Compression

[Robert]

 Thats the reason why I said to double check and loosen all the adjusters its kinda like a fail safe thing. To separate out the confusion as much as possible and to maybe pin point real problems like you are doing. The easiest thing to do is to is to make sure the piston is bottom dead center with play in the valves then put air in the cylinder. Do each cylinder seperatly and not by the book make sure the lobes are in a position that keep the valves closed and do this on each cylinder. The book will link cylinders together to do together forget it do each separately.I have tried to get it to tdc and had the engine spin on more than one occasion so its bdc so no spinning. With the engine like this put air in the cylinder and see if you get leakage from anywhere. I want to say that if you can disconnect the air line and the cylinder stays pressurized for say 4 to 10 seconds before all the air leaks out then thats good. You will hear air going into the crankcase air is always going to bypass the rings use the good cylinders as a comparison. It really hard to describe how much air you should hear thats why the air holding for 4 to 10 seconds is good. If you dont have air out the valves anymore I would reconfirm my valve adjustment and timing. Like I said these engines are pretty solid and I doubt that you have ring problems. Sorry about the oil filter deal  Let me say one more thing after doing what your doing many many times I like to eliminate as many problems as possible and not to have to redo steps. I know aggravation but take your time and like was said make sure you have valve lash when you do this test. Valve adjustment is easy and dosent take long so who cares about adjustment make sure to do the test completely and accurately and then do the next step. Who knows maybe all it was is the valve adjustment.

[Lonerbtw]

  Well hell who knew. (But you). Like I said I may have done it wrong. So made sure intake was closing then comming up on 1,2, mark adjusted valves then went to next. Valve cover back on and checked for leaks. No leaks intake,exhaust but still could hear some going into case. I must have been doing this when you wrote about it. Then did a compresion test and wow 150,145,150 left 140,135,145 right. Took it out for a ride, still had a backfire but 80% better than it was. Still sounds like a vacume leak to me will go through all that tommorow. Too hot and tired to do any more today. Will let you know it works out. And thanks again.
  Loner

[Patrick]

PHEW, GOOD !!  I'm glad all is well..  Now its easy,, just check/replace the vacuums lines and caps.. Thats generally where the vacuum leaks are on these monsters.. If it continues it could a petcock diaphram or an intake o-ring..If you still get a burble and its running poorly at low engine speed you could try some heavy doses of carburetor cleaner[ I still prefer Sea-foam] to see if it will clean up the low jets.. If you are using open or after market exhaust, I think a certain amount of burble is normal..

[Robert]