84 cadi deville
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  • 1 Post By lacville78
  • 1 Post By carnut
RWD 19xx-1984 DeVille and Fleetwood,
1985-1996 Fleetwood and Brougham Forum Discussion, 84 cadi deville in Past Cadillac Vehicle Discussion; Hi I have an 84 cadi deville with a HT4100 v8 4.1 its making a constant popping noise to the ...
  1. #1
    BigDromerO is offline Cadillac Owners Member
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    84 cadi deville

    Hi I have an 84 cadi deville with a HT4100 v8 4.1 its making a constant popping noise to the throttle body please help

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  3. #2
    jayoldschool's Avatar
    jayoldschool is offline GM RWD V8 addict
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    Re: 84 cadi deville

    I know you said "constant", but I think we're going to need more info. In park, idle? Revving it? In drive, idle? All gears? Acceleration? Cruise? No load? Load? Deceleration? AC on? Off?

  4. #3
    lacville78 is offline Cadillac Owners Fanatic
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    Re: 84 cadi deville

    You've come to the right place! Maybe pop the hood and get a video of under the hood. Then upload the video to Youtube and get us a link. That should help provide the info needed to solve your problem.
    nebulosity likes this.

  5. #4
    csbuckn is online now Cadillac Owners Master
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    Could it be anything else besides timing that would cause backfiring?

  6. #5
    BigDromerO is offline Cadillac Owners Member
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    Jayoldschool. Its all the above. It pops louder when you hit the accelerator. in Park in drive in neutral it still makes a constant popping through the throttle body can't figure it out done timeing done spark plugs wires done distributor cap. still the same thing

  7. #6
    csbuckn is online now Cadillac Owners Master
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    Wire routing?

  8. #7
    BigDromerO is offline Cadillac Owners Member
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    I got the wiring diagram and they're all correct

  9. #8
    carnut is offline Cadillac Owners Master
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    Re: 84 cadi deville

    Flat cam shaft. Put it in gear and hold the brake pedal down hard and apply throttle little and hold it awhile. If it pops thru the top of the throttle body, its a flat camshaft.
    The Ape Man likes this.

  10. #9
    talismandave's Avatar
    talismandave is offline Cadillac Owners Master
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    Re: 84 cadi deville

    Quote Originally Posted by carnut View Post
    Flat cam shaft. Put it in gear and hold the brake pedal down hard and apply throttle little and hold it awhile. If it pops thru the top of the throttle body, its a flat camshaft.
    That takes me back to the 80s appraising trade ins. That was standard operation on Chevy 305s. they had a bad run for a while.

  11. #10
    carnut is offline Cadillac Owners Master
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    Re: 84 cadi deville

    To further confirm a flat cam, remove drivers side valve cover and start the engine, if flat you will see a noticeable difference in rocker arm movement. The flat lobe will cause very little pivoting of the rocker. In most cases the cam went flat because of coolant that leaked into the lifter valley and washed the oil off the cam. That washing usually damaged the crank bearings as well. In most cases an engine replacement is in the near future!

  12. #11
    BigDromerO is offline Cadillac Owners Member
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    Damn! I was hopeing it would be an easy fix. Well thank u guys for all ur help. Looks like im lookin for a motor

  13. #12
    cadillac kevin's Avatar
    cadillac kevin is offline Cadillac Owners Master
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    Re: 84 cadi deville

    Quote Originally Posted by BigDromerO View Post
    Damn! I was hopeing it would be an easy fix. Well thank u guys for all ur help. Looks like im lookin for a motor
    don't put in another 4100....go for an olds or chevy V8 (would allow you to keep the transmission, although you'd have to change the driveshaft for the proper one (or get yours lengthened/ shortened).

  14. #13
    BigDromerO is offline Cadillac Owners Member
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    what would be the easiest swap to do

  15. #14
    85 FLEETWOOD COUPE's Avatar
    85 FLEETWOOD COUPE is offline Cadillac Owners Fanatic
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    Re: 84 cadi deville

    I want to say its one of the camshaft lobes worn down,happend to me

  16. #15
    cadillac kevin's Avatar
    cadillac kevin is offline Cadillac Owners Master
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    Re: 84 cadi deville

    Quote Originally Posted by BigDromerO View Post
    what would be the easiest swap to do
    olds 307 (available in pretty much every early 80s- 1990 RWD buick, olds, and pontiac) /350 (available until 1981? in RWD oldsmobiles)

    chevy 350- available in everyhting from trucks/ vans to caprices

    both would allow you to keep the trans.

    getting a brougham with the drievtrain you want would be easiest (have all the parts you'd need for the swap) and get you a

    an olds 307 or 350 would be cheaper probably (alot of cars with those motors still floating around and the driveshaft for it can be sourced from the junkyard. you will need the computer and carb if you decide to keep the CCC system (else you will need a new carb and distributor)

    a chevy 350 would give you more power at the expense of possibly shortening the life of the transmission. your driveshaft would need to be shortened most likely (cost me about 150 to have mine shortened, balanced, and painted). if you go with a 1987-95 engine (serpentine setup), you can use the AC lines from the 1991-92 brougham. you will need to either get an inline fuel pump for the TBI unit or go carbuerated (check to make sure that there is a hole behind the plate on the pass side of the block down low for the fuel pump if you want to go carb'ed)

    All in all, I'd expect to spend 2k-2500 from start to finish given someone else does the labor. subtract whatever you get for the donor car/ truck in parts/ scrap

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