Null


gublube

  • Karma: +0/-0
compression problem, help????
« on: September 25, 2010, 09:05:43 PM »
ok all,ive got a compression problem.i just bought a boat few weeks ago,it ran ok but didnt seem to have what it should,needless to say it had cracked head,both heads,bad valves few on each,spark plugs way off gap,couple were wet with water and the electrode was gone,ate up to nothing.so we did compression test and its what led up to pulling the heads,besides checking oil and it was milky with water.so i go to reputable custom engine builder and he tests them and says cracked and bad valves,he finds some old ones laying around that match my number and exact heads,he acid washes them,re seats the valve seats,tests and changes all valves that are bad,how many im not sure.they looked great.installed heads and got it all together,fired rt up,sounded great.took it to lake to test run and adjust rockers.well it sounded good and seemed to run ok,just didnt have the power i know this bbc 454 should have.so we come home and do compression test with throttle wide open with 2 dif testers,one being opened rt there,they both read about 50-55lbs,thats all cylenders,wow,very low.were totally puzzled how it runs like it does with low compression.so we do a leak test,we take off all rockers so the valves are all closed nice and tight,we hook up air compressor and pump air into the cylender,intake doesnt leak,but the exaust does.thats on all exaust valves too.remember these are newly rebuild heads and valves,no valves touchin piston contact or anything.although they did on other heads,but that shouldnt affect the new ones.anyone with any help i surely would appreciate it.ive posted on pb and most have helped somewhat,most dont beleive its running at all on 50lbs compression.but it definately is.im located in bakersfield if anyone is local and would like to see.im gonna take heads off and back to guy on monday and see if he might have done bad job.i dont know what else could be

john
« Last Edit: September 25, 2010, 09:32:48 PM by gublube »
  • Like
    Dislike
    Love
    HaHa
    Angry
    Surprise
    Sad
    Party

GT Jets

  • Karma: +192/-0
Re: compression problem, help????
« Reply #1 on: September 25, 2010, 09:53:31 PM »
As I said on the other site......You have bent stuff....Either piston to valve contact or a guide clearance problem, something is amiss in the valvetrain geometry... :thumbup:

GT
  • Boat #1: 1992 Carrera 20.5 Elite (I/O bitches)
  • Boat #2: 19' Bubble deck Jet BBC Berkeley
  • Like
    Dislike
    Love
    HaHa
    Angry
    Surprise
    Sad
    Party
If i get some free time tonight at work, ill play with it and post it for everyone to see.

Time to man up and yank it John!  :banghead:
Ray

gublube

  • Karma: +0/-0
Re: compression problem, help????
« Reply #2 on: September 25, 2010, 09:58:55 PM »
thanks again,someone just said i have solid lifters on other site,im waiting for them to explain why this is my problem.feel free to see who and what they are talking about and help.im sure your probably rt and if i knew what to look for id be on it all nite.so im just hangin out with nothing to do till i know for sure what it is and tomorrow i can see better and start diggin deeper.thanks for the info and i hope it helps,even if its the worst problem,i just wanna get it fixed.


john
  • Like
    Dislike
    Love
    HaHa
    Angry
    Surprise
    Sad
    Party

GT Jets

  • Karma: +192/-0
Re: compression problem, help????
« Reply #3 on: September 25, 2010, 10:26:26 PM »
Actually, looking at your pictures, they do look like solid lifters....

If you are near the boat, try to push the lifter center with a push rod, they should "give" a little and feel spongy, or springy...If they feel hard as a rock, you have a solid cam.

Relevance? There are two completely different methods of adjusting the valve train.

On the hydraulic, the lifter needs to be loaded, this is done by adjusting out the "pumped up lash" and going another 1/2-3/4 of a turn down.

On the solid, the valves need to be adjusted with the proper "lash", this is done by using a feeler gauge to obtain a clearance from the rockers roller to the valve stem end, typically about .010-.015" depending on the cam card...

My feeling is, that if the valves were adjusted too tight, the exhaust valves could have been burned because they never actually fully closed, mind you this is just a hunch, or even a best guess...

GT
« Last Edit: September 25, 2010, 10:38:03 PM by GT Jets »
  • Boat #1: 1992 Carrera 20.5 Elite (I/O bitches)
  • Boat #2: 19' Bubble deck Jet BBC Berkeley
  • Like
    Dislike
    Love
    HaHa
    Angry
    Surprise
    Sad
    Party
If i get some free time tonight at work, ill play with it and post it for everyone to see.

Time to man up and yank it John!  :banghead:
Ray

gublube

  • Karma: +0/-0
Re: compression problem, help????
« Reply #4 on: September 25, 2010, 10:34:50 PM »
well that sure makes some sense,i dont think we ever adjusted the valves too tight,we just closed the valves and tightened them til the push rod barely spin with our finget and did that to all in the down position,after about a 300 yard test run,easy driving and one push to see what it would do as far as power,and let off at about 50 yards,we didnt drive it anymore,we pulled it out and adjusted the lifters and did compression test rt on lake,decided to just bring it home and not chance anything since we had lo compression.


john
  • Like
    Dislike
    Love
    HaHa
    Angry
    Surprise
    Sad
    Party

GT Jets

  • Karma: +192/-0
Re: compression problem, help????
« Reply #5 on: September 25, 2010, 10:39:52 PM »
Valve clearance is a funny thing, I recommend adjusting them both hot and cold..

Your method I am sad to say is totally incorrect and may be the only issue you are fighting... :-\

Sorry bro.

GT
  • Boat #1: 1992 Carrera 20.5 Elite (I/O bitches)
  • Boat #2: 19' Bubble deck Jet BBC Berkeley
  • Like
    Dislike
    Love
    HaHa
    Angry
    Surprise
    Sad
    Party
If i get some free time tonight at work, ill play with it and post it for everyone to see.

Time to man up and yank it John!  :banghead:
Ray

gublube

  • Karma: +0/-0
Re: compression problem, help????
« Reply #6 on: September 25, 2010, 11:22:37 PM »
i am open to all advice,im far from a know anything at all,matter fact i dont know crap,thats why im hoping guys like u will help me.if our method of adjusting is wrong please help.just doing what guy that built heads said to do.we adjusted them cold when we put on heads,after a short run we popped off valve covers and went through them again.did compression check rt away cause we knew it didnt have what it should.compression was low,so we took it home and did pressure test,we can hear the air leaking out exaust valves,all of them,and hear it well inside headers.

john
  • Like
    Dislike
    Love
    HaHa
    Angry
    Surprise
    Sad
    Party

GT Jets

  • Karma: +192/-0
Re: compression problem, help????
« Reply #7 on: September 25, 2010, 11:30:01 PM »
i am open to all advice,im far from a know anything at all,matter fact i dont know crap,thats why im hoping guys like u will help me.if our method of adjusting is wrong please help.just doing what guy that built heads said to do.we adjusted them cold when we put on heads,after a short run we popped off valve covers and went through them again.did compression check rt away cause we knew it didnt have what it should.compression was low,so we took it home and did pressure test,we can hear the air leaking out exaust valves,all of them,and hear it well inside headers.

john

John, need to know what lifters you have before we can even venture a guess....Get it apart and hit me with a PM, we'll get it right... :thumbup:

The unfortunate part is, I think some damage has been done if there is leaking past the exhaust valves with the rockers backed off....The machine shop should be able to vacuum check them if the damage is not evident right away..

You will look for pizza pie slices missing from the valve or a bent stem causing the valve to seat crooked and not seal all the way around...

Good luck  :thumbup:

GT
  • Boat #1: 1992 Carrera 20.5 Elite (I/O bitches)
  • Boat #2: 19' Bubble deck Jet BBC Berkeley
  • Like
    Dislike
    Love
    HaHa
    Angry
    Surprise
    Sad
    Party
If i get some free time tonight at work, ill play with it and post it for everyone to see.

Time to man up and yank it John!  :banghead:
Ray

gublube

  • Karma: +0/-0
Re: compression problem, help????
« Reply #8 on: September 26, 2010, 12:10:42 AM »
ok,thanks alot.will do.first thing in the morning ill get them apart and not worried about damage as long as its just new valves.whatever it takes to get my boat hoppin like it should,i need to feel what it gots,hopefully it will be simple and easy fix.

john
  • Like
    Dislike
    Love
    HaHa
    Angry
    Surprise
    Sad
    Party

Horizonjet

  • Karma: +0/-0
Re: compression problem, help????
« Reply #9 on: September 26, 2010, 12:13:41 AM »
I thought if the a valve was not closing all the way you would have a rough idle and feel like a lost cylinder while driving.     ???
  • Like
    Dislike
    Love
    HaHa
    Angry
    Surprise
    Sad
    Party
72 Horizon BBC

gublube

  • Karma: +0/-0
Re: compression problem, help????
« Reply #10 on: September 26, 2010, 12:24:51 AM »
`well my boat never idled rt anyways,idle would stick,new cable is needed,kinda wore out and bent some.it didnt feel like lost cyl,just didnt have the power it should,but its my first jetboat so i really dont know,but im def learning .thanks to all u guys.

thanks again john
  • Like
    Dislike
    Love
    HaHa
    Angry
    Surprise
    Sad
    Party

gublube

  • Karma: +0/-0
Re: compression problem, help????
« Reply #11 on: September 26, 2010, 06:16:52 PM »
i just decided to take it to tom at performance boats.he will do diagnostics and go from there,ill keep ya all posted.

john
  • Like
    Dislike
    Love
    HaHa
    Angry
    Surprise
    Sad
    Party

GlassCutter

  • Karma: +31/-0
Re: compression problem, help????
« Reply #12 on: September 26, 2010, 06:22:41 PM »
WINNER WINNER CHICKEN DINNER

That IS the right answer for your problems.
  • Boat #1: 1973  Wriedt Montara 23
  • Boat #2: 1978 Spectra 20 460/Berkley
  • Like
    Dislike
    Love
    HaHa
    Angry
    Surprise
    Sad
    Party
Also, I will kiss bare male ass in the middle of the Vegas Strip  . . .  I will post pics if I need to.  --  IRRebel 2013

"Go ahead Rivertard does it.  Take a video though."

"If you did it in a dodge it would have shifted perfectly ran a thousand miles per hour and got optimum fuel mileage!"  Nordie  2012

SS-201

  • Karma: +0/-0
Re: compression problem, help????
« Reply #13 on: September 28, 2010, 04:09:05 AM »
The picture of your lifters showed the cup down in the lifter. It would seem to me the valves are not lifting the valve to specs and letting enough air in.. The compression needs an amount of air coming in to perform the task, One reaon for having the throttle open when performing the task.
  • Like
    Dislike
    Love
    HaHa
    Angry
    Surprise
    Sad
    Party

GT Jets

  • Karma: +192/-0
Re: compression problem, help????
« Reply #14 on: September 28, 2010, 07:04:08 AM »
The picture of your lifters showed the cup down in the lifter. It would seem to me the valves are not lifting the valve to specs and letting enough air in.. The compression needs an amount of air coming in to perform the task, One reaon for having the throttle open when performing the task.

Solid cam....Lifter cups don't move....Just so ya know... ;)

The end result was posted on the "other" site... :thumbup:  :)

GT
  • Boat #1: 1992 Carrera 20.5 Elite (I/O bitches)
  • Boat #2: 19' Bubble deck Jet BBC Berkeley
  • Like
    Dislike
    Love
    HaHa
    Angry
    Surprise
    Sad
    Party
If i get some free time tonight at work, ill play with it and post it for everyone to see.

Time to man up and yank it John!  :banghead:
Ray

SS-201

  • Karma: +0/-0
Re: compression problem, help????
« Reply #15 on: September 28, 2010, 07:36:15 AM »
Sorry, must have been another post, he had a hydraulic lifter cam
  • Like
    Dislike
    Love
    HaHa
    Angry
    Surprise
    Sad
    Party

 


Null

SMFPacks CMS 1.0.3 © 2026