302 smoke accompanied by misfire

[Brownie Mobile]

So I've been trying to track down a really inconsistent misfire for a while now. Thought I had it paid 160 for a tuneup performanceish stuff helped a ton. Never would've thought cap coil wires would make such a difference. This didn't get rid of my misfire but it made it way less frequent. Still there though and that bugs me. To qualify this is a truly inconsistent misfire. I'll start it one day and it'll run great for 2 or 3 days I feel like I could pull pikes peak in final gear (4th). Then one day it'll run like crap doesn't matter what temp it is. Outside if it's running crappy it's running crappy. But is dominantly running good since tune up. A couple days ago I was watching the radiator for leaks with it running ( on All 8) and it starts missing and not a 1/4 seconds later smoke started coming out of the valve cover oil fill and breather......thing. I've come to a few hypotheses. Getting water in combustion chamber head gasket etc. ( no water In oil or vise versa). Valve issue someone mentioned valve timing could be off. Bent valve. Flat spot on lobe ( aftermarket cam). Oh and I can't say for sure but judging by my spark plugs which were not rusty looking btw. 7 is the one missing. Also engine wants to die when turning heavily.( last pull into my parking spot is a sharp angle) has died a few times in that single situation turned up the idle good now. But sometimes it'll drop down to 5 or 600 rpm I set idle to 900 because of preference. And it won't come back till I hit the gas and then it returns to 900 rpm
Also considered fuel pump issue or other fuel delivery issue. Not enough flow for a 4 bbl? (Edelbrock 500 or 650 cfm not sure)Sorry for brownie mobile novel #2 hope somebody can help thanks.

 

[RonD]

As for the sharp turn and dieing, check float level, could be too high and you are flooding engine via the vent.

What color was the smoke?

Coming out the valve cover at idle would mean either the PCV Valve failed, or you have a cylinder with very bad rings.
Exhaust smoke is where head gasket issues show themselves.

All piston engines have "blow-by", blow-by is when a cylinder fires and some of the expanding gases, that give you power, are pushed passed the piston's rings.
The Blow-by gases are very hot and vaporize some of the oil on the cylinder walls, this is where oil vapor in the crankcase and valve covers come from, the oil lubing the valve train is not a vapor, it is sprayed but not vaporized.
The blow-by also increases the internal pressure in the crankcase and valve covers, in the old days there would be a vent tube in the lower block or upper oil pan that would vent this vapor and pressure to the outside, this tube was just pointed down at the ground and would have a constant drip of oil as the vapor condensed inside the tube.
PCV(positive crankcase ventilation) was added to prevent this leaking of oil on to the roads.
The PCV valve creates a suction, via intake vacuum, and pulls the blow-by oil vapor into the intake to be burned instead of dripping on the road.

A vacuum gauge test can tell you general ring condition, vacuum gauges are $25 and a good tool to have, read here for testing:
http://www.gregsengine.com/using-a-vacuum-gauge.html

A dry then wet compression test on each cylinder would tell you which specific cylinders are effected.


Check distributor rotation, worn shaft bushings can cause a wobble that can come and go, real pain to track that down, new cap and rotor may have made it less noticeable.

 

[Brownie Mobile]

I wanna say it was white so I've been leaning toward head gasket or head problem. Don't have my pcv valve hooked up yes it smoked a bit more after I removed it but not this bad. This engine should be alright as far as rings it was recently rebuilt ( I didn't do it nor do I know who did but a few car savvy people said it seems fresh rebuilt) float level got it. Vac gauge coming on payday I can do the compression rest though sometime soon. Best way to check dizzy Rotation? Was thinking possible timing chain issue? I know a lot of my theories wouldn't cause misfires per say but I've heard of strange things happening like rings lining up etc that could be accentuated by these problems.

 

[ab_slack]

I don't know the 302 and RonD usually has good info.

I wonder why not have the PCV hooked up?

Just some general thoughts.

I tend to think hard mechanical issues like valves, cam and such wouldn't cause good to crappy intermittent stuff. I suppose there are some times if something on its way out it might. Similarly a blown gasket.

I tend to think of things like intermittent connection, flakey vacuum line or moisture getting into something.

RonD's comment about the float makes sense for the turning issue. That can also be vacuum or electrical if it shifts wires or vacuum hoses just a little.

I'd be inclined to check out vacuum lines. If the crappiness is noticeable at idle, wait till it happens and then poke at lines, make sure no cracks and connections are snug.

 

[RonD]

White smoke out the tail pipe would be head gasket
White smoke out the valve cover would not be head gasket, could be cracked head but in the top of the head and you would get a sh!t load of coolant in the oil pan if that were the case.

And reinstall the PCV valve, engine and carb are setup for that "controlled vacuum leak", and make sure oil fill cap goes on tight and dipstick is in all the way, that seals the system and allows the Breather to pull in fresh air as needed.

Pull off distributor cap move it out of the way and have some one crank engine, watch the rotation to see if there is a wobble, also push and pull on the shaft to see if there is any play.

 

[Brownie Mobile]

Weathers kinda shitty right now so I got the day off unfortunately that means i can't do anything on my truck either. Talked to a master mechanic with 40 plus years of experience he said sounds like a valve seal starting to go out and that's why it's been inconsistent. So a long with the vac gauge gonna do valve seals as well I needed new valve cover gaskets anyways doing the typical ford thing..... I'll try to keep you posted but won't be able to do much between work and weather right now. Got to find a place I can fit our service truck and my truck in doors. Edit: just realized valve seals is an incredibly involved process going to do precursor tests and see if I can track the problem down better gonna do as you guys suggested. I think I hear from someone sometime they did valve seals in like 2 hours I don't see why you'd have to take the head off to do this? Knowledge would be greatly appreciated. Thanks, Brownie

 

[RonD]

Head on valve guide seals is done in one of two ways:
1. Air pressure method
You need an air compressor/tank and hose with fitting that can be screwed into spark plug hole
Remove valve covers and spark plugs
Remove rockers and/or valve train.
Place cylinder you are working on at TDC, it's piston at the top.
Apply air pressure to that cylinder, this holds valves in place.
Remove valve spring and replace seal
Reinstall valve spring
Repeat for next valve

Repeat all for next cylinder

2. Rope method
You need a rope that will fit in the spark plug hole and will coil up inside cylinder, nylon works well.
Remove valve covers and spark plugs
Remove rockers and/or valve train.
Place cylinders piston about 1/2 way down
Feed rope in
Rotate crank to force rope coil to top of cylinder, this will hold the valves in place.
Remove valve spring and replace seal
Reinstall valve spring
Repeat for next valve
Remove rope

Repeat all for next cylinder

For either method place a towel over oil drain holes, the valve "keepers" like to fall down there, won't hurt anything but you will need to go to the parts store to reinstall that valve spring.
And since they are not expensive and are required ASAP if lost, I would buy a few "keepers" just to have handy, i.e. sh!t happens