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info on 308 engine leakdown readings

Discussion in 'Technical Q&A' started by groovzilla, Nov 28, 2003.

  1. groovzilla

    groovzilla Karting

    Nov 28, 2003
    117
    seattle, wa.
    Full Name:
    william
    can anyone please let me know what the comprssion leakdown readings would be on a carburetted 308 motor...please relay what excellent/good/bad readings would be for a high mileage engine (74K) and a low mileage engine(36k)...i am looking at 2 cars and these answers would help a great deal!!...thank you so much!!
     
  2. yelcab

    yelcab F1 Veteran
    Consultant

    Nov 29, 2001
    9,067
    San Carlos, CA
    Full Name:
    Mitchell Le
    My 308 engine, right after the rebuild, with new rings, and honed cylinders, register 180 psi across the board. I have not checked it lately but the car runs good so I really don't care.

    The important thing is to have good compression (140-160 psi) with an old broken in engine, to have them fairly even across all cylinders (145-155 psi all across is better than 165 for 6 cylinders and 120 for 2 cylinders). What is more telling is the percentage leak down (if you do a leak down test).
     
  3. groovzilla

    groovzilla Karting

    Nov 28, 2003
    117
    seattle, wa.
    Full Name:
    william
    thank you so much for your post...i will be having a "leakdown" preformed when i have the buyers inspection done...if leakdown is based on a percentage, what should these figures be on a an excellent/good/poor 308 engine for both a high miles(74K)and low miles(36K) motor..

    thanks...
     
  4. pma1010

    pma1010 F1 Rookie
    Silver Subscribed

    Jul 21, 2002
    2,556
    Chicago
    Full Name:
    Philip
    My data:45K mile engine
    Leakdown 5 - 7 percent. One cyl at 12 - 14.
    Compression: 185 +/- 5
    HTH
    Philip
     
  5. thecarreaper

    thecarreaper F1 World Champ
    Silver Subscribed

    Sep 30, 2003
    15,225
    Savannah
    Full Name:
    name
    excellent thread...... i too am searching for a carb 308. thanks for the info. micheal
     
  6. 4re gt4

    4re gt4 Formula 3

    Apr 23, 2002
    2,279
    Roseburg, OR
    Full Name:
    Hans E. Hansen
    Note that gauges can vary, and altitude seems to make a difference. Mine read 165 +/- 5, but I heard of a car measured at Denver that was a consistent 135. Leakdown showed it to be in good condition. Also, if a cam's timing is a bit off, it can affect readings. Several here have had sizeable differences front-to-rear, with all cylinders on a given bank similar. They invariably found a cam that wasn't timed correctly.

    Also, cams with high overlap give lower readings. Early '80s cars will give somewhat higher readings than mid-70s cars for that reason.
     

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