Grey Smoke During Deceleration

The cheapest solution is “run it”.

Did you get the umbrella seals, or the Viton clip-on seals?

With the head work you had done, it shouldn’t be leaking from the valve guides or seals…

Any difference between the sides of the engine?

How do the plugs look?

Rocky

Steve,

Possible intake manifold gasket leak.

John

The valve job was done with Viton clip-on seals.

Grey smoke was coming from both sides and that made me suspect a bad seal from the intake manifold gaskets.  I re-torqued the intake manifold and upon startup it still smoked but that could be residual oil.

I will be mounting a camera that records exhaust output in an effort to better understand this issue.

It may simply be that the rings are not seated yet? It may take maybe a thousand miles for it to settle down?

I am guessing the engine has more than 10,000 miles on it and the rings are seated (maybe even a little worn based the compression test).

I don't think the engine was smoking at startup prior to the Sunday outing.

As John suggested, I will pull the intake manifold and inspect and replace the gaskets.

Again, smoke is coming from both sides.  Here is a picture of spark plugs.

The problem might be fixed.

I reinstalled the spark plugs and fired the engine prior to pulling the intake manifold.  To my surprise, there was no smoke!  As I mentioned earlier, I re-torqued the intake manifold bolts.  When doing so, I found the four 5/16 bolts were not very tight while all of the 3/8 bolts were already snug.  Tom Monroe's book for the 351C says torque for the 5/16 bolts is 21-25.  I have been using 25 pounds and have always thought it was a little light.  This time for the re-torque I simply muscled them down until they felt snug.

Spinning the motor for the compression test may have purged excess oil that had been hanging around prior to re-torque of the manifold.

Last Sunday's outing was the most demanding the car has done since the cylinder heads were reinstalled and may have revealed the problem with the under torqued bolts.

This Saturday our club has another event at Hillbanks Motorsports in Irvine and I will be taking the car there.  It should be a good test.

Grey smoke continued to be an issue and I pulled the intake manifold today.  It looks like the bottom of some the intake ports are not sealing correctly.  The gaskets are FelPro 1228.  The intake is Edelbrock Torker.  Cylinder heads are the original 351C 4V.  I am trying to figure out how to avoid this again.  Earlier I found that the four 5/16" bolts were not tight enough even though the got 25 lbs torque at installation.  I appreciate your suggestions.

Do you have a closed PCV system?

The PCV valve is on the left valve cover.  A hose runs from it to the PCV port on the carb.  There is a breather cap on the other valve cover.

The connection to the carb needs to be higher then the connection at the valve cover otherwise you will siphon oil into the intake manifold.

This is a common issue with Fords and their PCV system.

You also need a proper operating PCV valve in order to apply negative pressure (vacuum) to seal the piston rings.

The oil filler cap also needs to be vented as the fresh air source into the PCV system. If it isn't, for sure you are siphoning oil from the valve cover. Depending on the cam profile as far as how much idle vacuum it gives you, it is possible that you may need to restrict the fresh air intake.

I had to do that with my Weber set up. Webers aren't often run with a "closed" PCV. In order to maintain a decent idle vacuum, the air intake needed to be restricted.

As I said previously, it sounds like your rings are not completely seated and it may be related to a non-functioning system.

Put a clean white t-shirt over one of the exhaust tips while the engine is idling. See if there is oil residue on it.

You can get exhaust smoke from the carburetor as well. Usually the accelerator pump but it could also be that the float level is set just a little bit too high.

With a Holley carb and E85 fuel, you need to set the fuel level in the bowls about 1/8" lower then the edge of the site plug hole.

With the current E85 fuel, the Holley fuel level setting instructions ARE WRONG. You will be set too high if you follow them.

The Edelbrock Torker intake is single plane and is some what of a tall manifold.  Once the Holley 750 mechanical secondary carb is in place it looks like the PCV intake port is well above the altitude of the PCV valve's location on the valve cover.

The PCV valve is new and seems to be working correctly.  However, it is difficult to ensure that the valve I purchased is correct and optimal valve for this engine.

The breather cap on the opposite valve cover is vented and self filtering.  I do not know the specs on this cam but it seems to produce good vacuum at idle.  When disassembling the intake I noticed that the brake booster tube was not tensioned properly and could have been a vacuum leak.  Perhaps my brakes will work better after this.

It looks like the floats on my carb are adjusted too high.  I have been suspecting such.  This Holley carb has built in sight windows.  I will lower the floats as you suggest.

I am letting the silicon sealant on the manifold dry overnight and will test this in the morning.  Testing is a little tricky because it involves watching the the rear view mirror (looking for smoke) and scrutinizing the dip stick for oil consumption.  I am hoping the new gaskets, increased tension on the intake manifold bolts, and lowered carb floats solve the problem.

Also, it is better to take off the deck lid when doing this type of work.  It is only the removal of a couple of bolts and hinge pins, and assistance from a helper to remove it.  Doing so makes reinstallation of the intake manifold easier and more precise.

@stevebuchanan posted:

The Edelbrock Torker intake is single plane and is some what of a tall manifold.  Once the Holley 750 mechanical secondary carb is in place it looks like the PCV intake port is well above the altitude of the PCV valve's location on the valve cover.

The PCV valve is new and seems to be working correctly.  However, it is difficult to ensure that the valve I purchased is correct and optimal valve for this engine.

The breather cap on the opposite valve cover is vented and self filtering.  I do not know the specs on this cam but it seems to produce good vacuum at idle.  When disassembling the intake I noticed that the brake booster tube was not tensioned properly and could have been a vacuum leak.  Perhaps my brakes will work better after this.

It looks like the floats on my carb are adjusted too high.  I have been suspecting such.  This Holley carb has built in sight windows.  I will lower the floats as you suggest.

I am letting the silicon sealant on the manifold dry overnight and will test this in the morning.  Testing is a little tricky because it involves watching the the rear view mirror (looking for smoke) and scrutinizing the dip stick for oil consumption.  I am hoping the new gaskets, increased tension on the intake manifold bolts, and lowered carb floats solve the problem.

Also, it is better to take off the deck lid when doing this type of work.  It is only the removal of a couple of bolts and hinge pins, and assistance from a helper to remove it.  Doing so makes reinstallation of the intake manifold easier and more precise.

It just seems SO unlikely that the intake and gaskets are leaking anything.

DO NOT over tighten the intake bolts. 20 lb-ft is PLENTY.  The end bolts have been known to snap off the ears of the intake manifold itstelf. Particularly the driver's side, left rear.

I'd recommend the M.E.Wagner set up. It isn't just for the adjustability but it is the only PCV that comes close to closing 100% at idle.

Unfortunately the "replacement" PCV's that are obtainable supposedly as original replacement are totally and completely trash.

In a situation like you are in, they just complicate matters.

IF you haven't already tried to eliminate the PCV from the car for testing, you should however there are other sources of oil getting into the intake system that are possible and one of those is valve guides.

NONE of the valve guide systems are 100% tight and in reality they shouldn't be because the stems do need lubrication.

In the past I have been in a similar situation as you are now and sometimes just putting up with the smoke for now and driving it clears up the issue.

Best that I can do for you at this point is wish you good luck and hope that this is all caused by something silly that was overlooked and an easy fix.

You wanna' see exhaust smoke? Watch one of these bonsai starts with a Weber set up. The exhaust throws absolutely everything out but bolts.

Thanks Doug.

I will likely get the ME Wanger adjustable PCV.

Also, I should have mentioned that three of the intake port walls in the cylinder heads were tacky with oil while the others were dry and clean.  The three ports were the ones with oil on the gasket face.  And the entire intake manifold was clean on the inside with no signs of oil.  Thus, it is kind of pointing to the gaskets at this time.

You have a very unusual scenario. You need to look for something very unusual.

However if there is oil in the intake ports, it's more likely then not that it is the pcv.

I telling you, that is very common on a Ford and constantly overlooked.

It's very uncommon for the intake gaskets to leak.

Steve, the only thing I can imagine which hasn't been covered is the possibility that the block, heads, or intake manifold were not machined correctly.  Your OP stated you got the car with the heads off, so you may not know exactly what work was done previously.  Your photo of the intake valley leads me to believe that the head and intake surfaces are not parallel.  Now you would think that would also be a big vacuum leak, but with a closed PCV system, it might not be enough to notice.  Just a thought.

I was wondering the same.  The Felpro gaskets are very thick and perhaps they are intended to help compensate for this type of issue.  The thickness of the gaskets may have worked against me.  During the current reassembly I noticed that I used thin washers on the the 5/16 bolts and they had deformed.  Perhaps this was from heavy torquing later.  In any case the gaskets and washers may have added to the problem by relaxing when everything got up to temperature and then shrunk after cooling.  It is now reassembled with new gaskets, clean surfaces, and thick washers.  So far, so good,  During this I found a likely vacuum leak in the brake booster hose connection.  And Doug has identified a likely carb float level issue and possible improvements in the PCV system.  When the car fired up today it sounded better and I could not detect grey smoke.  I drove it a fair amount without issues.  My fingers are crossed.

Steve - did one the prior posts say that you were running e85? If so, just curious as to why?

No, I put 91 octane fuel in the car.  I think Doug was saying that the Holley float needs to be lowered if anyone has to run E85.

I have good news and bad news.   We ran the car today and it looked good at first and there was no smoke.  Then I ran it in first gear to red line and released the throttle in an effort to produce maximum vacuum in the engine.  The engine released grey smoke on left side only.  This is actually a step forward because the smoke had been coming from both sides.  Maybe the intake gasket slipped when installed.  I will pull the intake again and try to find the root cause.

Steve, with your roller cam and the late model dogbone spider to hold the lifter wheels in alignment, did you notice if the spider fits flat to the valley surface of your block? On the retrofit hydraulic roller cams in 351-Cs I've seen, that sort of installation completely or nearly blocks off the Cleveland's rather skimpy valley oil drains. If so, depending on your oil pump it's quite possible to substantially fill the whole valley up with oil. That much extra oil in there might be intruding into areas it shouldn't be able to reach. And of course by the time the intake is pulled, the excess oil has drained back in the pan so there's no evidence.

To fix this on my neighbor's 427 stroker Cleveland, we added three flat washers as stand-offs between the block and the spider for each of the spider bolts. We used longer bolts also. Late model roller blocks have the spider holes threaded in 1/4" high cast stand-off bosses to keep this from happening. There's enough tension in the springy spider to absorb that much stand-off. Cam sellers apparently never mention this possibility in their instructions.

Try it- its cheap, simple and has no negatives if it doesn't fix your smoke problem. Good luck.

I prefer the Mr.Gasket's. It could be the high tech that's killing you?

Fel-pro's are not the best choice on intake gaskets.

I have the intake off again and everything looks perfect.  It does not look like oil is getting past the intake manifold gaskets on this go around.  I called Wilkinson and he is thinking there was too much crankcase pressure during the hard deceleration test and it pushed oil up cylinder walls into the combustion chambers.  The cylinders with the lowest compression are on the driver side and that is where the smoke appeared.  He suggested doing the same deceleration test with the PCV valve disconnected.  I get a new set of gaskets tomorrow and plan to test again on Monday as the silicon will be cured by then.

Jack, I pulled the retainer for the lifters and found they had drilled four holes likely to help oil find its way down from the valley.  The two holes without arrows are for the bolts.  I will continue with this setup for time being.

IF you have too much crankcase pressure it will push oil past the seals on the crank.

The seals can only hold about 15psi max.

If you only smoke under that condition you created and not all of the time, you do not have an issue.

I already suggested that your rings still aren't 100% sealed. This is a symptom. You need to put mileage on the car, not just idle it.

It needs to go through cycles of acceleration, deceleration, hot starts, cold starts, etc.

Depending on the rings that are in there and how tight the pistons are to the walls also affects oil blow by.

A certain degree of it will always be there.

Steve - you must have incredible patience to do multiple manifold r&rs!!! My back is sore just reading this thread.

As a newbie Pantera owner who will be replacing my intake soon, do you go to the trouble to remove the 'trunk' lid? Do you have to access any fasteners through the bulkhead opening??

Thanks

Thanks Doug.

Interesting.  I am not seeing much oil dripping from the crank seals.  But I have noticed the front of the motor had a lot of old oil buildup that I have not seen on other Panteras.

The amount of smoke the car emitted is beyond what is acceptable to me even though it is not happening most of the time.

I don't know the history of this car but I get the impression that is was a street racer back in late 90's.  It had every ignition upgrade that MSD offered at the time including a crank trigger distributor which tells me they built it for high RPM use.  When I got the car It had been sitting for 20 years.  It had a blown head gasket between #6 and #7, the heads were off, and most of the ignition upgrades were MIA.  There was no lip on the cylinder walls.  Its clutch slips on the freeway.  My hunch is that the engine has seen a lot of hard running and the rings are well beyond seated and perhaps even tired.  You can see it in the compression test at the beginning of this thread.  When time permits I plan to pull the engine and trans.  Then I can replace the clutch and methodically go through the motor and at a minimum replace the rings and hone the cylinders.

The more I can do now to sort out engine issues will contribute to a more successful engine refresh later.  And I get drive around a Pantera in the interim.

Rob,

It is best to remove the rear deck lid when removing and installing the intake manifold.  This is especially true for the installation of the manifold.  The deck lid comes off readily by placing a length of PVC pipe (or a stick) to hold up the lid, removing the top bolt on the struts, tap out the hinge pins, and then slowly lower the lid.  Then you and a helper can lift it off the car.

You do not need to open the bulkhead cover to work on the manifold.

And Rob, Welcome to the party!

If you plan on doing a lot of engine work to the car consider install a block and tackle hoist in one section of the garage for the deck lid.

Rebuilding the short block is another alternative.

Suggest checking to see if the pcv valve is not flowing because it's bottoming out against the sheet metal piece that sits too close to the PCV in some valve cover's hole.

Richard O.

I did the test with the PCV valve removed and it smoked more than when it was in place.  At this point I am thinking the rings are tired and the engine needs a rebuild.

Richard, I don't think the PCV valve is having that problem because the valve covers are tall and there is a lot of clearance.

The fact that you blow oil, more oil with the pcv disconnected is an indication of rings not sealing.

The vacuum that the pcv system provides to the sump aids in sealing the second ring, the lower ring.

I presume that the grey cloud is bad enough now to want to correct it?

I should also point out that valve guides with not enough sealing will also give you puffs of exhaust smoke.

From how you are describing your frustration probably the only way to deal with this is pull the engine out and disassemble it for examination?

Best of luck on this project. There isn't anything tricky about a Cleveland. Just put the right parts into it, assemble it carefully and it should be fine.

Thanks Doug.

During normal driving there is no smoke at all and at this point there is only a puff on the driver's side during the hard deceleration test.  I won't be able to work on it for about six month and the motor is good enough for the time being.

The motor should be nicer after the rebuild with all eight cylinders at about 160 PSI compression. Along with any other issues I can find and fix it will be a step in the right direction.

When the engine and transaxle are out it will be easy to clean up the engine bay. And the transaxle can get new seals and gaskets and then it will leak less.

Sounds like a plan.

The only additional  comment that I would have at this point is that you don't want 160psi compression. That's too high for pump gas.

You want 125 to no more then 140. 135 is a good target to shoot for.

160 is an indication that the cam you have is too mild for your application. That's like an RV cam. You are just going to have problems with detonation on pump gas.

You need a cam profile that keeps the exhaust valves open longer to blow off some of the compression.

It should be at least around 235° @.050 to get there.

Be careful of too much static compression with a Cleveland. To me, 9.5:1 is about right.

For some reason the shape of the small chamber heads can't handle too much more without serious detonation.

10.5:1 ADVERTISED is about 9.8 actual. That's right on the edge. 9.5 IS  a safe compromise.

IF you would accept running on pure leaded racing gas of 108 octane, you can easily get 800hp out of these engines.

A half year later I may have identified the problem.  The car sat inside a mechanic's shop with the cylinder heads off for about 20 years.  The mechanic eventually moved to a new location and the car ended sitting outdoors for a while.  There was a small amount of water in some of the cylinder bores when I got it.  My hunch is that the some of the piston rings are frozen with rust.  I am thinking that the inconsistent compression readings are due to frozen piston rings.  This may also be the source of grey smoke and oil consumption.

...Roller Cam with OPEN chamber Heads?? How does that work? Roller builds power...Open chambers won't 'Allow' it, lose the HP.

Compression test, either No carb or Throttle Blocked Wide Open, and after shooting a couple shots of oil into cylinder, when engine is cold. Or test when Hot. Your numbers look OK, All with-in 10% of each other. I run Closed Chambers at 10.5:1 CR on 91 Octane 'Pump Gas', 118F Ambient Temperature...I Have Never had a Problem with it! This is NOT Theory! It has been Proven!

You said the engine still smokes after eliminating the PCV, Got it. You also mentioned, the Center 5/16" Bolts* were 'loose'. The Exhaust Cross-Over in the Head is Open through the Port in the Gasket, (see Pic) Oil can be Syphoned/Scavaged into the Exhaust and Burned in the system, when the gasket fails to seal the Port!

There are 7 ways a V-8 Engine will Burn Oil:

1. PCV (eliminated)

2. Head Gasket

3. Intake Gasket at the Ports or Syphoning at the Exhaust Cross-Over. (mentioned)

4. Air Cleaner (inside) Breather Hose (opposite valve cover to the PCV)

5. Valve Guides and/or Seals (mentioned)

6. Pistons and Rings

7. Ruptured (mechanical) Fuel Pump DIAPHRAM. Pump works 'So-So' and Mixes Oil into the Gasoline and is Burned. But would show on Both Sides Engines' Exhaust.

* For those who did Not receive My Memo:

When installing a Intake Manifold onto a Cleveland...first take (4) 5/16" x 3" Bolts hacksaw off the heads, or obtain 5/16" studs, hand thread them into the 4 center holes, hand snug. The Manifold will guide down onto the Gaskets, Perfectly! Remove the Studs After all other bolts have been Started. Most important, these Studs also prevent the Gaskets from Slipping Down, out of position. Pull the studs out, put the bolts in and do the final Torquing in proper sequence and in increasing levels of torque. Do NOT Over-Torque.

MJ

The Edelbrock Torker  2760 for the 351c does have a heat crossover as well as the choke well. The Ford Motorsport A331 version does not.

...The Exhaust can Scavage Oil at that Point should the Gasket Fail.

MJ

Marlin wrote:   ...Roller Cam with OPEN chamber Heads?? How does that work? Roller builds power...Open chambers won't 'Allow' it, lose the HP.

Well, Marlin is the second person to comment on this and it got me thinking.  Wilkinson saw the car running and essentially said "Closed chambered heads would add about 100hp!".  That would be great if it pans out and I will take almost any fraction of that.  I recently found a set of original and unrestored D0AE closed chamber heads and will try to get them setup similarly to the open chamber heads currently on the car.  That way I can safely swap them in and hopefully enjoy the performance improvements described above.

...After Installing a set of Closed Chambers (over the 'Open') You will be Amazed at the Improved performance! At a 63cc 'Combustion Chamber'. I believe, correct me if I am wrong...the Open chambers are 111cc? 117cc? chamber.

At any rate, you are Increasing the compression ratio from 8.0 to 9.5 IF You keep the 'Dished Pistons' (or have they already been replaced?) as Closed chambers with FLAT Top pistons, with valve reliefs give 10.5:1 CR.

Be sure to have the heads Machined for 7/16" Screw-In studs. ala 'Boss 351'. And be sure to have ALL Sharp Edges Polished Off.

The Two 'Major' Parameters that Drastically Increase Horsepower, in My Book, are,

Compression! And Valve 'Curtain' Size, along with Valve Bowl Polishing, the way I went. The Valve 'Curtain' is The Intake Valve Diameter X Actual Vale Lift Off the Seat. And remember, the 'Actual' Compression is determined by the Opening and Closing, Timing and the Durations of Both Valves...Relative to the Position of the Piston during it's Stroke. 2.190" Intakes are Huge on the Cleveland 4V Heads. Some have gone to Aluminum Heads with smaller Valves believing this increases Flow, as It does increase Air Flow Speed, (I) Don't know for sure, may be a 'Trade-Off'. On the Dyno...it's All About 'Volumetric Efficiency'!

Do it! When You're seeking Much Higher Performance. You will Not Regret it!

Just do it right and Complete it. Every piece must compliment the others, starting with the CAM, Heads, Manifold, 'Carb', Headers. And Yes, the Ignition and it's Timing is Crucial, and a Whole 'Nother 'Ball-Game'.

Good-Luck with it!

You don't have to 'Hope' for it!! You WILL be Gloriously Rewarded! HOPE is Not a Strategy!

MJ

Open chamber heads volume is 78.5cc (measured on my heads).
It is quite possible to increase the static ratio with another form of piston heads and/or by milling the cylinder heads. I have a static ratio of 10.6:1 on my 382 CI stroked engine with my open chamber heads.
Closed chamber heads are certainly better but they are hard to find here in Europe and are very expensive.