PotM GrandMarq.NET - Panther Headquarters Forum Index PotM
GMN Chat Room GMN's STORE!! GMN's Gallery Please!!
Page 1 of 2 12 LastLast
Results 1 to 20 of 28

Thread: CFI and dual exhaust-will it run too lean?

  1. #1

    Default CFI and dual exhaust-will it run too lean?

    I want to run dual exhaust on my 85 Grand Marquis, but I thought I remember reading somewhere that there were issues with lean conditions after that. So who has done it successfully? And would you relate your experiences please?

  2. #2
    Domestic Tourist Lincolnmania's Avatar
    Join Date
    Sep 2004
    Location
    Birdsboro PA.
    Posts
    17,526

    Default

    it will work fine as long as you keep the cast iron manifolds or you use 90 town car manifolds or stock mustang shorty headers.
    2" would be the best size for a stock engine

    1986 lincoln towncar signature series. 5.0 HO with thumper performance ported e7 heads, 1.7 roller rockers, warm air intake, 65mm throttle body, 1/2" intake spacer, ported intakes, 3.73 rear with trac lock, 98-02 front brake conversion, 92-97 rear disc conversion, 1" rear swaybar, 1 3/16" front swaybar, 16" wheels and tires, loud ass stereo system, badass cb, best time to date 15.94 at 87 mph. lots of mods in the works 221.8 rwhp 278 rwt
    2006 Lincoln Town Car Signature. Stock for now
    1989 Ford F-250 4x4 much much more to come, sefi converted so far.
    1986 Toyota pickup with LSC wheels and 225/60/16 tires.
    2008 Hyundai Elantra future Revcon toad
    1987 TriBurner and 1986 Alaska stokers keeping me warm. (and some pesky oil heat)

    please be patient, rebuilding an empire!


  3. #3

    Default

    I am for sure keeping the manifolds. Do you think the fuel pressure regulator will need adjusted?

  4. #4
    Beater gonna beat sly's Avatar
    Join Date
    Mar 2010
    Location
    Lewisville, TX
    Posts
    21,751

    Default

    Nothing will need adjusting if you're not changing the headers. The computer should be able to compensate for dual exaust without issue. If you're doing a cat-back setup (remove the Y pipe, put in H-pipe and driver side muffler/tail)... then you're fine without any tuning.

    Only two things are infinite, the universe and human stupidity, and I'm not sure about the former. -- Albert Einstein
    rides: 93 Crown Vic LX (The Red Velvet Cake), 2000 Crown Vic base model (Sandy), 2003 Expedition (the vacation beast)
    Quote Originally Posted by gadget73
    ... and it should all work like magic and unicorns and stuff.
    Quote Originally Posted by dmccaig
    Overhead, some poor bastards are flying in airplanes.

  5. #5
    Member
    Join Date
    Oct 2008
    Location
    St. Louis, MO
    Posts
    619

    Default

    My '84 CV was converted to duals way back in the late 80's by my Dad and it remains like that today with over 400K on it. Stock exhaust manifolds/pipes used. No issues, so go for it.
    These are highly engineered precision vehicles, the first step in diagnosing the problem is to strike the suspected offending part sharply and repeatedly with a blunt object, then re-test.

  6. #6

    Default

    Cool beans! So I can still get the OE walker tail pipes on Ebay. Does anyone know the part number for the original Walker H-pipe? It shows it in their catalog, but I think it is obsolete; because there is no current part number.

  7. #7
    GMN Regular DerekTheGreat's Avatar
    Join Date
    Sep 2014
    Location
    Warren, MI
    Posts
    6,011

    Default

    Like others have said, it'll be fine. Dual exhaust was an option from the factory. I put duals on my '85 CFI car and it was fine, not to mention someone deleted the cats before I bought it.
    1985 LTD Crown Victoria - SOLD
    1988 Town Car Signature - Current Party Barge

  8. #8
    Wagon Addicted Tiggie's Avatar
    Join Date
    Mar 2006
    Location
    Bedford, VA
    Posts
    5,807

    Default

    You can use a newer 92-94 H-pipe no problems.

  9. #9
    Fastest Box In South Jersey 86VickyLX's Avatar
    Join Date
    Jan 2007
    Location
    Westmont, New Jersey
    Posts
    10,380

    Default

    The ECM doesn't care what you're running past the O2 sensors.

  10. #10
    I'm an air-conditioned gypsy gadget73's Avatar
    Join Date
    Jan 2005
    Posts
    39,550

    Default

    the heads and intake can't move enough extra air for dual exhaust to make it run lean anyway.

    86 Lincoln Town Car (Galactica).
    5.0 HO, CompCams XE258,Scorpion 1.72 roller rockers, 3.55 K code rear, tow package, BHPerformance ported E7 heads, Tmoss Explorer intake, 65mm throttle body, Hedman 1 5/8" headers, 2.5" dual exhaust, ASP underdrive pulley

    91 Lincoln Mark VII LSC SE, triple black (Timewarp) - poly front bushings, KYB struts and shocks, Holley SystemMax1 lower intake, SilverFox AOD valve body,

    1984 Lincoln Continental TurboDiesel - rolls coal

    Quote Originally Posted by phayzer5 View Post
    I drive a Lincoln. I can't be bothered to shift like the peasants and rabble rousers

  11. #11
    all the CFI are belong to me
    Join Date
    Feb 2014
    Location
    Windsor, ON
    Posts
    1,839

    Default

    Quote Originally Posted by 86VickyLX View Post
    The ECM doesn't care what you're running past the O2 sensors.
    Kinda sorta...it has long been rumoured/reported that EEC-IV CFI throws a lean code after dramatically improving exhaust flow, after the heads.

    There are all sorts of reasons why that might happen and they basically all come back to a design that doesn't scale well, and that's kind of whatever.

    I never did check mine for codes after going dual...

    OP: the correct direct-fit H pipe is a Walker 40483. It is kind of hard to find now, but RockAuto just started indicating they can get it again, with a delay, which probably means it's built to order by Walker. The price isn't pretty compared to what they used to be, either. The box Lincoln one is 40492 - it's longer because the Lincolns are longer. It won't fit at the muffler end without some hackery, but depending on what you're running for mufflers, it might be easy to make fit.

    Reports that you can use an Aero H-pipe are something I tried to figure out some time back and the answer looked like it was probably no, because the exit pipes on the cats were not positioned quite right. I'd love to know with 100% certainty that they'll fit if that's the case.
    Last edited by kishy; 12-23-2019 at 12:53 PM.

    83 GM 2dr POTM 10/2019 | 84 TC POTM 1/2017 & 4/2019 | 85 CS | 85 Ranger +trlr | 86 GM | 91 GM POTM 12/2017 | Junkyards
    Gone: 97CV | 83 TC

  12. #12

    Default

    Thank you for that info and the part number! After doing a bit of research, I learned that AP Exhaust still makes an h-pipe for it. Their part number is 93950. Has anyone used this kit? https://www.macautoparts.net/80-88-f...st-super-turbo

  13. #13

    Default

    The kit looks like exactly what I wanted to do, but it seems a little pricey. I am tempted though. It would be nice to just put it together in my own shop.

  14. #14

    Default

    As long as your existing muffler and tail pipe are in good condition you could always buy just the h pipe, muffler and drivers side tail pipe and save some money. The only issue youíll run into is finding a way to hang the tail pipe on the drivers side. The original part is long since discontinued and even the alternate bracket with the hook and rubber hanger has been out of production for years. Now if you took it to a shop they could fab something up no problem.


    Sent from my iPhone using Tapatalk

  15. #15

    Default

    I think I am going to just have to take it to a muffler shop anyway. I finally crawled under it and looked around. Someone cut off the factory flanges behind the cats and welded up a new y pipe, so just bolting up the oe duals is out of the question. Does anyone know if I can remove the cats without any ill affects? I wouldn't normally do this, but the air tube coming from the air pump is rusted off at the cat. I wouldn't mind just getting rid of the whole air system and the cats if I could. I thought I had read somewhere that if you had a one-wire non-heated oxygen sensor, removing the cats would make it fail to work correctly because of the lack of heat. Anyone know?

  16. #16

    Default

    Thats not true, the o2 sensor is located before the cats so that would have no effect. The air system is about emissions thats it.

    You know funny enough my 85 ltd had the flanges cut off and welded too.


    Sent from my iPhone using Tapatalk

  17. #17
    Road Warrior Kodachrome Wolf's Avatar
    Join Date
    Nov 2014
    Location
    Evans, GA
    Posts
    1,637

    Default

    You can remove the converters without issue. The non-heated O2 sensor will certainly still heat up with the heat being generated.

    Personally I like having converters mostly due to the smell of un-catted exhaust. You can get away with just capping or welding the tubes shut. I have converters but no Thermactor system since the system was generally inop when I got my car. The smog pump can be removed with a shorter belt run if you desire to keep the A/C (or just don’t have any belt if you’re not fixing/deleting the A/C) and the piping can be removed outright. Just cap off the white and black vacuum lines that run to the solenoids.

    If the CFI cars are similar to the SEFI cars, there’s a smog pipe at the back of the head with a check valve where the Thermactor hoses attach to. You can just leave that alone unless you don’t like looking at it, then you’ll need to block the ports on the back of the heads.

    The only thing I remember being different on CFI cars was the existence of some heat riser or valve on one of the exhaust manifolds? I forget to what extent and purpose its job was.

    My Cars:
    -1987 Grand Marquis Colony Park LS (325K Miles) - April 2017 + September 2019 POTM Winner
    -1989 Sable LS Wagon (88,710 Miles) - Sold
    -1997 Grand Marquis LS (210K Miles) - The Daily Workhorse & March 2015 + January 2019 POTM Winner

  18. #18

    Default

    Its been a while since I had my 85 but I donít remember it having a crossover to the back of the heads but it still had a diverter valve so maybe it was just set up differently.

    As far as the heat riser goes I believe it was there to heat up the intake charge to shorten warmup time but I could be wrong. My 85 had a broken one so I threw it away and didnít have an issue. Plus the valve didnít work anyway so the heated air was funneled into the air cleaner anyway.


    Sent from my iPhone using Tapatalk

  19. #19

    Default

    If I can just get away with capping them, then that would be fine. I always thought the Thermactor system was to keep the cats from plugging up. I do not want to unnecessarily pollute if I don't have to.

  20. #20
    Road Warrior Kodachrome Wolf's Avatar
    Join Date
    Nov 2014
    Location
    Evans, GA
    Posts
    1,637

    Default

    The Thermactor system was designed to primarily heat up the converters faster to get them doing their thing faster. There’s a few members here running around with original style converters and no air system.

    My Cars:
    -1987 Grand Marquis Colony Park LS (325K Miles) - April 2017 + September 2019 POTM Winner
    -1989 Sable LS Wagon (88,710 Miles) - Sold
    -1997 Grand Marquis LS (210K Miles) - The Daily Workhorse & March 2015 + January 2019 POTM Winner

Page 1 of 2 12 LastLast

Posting Permissions

  • You may not post new threads
  • You may not post replies
  • You may not post attachments
  • You may not edit your posts
  •  
GMN Approved Links!


www.rockauto.com www.adtr.net