Guys,

I've had this issue where I start my '69 427 (390hp - Stock w/cam) and it smokes out of the driver side tailpipe only. This usually happens ESPECIALLY after the car sits for a while. It clears up once the car runs for a little bit- but it's weird that it does this at all. And why just the DRIVER side and not both?

Also... I did a rear main seal change because the car was leaking oil like a sieve. To the best of my recollection we filled the filter up with oil and topped off the motor before I drove the car.

Directly after the RMS change, I drove about 5 hours from my dads house home and on my next cruise the thing started ticking and running like sh*t. Checked the oil and it was off of the dipstick. I refilled the oil and it's not ticking but it has sat for a few months since... and now it's smoking- again. I'm wonder if this is all related??

See video attached.

SMOKING PROBLEM!!!

Some Background:
1.) The motor has less than 3000 miles on a fresh rebuild, full motor machining, rings/pistons, full head work (new guides, seals, valve job, etc.)
2.) Head gaskets are Cometic multi-layer steel.
3.) Head bolts (stock GM) have been re-torqued (I didn't get much out of them when I did this)
4.) Inspected all driver side valve seals and they look good and in place (without removing springs - so from what was visible thru the springs).
5.) Oil doesn't appear to have any coolant in it
6.) The exhaust has a very slight "sweet" smell to it, which makes me think it's coolant - plus the while color.
7.) Coolant looks clean (maybe a slight light brown tint). Coolant has been in there for a while without refill.
8.) I've got new intake gaskets due to an oil leak at the back of the block. I always use The Right Stuff around the ports for safety. This is the 2nd set of intake gaskets I've had recently... it smokes with both sets of gaskets.
9.) Coolant canister combustion gas test showed up negative (checking for blow head gasket)
10.) The plugs on this side didn't look strange the last time I checked them - but I can check again.
11.) The "exhaust valve" to heat the manifold on the passenger side exhaust pipe at the exh. manifold is in place, but the "flap" has been deleted.

HELP!
Sum

 

Since you rebuilt the engine/heads the machine work on the block and heads might have changed the mating surface angles/geometry between the intake and heads slightly. Since the smoke is only on one side and you are using a bunch of oil I would bet you have an intake gasket leak and it's sucking oil in from the galley. It's possible you are also sucking coolant. Check it out and if that's the problem and you are still using the stock oval port heads try a set of Felpro 1212's which have a .060 thickness. I also use The Right Stuff front and rear. See the example below:

 

You can’t really see if a valve guide seal is off it’s seat without removing the spring.

check plugs to see if you can isolate it to a specific cylinder(s) or is common on all the cylinders on that side.

if one cylinder then persue that with leak down test to check ring condition, and check that cylinders valve seals by removing springs.

if those check good then I would suspect intake leak.

this oil may be your tipping point for your detonation problem in your other thread. So I would persue this first, then see if you still have a detonation problem once it’s cleared up.

 

In addition to above suggestions ...
You mention fresh rebuild with "full motor machining"

if block was decked ( and depending on how much)
and
if heads were resurfaced/milled (depending on how much)

it can & does change the fit relationship between intake and head
if only a little difference, some RTV will usually solve it & seal it.
but depending on how much that angle has changed, the intake must be milled to fit (or the intake gasket cannot seal & will leak)

see the table
https://www.crankshaftcoalition.com/...cylinder_heads

if the heads were "angle-milled" that further compounds the bad fit.

all that depends on how much was milled off decks/heads.

 

O.P. says nothing about specifically block decking, just full machining which could be just bored out, align-bore, etc. Nor does he say the head surface was milled. He needs to clarify that.

I would suspect the intake gaskets. Particularly the bottom edge near the lifter valley. Few people seal that part real well with RTV. Then it sucks all the oil vapor out of the valley into the cylinder.

 

OP
Did you assemble / rebuild motor?

Did the new RMS come after the rebuild?

 

what i like to do with intake gaskets is RTV or other sealant below the gaskets. use the rubber china wall pieces-for now. set the manifold on with no sealant above gaskets and walk away. later pull manifold off and make sure gaskets are where they need to be and stuck down good. replace china wall rubber pieces with preferred sealer. bead of sealer around water and intake ports. install manifold. and number 11 in your first post is called a heat riser.

 

Ok... So I did a 15PSI coolant system pressure test for 15 minutes today with the motor cold and there was ZERO pressure loss. Then I took the plugs out and the #3 cylinder plug looked like this...

#3 Cylinder Spark Plug Condition

All the plugs were a little bit dark brown on the electrode, but the #3 plug looks like an oil problem. I checked all the valve seals and they all seem to be in place and the valve stems look smooth and not grooved/galled.

I'd guess that if there is an issue with the valve seals 2 things would be true. 1.) The smoking should clear up when the engine gets hot or else its a piston ring issue (pretty unlikely I think). 2.) The issue is probably with the intake valve seal where vacuum from the intake stroke can pull oil into the cylinder.

Additonal Comments?

 

I got a little over-zealoused with my "engine machining" comment. Motor was bored, honed, line, bored, rods re-conditioned. No decking or manifold machining.

 

Jackson... Yes... RMS was replaced recently and also on the fresh rebuild. Long story short, it was probably damaged on first start.

The Long Story:
I installed the dist. in 180 degrees off. It had been 2 yrs since valve adjustments and the mark on the HD was showing TDC.... just the wrong TDC (the last position in the valve adjustment procedure). So fast forward 2 years and I install the distributor in the wrong position. I also installed a new solid state (transistorized ign.) replacement board for reliability. Unknown to me this new style board required 12V to fire from my worn out TI distributor but I was only getting 9V. So when I did my first start I had ZERO fire... and we turned to motor over a lot during troubleshooting.

About an hour later, I decided to try installing the original TI board and finally started getting some "starting sounds". Then... the motor backfired out of the carb and made a small flame on the manifold. I blew out the fire from the driver side facing directly toward the pass side crank case vent and BOOM!!!!!!! The fire ignited all the fuel that had flooded into the crank case and was now a fuel vapor bomb inside the motor.

The explosion blew the valve cover gaskets out from under the valve covers all over the motor. It even and bent the valve covers up from the mounting bolts making them completely unusable. I nearly sh*t myself. My thought is that the RMS was damaged during this explosion, but who knows.

#NOTProud

 

Actually warming up the engine will not correct a valve seal issue. Most smoking however will occur with a valve seal issue, at high vacuum times. Such as letting off the gas when slowing down or after sitting at a traffic light for a few minutes and then taking off. These are most evident to you at night when someone is pulled up behind you at a light and you take off. Their headlights will easily reveal a cloud of smoke.

Do you know if the valve seals were replaced? If so, with what type of seal? O-ring or umbrella?

Good luck... GUSTO

 

Was the block honed with a torque plate? If the cylinders were not round and straight to start with, honing without a plate will make them worse.
I'd suggest a full leakdown test along with a compression test..
When the heads were done, did they do a good check on the condition of the valve guides? All the valve seals in the world won't fix bad guides.

 

Ditto on the leak down at least on the cylinder that's burning oil. I wouldn't do a compression test so much if you leak it down. Find out if it's a valve seal (leak down test will show good) or if you have something else going on. Might have a broken ring on that cylinder. After I saw what the number 3 was doing would I proceed on the rest of the motor.

Like others have commented, don't worry about your pinging issue. Correct the oil burning first.

 

Clearly there have been some problems associated with this particular build, and the best way to get to the bottom of the situation is to do a proper diagnosis. If it were my car and it had suffered a mini-explosion like the one you describe I'd be inclined to pull the engine, tear it down, and go through the entire unit looking for any and all damage, but that's just me...

You SHOULD perform a throttle-open compression test as well as a leakdown. Judging by the #3 plug it is definitely oiling that cylinder, so the question at this point is why. It could be any one or more of a number of things-poor piston fit, improperly installed or seated ring(s), valve stem seal issues, or leaking at the head/intake joint.

I personally have seen oil consumption rates of as high as 125 miles/quart with leaking intake gaskets. Others here have outlined how to correct that; I would remove the intake, carefully seal around all the intake ports with Permatex hi-temp grey RTV on both sides of the gasket, then reinstall it using factory torque recommendations. When my small block Vette was doing this I wasn't seeing oil smoke out the pipes, presumably because it was just a constant thin oil vapor being sucked into the cylinders.

If you're lucky, that will be the source of the problem. If you have a serious leakdown/compression discrepancy on one or more cylinders, disassembly and further diagnosis would be in order...

 

I have a question for the OP, was the engine smoke free/no oil usage for the first 3000 miles?

The spark plug picture makes me think second ring upside down on that piston, it certainly could be valve seals or intake but if all other plugs look good I'd be very suspicious of ring issue.

 

That explosion is a concern. I can say I have never herd of anyone experiencing that . It may be as simple as it dislodged or damaged valve stem seals or a damaged piston ring . Post pics of those valve covers if you can. I am curious to see just how much force that crank case explosion caused

 

If you are using MLS head gaskets and did not deck the block you probably have an issue. Almost every MLS gasket I have dealt with requires a certain finish to proper seal. This often requires the heads and block surfaces to be finished. Cometic recommends a 50 RA or finer for their gaskets.

 

Ok guys.

So despite all my former issues with the build that I mentioned, I managed to do some troubleshooting and I figured out what the issue was. Here were my steps and the conclusion.

1.) I borrowed a $20K GE XLG3 bore scope from work, removed my carb and checked the seal around my #3 cylinder looking for sealant around the #3 intake port to make sure that there was no oil coming from the valley. This saved me from having to pull the intake manifold and do another re-seal job if it wasn't really needed. Everything checked out fine and I gotta say the equipment was amazing
2.) I pressure tested the cooling system to 15psi for about 30 minutes using a tester from Autozone and didn't lose any pressure.- So it wasn't the cooling system.
3.) I leak down tested the whole motor and all cylinders were easily <5% leakage and there was no bubbling in the cooling system either- so no cylinder head gasket issues!! WHEW!!
4.) When I removed the carb to use the bore-scope, I noticed quite a bit of oil in bottom of the driver side of the manifold. While probing I also saw a lot of black crap on the walls of the #1 and #3 cylinder passages in the manifold- mostly wherever there was a change in flow direction.
5.) This got me thinking... why the hell would there be oil in the intake manifold? Where would it be coming from? Surely not from the valve seals all the way back into the intake manifold.
6.) Answer --> the PCV valve.
7.) Plugged the PCV port on the carb and installed a breather on the driver side valve cover and I also drilled 4x 1/8" holes in the baffle/slash guard below where the PCV mounts in the valve cover; just to make sure oil wasn't able to pool in any appreciable quantity below the PCV valve. I fired the car up and it smoked for about 1 minute after start-up and then cleaned up beautifully! I took it out for a drive and then checked the plugs and they looked MUCH better.

Conclusion and Final Thoughts:
It basically turns out that this was another case of "performance parts" on a "stock look" build. My cam doesn't make enough vacuum to keep the stock (correct) 427 - 390hp PCV valve closed so it's basically sucking oil with the PCV valve open at idle/cruise- hence the high oil consumption. The stock motor makes about 14" Hg and I'm more like 10" Hg. In addition to fixing the smoking issue my idle and measured idle vacuum are MUCH more stable than ever before! The car doesn't hunt for it's idle speed like it used to which was another outstanding annoying and unknown problem that was luckily solved by this little project. I haven't yet installed a new valve to see how it runs with a different type, but the stock CV 735C AC Delco PCV valve was definitely not correct for this application. The next one going in is equivalent to an late 60's L-88 AC Delco part number CV 746C. **As a side note this may actually fix my engine knock issues at only 30 degrees of advance- possibly from oil in the intake charge significantly lowering the fuel octane (a separate post I made).

I seriously still can't believe that this little $6 piece of sh*t was the problem. I was literally about to start ripping the motor apart or doing some otherwise SERIOUSLY time consuming and invasive work. Considering how little information there is on the internet and even here on CF about the influence of these PCV valves, it really makes me wonder how many guys out there are suffering from the same types of issues (oil consumption, knock @ low advance, crap idle), not knowing that it's a PCV valve mis-match. They don't even have any specs/details for these valves so that you know what to use or how to test them etc.! It's pretty crazy. You really only have 3 options, PCV delete, pick one from a similar stock high perf. application, or just go through trial and error until one works correctly.

In any case thanks for the help and words of wisdom guys! Tell your friends about this one and save them some work!
Sum

 

If you ever want to check your PCV valve to see how much oil is getting sucked through there just place one of those cheap glass inline fuel filters between the pcv port on the carb and the hose from the valve and go for a 10 mile drive. There are 60 tablespoons to a quart so if the filter has a tablespoon in it after say 10 miles, you would be burning a quart every 600 miles right through the valve. Most of the time aftermarket valve covers with poor baffling are the problem. My "tester" is below.

 

Great findings, I've always been a proponent of keeping the PCV system functional (using a PCV Valve) but never really thought about the changes a Cam can bring into the mix. I went the extra mile on my build and fit what appears to be a well designed baffle on the the PCV Valve side (not fun due to stud girdles, also didn't want small hardware inside V/C that could work loose so I machined some captive mounts), I will be checking the efficiency using the CGrant method (genius, even if CG didn't come up with it).