The Stovebolt Site Forums The Shop Area The HiPo Shop 383 "New build" smoking

I built a 383 for my 3600 from a 1991 350 TBI and it runs well, pulls strong, etc. and it has about 400 miles on it so far. The block was machined 0.030 oversize and honed by a machine shop that I trust but don't have any personal experience with.

The problem is that when driving to car shows and similar when I arrive and putter around the parking area to get to my parking space it smokes noticably, I believe from both exhaust sides (independent dual exhaust). Oil is 5W30 and it used about a quart in between the first oil change (roughly 100 miles) and the next 200 miles. Typical drive to the shows is 40-45 miles, mostly at 55-60 mph with no noticable smoke when driving or initial operation in town after highway driving at 25-30 mph. Engine speed at 60 mph is approx 2200 rpm.

I suspect that I don't have the rings/bores suitably broken in but wondering about all sorts of other potential issues. I have tried to do high load pulls like 4th gear from 30 to 60 mph (roughly 3000 rpm) to help seat the rings but I'm not sure that is working.

It has been a few years since the engine was assembled and I am now questioning what I did for valve stem seals (memory is a terrible thing to loose).

My PCV system has the valve mounted in the passenger side valve cover connected to the base of the carburetor - connected to the intake manifold vacuum with the "clean air" supplied from the clean air side of the air filter to the driver's side valve cover. I don't recall what variation of PCV valve I have.

Any advice about what to investigate or was to get the rings seated would be appreciated.

If this should be in the engine forum please feel free to move but as a non-standard engine I assumed it should go in the HP forum.

First thing to check is the PCV hose, does it have oil in it? A simple test is to install a clear 3/8" inline fuel filter in the PCV line then go drive it. If it's sucking oil the filter will have a bunch in it.

Next is pull the valve covers and see if you can see the valve seals, its pretty hard to see them but you want to make sure they are still installed correctly. You may need to fill a cylinder with cotton rope and pull the valve springs to check. I worked on a Pontiac that sat before starting, all 16 seals were riding up and down with the valves, they installed cheap seals that didn't fit the head and after it sat they dried out.

Thanks Joe. The PCV test should be pretty easy as a starting point.

If I need to pull the valve springs and check/replace the stem seals I may wait until winter. The engine did sit for at least 2 maybe 3 years between assembly and first firing, and almost a year after that before it got any real operation due to the remaining activities associated with my build.

Under the valve cover do you have a baffle where the PCV goes?

To use that much oil that quickly, the valve guides would have to be sloppy loose- - - - -even bad stem seals won't cause that rate of oil loss. I diagnosed one failed rebuild that was using oil about that badly- - - - - -it turned out that the rebuilder had forgotten to install the oil ring on one piston. That guy got a pretty bad case of Budweiser Fever on a regular basis! Another one (my own fault) was a re-ring job on a Rambler American flathead six that completely wore out the rings on a 2500 mile trip from California to Tennessee. By the time we arrived in Nashville, it was using 3 quarts of oil to a tank of gas. I hadn't cleaned up the cylinders properly after honing them, and the hone grit imbedded in the cylinder wall pores wore out the rings. The oil ring expanders were rubbing the cylinder walls, and the compression rings were less than half their original thickness. I'd recommend a complete teardown and inspection of the piston ring installation.
Jerry

I join with Jerry on the valve guide idea as the main problem.

Also there could be a secondary problem...Did you use chrome piston rings? About 50 years ago I used the last of those I will ever put in any engine. You can see an image below showing the hatch marks are still visible. The engine had over 25,000 miles on it when I removed it. The rings never did break in correctly. Just another thought.

There are baffles in the valve covers for the PCV connections.

I need to check back on what rings I used, I don't recall them being chrome but my memory is not the best on the details.

I am pretty sure the valve guides are not sloppy loose but again it has been a while since it was put together.

I'm not anxious to pull the engine and tear it down but if I need to do that it will be a winter project.

WICruiser, I built a 355 years ago and put in a big block oil pump only to help smooth the pump and distributor, the big block pumps have larger gears with more teeth and run smoother. I ended up pulling that pump out and installing a stock small block oil pump, no high pressure or high volume. Oiling troubling was solved with the stock pump. Just wondering if your 383 has a high volume and/or high pressure pump?

78buckshot, as I recall I installed a high volume but not high pressure pump reasoning that more oil was a good thing (maybe too much isn't).

Oil pressure is about 60 psi cold, 45 psi warm at 2200 rpm, 30 psi warm at idle.

Coolant is running at 185 or so with the fan on full time (I have a thermo switch issue so bypassed for now). Temperature comes up normally to the thermostat opening temperature (I bleive it is a 195 if I recall correctly). Before bypassing the thermo switch I did have temperatures as high as 220 when vehicle speed was low that came down with increased vehicle speed.

Those numbers are pretty close to stock, probably not causing the problem. If you happen to pull the oil pan and have a stock pump on hand, it might help to use it. From your original description, my bet is a piston/cylinder/ring seal issue.

I am slowing, grudgingly coming to the conclusion that the problem is ring/bore sealing and while it's possible that the rings will still break-in my confidence is not very high.

The engine was built using a Scat rotating assembly kit that included pistons and piston rings that were described as having "Plasmamoly" facing material.

Thanks for all of the input received to date. I have a list of things to evaluate and continue to hope that I do not need to pull the engine for a tear down this winter season.

Perform a cylinder leak down test, that should give you a little more info to chew on.

Unless you're running extremely loose oil clearances on all the bearings, the only thing a high volume oil pump does is puts a lot of unnecessary stress on the distributor drive gear. On the race engines we ran .0025-.003" bearing clearance to allow the engine to rev up quickly, so a high volume pump was necessary just to maintain normal hot engine oil pressure. Doing race stuff on a street engine is usually a foolish thing to do. We built those engines to produce lots of power for a very short time. A round track engine with 1K miles on it was an antique!
Jerry

HRL - thanks, I should have known that and agree with the idea that race stuff on street engines is stupid squared but I guess that puts me into that cast of characters.

I contacted Scat (the source of the pistons and rings) but all they could say is they need to know the piston to bore clearance and ring end gaps so until I tear it down thay are not going to be any help.

I have read elsewhere that there may be a leak from the valley into the intake past the manifold gaskets. I'm running the original cast iron TBI heads with an Edelbrock Performer EDL-2104 intake manifold. I plan to check/re-torque the intake manifld bolts but is there anything else I should be doing/checking to confirm or eliminate this potential leak path?

This.......

You stated that it runs real well, if you have a significant leak on the underside of an intake gasket, I think you would notice low vacuum and poor running. You could pull the spark plugs and keep them in order, then compare plugs with each other. If one or more plugs looks oil fouled, you may have a leak but not very probable.

I am waiting on a leak down tester but looked at the PCV valve (no excessive oil in the hose), a few spark plugs (all were similar with one light and one dark side of the center porceline, no evidence of oil), and attempted to look at the valve stem seals (valve springs prevent viewing them). I did confirm that there was no obvious oil smoke on start-up after sitting for several days compared to significant oil smoke at idle after driving.

Once I have the leak down test information I may be better informed but I am leaning heavily toward running it for the rest of the summer to see if anything changes and if not plan to tear it down over the winter months. Other than the anoyance factor of being a smoky truck when driving into car shows and needing to add oil more often than desired there doesn't appear to be any significant risk of additional damage to anything.

I also confirmed that the oil pump is standard volume and pressure so my memory was wrong but my selection was okay.

You won`t be any fan of somebody behind you whilst driving.
Most likely a burnt/warped ring. Running too hot or w/o enough oil. But I think you`d notice power loss.

No visible smoke when driving except at slow speeds after driving at highway speeds and no apparent power loss. Engine is operating at normal coolant temperatures and oil level is in the safe range.

I agree that people behind me when driving at slow speeds will not be my fans so I will try to limit that situation but car shows tend to require a fair amount of such driving between the entry point and the eventual parking spot.

I should have leak down results in a week or so and probably will determine how best to hold an intake valve in place so I can remove one valve spring and get a good visual of the stem seal. I am pretty sure I can find a tool to compress the valve spring with the head in place (my normal spring compressor requires the head to be loose). If the problem is stem seals I can probably remidy that with the engine in place but just about anything else will require engine removal and tear down.

Its smoking when you are going fast, you just don`t see it as well. with my 327`s and the price of oil.
I solve every oil leak I can. I have it down to one very minor leak with the mechanical fuel pump. Just a drop or 2.
Dang quart of oil is up there.

Here's the tool you'll need for "head installed" valve spring removal:

www.ebay.com/itm/127446696906?

Either rig an air pressure adapter from an old spark plug shell and a quick connect air hose fitting to hold the valves closed with a manual transmission in high gear, or use two pairs of vise grips on the flex plate of an automatic trans, or pack the cylinder full of 1/4" nylon rope (20 feet or so) and turn the piston up against it. Be VERY careful not to drop a valve into a cylinder, or you'll definitely be pulling a head!
Jerry

I agree that it is probably burning oil when I am not seeing significant smoke but even at today's oil prices it is cheap compared to all the gaskets, rings, etc. required to rehone the cylinders (not that I won't do it over the winter).

I purchased a cheap leak down tester and after I was able to get it working (I think) I measured leak down at 15-20% cold (I know hot is better but much harder for me to accomplish). Inlet pressure was only 28-29 psi for this tester so not the 50 or 100 psi I have seen referenced but don't know if that affects the results. The output gage is marked in percent leakdown with my readings in the green (okay) region.

The plugs vary a fair amount in color/deposits. I tried to take pictures from 2 opposite angles but its hard to see anything meaningful in them. Number 8 is very clean, almost too white whereas some of them show more significant deposits. Leakdown on #8 was no different than the others.

I plan to remove at least one of the intake valve springs to get a better picture of what I have for valve stem seals. I doubt that the stem seals are the majority of the issue but I want to refresh my memory about what I did when I assembled the heads. HRL thanks for the link to the tool required and the procedure to secure the valve.

Have you looked at a plain old vacuum gauge test and a compression test? Vacuum readings can reveal a lot...

Jon, I have not, but always good to have more information so I will add them to the list of things to test before developing a plan.

"Cylinder leakdown" is probably one of the most useful, yet misunderstood tests for engine diagnosis, and doing it right is extremely simple. All you need is an air compressor capable of developing 100 PSI, a pressure regulator with a gauge, and a way to apply the air pressure to the cylinder. The same quick connect adapter used to hold the valves closed while changing valve seals also works for a leakdown test. With a manual transmission vehicle, just put the transmission in high gear, chock the wheels front and rear, and pressurize the cylinder with both valves closed. The simplest way to do that is to loosen both rocker arm adjusters so both valves are closed with the piston close to the top of its travel on the compression stroke- - - - -not necessarily right at top dead center. Adjust the air pressure to 100 PSI with no air flowing, plug the air line onto the cylinder, and look at the pressure gauge. For instance, an 85 PSI reading would be an 15% leak rate. A recently rebuilt engine should test in the mid to high 90% range. Below 80% is a disaster. Listen for intake valve leaks at the carburetor, exhaust valve leaks at the tailpipe, and piston ring leaks at the oil fill cap. It's not "rocket surgery"!
Jerry

At this point, you already know its leaking past the rings or the valve seals. There is no reason to keep checking it. You either keep driving and watching the oil level or you pull it and fix it. If you used a flexible sealer when assembling the engine, most of the time they come back apart pretty easy and you can get away with just a few new gaskets. I would recuse the head gaskets if they come off clean.

I don't remember if you said what cam and lifters you have, so choose your oil wisely. If I was spending $10 or so per quart of good zinc oil, pulling it now would be my choice. I couldn't stand not knowing what's wrong.

I refreshed my '85 Dodge 318 over a weekend, it was my only transportation, so I did a fast clean up and used fairly cheap parts, no machine work. The rings never seated in the freshly honed cylinders, it was using 3 quarts of oil everyday. The next weekend it came back out for a ring change. It came apart easy, I replaced the rings with a better set. I got it back together for work on Monday and the oil usage was gone, it ran another 80,000 miles before I sold it off. Compression before the refresh was so low, the leak down test would spin the engine like a starter, it only took one cylinder test to know it was worn out.

I am leaning toward pulling it because I want to know what I did wrong the first time. I agree it should come apart fairly easily, and hopefully it will become obvious what is wrong once I pull it apart.

I used the COMP Cams SK12-242-2 cam and lifter kit when it was built, so all new but flat tappet.

I have been using Vavoline 5W30 oil that says its a synthetic blend (can't seem to find any oils that are not partially synthetic) and I suspect that is not helping the ring seating process. I added a ZDDP additive to the initial fill and again at the first oil change (rooughly 100 miles) to try and protect the flat tappet cam.

I am assuming that I will need to tear it down completely, flex hone the cylinders to break up any glazing, wash everything and reassemble. If I put the lifter back into the same locations they should be fine. New piston rings and some gaskets.

Thankfully time is not really a factor as the only thing having it sitting prevents is attending some car shows that I go to just to participate (didn't build it as a show truck).

I'll second Joe's comments. Back in my poor boy, broke days I reused many a head gasket. If they looked good, I'd wipe em clean with gasoline, and spray a heavy coat of aluminum spray can paint on both sides, while it was wet slap the heads back on. Never had a failure. A couple times I did this cheap....uh, frugal method on some pretty good running 10.5 340 engines.

Another poor boy trick that never failed was instead of boring and honing, which is always best, I'd knock the ring ridge out of the cylinder and hand sand with my best cross hatch twist using dry 180 grit.

On piston rings, the cheapest were often chrome rings. Against all common wisdom and advice I installed them dry, no lube in the cylinders. They seated (broke in as we used to say) instantly, no smoke or oil use. Never had a problem like broke rings or early oil use from cylinder scarring. As a old friend liked to say, sometimes better to be lucky than smart.

RonR

this oil for break in

The rings won't seat with 5w30 synthetic blend. Change it and put the 30w in with the zinc additive. Then go out and floorboard it from 30 to 60 in high gear, then coast back down to 30, repeating this process at least ten times. That's how I've broken in every engine I've ever rebuilt, and not one ever used any oil. Either moly or cast rings.

Tronman, do you think the process will still work now that the engine has about 500 miles on it, or will the bores be glazed too much?

Guitplayer - where would I get the break-in oil you suggested?

Summit racing sells the Penn-Grade oil, the break-in is 30w and really works good. You are correct on the cam and lifters, do what ever you have to do to keep them in the same location, you should be good on break-in after 500 miles, so go with a 10-30 Penn Grade oil, no more mixing additives. A rougher hone and different rings should get you back on the road.

summit or amazon wicruiser

If you have to take it apart and start again be sure (really certain) the clearance between piston and cylinder is spot-on correct and also that the cylinders are round with no taper. I'm not a fan of break-in oil. As long as you're using an oil that's good for a flat tappet camshaft (like VR-1 30 weight for example) I feel you'll be fine. I know some folks are real fans of this or that oil...and that's fine but I'm just not in that crowd. And get it honed properly for the rings you'll be using. All this is important. I expect you've got some glazing now. As somebody else said get away from any synthetic oil. Good luck!

Thanks Jon, I understand your comments about oil preferences.

I am still hoping (maybe unrealistically) that I can save it without taking it apart. If I do take it apart, piston to bore clearance is one of the many things I plan to document (kicking myself for not doing it originally).

If you can give us the results of a vacuum test at idle, I think there'll be some good clues there. A leak-down test will be good also, but I think a plain old vacuum gauge reading is easier for most folks. A leak-down test will not show bad valve guides whereas a good vacuum gauge probably will. If you have a liquid filled vacuum gauge it will dampen the bounce effect of the needle at idle (which if it happens will negate any sort of idle vacuum accuracy). If you have a non-liquid filled gauge and the needle at idle is bouncing back and forth like crazy, try pinching the hose. That will normally cause you to get a more realistic reading. Back when these gauges were more universally popular (hence engineered better and made in the USA) most of them included a restriction but the ones I see today (from a country with five letters, beginning with the letters Chi which is not Chile) just ignored that kind of thought. I attached an image of the connection spot for a Helicoid brand gauge so you can see. Hope it is helpful.

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Good luck!! I hope you get it figured out.

Not know much about SBC's, could this be different block with harder cylinders? Seems to me I have read somewhere the material is different which makes the cylinders harder for longer life, this could explain the rings not seating if the walls are not honed correctly.

I'm betting it won't seal up, after 500+ miles, it should have by now. I have never used synthetic oil or blends for break-in, its been said its too slick for the rings to seat. But you can't just throw in any oil due to the flat tappet cam, so ask the ring manufacturer what they recommend.

Good luck,