1978 seville
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
5.0 and 5.7 Discussion, 1978 seville in Cadillac Engine Technical Discussion; Hi I have a 78 seville with the 350ci olds fuel injection engine. I would like to replace the single ...
  1. #1
    coatongo is offline Cadillac Owners Member
    Automobile(s): 1978 Seville sedan
    Join Date
    Apr 2010
    Age
    58
    Posts
    3

    Cool 1978 seville

    Hi I have a 78 seville with the 350ci olds fuel injection engine. I would like to replace the single exit exhaust with a dual one. does anyone know which Olds model I could use the manifolds from to get rid of the cross over pipe from left to right manifold?

    Thanks

  2. Remove Advertisements
    CadillacForums.com
    Advertisements
     

  3. #2
    lovemycadillac's Avatar
    lovemycadillac is offline Cadillac Owners Member
    Automobile(s): 1988 Superior Hearse, 1990 Sedan deVille, 2001 ESC
    Join Date
    Oct 2008
    Location
    Water Winter Wonderland
    Posts
    40

    Re: 1978 seville

    I once had a 1979 Oldsmobile Ninety Eight that I put duals on. It had the 350 Olds R code engine, and was not fuel injected. The shop that I had put the pipes on plugged one of the outlets on the passenger side exhaust manifold to eliminate the need to change to a new manifold.

    I don't know if your fuel injected engine is like this, but mine had a positive back pressure EGR valve, which means that back pressure is required along with vacuum for the valve to work properly.

    The car ran and sounded great with the duals, but the EGR valve did not operate because the back pressure was very low. It ran hot, smelled hot, and there was lots of spark knock. I had no idea about the EGR valve and spent lots of time trying to figure out what the problem was.

    I eventually figured out what the problem was, and put on a universal EGR valve that was adjustable, and did not require back pressure to operate. The car still never ran as good as it did when the original exhaust system was on there.

    I'm not trying to discourage you from wanting to put duals on, but maybe my experience will prevent some frustration on your part if you are able to check out the EGR first.

  4. #3
    cadillac_al is offline Cadillac Owners Connoisseur
    Automobile(s): Cadillac 78 Seville, 78 Coupe de Ville, 92 Sedan de Ville
    Join Date
    Feb 2007
    Location
    Maine
    Age
    53
    Posts
    2,779

    Re: 1978 seville

    Hey Seville brother, There was a block off plate made for that manifold but I'm quite sure it has to be discontinued now. They were used on the 79 Seville and Chevy pickups with the Olds diesel engine. Most muffler shops can block it off their own way. You could also run a transverse muffler from a Camaro Z28 and it will give you two tailpipes to balance the rear of the car. I've never heard of that positive back pressure EGR stuff but I never ran EGR on any of my 70's cars. I'm positive Cadillac didn't change the EGR or computer on the 79 Seville to accommodate the duals.

  5. #4
    coatongo is offline Cadillac Owners Member
    Automobile(s): 1978 Seville sedan
    Join Date
    Apr 2010
    Age
    58
    Posts
    3
    Thread Starter

    Thumbs up Re: 1978 seville

    Thanks to both you guys for your help! i now have a couple of options for my pipes.
    pete

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