Help w/FE 390 slight smoking one exhaust pipe. Some black oil on 2 spark plug threads

[stotzbotz]

Hello friends. You guys are such great help that I thought I would ask before performing any repairs. My 68 Fairlane 500 Fast back is smoking slightly out of the driver's side pipe. If you rev the engine it doesn't get worse but it does seem consistent at low rpms. I pulled all of the plugs cylinders 5 through 8 and all of them look exactly alike. No oil on the insulator or tip of any of them. Insulators are all uniform in color, just slightly off white. #5 and #8 spark plugs however do have some black oil on their threads though. My valve covers are not leaking. My brother agreed with me that the smoke coming out smells more like gas than oil but I do notice a slight drop in oil on my dip stick. This engine was recently rebuilt and had about $1000.00 worth of work done to the heads. Bored .060 over with solid lifters and racing cam. Ne Edelbrock Performer intake and ne Edelbrock carb. Othere than the slight smoking the car runs like a rocket and I do admit I enjoy this car to it's fullest, maybe a little too much. The rebuilt engine has maybe 500-700 miles on it. My question is that I'm thinking the intake manifold gasket might be trying to fail on the driver's side causing possibly the leaking and sucking of fuel and oil to go where it's not supposed to. I don't want to pull the intake unless this is the case and wondered if anyone knew if there was a way to tell before I perform this fun task. I also wanted to know if anyone though there was a better than felpro gasket set to use on this type motor with the aluminum intake. Any help would be greatly appreciated.

[firebird77clone]

Small squirts of carb cleaner around the suspected spots while engine idles will result in raised idle if there is a leak. A manifold vacuum check could also be helpful.

[jerry clayton]

#5 and 8 get fuel from same side of carb so if it smells like fuel probably a issue with the carb--

Also-------the way the spark plug wires were routed on the left side created issues after tune ups , etc---------the factory routing of the left side wires separated them in the loom spacers 7-5-6-8 to keep 7&8 from cross firing---------sooooo when the dudes tuned up or redid their plug wires and put them 5-6-7-8 then they had 3 wires in the wrong location with only #8 firing when it should--this would go pretty much unnoticed because checking tune up with timing light was on #1 cyl and it would be ok--------So please check your wire routing and positioning--------


Also could be an issue with valve seals and oil getting in from exhaust valves---intake leaks would show on plugs----------and where in the manifold does your PVC hook up?????????

And could be all of above

And as for carb cleaner around ports on an FE doesn't work as ports are completely under neath valver covers-----an issue common only to FE engines

[HOSS429]

did the engine run bad before you rebuilt it ?.. use oil and smoke ... is there a chance you are burning residual oil out of the exhaust ?

[jerry clayton]

Stotzbotz------------


so you were back on here today at 12:51 but no comment/answer to any of the above ??????

[HOSS429]

Stotzbotz------------


so you were back on here today at 12:51 but no comment/answer to any of the above ??????

he read what you said and is now out in the shop trying it ...

[stotzbotz]

Thanks everyone for dropping by and giving your thoughts. Been gone since I wrote my plea for help. My pvc valve and line goes from the front of the carb at the bottom to the passenger side valve cover. My 7 and 8 plug wires are touching at the boots at the distributor cap and probably at least one place along the way to their respective spark plugs. The heads were supposed to be fitted with bronze valve guides and new seals. No I didn't place the manifold on without the gaskets to check for proper fit before I installed it. It was a brand new Edelbrock performer and it felt good and seated when it was installed. The intake port sides of the heads were not machined but well cleaned and bright when I got them back. The engine was not running and in pieces when I purchased the car. I wasn't sure if I should re torque the intake and maybe adjust one of the two fuel/air mixture screws slightly.

[jerry clayton]

I had posted quite a long post about issues such as yours specific to the Ford FE engine but its disappeared or didn't post?
Basics about the spark plug wire routing and crossfire, valve stem clearances, seals, etc

[HOSS429]

you referring to post # 3 .. i still see it ..

[stotzbotz]

Well folks I installed some plug wire spacers separating 7 & 8 cylinder wires by a good inch. I gave the right fuel/air mixture screw on my Edelbrock Performer carb a 1/3 clockwise turn to run just a pinch leaner on the 5-8 cylinder side. I spoke to Edelbrock folks who said that there might still be some blow back that might be causing slight oil or unburned fuel on some plug threads that may ease up as the engine is breaking in more. I will re torque the intake tomorrow and then go have some fun to see if anything is improving although it might take a little time to tell if blow back has anything to do with it.

[stotzbotz]

I was just going by what Edelbrock told me. I have a vacuum gauge. Can you tell me the proper way set those screws?

[NTFDAY]

I will tell you my way, others may have a different way. With engine off plug vacuum advance and turn both screws clockwise until you encounter resistance and then a slight turn and they should be set, going too far can and will damage the screws and possibly the seats. With the vacuum gauge attached to manifold vacuum fire the engine and hopefully you won't have to increase the idle to keep it running. Observe the reading on the vacuum gauge for the highest reading as you adjust the screws one at a time. If you had to increase the idle you will probably be able to adjust each screw clockwise no more than a half turn to get the highest reading. Otherwise you'll go counter clockwise about the same. The more radical the cam the lower the reading and the more the needle tends to fluctuate.

[jerry clayton]

well 5 and 8 are on the left side so you turned wrong screw?????(edit----I worded this for a test to see what kind of comments I might get-----but with the manifold being an 180* type, 5 and 8 are fed from the right side of carb-sorry for the baited response)

And it isn't just an issue to separate 7 &8 wires-its that with them spaced from factory by having the 5 & 6 wires between them in the spacer/holder brackets but that them peeps put them on the plugs in the wrong order --------and actually end up with 3 wires wrong plugs.

Hoss------it wasn't post 3 but would been 8 or 9, maybe 10---------

I discussed usage of oil amounts related to valve seals, the operating conditions that would cause leakage and results differing between intake or exhaust guides, 180* manifold characteristics, and a few more issues as relate to FE manifolds such as how they fit under the valve cover, porting thru into pushrod passage holes, head porting thru to the bolt hole that is the oil passage from cam bearing to rocker system, and use of splash shields to aid the oil drainback so as not to have so much oil in valve covers causing excessive guide oiling.
Issue of PVC from base of carb to valve cover without adequant air flow from opposite valve cover----

Just seems like the Russians hacked me-------