355 exhaust valve/GTS top/newbee questions | FerrariChat
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355 exhaust valve/GTS top/newbee questions

Discussion in '348/355' started by FDT, Jan 4, 2011.

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  1. FDT

    FDT Formula Junior

    May 18, 2010
    423
    La
    Full Name:
    Ric
    #1 FDT, Jan 4, 2011
    I really do not want to start any major discussion concerning the rattling valve. I just got my new to me 95 355 GTS off the truck last night so I have a whopping 44 miles on the car. Certainly not enought to form much of an opinion but I have four questions. I searched through various threads but never really got specific answers to my questions.

    1. at what RPM does the exhaust valve open? In my short drive I was not able to hear the F1 shriek difference at high RPMs that I hear on various videos. The car has stock headers and cats but a Tubi exhaust. Visually the valve does not appear to be wired open and does not rattle. Having someone rev the car while I watched the valve it did not move until around 6500 RPM, and then it just kind of jerked. The vacum hose to the diaphram was recently replaced and looks new. How can I tell if it is working properly?

    2. The top creaks a lot........is there any type of lube that may quite the noise?

    3. Are you supposed to be able to see the tops of the cam gears. The cam belt cover leaves about a 1/2 inch gap at the top. The cover appears to be a bit tall, there is even a screw hole at the top not being utilized. This applies to both sides of the engine.

    4. The car is very smooth throughout the RPM range except for one spot between 4k and 5K where I feel some vibration. Is this a normal occurrance or am I looking at some engine mounts?

    The car did undergo a PPI and was cleared.......am I paranoid or just too new to know what I am talking about? Appreciate any advice I can get. Thanks
     
  2. bcwawright

    bcwawright F1 Veteran

    Jul 8, 2006
    5,234
    Georgia
    Full Name:
    Bruce
    #2 bcwawright, Jan 4, 2011
    I'm goin to be very overly simplistic on the exh. valve operation......under normal driving conditions it should be opening somewhere in the lower 4K rpm range.....somewhere at this point it is also changing from closed loop mode to open loop mode in the ecms.

    The 95 variant indicates a shield that covers the opening so you can't see the top cam pulley's...however these could have been taken off by the previous owner or simply left off during the factory engine build when it was new. The newer 355's do not have these and you can see the top of the cam pulleys.
     
  3. FDT

    FDT Formula Junior

    May 18, 2010
    423
    La
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    Ric
    #3 FDT, Jan 4, 2011
    Would the exhaust valve be opening while the vehicle is sitting being revved in nuetral? How can I tell if it is operating properly?
     
  4. Mitch Alsup

    Mitch Alsup F1 Veteran

    Nov 4, 2003
    9,741
    #4 Mitch Alsup, Jan 4, 2011
    WSM says that the valve opens at 2760 RPMs except in 3rd gear where it opens at 4000 RPMs.

    Just exactly how it determines if you are in third gear has not been determined.
     
  5. JSBMD

    JSBMD Formula Junior

    Mar 17, 2007
    453
    The OC
    Full Name:
    John
    #5 JSBMD, Jan 4, 2011
    I have a '98 Berlinetta with Fabspeed headers and high-flow cats, but I imagine our cars' exhaust valves don't operate that differently...

    Seems my exhaust bypass valve doesn't have a "set" opening/closing rpm. Rather, it seems to be dependent on the throttle position/load on the engine. In other words, even at say 2500 rpm, if I mat the gas pedal the exhaust sound changes from "sorta sport bike-ish" to "howling". If I'm driving along at 4500 rpm, on the other hand, and mat the pedal, it will definitely change from "sport bike" to Formula 1-like shreik (and I do mean shreik!). I kind of doubt you'd be able to get the valve to really open if the car is just sitting in neutral revving, I think you need to be driving it so that there is a load on the engine.

    Probably the aftermarket headers/cats allow additional sound volume out through my stock muffler, but I imagine your car IS in fact making F1-like sounds, you may just not be hearing it well. Inside the car, easier to hear the engine sounds than it is to hear the exhaust sounds others are hearing as you pass. This is why most 355 owners know the whereabouts of the nearest tunnels to their houses! Remember to lower your windows and slow down to 2500 rpm in 2nd gear before you enter the tunnel, otherwise you'll be doing 125 when you shoot out the other end of it!

    Congrats on the new car! Enjoy it!

    John
     
  6. FDT

    FDT Formula Junior

    May 18, 2010
    423
    La
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    Ric
    #6 FDT, Jan 5, 2011
    Thanks for advice on the valve. I reached in last night and I can move the valve by hand, there is some resistance, so it appears to be right. I live in Louisiana, not a lot of tunnels.....:). I will see what I can find. Since this is my first F car, I am sure there will be lots of learnings in front of me.

    Do you experience and vibration at certain RPM levels? Not severe but enough to notice through the pedels? I was wondering if I am looking at needing new motor mounts.
     
  7. INTMD8

    INTMD8 F1 Veteran
    Owner Silver Subscribed

    Jun 10, 2007
    6,813
    Lake Villa IL
    #7 INTMD8, Jan 5, 2011
    Make sure the exhaust is not touching anything and the Y-pipe has clearance over the rear subframe assembly.
     
  8. Sandy Eggo

    Sandy Eggo F1 Rookie
    BANNED

    Jun 4, 2009
    3,636
    Encinitas, CA
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    Rick
    #8 Sandy Eggo, Jan 5, 2011
    What are you doing with the top on?!!! :D

    Can you localize the noise to the rubber stripping or is it with the clamps and placement pins?

    Most people recommend a silicone based spray lube for the rubber (the sort you could find in most auto parts shops or RV / Camping World...specifically for rubber).

    As for the clamp mechanism or locating pins, I'd think you could hit it with WD-40 and see if it improves.

    On mine, I noticed that after a brisk drive with the top on - the creaking goes away considerably (either that, or I stop noticing it!).
     
  9. FDT

    FDT Formula Junior

    May 18, 2010
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    Ric
    #9 FDT, Jan 5, 2011
    I will check the clearance of the exhaust tonight. As far as the top goes, hard to say if it is the pins/clamping mech or the rubber, just a lot of "creaking" I will use some silicone and see if it quiet downs.
     
  10. FDT

    FDT Formula Junior

    May 18, 2010
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    #10 FDT, Jan 5, 2011
    Last edited by a moderator: Sep 7, 2017
  11. INTMD8

    INTMD8 F1 Veteran
    Owner Silver Subscribed

    Jun 10, 2007
    6,813
    Lake Villa IL
    #11 INTMD8, Jan 5, 2011
    Very nice!!

    Also, to address your exhaust question, I'm not sure how much "F1" sound you will get out of a Tubi system. All Tubi F355 mufflers I have seen only have 2 exit pipes, meaning all of the exhaust mixes in the muffler.

    The mufflers that have the very distinct "F1" sound such as Capristo, Kreissieg, etc, have 4 outlets on the muffler and separate exhaust paths for the primary and bypass exhaust.
     
  12. f355spider

    f355spider F1 World Champ
    Owner Rossa Subscribed

    May 29, 2001
    18,055
    USA
    #12 f355spider, Jan 6, 2011
    Wow, very tidy and clean example, and a GTS as well. Drive and enjoy it! ;)
     

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