355 - Best valve guides | FerrariChat

355 Best valve guides

Discussion in '348/355' started by wilhit10, Feb 14, 2021.

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  1. wilhit10

    wilhit10 Rookie

    Feb 18, 2004
    43
    My 355 is probably going to need new valve guides and was wondering what the best brand is. I have two cylinders with very poor leak down results. The ones I am looking at:
    Superperformance
    SuperTech
    NickForza's.

    Any heads up would be appreciated. I am going to pull the motor, pull heads and check the cylinders.
    My compression/leakdown test resulted in(my guage has always read light, we are looking at consistency here).
    1. 130 27%
    2 140 8%
    3. 150 5%
    4. 120 28%
    5. 130 7%
    6. 150 1%
    7. 130 6%
    8. 150 1%
     
  2. MAD828

    MAD828 F1 Rookie
    Silver Subscribed

    Oct 8, 2011
    2,539
    Sydney
    Full Name:
    Elliott Caras
    When I did my valve guides I used the Ferrari valve guides for the 360. Part number 176437 inlet and 174638 exhaust.
     
    ShineKen likes this.
  3. Targatime

    Targatime Formula 3

    Feb 22, 2014
    1,211
    Los Angeles
    Where is the leakage from? LD test will only reveal worn guides if they're *really* worn. You should have significant oil consumption as well.
     
  4. Kokose7en

    Kokose7en Karting

    Dec 5, 2019
    207
    SF Bay Area
    I would run a fuel cleaner and drive the car. Few hundred miles. Make sure it isn’t carbon buildup on the seat of the valve. Then retest. Assuming the car drives smoothly and it’s able.

    Leak down testing is not very accurate at deeming valve stem seals. Though, a high leak number COULD relate to a worn valve stem seal, it is not necessarily always the case. Too many people are using this test too literally as “The Test”.

    Keep in mind. Valve guides could be worn and could show good leak down numbers.

    If you’re planning on removing the heads anyways. Measure the clearance of the valve stem and guides or measure K-Angle. Those measurements will guarantee, with confidence, the guides are worn or not. Then proceed with guide replacements or just a valve job.
     
    GTUnit likes this.
  5. wilhit10

    wilhit10 Rookie

    Feb 18, 2004
    43
  6. Beetle

    Beetle Formula Junior

    Apr 10, 2013
    776
    Carbon build up on valves and seats. Don't rely solely on a LD Testing
     
    GTUnit likes this.
  7. fboutlaw

    fboutlaw Karting

    Dec 3, 2014
    237
    Woodside, CA
    If you determine you really need to strip apart the block, take it to a machinist and let them decide what they’re comfortable working with. Mine ordered his own valve seals and some guides that he uses in modern gt3 cars for a lot less than the Ferrari parts. Works great.


    Sent from my iPhone using FerrariChat.com mobile app
     
  8. taz355

    taz355 F1 Veteran
    Owner Silver Subscribed

    Feb 18, 2008
    5,942
    Indio Ca/ Alberta
    Full Name:
    Grant
    What year is your car
    How long have you had it
    What was the leak down during your ppi when you bought it to give us an indication of miles vs leaking
     
  9. wilhit10

    wilhit10 Rookie

    Feb 18, 2004
    43
    The car is a 1995. The car is running extremely rich. The car is due for a major so the engine is coming out anyways. Since the engine is coming out, and the car has compression issues I am planning on doing the heads and the guides. This car had a PPI a few thousand miles ago and supposedly had good compression(you never know if a dealer actually does the test). My guess is either a valve has messed up a seat moving around due to poor guides, or maybe something else is a miss. I have done a smoke test, and of course looked at the plugs.
     
  10. kryten2001

    kryten2001 Formula 3

    I'm actually curious about the process required to replace the guides. Do you really need to pull the heads off, or can you do it by removing the rocker covers?

    I'm due a major soon and my car's a 94. I don't believe I have bad valve guides as the issue would have likely shown up by now, but hey if the engine is out and it's not that big a deal then why not just get them done for the peace of mind?
     
  11. Targatime

    Targatime Formula 3

    Feb 22, 2014
    1,211
    Los Angeles
    kryten2001 likes this.
  12. Targatime

    Targatime Formula 3

    Feb 22, 2014
    1,211
    Los Angeles
    I would figure out the answer to that question before assuming guides. Worn guides will smoke and burn oil but they won't make the car run rich....
     
  13. wilhit10

    wilhit10 Rookie

    Feb 18, 2004
    43
    It's unburnt fuel do to low compression, or running rich from header leaks. The spark tests well, as does the smoke test. No codes coming from the lambda sensors. Either way the engine needs to come out to do headers, and full service. If the engine is coming I am definitely pulling the heads to fix the compression issue as well as doing the guides. With 25% leak down, that can definitely misfires(lack of combustion). If its in the head, and I continue to run the motor, the cylinder will wash.

    FYI, I am not contributing the lack of compression/leak down specifically to the guides. I just know if I have to tear the motor that far apart, then I may as well do guides. One thing I've learned over the years of building cars, fix the obvious issue first.

    I am open to other ideas to see why this thing runs like a pig.
     
  14. Targatime

    Targatime Formula 3

    Feb 22, 2014
    1,211
    Los Angeles
    What do the plugs show?
     
  15. wilhit10

    wilhit10 Rookie

    Feb 18, 2004
    43
    Plugs look fine, but I believe the 2 holes that are having issues smell more like gas than the others. You'd think if it was like a valve seal, or guide I would see a lot of oil burning on the plug(dark plug). I do not. All look similar in their wear and spark.
     
  16. Beetle

    Beetle Formula Junior

    Apr 10, 2013
    776
    I'd be finding and isolating the issue before pulling engine or you may be pulling it again. As previously stated run an injector and or carbon remover/cleaner through it. If comps and LD come up then you can eliminate guides and seals. A good sign of valve guides and seals being worn are blue smoke on cold start. Or restart after 2 hrs from being at running temp. Get someone to start and you stand at back of car. If it blowers quite a bit of blue smoke then there is an issue. 95 cars run rich on start up from what I've read that alone will produce a carbon build up problem.
     
  17. Targatime

    Targatime Formula 3

    Feb 22, 2014
    1,211
    Los Angeles
    Since you're going to pull the engine for the major, easy enough to get a borescope in the cylinders to check everything out. If you have worn guides, you will have oil consumption consistent with the wear. Is it burning oil? On cars with cats it can be hard to see blue smoke, better to go on oil consumption.
     
  18. wilhit10

    wilhit10 Rookie

    Feb 18, 2004
    43
    I’ve put a boroscope in the holes and they look good besides a few scratches. Of course you really can’t tell if they are a big deal until you pull the heads.


    Sent from my iPhone using FerrariChat.com mobile app
     
    Beetle likes this.
  19. Targatime

    Targatime Formula 3

    Feb 22, 2014
    1,211
    Los Angeles
    I'm doubtful you have worn guides -- if you did to the extent your LD test suggests, you'd have oily or sooty plugs and see carbon buildup in those cylinders.
     
    Beetle likes this.
  20. Beetle

    Beetle Formula Junior

    Apr 10, 2013
    776
    It's only hard to see blue smoke on cat equipped car when the cat is hot. If you cold start the car as previously stated and you have a guide or guide seal problem you will see a good ploom of blue smoke. If you don't then I doubt you have a guide issue either.
    Do some checks or sure go ahead and pull the motor and spend a few grand on something that most likely wasn't the issue to begin with. Engine shops love this sort of self diagnosis it makes them money. Bore scope the back of the valves for a carbon check. Good luck I hope it's just a bit of carbon. In Australia due to unleaded fuel all my cars have 1 range hotter plugs. This is because on cold start unleaded burns cold and produces soot, its an issue. Soot leads to carbon deposits.
     
  21. wilhit10

    wilhit10 Rookie

    Feb 18, 2004
    43
    The motor is being pulled for a major(its been 7 years) and has a few oil leaks. Anyways, what I could do is clean the valves when the headers are off and try another leak down(like people do on modern BMW's). It'll be a lot easier to see the exhaust valves and the carbon/soot on them when the headers are off.
     
  22. Targatime

    Targatime Formula 3

    Feb 22, 2014
    1,211
    Los Angeles
    If you're taking the headers off, and you have worn guides on the exhaust side, it'll be perfectly obvious and no more need for guesswork or further guesswork. Just unbolt the headers and take a look.
     
    [email protected] and Beetle like this.
  23. wilhit10

    wilhit10 Rookie

    Feb 18, 2004
    43
    To be continued in a month or so. I have a 997 motor to assemble and then I will start working on this car.
     
  24. PaulK

    PaulK F1 Rookie
    Silver Subscribed

    Apr 24, 2004
    4,603
    Michigan
    Full Name:
    Paul
    What would they look like? Really caked with carbon?
     
  25. Targatime

    Targatime Formula 3

    Feb 22, 2014
    1,211
    Los Angeles
    With headers off you'll be able to look into the exhaust ports and see the backsides of the valve heads, roll the motor over, etc. If you've got worn guides you will see a caked on carbon mess of burned oil.
     

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