Grrrrr so my SBC is smoking like crazy at stoplights through the valve cover breather on the driver's side. The one on the passenger side has a line running into the carb from the breather, so no smoke. The motor has about 10k on the rebuild. When I've checked the exhaust it doesn't look sooty or smokey, maybe a *whisp* of dark smoke from the driver's side but can't really be sure. At a stoplight, though, I'm killing mosquitos! I'm pretty clueless about this kinda stuff so any advice is appreciated! My natural hillbilly inclination is to just slap a breather on there with a fitting and splice it into the carb with the other breather, but I figured for once I'd look before I leap and ask a few questions! I dunno if it helps but I figure it can't hurt so I took some pics. You can see some oil leakage from the breather onto the valve cover here. The breather itself is pretty oily if you pop it off. The passenger side with the tube is oil free. Wiring is still messy, but that's for another day
Sounds like alot of blow-by to me. Im guessing that mabey your rings didnt seat all the way after the rebuild. I had an old timer tell me that when you rebuild a flathead, sometimes the rings seat, sometimes they smoke forever. Im probably wrong. Wouldnt be the first, and definatly not the last time. Just an idea
Try running a hose to the carb from the valve cover with out the breather. This way you are pulling gas from both side of the engine. Check compression. Check for compression "leaks". Check plugs for oil.
Where is the PCV valve located? Is it inside this fitting? If it's inline, did you check the flow direction? Does it have suction at the base of this fitting with the engine idling? It's difficult to believe that if this is pulling a vacuum correctly that the other breather could be huffing that much smoke at idle. If the rings are shot or never seated it could smoke a lot out of the breather when you get on it but a properly working PCV valve should eliminate any smoke at idle from the other breather. I'd bet that you are not getting the proper vacuum at this valve cover for some reason.
If the engine was a recent rebuild, the intake manifold may not be seated correctly. I had an Edelbrock tri-power manifold that took several tries before it seated properly.
Hey bud, long time no speak to. Did u ever find the 4CV's? As far as the smokey joe or ssbc, did u use break in oil to seat the rings? There are many opinions as far as the right oil to use. I have heard Rotella T is ok. I myself use non-detergent 30W oil, since this has worked for me in the past and was mentioned to me when I first started rebuilding engines years ago. But things have changed over 30 years and you should probably go with the engine rebuilder's recommendations. Anyway just a thought.
I have read that Chevrolet recommened Bonamy to their dealers be sprinkled down the carb. to seat the rings. You didn't hear it from me though. Gary
Blowby from a rebuild issue. By 10k it should've seen enough throttle to seat the rings. Are you double sure it's coming out the breather, and not a weepy valve cover gasket dripping onto the exhaust? good luck
1 of 2 problems 1)Stuck PCV 2) Ring collapsed I would bet on #2, due to the fact I just went through that with my buddies car.. He bought a rebuilt and running motor out of a car and let it sit for awhile. We put it in a few months later and all she did was smoke through the breather. Should get worse as it warms up, Right????
Could also have the ring gaps too close together - i.e. almost lined up. Is it going through oil, or just smoking a bit too much?
Here's another neato trick to help narrow it down Have a buddy follow you. Floor it, wind the car out in first gear. Instead of shifting, let off and leave it in first. Smoke on acceleration generally means ring seal issues. Engine's gotta come out. Smoke on deceleration generally means valve seal issues. Time to R&R the heads.
I was getting ready to post about the valve guide seals. They can be replaced with the heads on, but be careful doing it. There was a post on here within the last week or so with ideas about doing it safely.
I agree about the valve seals being a possible fix, but if it's eating valve seals at 10K I'd want to know why. And the only way to really know is to disassemble the head. Valve guides seem to be the #1 most overlooked thing on a low buck rebuild. In some ways that would be a happy ending, cause the shortblock stays in the car and heads are comparatively cheap.
Question ?? Do you have a PCV in the system and 2 if so is it plumbed into the intake manifold vacumm,either into the carb base or manifold. Won't work if into the air cleaner. Look at the diagrams above and set it up that way. From the looks of things I'm guessing it is not a internal problem unless your PCV is set as the diagram.
Hey thank you everybody for your help! It looks like I have some more diagnosis and underhood time ahead of me! I just didn't know which way to start but it looks like I'm far from alone with this problem First things first, I'm gonna make sure my PCV system is working and set up properly, and I'm going get a new breather with a bung to vent the smokey joe side to the air cleaner. Then I'll take it from there and see where the heck I'm at! Hopefully not looking for a new long block! Thanks again, you guys are lifesavers! I'll post my results. If I'm not crying. I found this post from tunglegubbin from back in 2004 that really broke it down for me what my pcv options are : "If you should list the ways to do this in order of environmental correctness if would go some thing like this, for a street engine: Number one: One connection from crankcase to manifold vacuum via PCV valve and, One connection from crankcase to air cleaner Drawbacks: May be hard to incorporate on a traditional looking Hot Rod engine Number two: One connection from crankcase to manifold vacuum via PCV valve and, One connection from crankcase to air, with some filtering. As in vented oil filler tube in front of manifold on old SBCs Drawbacks: During high blow by situations you will get a goey filler tube since the excess air will come out there. Number three: One connection from crankcase to road draft tube One connection from crankcase to air, with some filtering. As in vented oil filler tube in front of manifold on old SBCs Drawbacks: Oily everything but very traditional. You need an overflow path for the situations where the PCV valve alone cant handle the flow. You either put the overflow into your air cleaner or into the air depending on how messy you like to be."
Pull the line and breather cap off of the valve covers and look inside of the hole. If you can see the rocker arms take the valve covers off and throw them in your next load of scrap steel. You need baffles. Look inside of the hose going to that funky fitting going into the valve cover and see if it has oil dripping out of it. Get rid of the cheap chrome shit, it's all junk
I had a nailhead that smoked a ton once it warmed up. It was pure band aid but 2 pcv valves plummed to manifol vacuum made it run smoke free.
OK well thanks to all y'alls help I found at least part of the problem. I've got the daggone PCV plugged into the wrong port on the carb! I never knew anything about PCV and figured it didn't much matter anyhow so I plugged it into the 'cannister vapor vent' that I happen to have on my smog legal carb. I'm going to switch it around to the right spot and reset my idle as needed and see where that gets me! I'll update when I'm done. Thanks! and thank you Tommy for your killer pcv-valve tech! It's the best explanation I've found!
OK just to update so there's an end to this story...I cocked up every vacuum line I came near...I got the pcv on the right one now and that solved 90% of my smoking problem...I still have a little smoking coming from somewhere, just enough to be seen in my headlights and make my eyes burn when I'm driving! I know part of it is surely from exhaust getting in through the trunk, but the rest I'll have to do some detective work to figure out. Thanks all!
I just rebuilt my 47 flat head and when it is cold,no smoke,when it gets warm it smokes like a chimmeny. Been using 30 wt. non-detergent oil.Only about twenty miles on engine. Was thinking about changing oil to 20-50 racing oil that has a lot of zinc in it,heard that it was better for adjustable lifters. Anyone else run into this problem with their flathead? What about using Rotella 15-40 for break in oil?
Vacumn gauge ,get some readings ,compression gauge get some readings,possible cracked intake manifold underside wher you cant see it or an intake gasket allowing oild to be sucked into the runners. Never overlook the obvious,a little time with gauges ,and take some time with carb cleaner and acetylene to narrow down the issue. BE carefull with the acetylene !!
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