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Thread: Avanti II ignition/spark plug wire shielding

  1. #1
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    Avanti II ignition/spark plug wire shielding

    Still coming to terms with my new (to me) 1966 Avanti II RQA-0090, mostly trying to figure out whats been removed, altered or hacked in its long checkered past...

    Up for consideration today is the question: did the 327/300hp Corvette engine equipped Avanti II's come from the factory with the Corvette many-pieced ignition wiring shielding? I know Studebaker Avanti's did, and Corvettes of that era did, but did Avanti Motors include it on the early cars?
    My car has sheet metal shields around the spark plugs, and tabs to route the ignition wires below the manifolds, as well as brackets bolted to the intake manifold on either side of the distributor (along with the coil mounting) that suggest the answer is affirmative.
    However, before I blow $700+ for a set of reproduction sheet metal, I'd like to be fairly certain that it (A) is correct and (B) will fit on the Chevy motor in the tight Avanti engine compartment. Particularly worrying is the Studebaker style throttle linkage...looks pretty close to where the stainless steel top and left side shrouds fit on the Corvette.

    Any first-hand information (or educated guesses...I'm not picky!) will be appreciated.

    Great car, great forum!

    Thanks
    Marc

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    1966 Brochure, hard to see but no shielding. I know the mid 70's and up didn't have shielding.

    , ,

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    I have pics of many cars prior to yours that do NOT have any shielding
    64 GT Hawk (K7)
    1970 Avanti (R3)

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    Our 66 is RQA-0107. It did not have shielding on it when I bought it in 83 but some of the unique parts for the shielding was there so it might have. It has a Correct Corvette tach drive distributor with a cap over the provision for the cable. The original Holley carburetor was missing when I bought it. I found a 3367 at a swap meet and that should work (I currently have a universal 600CFM 1850 on it). What number Holley is on yours? (number on the front of the choke air horn). I don't see any reason why the shielding would not fit. The Avanti Authenticity manual will probably have your answer. I do not have one.

    Jim
    james r pepper

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    President Member Lou Van Anne's Avatar
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    My 79 has shielding.....so how is radio static prevented without the shields?
    Lou Van Anne
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    Thanks to all for the input. I checked the Bob Johnstone Avanti registry for engine compartment pics on the RQA cars. Few entries have clear engine pics, and many of those show mods (HEI distributors, aftermarket wiring looms, changed air filters,etc) and I saw zero shielding.

    Corvette owners covet those rare and valuable pieces, and they’re a PITA to work with (the shielding parts, not the owners) so there’s a twofold rationale for them to disappear from the less-collectible Avanti II. Sigh.

    I did check and my car does have the tach drive distributor. When I bought it, it had an old Carter AFB carb and a tiny pancake chrome air filter, so I can’t say about a Holley.

    Will keep looking....

  7. #7
    President Member RadioRoy's Avatar
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    Quote Originally Posted by Lou Van Anne View Post
    My 79 has shielding.....so how is radio static prevented without the shields?
    There are two types of spark plug wires that do not generate the same amount of electrical interference as old copper core wires did. The first has a fiber core infused with carbon. The second is, I think but do not know, a coiled conductor.

    Neither of these types were available, as far as I know, when Studebaker Avanti was in production.
    RadioRoy, specializing in AM/FM conversions with auxiliary inputs for iPod/satellite/CD player. In the old car radio business since 1985.

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    I checked the Authenticity Manual; it has no info or pics related the Avanti II. I guess the next question would be directed to any and all II current owners; If the GM/Corvette shielding was not used, how are the spark plug wires routed on your car? The ram's horn manifolds make it tricky; routing over the top can cook the wires, and routing beneath would require some kind of method to restrain the front cylinder wires from contact with the header pipe. That's why GM used the "V" (or "boomerang") channels. I'll try to insert a pic showing this method if I can conquer the computer.

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    DressOut - 13.jpg
    Heres a rear view of a '66 Corvette 327 with all shielding in place. Note the nice gap to the left of the distributor for the 'Vette throttle linkage..my concern is that this may not give enough clearance for the Avanti bell-crank mechanism.
    And these parts are not cheap...modifications are at my peril!


    DressOut - 05.jpg

    here's the left side
    showing the wire routing

    DressOut - 12.jpg

    and here's the whole enchilada. Modern radio suppression wires are a wondrous thing! On the other hand. it would be nice to just have the plug wires neatly and safely routed!
    Last edited by MarcD; 11-01-2018 at 12:46 PM. Reason: add new pic

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    Marc,
    My '70 came with the shielding albeit my memory thinks it looks somewhat different from yours, and I also think the point/condenser style of GM distributor had the tach drive but I'll dig it out and check for sure. The top cover is much squarer than what you are showing. A quick search shows '70-72 as being different from other years.
    Luck,
    Bill

  11. #11
    President Member Gunslinger's Avatar
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    When Avanti Motors purchased Corvette spec crate engines they didn't come with RFI shielding (AFAIK). They were crate engines available to anyone and since Chevrolet didn't know what kind of vehicle a crate engine would go in they were not shipped with shielding. It would have been sourced separately if desired.
    Poet...Mystic...Soldier of Fortune. As always...self-absorbed, adversarial, cocky and in general a malcontent.

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    My 68, RQA257 has it, doubt it was original. Drivers side shield won’t clear the throttle bell crank.
    Matthew Wendt

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    Thanks for weighing in, Mathew! Just saw your car on Bob Johnstone’s registery...nice! Was it black from the factory?
    Will you please consider posting some engine compartment pics showing the shielding you described? The bell-crank clearance is my main concern.

    Gunslinger: your observation that GM just sold crate engines that wouldn’t necessasarily include intended car installation is logical, especially if the buyer was a single-engine customer like a repair garage or hot-rodder.

    However, I wonder if Avanti Motors had sufficient volume purchasing power to specify the shielding used by that other fiberglass American sports car?

    Heres some pics of ‘66 factory wire routing without the shielding:F5A5CC8B-7837-47C1-B97E-C0A78A32DD7B.jpg41BEF691-493D-4340-B6EE-66D5AB421956.jpg

    Other Avanti II owners: is this what your car has?

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    Oops, my bad...the pics are of a ‘64. But you get the general idea.

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    My understanding, most likely based on something I read somewhere, is that motors were purchased in batches such as 50 or 100 at a time, in order to get the best pricing. If they were known to be eventual Corvette recipients, then the shielding may have been included. I emphasize that my original shielding does not look like these pics. My car is RQA 0332 and was a virgin when I purchased it so the shielding was original to the 1970 model year.
    Bill

  16. #16
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    Hi Bill

    That sounds logical.
    So your car would most likely be a 350
    with an HEI distributor (integrated coil), which would probably look like this 1970 ‘Vette:
    95290D78-1B15-4E4D-9AB8-B752B8F2385B.jpg

  17. #17
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    Quote Originally Posted by Buzzard View Post
    ......when I purchased it so the shielding was original to the 1970 model year.
    Bill
    Can you put up a picture?
    64 GT Hawk (K7)
    1970 Avanti (R3)

  18. #18
    President Member Gunslinger's Avatar
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    HEI wasn't introduced by GM until 1975. In 1970 in at least the new RQ-B series, a GM Capacitive Discharge transistorized ignition was made standard. The distributor externally looked the same but had no points inside. The Capacitive Discharge control box was mounted on the passenger side fender apron and used a standard appearing coil matched to the system. My '70 Avanti came with it and company promotional materials listed it as standard. Whether my '70 came with shielding I can't say as there was none when I first purchased the car but I doubt if it did. I've never seen an original Avanti from that period that had shielding and no company ad photos I've seen show it. If it did I would think the company would list it in promotional brochures as a standard item.

    It's always possible any particular car suffered RFI noise in the radio (especially if the radio was AM only) and the shielding was installed as a remedy.
    Poet...Mystic...Soldier of Fortune. As always...self-absorbed, adversarial, cocky and in general a malcontent.

  19. #19
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    Mine is a '70 so Delco Points and condenser originally. I used the High RPM points made for the Corvette by Standard Ignition. Gunslinger, it was a 300 HP 350 but no Capacitive Discharge unit.
    When I can get out to the shop I'll see if I have anything of interest for pics but right now I have the motor out ready to drop back in with two 4 BBL's and a Doug Nash 5 speed (tells you how long ago I started this project).
    I''l try for the shielding if I can lay my hands on it.
    Luck,
    Bill

  20. #20
    President Member Gunslinger's Avatar
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    Repop shielding is available from Corvette restoration vendors...Zips Corvette, Corvette Central, Corvette America and Ecklers should all carry it.
    Poet...Mystic...Soldier of Fortune. As always...self-absorbed, adversarial, cocky and in general a malcontent.

  21. #21
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    I had a '75 400 c.i. Avanti II that had shielding.

  22. #22
    President Member TWChamp's Avatar
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    I toured the late Virgil Marple huge Studebaker collection today, and took a couple Avanti ignition shield pictures for you. The Avanti parked next to this one had the identical shielding. This is the largest Avanti collection I've ever seen. It's no wonder you seldom see an Avanti around.........They are all in these buildings.

    007.jpg 008.jpg

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    Tom,
    Thanks for posting pics but I believe we are trying to sort out the OEM shielding on Corvette motors in Avanti II's. From memory, I think my 350 shielding looks more like the Studbaker set up you have shown.
    Bill

  24. #24
    President Member Gunslinger's Avatar
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    The shielding box around the distributor and coil Chevrolet used on big block engines looks closest to the Studebaker shielding box but Chevy didn't use shields for big block spark plug wires...they instead used spark plug wires wrapped in coiled metal sleeve around each wire. The small block Corvettes used a different appearing shielding. If Avanti Motors installed shielding from the factory they may have used something other than Corvette small block shielding...maybe leftover Studebaker Avanti shielding since they already had them in inventory. Adding different brackets to mount them probably wasn't too difficult to fabricate.

    Corvette small block spark plug wires may also have been different for an Avanti as for the Corvette they were routed through the engine mounts.
    Poet...Mystic...Soldier of Fortune. As always...self-absorbed, adversarial, cocky and in general a malcontent.

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