Where should the numbers be across the board?? Is the 210-220 range across all cylinders OK??
Check these out...... http://www.ferrarichat.com/forum/showthread.php?t=106192&highlight=355+compression http://www.ferrarichat.com/forum/showthread.php?t=104494&highlight=355+compression http://www.ferrarichat.com/forum/showthread.php?t=51790&highlight=355+compression http://www.ferrarichat.com/forum/showthread.php?t=51885&highlight=355+compression http://www.ferrarichat.com/forum/showthread.php?t=54782&highlight=355+compression
According to Grand Touring mechanic---leakdown tests should only need to be performed IF the compression check comes back low. If all the compression rates are OK--not need for leakdown.
I would agree. Those # look very good. Alot of this test are operator dependent. Uniformity in #'s is more important than actual readings.
My service facility (Continental Autosports) recommends always getting a leakdown test on an F355, claiming it is always more accurate.
A leakdown test helps find a "bad compression ratio"--if the ratios are fine no need for it. It's like buying a tire and filling it with air to discover no leaks. Then breaking down the tire to look for a leak.. If it doesn't leak --leave it alone. No sense in doing it. Now if the tire had a small leak-----then you would break down the tire to find out WHY it is leaking...Hence leakdown test... If that analogy makes any sense.
That is going by a mechanic at Grand Touring for over 30 years. Just what he said. Can you explain the differences please, so I know what is true.
Leak down test pressurizes a closed cylinder and measures the pressure that the cylinder holds. It is not affected by user methodology. It is also much better at finding ring issues, something that affects many 355's. In many cases of ring wear oil is passing by the rings and while cranking temporarily aiding the ring sealing on compression stroke. That will only be found with a leak down test. I recently did a ring job on a 355 that had just changed hands. It had a recent valve job but no one did a leak down test and it still oil fouled a spark plug. The new owner found himself paying a big bill. It is a big enough problem on 355's that I bought a special tool that allows me to perform a leak down test after the heads are off so on a car with bad compression I can still test the rings. Both tests are good and have overlapping information but neither is a replacement for the other.
