472/500 exhaust manifolds on a 425
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 7 of 7
500, 472, 425, 368 Discussion, 472/500 exhaust manifolds on a 425 in Cadillac Engine Technical Discussion; So I know the 425 exhaust manifolds are restrictive, while the 472/500 aren't anything for performance, they do flow better, ...
  1. #1
    Night Wolf's Avatar
    Night Wolf is offline Cadillac Owners 10000+ Posts
    Automobile(s): Unicycle
    Join Date
    Mar 2003
    Location
    Where I park it
    Posts
    11,009

    472/500 exhaust manifolds on a 425

    So I know the 425 exhaust manifolds are restrictive, while the 472/500 aren't anything for performance, they do flow better, I was wondering if the exhaust manifolds would bolt right up and have no issues running them in the '79 DeVille chassis.

  2. Remove Advertisements
    CadillacForums.com
    Advertisements
     

  3. #2
    davesdeville's Avatar
    davesdeville is offline Banned
    Automobile(s): 1995 ETC, 75 Deville, Cad500 powered 73 Apollo, 94 Mark VIII
    Join Date
    Aug 2003
    Location
    Albuquerque, NM
    Age
    27
    Posts
    7,971

    Re: 472/500 exhaust manifolds on a 425

    IIRC they'll work but you'll need to cut some excess thread off of some bolt that's in the way. I don't know if I'd even bother though, since the stock manifolds suck and since it's not too hard or expensive to do headers.

  4. #3
    Night Wolf's Avatar
    Night Wolf is offline Cadillac Owners 10000+ Posts
    Automobile(s): Unicycle
    Join Date
    Mar 2003
    Location
    Where I park it
    Posts
    11,009
    Thread Starter

    Re: 472/500 exhaust manifolds on a 425

    well, i heard they flow alot better then the 425 manifolds....

    I would love to throw headers on there, but there are no after market headers that will fit in the '79 chassis (C-body) so clearance is an issue.

    basically any exhaust work I do (manifolds/dual exhaust) I want to be able to use when I get the 500.... so I wouldn't mind spending the money on a pair of headers for the 425, if they'll bolt to the 500.

  5. #4
    Fleetwood472 is offline Cadillac Owners Fanatic
    Automobile(s): 78 Fleetwood w/ FI 472/ Switch pitch TH400
    Join Date
    Aug 2005
    Posts
    236

    Re: 472/500 exhaust manifolds on a 425

    Hey Nightwolf, yes the manifolds will bolt right up and like davesdeville said the only clearance problem that you will have is on the passenger side in which you need to trim about a half of an inch from one bolt I believe the bolt is part of the suspension setup in the front. It wont affect anything by cutting off part of the bolt. That is what I am going to be doing when I swap in my 472 into my 78 fleetwood. Just be careful when you're swapping manifolds because those bolts manifold bolts snap pretty easy. The best time to pop them off is when the engine is warmed up.
    Good luck - Justin

  6. #5
    Night Wolf's Avatar
    Night Wolf is offline Cadillac Owners 10000+ Posts
    Automobile(s): Unicycle
    Join Date
    Mar 2003
    Location
    Where I park it
    Posts
    11,009
    Thread Starter

    Re: 472/500 exhaust manifolds on a 425

    hmm, in that case I'll have to pick a pair up next time see them... cheap way to get some better flow whenever I get around to getting dual exhaust.

  7. #6
    cadder2000 is offline Cadillac Owners Member
    Automobile(s): 1982 fleetwood w/ 500cid, 1990 Brougham 'D Elegance 5.7
    Join Date
    May 2004
    Location
    Phoenix,AZ
    Age
    37
    Posts
    18

    Re: 472/500 exhaust manifolds on a 425

    I think Al at MtS told me that the 425 manifolds flow the same as the 500's except on the #1 cylinder. I used the 425 manifolds on a 500 swap into an 82 Fleetwood with 2.5 in duals and it seems to flow ok. After I put the engine in I hooked up the stock exhaust for the drive to the muffler shop. I was a little disapointed with the performance. After getting the car back and mashing the pedal it was like a different car. LOTS BETTER. I would rather have headers but I don't know of any drop in replacements. Has anyone tried using some type of headers with caddy flanges and had any success?

  8. #7
    davesdeville's Avatar
    davesdeville is offline Banned
    Automobile(s): 1995 ETC, 75 Deville, Cad500 powered 73 Apollo, 94 Mark VIII
    Join Date
    Aug 2003
    Location
    Albuquerque, NM
    Age
    27
    Posts
    7,971

    Re: 472/500 exhaust manifolds on a 425

    Dunno if it will work with 77+ RWDs, but on my 75 I should be able to use Hooker 2445 (I think that's the part # anyway) BBC headers for 70-72 Monte Carlos, which run $150 for the non-ceramic coated version. Of course using Caddy flanges.

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