Help! My Truck runs like a Drag car!
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 9 of 9
500, 472, 425, 368 Discussion, Help! My Truck runs like a Drag car! in Cadillac Engine Technical Discussion; I just got finished dropping a Cadillac 500 into my 74 Chev 4x4. I got this engine kind of by ...
  1. #1
    Juztyn00 is offline Cadillac Owners Member
    Join Date
    Aug 2005
    Location
    Laramie, WY
    Age
    32
    Posts
    5

    Talking Help! My Truck runs like a Drag car!

    I just got finished dropping a Cadillac 500 into my 74 Chev 4x4. I got this engine kind of by luck but the more i researched it the more i realized it was the perfect motor for my big 3/4 ton 4x4. Well i got it planted in there and it runs pretty good if i were wanting to drag race my truck. unfortunately i want to wheel off road and i need it to idle and go slow with torque. It currently has an surging, loopy idle, it either feels like its about to die or running at 1800 rpm. It also seems to have a miss and vibrates a lot at idle. Might be running on 7 cyl, I'll check the plugs and wires tonight. Currently it has a Holley 750, Holley Digital Ignition System and coil, Pretty sure I got all the vacuum leaks stopped, I have a built TH 350 behind it (just since the TH400 i got with the motor wont fit my t-case) .. This motor is has awesome power and accelleration but i need a smooth low idle for rock crawling. Any Ideas?

  2. Remove Advertisements
    CadillacForums.com
    Advertisements
     

  3. #2
    Juztyn00 is offline Cadillac Owners Member
    Join Date
    Aug 2005
    Location
    Laramie, WY
    Age
    32
    Posts
    5

    Re: Help! My Truck runs like a Drag car!

    Just checked vacuum..... running a steady 12 in at idle... drops to 0 at WOT, and increases to 15 when decellerating.... about a steady 15 at 2000 rpm.. is this normal for a 500 or did the previous owner put a cam in it? I'm thinking power valve in the holley carb is loading it up... Any thoughts?

  4. #3
    Kev's Avatar
    Kev
    Kev is online now Cadillac Owners 10000+ Posts
    Automobile(s): 1989 Sedan DeVille is now just a fond memory ....
    Join Date
    Aug 2004
    Location
    Left Coast (Central)
    Age
    54
    Posts
    10,403

    Re: Help! My Truck runs like a Drag car!

    The 500 is the perfect "Torque Monster" unless someone drops cam in it. How much do you know about the engine? What was it built for? You may have to put in a cam that works for your application. You will want to match a good intake manifold for it then too.

  5. #4
    Kev's Avatar
    Kev
    Kev is online now Cadillac Owners 10000+ Posts
    Automobile(s): 1989 Sedan DeVille is now just a fond memory ....
    Join Date
    Aug 2004
    Location
    Left Coast (Central)
    Age
    54
    Posts
    10,403

    Re: Help! My Truck runs like a Drag car!

    Also, depending on which model Holley 750 you have, you will want to tune it to match cam and intake. There are dozens of variations for most Holleys.

  6. #5
    The Ape Man's Avatar
    The Ape Man is offline Cadillac Owners Connoisseur
    Automobile(s): '80 Fleetwood Coupe, 1994 and 1995 Mercedes 140 Coupe
    Join Date
    Feb 2005
    Location
    Southern NJ
    Age
    51
    Posts
    2,096

    Re: Help! My Truck runs like a Drag car!

    Triple check for a vacuum leak. There are a few spots where the Horriblley might not seal to replace a Rottenchester. Try spraying some carbonater cleaner around to see if the idle rises.

  7. #6
    Kev's Avatar
    Kev
    Kev is online now Cadillac Owners 10000+ Posts
    Automobile(s): 1989 Sedan DeVille is now just a fond memory ....
    Join Date
    Aug 2004
    Location
    Left Coast (Central)
    Age
    54
    Posts
    10,403

    Re: Help! My Truck runs like a Drag car!

    One other thought;
    If you are rock crawling you might find yourself in an angle that causes havoc with the carb. You might want to look into a fuel injection system for it so you don't 'run out of gas' on a 45+ degree angle.

  8. #7
    The Ape Man's Avatar
    The Ape Man is offline Cadillac Owners Connoisseur
    Automobile(s): '80 Fleetwood Coupe, 1994 and 1995 Mercedes 140 Coupe
    Join Date
    Feb 2005
    Location
    Southern NJ
    Age
    51
    Posts
    2,096

    Re: Help! My Truck runs like a Drag car!

    Another place for a vacuum leak would be some of the AC compressor bolt holes. Several go right into the intake ports.

  9. #8
    Juztyn00 is offline Cadillac Owners Member
    Join Date
    Aug 2005
    Location
    Laramie, WY
    Age
    32
    Posts
    5

    Re: Help! My Truck runs like a Drag car!

    Got it fixed! First put new plugs in, looks like in the last car they had it in they coldnt get the #8 cyl changed, Second had a cut in one of the plug wires so i put on an extra i had, third changed carb to an edelbrock 1406 650 cfm that i had rebuilt for my last motor to run the high altitude (i live at 7200 feet). The last really made the difference. Pretty sure the holley needs to be rebuilt since it was running waaaaaay rich no matter what i did. Still pulling only about 14 in of vacuum at idle which still seems a lil low but at least its idling steady at 500 rpm in gear. no hesitation or anything and IT SCORCHES the tires on my 5000 lb truck. I have all the other car guys at WyoTech jeolous of my cubes. I put a single 3 inch exhaust on there that runs real quiet (and considerably more affordable) and still have the 350 tags on my truck. excellent sleeper effect i believe. Since this is a long bed truck with stock suspension its not going to see to many extreme trails so i think the carb will work for the time being. At least til i get the 6 inch lift put on there. Thanks for your help!

  10. #9
    abcdefg is offline Cadillac Owners Member
    Join Date
    Mar 2004
    Posts
    51

    Re: Help! My Truck runs like a Drag car!

    Wouldnt the 500CI be a little harsh on the TH350?

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