Smoke after WOT

[josehf34]

My '74 Fury has a 360 but I've always noticed some smoke just after revving engine at wot. It looks like a gray smoke but some times i think he has some of blue

The engine is freshly rebuilt, engine and head gaskets has less than 2 months since installed, valve seals are new and when installed them checked the valve guides and I think they were ok so I don't know where should I look for this, i don't know if matters but 2 months ago installed a 262H comp cams camshaft and new lifters, this only happens If I rev the engine too much, in part throttle or light acceleration I don't see any smoke coming from exhaust

I suspect this has something to do with a rich condition under WOT, since I swapped my carter to a street demon I've been dealing with the tuning and I think isn't finished because all my plugs are dark black

Here's a short video of the problem: Dropbox - IMG_4760 (1).MOV

 

[Turboomni]

Sounds like it was missing when you goosed it and afterwards it was rich and maybe the cause of the unburnt fuel. I'm sure the experts will chime in.

 

[The Horvaths]

Secondaries are too rich. Or maybe your accelerator pump. Get rid of that Demon and put the Carter back on. I don't think it's missing; it sounds like the mic breaking up.
Or, it could be a bad gasket causing coolant to leak. Does it smell sweet?

 

[josehf34]

Sounds like it was missing when you goosed it and afterwards it was rich and maybe the cause of the unburnt fuel. I'm sure the experts will chime in.

I'm not sure if I the engine is missing, I think not or at least I have not felt that in any moment

Secondaries are too rich. Or maybe your accelerator pump. Get rid of that Demon and put the Carter back on. I don't think it's missing; it sounds like the mic breaking up.
Or, it could be a bad gasket causing coolant to leak. Does it smell sweet?

I can't put the carter back, is completely messed it only runs or too rich or too lean, but I agree with the possibility of secondaries running too rich, right now my main metering jet is a #76 and secondaries are #78, I think I'm going to try with #74 in primaries and #76 in secondaries or even lower

 

[Ripinator]

I'm not sure if I the engine is missing, I think not or at least I have not felt that in any moment



I can't put the carter back, is completely messed it only runs or too rich or too lean, but I agree with the possibility of secondaries running too rich, right now my main metering jet is a #76 and secondaries are #78, I think I'm going to try with #74 in primaries and #76 in secondaries or even lower

Sounds like you got two problems: one related to oil burning (blue smoke) and another related to a rich mixture condition (black sooty plugs). I wonder if your newly rebuilt engine is fully broken in yet. If not, that might contribute to a little blow-by at the piston rings, or if you didn't renew the valve guides during the rebuild, there could be a little oil slipping by there. What kind of oil (brand and weight) are you running? I've heard that some synthetic slippery oils actually delay or inhibit the break-in process. If applicable, maybe you could run some straight 30-weight dino oil for a couple of change intervals and see what happens.

As regards the rich condition, it seems like an often recommended solution around here is to replace the carb with Eddy 1406. Of course, you could first play around with the jets / needles, etc. until you get tired and frustrated, and then give in and buy the 1406 . . .

 

[josehf34]

Sounds like you got two problems: one related to oil burning (blue smoke) and another related to a rich mixture condition (black sooty plugs). I wonder if your newly rebuilt engine is fully broken in yet. If not, that might contribute to a little blow-by at the piston rings, or if you didn't renew the valve guides during the rebuild, there could be a little oil slipping by there. What kind of oil (brand and weight) are you running? I've heard that some synthetic slippery oils actually delay or inhibit the break-in process. If applicable, maybe you could run some straight 30-weight dino oil for a couple of change intervals and see what happens.

As regards the rich condition, it seems like an often recommended solution around here is to replace the carb with Eddy 1406. Of course, you could first play around with the jets / needles, etc. until you get tired and frustrated, and then give in and buy the 1406 . . .

I think the engine isn't fully broken in, I haven't driven the car too much since the engine was rebuilt and in these months I've disassembled the engine a couple times to change camshaft, lifters, check timing chain, change valve seals and try to find the reason for this smoke. Right now I'm using Castrol 15W30 mineral diesel engine oil with comp cams additive for the new camshaft I don't know if matters but my oil pressure at idle is 55 psi and at 1500 RPM and above is always 75 psi.

When the engine was rebuilt the machine shop guy told me that they didn't change valve seats or guides because the original ones were in good shape

About the carb... I think I'll stay for the moment with the street demon, is an awesome carb but have a serious design problem, a change jets or metering rods is way more complex that has to be.

I forgot to mention something: When I'm adjusting the idle screws of the carb (doesn't matter if is the carter or demon) and the engine is out of tune and popping through exhaust I can see blue smoke coming out but once the idle is fine and I've good vacuum signal the blue smoke at idle and part throttle disappears

I'll try to change jets again and let's see what happens

 

[thrashingcows]

What intake are you running? I was having a similar issue with my 440 in my wagon, but it's an old tired motor. Anyway during a WOT blast it runs super clean, no smoke, missing or other issues, but once you let off the throttle it would take 5 sec or so and it would pull a James Bond smoke screen.

I eventually figured it out, it was the intake and gasket had blown out on the heat cross over. I was running a late 440 spread bore, cast iron intake so i could run a TQ. I installed a Edddy performer, new valley pan gasket and sealed it well around the heat cross over on the heads....no where near the smoke it had before....just a little puff here and there from worn cylinders and rings etc.

May not apply to a small block situation, but something to look for and keep in mind. ;)

 

[1978 NYB]

Wait minute.....

Is this smoke generated when you are standing still or just when you are accelerating under WOT?

 

[1978 NYB]

If the smoke is generated under acceleration I would check the gasket at the back of the intake manifold to see if engine oil is leaking and going past the transmission and getting on the exhaust pipes.

 

[josehf34]

What intake are you running? I was having a similar issue with my 440 in my wagon, but it's an old tired motor. Anyway during a WOT blast it runs super clean, no smoke, missing or other issues, but once you let off the throttle it would take 5 sec or so and it would pull a James Bond smoke screen.

I eventually figured it out, it was the intake and gasket had blown out on the heat cross over. I was running a late 440 spread bore, cast iron intake so i could run a TQ. I installed a Edddy performer, new valley pan gasket and sealed it well around the heat cross over on the heads....no where near the smoke it had before....just a little puff here and there from worn cylinders and rings etc.

May not apply to a small block situation, but something to look for and keep in mind. ;)

I'm running an airgap intake. My intake gasket is new but was a really pain in the ... get it installed! honestly I used like 4 gaskets before getting it properly installed because was leaking coolant everywhere inside and outside the engine and If my memory is right I remember to see a little bit of oil in the intake runners. Is there any way to check this without removing the intake?

Wait minute.....

Is this smoke generated when you are standing still or just when you are accelerating under WOT?

I'm not 100% sure, If I'm standing still I think I'm not having any smoke but under WOT or maybe 3/4 of throttle I'm sure will have smoke

If the smoke is generated under acceleration I would check the gasket at the back of the intake manifold to see if engine oil is leaking and going past the transmission and getting on the exhaust pipes.

I've had that problem from a time ago, just yesterday changed again the valve covers gasket because I thought he was leaking through here. If i touch the engine near the transmission bell housing I can feel that there's some oil

How can this be related to this problem?

Now that we're talking about intakes and oil, I've always see a little oil pool between the intake and heads, in the gap between the carburetor and the bottom of the intake and in most of the spark plug holes I can see a little oil pool. Can this be related?

 

[1978 NYB]

I had that problem with my 73 Ralleye Challenger with a 340. Smoke like hell when under WOT acceleration. The smoke looked like Richard Petty with a blown engine at Daytona. LOL. The oil was slamming out past the rear intake gasket and getting on the exhaust. Only during WOT acceleration runs. I would take some engine degreaser and get the back of the engine, txsm, and exhaust cleaned off so you can check to see if the oil is leaking past the rear of the intake at WOT. I would start with that before assuming you have an internal engine problem.

 

[josehf34]

Yesterday I checked for oil in the rear of the engine, I didn't find a clear or big oil leak but some of the RTV sealant that is in the rear of the intake has some oil on it, also take the chance to check the spark plugs and none of them has traces of oil on it, them are only black (check attachments) and also I took a picture of the small oil pool in the plug ports, I don't know if it has something to do with burning oil just after wot. I forgot to inspect if the PCV has oil on it, I'll do it today and post the results

I'll degrease the engine and see what happens

 

[moper]

Sounds more like rings. Over rich will dilute the oil, causing the rings to not seat properly. If the wall finish is right and moly rings are used, they would be seated when the cam is done braking in (the first one). If the wall finish was too rough, the moly gets scrubbed off and then the rings should seat like the plain iron faced rings (that takes some miles). I would definately fix the rich condition, and then drive it for another 500 miles or so and see if it stops. If it doesn't, have a leakdown test done and post the results.

 

[celticwarlock]

Those photos do not seem to suggest straight-up oil burning. The deposits on your plugs look like the result of a very rich mixture. In my experience, a motor that burns oil will leave white ash deposits on the plugs. In any event, if the motor has not broken in, you can expect a certain amount of oil burning, yes? I'm sure someone will correct me if I'm wrong. If it is occurring after wide open throttle, then whatever the problem is, it's evident during a high vacuum condition. Quite often, such problems result from valve train issues. Please keep us apprised of how this all shakes out. I'm sure I'm not the only one (other than you) who is curious about the cause.