swirl port heads and excessive blow by

[2square]

Hey guys n gals,
i have a very annoying problem i have never experienced before. i am going to be extremely detailed to avoid confusion. here is goes. i purchases a sbc 350 that had some miles on it, it was burning excessive oil but ran well. i originally thought it had vortec heads but i have now become aware they are not. they are 1994ish swirl port heads #10110810 from a tbi truck. anyways the engine was rebuilt bored .30 over magnifluxed block and both heads. crankshaft grinded .010, resurfaced cylinders .007. knurilized valve guides. new flat top pistons, moly rings, new oil pump, oil pump shaft, main baring, rod baring. comp cam 12-238-2, int .462 ext .469 comp lifters. broke in cam with the recommended oil. here is where it gets interesting, engine runs great almost perfect, but it is still burning as much oil as before the rebuild! ill be honest it has alot of idling time as i was still working on the rest of the truck. i did not notice any oil burning, until i finally took the vehicle out. once warm it burns 1ltr every 100 miles. concerned i completed a leak down test cold. i have 20% leak on each cylinder. new pcv valve on drivers side cover, breather on passenger side.holly 4160 750 cfm, edelbrock intake. the intake center 4 holes have been reamed out to bolt to the swirl heads, i have removed the intake to review the gaskets. installed new fel-pro gaskets and confirmed they are sealing around the EGR port, as well as everywhere else. heat gauge reads 180, but some spots when skin touching valve covers are hotter then others. i see the puffs of steam out of valve cover breather and pcv valve when i pull them out and rev the engine.it appears i am getting excessive blow by on all 8 cylinders, all plugs are wet with oil. i only notice blue smoke when warm, it becomes more as the engine warms. im at a lose any ideas are appreciated. some extra info, it burned about the same amount of oil before rebuild, i found excessive carbon under intake before rebuild, im already seeing how this is continued after rebuild. i do not know what else to check? what other reason can be causing the blow by? maybe the rings did not seat? its peppy, and if it were not for the blue smoke i wouldn't think i had an issue its running very well

 

[HotRodPC]

You said wirty dord. I'm going to go with bad valve guides that dried out your valve seals and now you not only have bad valve guides but bad valve seals also. Knurling valve guides today is uncommon for a reason. It's kinda of like re ringing a worn bore and calling it REBUILT. It's a patch that doesn't last very long and nowhere near the life of a fresh clean bore and new rings. Many shops won't even knurl guides for this reason. They'll replace the valve guides. Yes, that runs the cost of a valve job up and why many times it's almost cost effective just to buy some ready to bolt on new aftermarket heads or remanned heads. The hotter than other spots on the valve covers is where you're bad valve guides are likley to be and where you're getting hot combustion escaping the cylinder and relieving pressure and compression through the valve guide and seals. JMO !!!

 

[2square]

You may be right about the valve guides. It has to be something, and what you say does make sense. I'm curious, would what you describe here not make the engine run a little funky? This thing is making power its responsive and I have no issues with anything until it gets warm zero signs of smoke until its been at 180 degrees for maybe 10 minutes. Zero smoke on start up(after sitting for a week) is it Just the oil thinning out?. I should note I've had some old trucks smoke a hell of alot more and burn a hell of alot less oil. Thanks for the reply I've tried everything else I guess the heads might be coming off. Ps the smoke is not thick blue and reaks of unburnt fuel

 

[HotRodPC]

Yep, that even makes me go for the valve guides even more so. That oil gets warmer and thinner and it's able to make it's way around those knurled guides.

 

[HotRodPC]

The raw unburnt fuel could be something else, but it wonder if your not getting some of your gas pushed up through the guides too. It seem to reason NO, because fuel is delivered on an intake stroke which is going down and creating a vacuum, unltess it pushing fuel out the tops of the guides before TDC and the spark plug ignites, but I'd say that is certainly possible. It could be you only have 2 or 3 valve guides that are bad enough to cause the problem and the valve seals help a bit keeping them at bay, but with all that heat escaping through the valve guides, it'll hardened and cook those valve seals. Regardless if this ends up being the issue but I believe it is, it's still not a waste of money to replace the guides. Bad guides will certainly cause blow by too. Have you by chance tried thicker engine oil yet? That will slow it down cuz the thicker oil won't get around the valve guides as bad. Try running 30wt rather and 10-40 or other mutligrade. This time of year should be able to get by with running 40 weight even if you can find it. The thicker oil will since it won't get past as easy will have somewhat of a sealing affect too and might lighten up the blow by.

 

[2square]

funny you say thicker oil i am planning on putting some 20w-30 in this weekend to see if that helps, I think I've eliminated everything else. Might has well try the oil. I just don't wanna pull apart my brand new motor in peak driving season. But I may have too I guess. Also I'm starting to lean towards ri ngs not seating again, as after a little more research into a leak down test it seems like 20% is actually quite excessive for a brand new engine... the tester gadge itself has it in the green "good range" until 40%. But I guess 20% is more on the your in trouble range... but I could not hear any air escaping through dip stick or anywhere else.

 

[Bextreme04]

You can check for bad rings by running a compression test dry and then again wet. Run the compression test dry and record the number. Then put about a teaspoon of oil in the cylinder and run it again. If the compression is higher on the wet test, your rings are the problem.

 

[HotRodPC]

funny you say thicker oil i am planning on putting some 20w-30 in this weekend to see if that helps, I think I've eliminated everything else. Might has well try the oil. I just don't wanna pull apart my brand new motor in peak driving season. But I may have too I guess. Also I'm starting to lean towards ri ngs not seating again, as after a little more research into a leak down test it seems like 20% is actually quite excessive for a brand new engine... the tester gadge itself has it in the green "good range" until 40%. But I guess 20% is more on the your in trouble range... but I could not hear any air escaping through dip stick or anywhere else.

Ok, nothing to lose by trying. So go back to square one and try to reseat your rings. This can be dual purpose cuz 30 weight it thicker. This is a flat tappet hydraulic cam right? The cam is already broke in so you're good there. The best thing to do to get rings to seat, is NON DETERGENT 30 weight motor oil. No synthetic, no fancy BS. Just straight 30 wt NON DETERGENT. You don't want slick oil. You want them rings to scrub them cylinder walls real good. So that's step 1, use 30wt NON DETERGENT. Step 2, Put a 195 degree thermostat in that engine for awhile. Letting it run hotter helps seat the rings. Run that 30wt NON D and 195 degree T Stat for about 1000 miles on good solid drives, not trips back and forth to the grocery store up the street.