[68 Pickup]

I would like opinions on a problem i'm having with my newly rebuilt 350. I believe i messed up when i coated the cylinder walls with Permatex Ultra Slick assembly lube. The engine has 2000 miles on it now and uses 1 qt every 200-300 miles. It seems to have some blowby, possibly sucking some through pcv, but not hardly any noticeable smoke. I really don't want to get into the all the issues that could be causing this and i have read alot of other posts on this. The main thing i would like opinions on is the assy lube on the cylinder walls. I have rebuilt a few engines before and always used motor oil for the piston installation but this time the block sat for awhile before installing heads and i noticed minor surface rust forming on the exposed cylinder walls so i put some assy lube on them and thought nothing of it. Now after searching around i am wondering if this may have glazed the cylinder walls? Maybe it will just take longer for the rings to seat? i have read anywhere from first 200 miles to 2k-3k miles. Could this really cause a problem that i would have to re-hone the cylinders? I appreciate any comments.

[va4cqd]

what kind of rings did you use?

[68 Pickup]

Plasma-Moly, 4.040 in. Bore, 1/16 in., 1/16 in., 3/16 in. Thickness.
I have used castrol gtx since start up. My cheap valve covers have baffles and it seems that since the engine runs about 3000 rpm on highway that it when i'm using most oil but i don't know this for sure. I have heard people having oil problems with gtx.

[va4cqd]

moly rings do take longer to seat then cast rings

i've used gtx for years and i never noticed any more oil comsumption with it than other oils

[techinspector1]

I used GTX in a '94 Quest from the day I bought it new to the day I sold it with 195,000 miles on it. It never used a drop of oil. Changed the trans fluid every 20K miles and the original trans was still in it when I sold it. Shifted like the day I bought it.

[baddbob]

I used STP oil treatment on the cylinder walls of one engine I rebuilt 20 + years ago and the rings never broke in properly. Since then I use thin 2 stroke oil on the bores and haven't had any breakin problems.

[dawg]

your gonna have to rehone the cylinders for sure.
also keep in mind you need to attain a crosshatch pattern.
Also just use non synthetic oil to coat the walls and for engine breakin.
walls are certainly glazed !

[Stroke]

Well, you ought not have done that. How about this, how were/are the heads? Were they gone through too? What do your plugs look like?

[68 Pickup]

Heads were gone through, All the plugs look perfect, light brownish except for #8 and it had got quite a bit of build up, dry crusty, on one side of electrode and conductor, #6 look similar but doesn't build up as fast. These cylinders did the exact same thing before rebuild, and i used the same pistons. Previous rebuild had 20k-30k and it was bored to .040 then. Only had it machined honed this time. I know i am getting some oil through the pcv valve, just not sure how much, maybe due to blowby. Could this oil be channeling mainly to those rear 2 cylinders?

[CNC BLOCKS NE]

There are a lot fo areas to look at as far using oil worn valve guides, valve seals, intake gaskets.

If your cylinders were plate honed and a good cylinder hone was used there should not be any problem with ring seal, We see up to .004 in distortion when the torque plate is bolted on.

We have seen engines on the dyno that guys did not have them plate honed and its unbelievable the differance in blowby at full load and wide open throttle. And these engines really seem to be down on torque and HP with that much blowby.

We build a lot of circle track engines and are breathere are always a dry and see othere engines with rags wraped around the breather from blowby issues and even at the end of the season there is still blowby issues which tell you the rings never seated and with .004 cylinder wall distortion how can they seal.

Stock engines are not as criticle but when your using performance cams that build more cylinder pressure, and smaller CC combustions chambers it magnafies the problem.

We use Clevite bearing gaurd on our cylinder walls with no issues so far and where we plate hone our cylinders with a good hone there is really not much break in for the rings.

Do a leak down test that sould tell you if you are have a ring seal probblem as we see around 1.5 to 2 % leak downs on our engines after a season of running if that helps.

And going to a .040 over bore there is more distortion compared to a smaller bore.


Here are some good links to look over.
http://www.chevytalk.org/threads/sho...page/0#1227305

http://www.camaros.net/forums/showthread.php?t=58964

[HAYWIRE]

Pick up a can of Restore works great or go to a GM dealer and grab their magic ring sealer in a can. The ford dealer here in town uses the GM stuff by the case in all their used cars....and it keeps you from pulling the engine.....by the way had much the same thing happen with a 327 I built years ago added 1 can ....still not burning oil today....Lorne

[Argess]

Lubrication is lubrication...a little different stuff on assembly shouldn't hurt. Different stuff in the oil pan (i.e. synthetic) is a different story and can be a real problem. Assemblyt stuff all gets scraped off (by the rings) in no time anyway. I would be more worried about the rust you mentioned. Could have scored the cylinder walls a bit as it was scraped free by the rings. I would suggest driving it a bit more to see if things improve.

[machine shop tom]

Originally Posted by va4cqd

moly rings do take longer to seat then cast rings

Moly rings do NOT take longer to seat in a properly prepared cylinder.

Was the block torque-plate bored and honed? What grit stones were used? Were the bores plateau-honed? Were the rings installed correctly (second compression rings installed upside-down will cause what you describe)?

What is the brand and part # of the rings used? Perhaps they are low-tension rings.

tom

[68 Pickup]

The rust was very minor surface rust and i cleaned it off ok so i really don't think it is an issue.

I doubt the block was plate honed, i took it to a reputable machine shop in my area and since i don't have this done much i just told them to hone it and hot tank it,,,i figured whatever they normally do is sufficient. Plus i'm somewhat on a budget, i just like working on engines this is not a daily driver nor a racer, more of a hobby i guess.
I really think i got the rings in right. I believe my main issue is blowby and alot if not most of the oil is going through the pcv valve and for some reason it is affecting the #6 and #8 cylinders more.

I really appreciate everyones help on this, i feel like maybe the assy lube may not be that much of an issue but anyway i think i have some ring seating issues. I plan to put several more thousand miles on it to see how it plays out and possibly try some "quick fixes" before i get bored enough again to pull it back out, in fact i may just build up another bottom end over the winter and try to do a little more precise job on it.

Again thanks a bunch to everyone for making this forum such a great resource.

[machine shop tom]

IF the block was not plate honed, IF the cylinder surface was not correct, IF the block was not properly cleaned........


You get the rest.

Still, got a part # for the rings?

tom