all compared to other cylinders. I am sure many of you guys are groaning at my methods...

    so, i would like your thoughts as to where to look next. Am i wrong to think that there should have been a pull on my hand? My thoughts: carb to manifold leak, manifold to head leak, pull valve cover to look at intake rocker and shaft, pull valve cover to look at exhaust rocker and shaft. I have seen a rocker come off a shaft that came loose once...

    Thanks ahead of time for your thoughts and comments!

    Ted
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  2. 05-23-2016, 03:05 PM #2
    thilmes
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    Maybe a broken valve spring? That may not make sense with the normal compression tho...
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  3. 05-23-2016, 05:31 PM #3
    thilmes
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    Ok. Mystery solved so i thought I would let you readers off of the hook. One set screw missing and the other one loose for the throttle shaft between barrels 2 and 3. Adjusted the shaft and tightened the set screw. Good as new now. Has this happened to anyone else?
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  4. 05-23-2016, 05:47 PM #4
    edmayo
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    Not common, but we've seen it happen, it's a known item to check for.
    Early S Registry member #90
    R Gruppe member #138
    Fort Worth Tx.
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