PapaSmurf Posted July 7, 2013 Share Posted July 7, 2013 (edited) I just rebuilt this l28 and finally got it to stop leaking out the rear carb (bad float valve) and got the clutch working again (clutch master cylinder) and today got it all dialed in with another hot valve adjustment and tuned the carbs and set the ignition timing. It would seem she's FINALLY ready to drive - but I have a concern. The first time I started her (after realizing that I had set the distributor shaft backwards again and fixing it- why can't they make a reversible dizzy rotor??) She squeaked. She started right up easilly purred pleasantly then squeaked about 30 times a second or two apart. It sounded like it was coming from the rear of the block. It sounded like I might have had a dry bearing. I checked the clearances of the new bearings with plastiguage everything was in spec the crank was polished and the bearings dipped in oil they should not squeak! This is my first L bottom end rebuild so what do I know though. I turned it off and let it sit a few minutes and started it again it squeaked once more and then was quiet. I ran it for about 20 minutes today at idle and up to about 3k while tuning the carbs and the squeak returned but much much quieter on first start it was so quiet it may have been my imagination. I'm just here to ask - should I be worried? Will this break in or should I tear it back down and inspect? I primed the engine before start up by taking out the plugs and running it without fuel or spark till oil reached the head so the only thing I could imagine that caused this would be a blockage in the crank oil passage ways. Oil pressure according to the lying gauge is lower than it used to be before the rebuild at idle and about right at load. I have another oil pump I might swap in this one is new and may be the cause of the low pressure at idle then again the oil pressure sender was removed with a pipe wrench and may have been effected - not that its a trustworthy indicator of actual current oil pressure anyways. Anyone want to slap me and tell me to drive it fast and stop worrying so much? Edited July 7, 2013 by PapaSmurf Quote Link to comment Share on other sites More sharing options...
PapaSmurf Posted July 7, 2013 Author Share Posted July 7, 2013 Crap the float vent is leaking again at 800rpms if I turn it up to 1000rpms it seems to keep up with the pump. It looks like my regulator really is the culprit I have a new holley one in the mail with a gauge anyways but I had hoped to drive this thing before then now i can't trust it. Anyways I didn't hear the squeak on its last run at all so I think the bearings are OK I'll just take it easy and keep an ear out I suppose unless someone has better advise Quote Link to comment Share on other sites More sharing options...
Tony D Posted July 7, 2013 Share Posted July 7, 2013 (edited) REAR TWO CAMSHAFT LOBES RUNNING DRY! That is your 'squeaker'---get it resolved, make SURE you are getting oil spray out the lobes or spraybar or within 500 miles you will be doing it anyway when you replace the cam! Usually inaudible at higher rpms, but returns intermittently at Idle. Sometimes it squeaks, sometimes not as there is oil splashed from adjacent lobes (especially at higher rpms) but they're not getting proper lube and it will take it's toll... Even with stock cam and springs. With a hot cam and heavy springs it will go away quicker! Edited July 7, 2013 by Tony D Quote Link to comment Share on other sites More sharing options...
PapaSmurf Posted July 7, 2013 Author Share Posted July 7, 2013 Aww hadn't thought of that its internally oiled p79 stock cam maybe I'll stick my oil spray bar in. Thanks tony I'll inspect the cam tomorrow and see whats happening Quote Link to comment Share on other sites More sharing options...
PapaSmurf Posted July 10, 2013 Author Share Posted July 10, 2013 Confirmed the issue the third lobe in from back is visibly damaged. Removing the oil filler cap when idling results in a mess from the higher oil pressure at the front of the cam. Good thing I have some spare cams I'll pick one and have it polished and install a spray bar while I'm in there to prevent this sort of thing in the future thanks tony! Quote Link to comment Share on other sites More sharing options...
steve260z Posted July 10, 2013 Share Posted July 10, 2013 Nice job Tony. Quote Link to comment Share on other sites More sharing options...
Tony D Posted July 10, 2013 Share Posted July 10, 2013 wouldn't have been so bad if I'd typed "cylinder's lobes" instead of freaking just "lobes"... "Do not post while drinking, you think you said things you really didn't. Or vice versa!" Too bad about trashing your cam. Bummer. Got tight clearances on the bottom end? Did you use RTV anywhere near the oil system so a gob could have broken free and plugged something? I watched a guy tear down a P90 Mechanical Head that WRECKED... I mean NOTHING looked like it got lube. He'd put red RTV on EVERYTHING including the head gasket "to make sure nothing leaked" and had COMPLETELY PLUGGED the orifices feeding the top end of the engine. Decided since he hadn't completed paying for the head, that he wasn't going to "since it was trashed and that the seller could take it back". Dude, NOT COOL! Somewhere around that time, I stopped selling parts to Z-People... Quote Link to comment Share on other sites More sharing options...
Tony D Posted July 10, 2013 Share Posted July 10, 2013 And what.... you guys don't have that Polycarbonate Valve Cover for checking this sort of thing without making a mess??? Quote Link to comment Share on other sites More sharing options...
ozconnection Posted July 10, 2013 Share Posted July 10, 2013 And what.... you guys don't have that Polycarbonate Valve Cover for checking this sort of thing without making a mess??? Yeah, thought about that one years ago....funny that no-one has got one and posted a pic or vid of it. BUT, how much would you really see with all that oil up there. At idle it might be ok but. Cool idea! Quote Link to comment Share on other sites More sharing options...
Tony D Posted July 10, 2013 Share Posted July 10, 2013 You would be amazed what you see. Even at idle it reveals which lobes aren't slinging oil pretty vividly. On spraybars it works better as you can visually watch the streams as the rpms rise and the thing 'burps out'! Quote Link to comment Share on other sites More sharing options...
skirkland1980 Posted July 11, 2013 Share Posted July 11, 2013 Would you see it while priming the engine with a drill? Quote Link to comment Share on other sites More sharing options...
Tony D Posted July 11, 2013 Share Posted July 11, 2013 I've never done that, and my reasons for not doing so are posted previously. If you use a VSD I suppose you could...see something... Quote Link to comment Share on other sites More sharing options...
PapaSmurf Posted July 12, 2013 Author Share Posted July 12, 2013 Nope no rtv anywhere in the can not sure what blocked it up but it needs reground for sure oh wells I've amassed lots of spares due to thinking ahead prior screw ups lol i got it running properly now and a new fuel regulator to mount tomorrow but ive found a rip in my rack boot and two ball joints that need my attention before its gonna go anywhere. Cheaper out and reused the clutch and that's slippery too so it looks like I'm out most of the summer Quote Link to comment Share on other sites More sharing options...
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