Failed the dollar bill test
Cadillac
 

Cadillac Forums | Help Us Help You | Advertise | Cadillac Parts | Cadillac News | Cadillac Classifieds / (Old System)

Cadillac Technical Archive | Cadillac Dealers | Cadillac Reviews | Cadillac Dealer Reviews | Cadillac Vendors

CadillacForums.com is the premier Cadillac Forum on the internet. Registered Users do not see the above ads.
+ Reply to Thread
Results 1 to 4 of 4
500, 472, 425, 368 Discussion, Failed the dollar bill test in Cadillac Engine Technical Discussion; As if "failed the dollar bill test" doesn't say it all, tell me if you guys agree with the diagnosis: ...
  1. #1
    man1ey's Avatar
    man1ey is offline Cadillac Owners Member
    Automobile(s): 1968 Deville Convertible
    Join Date
    Aug 2005
    Posts
    21

    Question Failed the dollar bill test

    As if "failed the dollar bill test" doesn't say it all, tell me if you guys agree with the diagnosis:

    Problem: rough intermittent idle, doesn't seem to be tied to one cylinder. Idle wobbles around by about 50 rpm but there's no pattern to it, backfires softly through exhaust with a lot of throttle or when coasting downhill, strong unburned gas odor.

    1968 472, 59k original miles, stock except for dual exhaust and MSD 5 ignition I inherited with the car. (Original ignition cannot be restored - I spent a week trying and it's not happy).

    New in last week: reman distributor, cap, rotor, points, wires, plugs, coil, reman Q-jet, fuel pump, fuel filter.

    Timing 5 deg at 550 w/ transmission in drive, vacuum advance plugged. Dwell dead-on 30 deg but apparently it doesn't matter per MSD tech support - points just act as a low-voltage trigger for the MSD box and box controls dwell.

    A vacuum gauge on the intake flutters rapidly over a range of 1.5 in Hg. No matter where the throttle is, it's always fluttering. It also fluctuates slowly at idle between about 15 and 20 in Hg, fluttering the whole time.

    Plugs look good on all cylinders, tan insulator, not wet, not sooty. Then again, I put about 30 highway miles on it just before I pulled them so it could have burned off something.

    Compression test with all plugs out:
    PASSENGER
    1 160
    3 134
    5 149
    7 162

    DRIVER
    2 156
    4 154
    6 156
    8 145

    Fails the dollar bill to the tailpipe test on the pass side - sucks the bill up about once per second or so. On the driver's side no suction. That makes me think it's valves on the pass side as opposed to slack timing chain, but starter has a tough time the first few revs even with timing correctly set, so I'm wondering if chain isn't slack or jumped too.

    I'm about to pull the heads and send them off, but would you guys try anything else first?

    Thanks,
    Mike

  2. Remove Advertisements
    CadillacForums.com
    Advertisements
     

  3. #2
    Katshot's Avatar
    Katshot is offline Cadillac Owners Master
    Join Date
    Jan 2003
    Location
    Newtown, PA
    Age
    55
    Posts
    6,472

    Re: Failed the dollar bill test

    I would think a tight valve guide or weak valve spring might cause your problem. Have you installed a vacuum gauge on it yet? Does the guage fluctuate?

  4. #3
    man1ey's Avatar
    man1ey is offline Cadillac Owners Member
    Automobile(s): 1968 Deville Convertible
    Join Date
    Aug 2005
    Posts
    21

    Re: Failed the dollar bill test

    Katshot, thanks for reminding me. I did try this a couple of weeks ago and forgot about the result.

    A vacuum gauge on the intake flutters rapidly over a range of 1.5 in Hg. No matter where the throttle is, it's always fluttering. It also fluctuates slowly at idle between about 15 and 20 in Hg, fluttering the whole time. What do you think?

    Mike

  5. #4
    Katshot's Avatar
    Katshot is offline Cadillac Owners Master
    Join Date
    Jan 2003
    Location
    Newtown, PA
    Age
    55
    Posts
    6,472

    Re: Failed the dollar bill test

    I'd suggest that a valve job would most likely cure your ills.

Quick Reply Quick Reply

Register Now

Please enter the name by which you would like to log-in and be known on this site.
If you do not want to register, fill this field only and the name will be used as user name for your post.

Please enter a password for your user account. Note that passwords are case-sensitive.

Please enter a valid email address for yourself.

Log-in

Human Verification

In order to verify that you are a human and not a spam bot, please enter the answer into the following box below based on the instructions contained in the graphic.



Bookmarks

Cadillac Posting Rules

  • You may post new threads
  • You may post replies
  • You may not post attachments
  • You may not edit your posts
Read about Lincoln | Buick | Kia Forte Forum
Need products for your Cadillac? Check out your options at the links below:

custom floor mats | Cadillac Chrome and Black Chrome Wheels | window tinting