Page 1 of 2 12 LastLast
Results 1 to 10 of 12

Thread: Compression test....SBC 350

  1. #1
    Sand Dawg
    Did a compression test on a 350 Mag the other day in my boat. 160 to 155 all
    the way around until # 3 went 50lbs. and # 5 went 45lbs.
    What is my problem?????

  2. #2
    cruser
    My guess: Head gasket

  3. #3
    Moneypitt
    3 and 4 are across the block from each other, so it would have to be 2 head gaskets, if that is the problem. Check the rockers for movement compared to the others, it is possible a flat lobe(s) could starve the cylinders of air, showing less on the gauge. You didn't say how old the engine was, but it could also be bad valve sealing in those cylinders.........MP

  4. #4
    obnoxious001
    3 and 4 are across the block from each other, so it would have to be 2 head gaskets, if that is the problem. Check the rockers for movement compared to the others, it is possible a flat lobe(s) could starve the cylinders of air, showing less on the gauge. You didn't say how old the engine was, but it could also be bad valve sealing in those cylinders.........MP
    His post shows #3 and #5, adjacent cylinders.

  5. #5
    Ralph Brunt
    do a leakdown test will tell the hole story my .02 ralph

  6. #6
    HP350SC
    I'll vote head gaskets as well. Either way you are yankin' the heads. Get wrenching :hammerhea

  7. #7
    rerfert
    Either way you are yankin' the heads.
    Yes but wouldn't you like to know what the problem is first??
    Do the leak down test.

  8. #8
    SmokinLowriderSS
    I'll bet #3 leaks down into #5 really fast. My $$ goes on the head gasket too. Make sure the head isn't warped before it goes back on, or a new one won't last long.
    I would also check the rockers for tension tho as well, quick & easy check. I would think 2 flat intake lobes would do such, but I think gaskets are more likely.

  9. #9
    Sand Dawg
    thanks guys

  10. #10
    Sand Dawg
    If I wanted to do a leak down test,
    how do go about doing it?

Page 1 of 2 12 LastLast

Similar Threads

  1. BBC compression
    By Towndrunk in forum V-Drives
    Replies: 0
    Last Post: 09-16-2005, 06:52 PM
  2. compression??
    By bakerjet in forum Gear Heads
    Replies: 10
    Last Post: 02-12-2005, 11:12 PM
  3. compression??
    By bakerjet in forum Jet Boats
    Replies: 4
    Last Post: 02-10-2005, 10:25 PM
  4. Compression Test
    By Kerny in forum Gear Heads
    Replies: 4
    Last Post: 05-10-2004, 09:55 AM
  5. Took a Compression Test>>>
    By HammerDown in forum Gear Heads
    Replies: 14
    Last Post: 11-03-2003, 08:32 PM

Posting Permissions

  • You may not post new threads
  • You may not post replies
  • You may not post attachments
  • You may not edit your posts
  •