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500, 472, 425, 368 Discussion, 500 V864 - is this even theoretically possible? in Cadillac Engine Technical Discussion; i posted that message before i saw what CLAY88 did with his adapter plate. i dont have enough privlages to ...
  1. #31
    eldrewado is offline Cadillac Owners Member
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    Re: 500 V864 - is this even theoretically possible?

    i posted that message before i saw what CLAY88 did with his adapter plate. i dont have enough privlages to send private messages yet. if you see this CLAY88 please tell me if you think 1970 AIR heads from an eldo could be used. i will try to find some pictures of some if u need them
    Also does anyone know if anything was done to address the fact that if the valves are deactivated right before the spark plug fires the mixture will ignite and not escape(ouch) or did the computer deactivate the hei for a split second or some other thing to counteract this or does it not matter if this happens? any input greatly appriceated.

  2. #32
    davesdeville's Avatar
    davesdeville is offline Banned
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    Re: 500 V864 - is this even theoretically possible?

    If that happens it will just be a compression stroke instead of an exhaust stroke and will act as an 'air spring.'

  3. #33
    eldrewado is offline Cadillac Owners Member
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    Re: 500 V864 - is this even theoretically possible?

    yeah ur right, i wasnt thinking about it right thanks also i found out there was no AIR in 1970-68 so i wont worry about it. but im still interested in the adapter plate. i havnt been able to find one online yet

  4. #34
    eldrewado is offline Cadillac Owners Member
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    Re: 500 V864 - is this even theoretically possible?

    alright everyone. I am going to do install 368 heads on my eldo 500 to achieve the 4 cylinder mode. because as of now the adapter plate is still a prototype and i got the heads cheap.

    to get the right compression, i am going to use multiple gaskets that will have a sparse layer of jb weld between them. if necissary i will make extra thick intake gaskets out of cork. it wont perform extremely well but i might just have the same power i started with because i have 120 cc heads @8.5:1 compression and even with my many gaskets i will have a gitch over 10:1. so althought ill have smaller intake and exhaust, ill have more compression.

    anyway on the 368 heads there are these spacers between the spark plugs and the heads. they make the spark plugs stick out alot. u cant see the terminal from inside the champer just a hole in the funky spacer thing. Does anyone know what these are? for some reason the 81 engine was Inundated with sludge, any one know about that either?

  5. #35
    Ted in Olympia is offline Banned
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    Re: 500 V864 - is this even theoretically possible?

    What cc do 368 heads have?

    I think it will ping like crazy with double head gaskets.

    TED

  6. #36
    eldrewado is offline Cadillac Owners Member
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    Re: 500 V864 - is this even theoretically possible?

    368 heads have 66 cc heads 68-70 500 heads have 76 cc heads im seeing how much a machine shop will charge to make the valve tgrain adapter if they want more than i got im gonna use the 368 heads i just want it so that i can use 93 octane (or less, haha)
    no one knows about the funky spark plug spacers?

  7. #37
    Ted in Olympia is offline Banned
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    Re: 500 V864 - is this even theoretically possible?

    66cc wow! This is going to be hard to run on any pump gas and if you use double gaskets the quench will be terrible.

    The 68-73 engines had the 76cc heads. I would think if you want to do this, and I think you put a lot of thought into it, it would be best to start with a 71-73 500 engine with 76cc heads and 8.5 to one compression. Or you can get these pistons for your engine.

    I have not seen 368 heads but I heard the ports are very small. If you get a chance to cc the intake and exhaust ports it would be interesting.

    For the 500 with 120cc heads the intake 184cc and the exhaust 120cc

    TED

  8. #38
    eldrewado is offline Cadillac Owners Member
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    Re: 500 V864 - is this even theoretically possible?

    as far as i knew the 76cc heads are from 68 to 70, and are 10 to 1 compression im told that ihave the 120s that the motor came with. any way i was wondering about the quench. that is a good point. but until i know it wont work, i still am tempted to try it because i asked a couple machine shops how much adapting the valvetrain with a plate (like clay 88 is trying to do) would cost, 500 bucks or more. the cost of trying the heads is 115 bucks. unless someone thinks it will explode or something as far as i know if it dosnt work it will make bad noises and run bad mabey pop a gasket but will this damage anything other than the heads? which are expendable

  9. #39
    davesdeville's Avatar
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    Re: 500 V864 - is this even theoretically possible?

    If the quench is bad it will knock and could trash the whole motor essentially. If you had an older motor that came with 76cc heads (68-73, ted is right) then you could try the 66cc heads on premium pump gas. If you have a 74-76 motor with 120/126cc heads you better try running E85 or straight alcohol (which means carb work) or it will pop.

  10. #40
    Ted in Olympia is offline Banned
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    Re: 500 V864 - is this even theoretically possible?

    The 71-73 came with 76cc heads but had a large dish in the piston to bring the compression down to 8.5. So if you started here you would be safe with pump gas. I have a couple of 71 to 73 engines around here if you were in the Northwest.

    TED

  11. #41
    eldrewado is offline Cadillac Owners Member
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    Re: 500 V864 - is this even theoretically possible?

    HAA! thats great. now knowing that i looked up what the dish was in ccsfor 71-73, its 47ccs. plugging in this new information into an online compression calculator means the compression from the 66 cc heads gives me9.3 to 1 compression. well within a safe range and i dont have to use more than one gasket. i wondered why it was being so hard... thanks for your help it makes more sense now guys

    although i am confused about one thing thats a side issue.... if i have 8.7 compression why does the sticker say to use 91 fuel? it used to be my grandfathers car he says he used to put cheaper stuff in and it was ok but i was afraid to try it. no i wont be leaving texas for awhile yet

  12. #42
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    Brother_B is offline Cadillac Owners Fanatic
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    Re: 500 V864 - is this even theoretically possible?

    Quote Originally Posted by eldrewado View Post
    no one knows about the funky spark plug spacers?
    This discussion is way over my head, but the first thing I thought of was anti-fouling spacers. I guess they help by sparking outside the compression chamber? I think I read about them when researching engine knock.

  13. #43
    eldrewado is offline Cadillac Owners Member
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    Re: 500 V864 - is this even theoretically possible?

    ok guys the head and exhaust gastkets will be here in a couple days and that weekend i will install the 368 heads and deactivation hardware. and then.....well see

  14. #44
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    Re: 500 V864 - is this even theoretically possible?

    Keep us posted.

  15. #45
    big block fiero is offline Cadillac Owners Member
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    Re: 500 V864 - is this even theoretically possible?

    I have tried this deactivation concept on my 500 powered fiero.what happened was my engine is built with .519 lift. The 8/6/4 rockers have a shutter that locks out the movement of the pivotal axis on the rocker arms. That shutter from locked to unlocked allows a pivotal axis varience of only about 1/4". to make this work with the 1.6 ratio rocker i would have to limit my valve lift to about .380 wich would trash my total horsepower production.

    so to keep it simple I cut the throttle shaft on my two barrel throttle body.I shut off four injectors to one plane of the dual plane manifold then open just one barrel of the throttle body.

    displacement on demand as done recently by the carmakers does so by changing oil pressure at the lifter. these lifters allow proper funtion with a greater amount of valve lift. if you were to try a cam with more lift this system would malfuntion as well.

    Your lift will allways be governed by the design of the deactivator travel.If you try to get to much out of it the valves wont shut to create the air spring.At that point you may as well do what i did wich may not offer the fuel savings you were expecting. Mine also has purpose for the car to sound like it has a four cylinder motor because my 500 caddy motor is concealed and the car looks stock.

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