[youngmuscle]

Hey guys,

Background: Currently stationed in Germany. Bought the motor from someone who claimed rebuilt as 468 but I doubt it. Redid cam, oval port ProComp Aluminum Heads with Comp Cams hardware and Oval Port Air Gap with 850DP. Running a T56 (Yeah its awesome) behind it for the long commute and Autobahn. After she was done in the states I had it shipped over here.

Got an issue. Just got the Chevelle over here and couldnt be happier. I havent revved the engine past 3,000 RPM and the break in oil was just changed. However, it recently started smoking out of the driver side. I didnt notice a real difference in power however its a bit irrelevant as my old engine was a 350 and much more mild and this engine is new and Im still tuning the carburetor. She smokes more when its warmed up and I noticed less in the morning than in the afternoon, its also not consistent.

Bad news: Did a compression test and all on driver side came back as 125 psi but number 7 was at only 25 psi. All plugs were black (playing with carb still I guess), but number 7 looked unburnt and had fresh oil on it. Only thing to add is that that plug has always felt like its slightly misthreaded. It was harder to take off when I first got the car and put on (the others I can hand tighten all the way. I figured this is irrelevant however due to the fact that it still had oil on it and looked unburnt. They didnt have the equipment for a leakdown.

Well guys... What do you think. I still need to do the leakdown, but what are my options. I dont have a billion $ to blow but if I have the engine out and apart I may as well stroke it and put new higher compression pistons. Or I could just say to hell with it and sell it to a German and buy an LS (already have a T56). I really love that big block, but I know now it was down on power (lugs a bit uphill etc) because its on 7 cylinders.

Just looking for any advice really. Some guys I talked to here that have done this a bunch of times in the past seem to think its an easy job that would take a day to do.... Just not sure really. Its a real dissapointment because I just got the car done and here and a ring goes out. I will be leaving this summer sometime for an extended vacation in Middle East, so I may just wait and get it done while Im gone....Any advice/opinions/tips from you guys is greatly appreciated

-Paul

BTW Holy %[email protected]# does this thing sound mean. Lovin it as a daily driver

 

[Blownchevelle68]

How do the threads look on the plug for #7. IS it a possibility that it was cross threaded and screwed the threads up on the head-maybe leaking past the threads? 25 is a pretty drastic difference from the others....Maybe someone else will chime in, but even if the rings in that cylinder were upside down and all the gaps lined in a row, I would think you would have more compression than just 25??

 

[mfret1970]

Maybe a valve adjustment issue? Maybe the valve on that side is hanging open, blowing the compression back through the port. Just a guess, really.


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[1bad69]

It definitely sounds like a broken ring. I would do a leakdown test, most leakdown testers (the good ones) can point you in the right direction... hope it didn't scar up the cylinder... if it did... you will be tearing it completely down...and machining again... you might get lucky and just be able to change the ring if it didn't do any damage... Pro Comp heads have been known for their terrible machine work...maybe could be a guide in the head that was machined wrong...I have heard horror stories if they weren't done by a reputable machine shop. That would be best case scenario, as you wouldn't have to pull the motor for that...

 

[427L88]

Yup. Leak down is next step to determine plan of action. Sucks man, but.... it is what it is.. and I might even encourage an LS swap if you have to pull the rat. 125 is pretty anemic cylinder pressure anyhow. *( btw when cranking pressure are near 200 psi, its very hard to notice a cylinder down at times)

hoping you find some ****ty valves guides. Real ****ty.

 

[youngmuscle]

Damn this sucks... I always planned to run an LS eventually but I really wanted to get one BBC under my belt and I just got this one going----Id hate to shelve it already. If I pull the engine I may as well get a stroker kit etc but machine shops in Germany (the few that exist) will charge an arm and a leg to bore the block. My understanding is to just order a complete kit that should include everything. If this indeed turns for the worse Ill start a new thread on a max power 496 daily driver vs LS (cost etc).

Meanwhile will it hurt the car to still drive to work? Are there any preventative measures (oil additives etc), it definitely smokes far as it gets hotter, but nothing when cold (guessing viscosity increase). Should I disconnect the wire from the plug on that cylinder for now to prevent it from burning more oil?

Ill keep looking into the partially stripped spark plug hole, but I dont know if that would cause oil to get into the cylinder like that.

 

[rp930]

You are digging a deeper hole. Do not drive it until you diagnose it. Do the leak down test first.

 

[youngmuscle]

Well guys... For cost effectiveness what is the minimum but RESPONSIBLE thing to do here. If the guys I know here are right and it would only be a 2 day or so job what would I need and have to do to fix this? Im guessing pull the engine and replace the rings on all cylinders. Would I need to hone the cylinders? Just trying to weigh my options. Thanks for all the advice guys, a huge help as always.

 

[BBimp]

Have you tjecked the dis cap a plug wire?? If it don't run the gasoline will wash the oil away from the cylinder and you will have no compression.
Try to spray some oil in the cylinder crank it over a coupel of times and make a new compression test

 

[youngmuscle]

Have you tjecked the dis cap a plug wire?? If it don't run the gasoline will wash the oil away from the cylinder and you will have no compression.
Try to spray some oil in the cylinder crank it over a coupel of times and make a new compression test

Ill run by the auto skills center (a place where Soldiers can wor on cars for real cheap) after work and report back in a few hours after a wet test as well to see if it changes. Ill also pull the valve cover and check the valves for that cylinder (make sure theyre opening/closing). The spark plug looked unburnt for sure, just covered in fresh oil. Ill cross my fingers.

 

[427L88]

Off topic, but I miss those auto skills centers. Made some decent beer money fixing on fellow soldiers rides at Ft. Ord back in the day.

 

[youngmuscle]

Off topic, but I miss those auto skills centers. Made some decent beer money fixing on fellow soldiers rides at Ft. Ord back in the day.

Haha, I hear ya. Its a good resource, and still around even during budget cuts.

So I figured it out! Thank god. Pulled the valve cover and sure enough the rocker arm was ridiculously loose, had a quarter inch play up and down. Hoping it was just a loose rocker I ran the engine and torqued it down until it stopped chattering plus a quarter turn. Looking at the cylinders when the intake valves were all closed the newly tightened rocker arm was lower than the others and when running that rocker was moving far less. I think it indicates a dropped lifter. Either way far more manageable. Ill start getting the parts list together, hopefully I can just buy 1 set of lifters (its a recently broke in cam). The only thing I can think of that can happen in the first 500 miles of a cam break is a bad install (rocker arm torqued too tight) but not really sure.

 

[rp930]

My guess is the cam is history.

 

[nitrofox]

It doesn't sound very good.

 

[Blownchevelle68]

Ill keep looking into the partially stripped spark plug hole, but I dont know if that would cause oil to get into the cylinder like that.

Ok I missed the oil burning part as well and thought you just had low compression-not both.

So is it a FT cam or roller? I would imagine the lobe is gone if a FT and the lifter as well...



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[youngmuscle]

Cam is a hydraulic lifter with roller rockers. I have another cam and set of lifters my engine builder is going to send Friday just in case. Ill pull the valve cover, mover the rocker and pushrod and look down as I have someone manually crank the engine. It DOES suck, but either way at least I didnt have to pull the engine and rebuild it I dont think but Ill do another compression test once I figure this out and fix it.

Either this was the reason for low compression or a coincidence, but there is definitely something wrong in that it moves a fraction of the rest of the valve train and when I torqued it down a bit more it ran better/smoother. So can a wiped cam or lobe=low compression with the intake valve kept open? Thanks guys....

 

[BBimp]

A dead intake lobe can easy give you low compression. The valve don't open enough and let less air in

 

[pauls72]

Sounds like a flat lobe for sure

 

[Doug F.]

Check your oil filter for trash. If its full and your bypass wasn't blocked, your bearings and journal surfaces are probably trashed. Definitely don't run it anymore.

 

[Blownchevelle68]

You'll want to change the oil and filter before firing it up again, which I'm sure you would anyway.

May be a good time to get a filtermag and magnetic drain plug. Plan on changing oil again after you get it running very soon-flush the system


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