I have what I assume is a silly question. The other day I decided to hook up the PCV that has never been connected to vacuum since the rebuild. After just a short drive, the car started running awful...stumbles as soon as you roll the throttle, idles rough. The odd thing is, it seemed to have a nice amount of power once you got through the stumbling. I disconnected the PCV and capped the vac line, but the car continues to run poorly. I pulled all plugs, and they appear that the car is running rich, but that may be oil coating the plugs instead of carbon. I cleaned all plugs before re-install. I had oil in the line from the PCV to the intake.

Car is still running rough 2 weeks later. Today I noticed the front vac line on the carb had an oily build up on it. It looks as though the PCV allowed a considerable amount of oil through into the intake and coated everything. Is this possible? How do I clean if thats the case?

I also notice that my valve covers have a mist of oil on the outside. Could this be from running it so long without proper PCV? Also, the distributor leaks where it meets the block. Again...could this be from lack of PCV? They are aftermarket valve covers with ( I believe) a baffle installed.

The engine is a 350, bored .030 over.
TrickFlow 62cc aluminum heads (195 intake and 75 exhaust runner volume)
Trick Flow Cam
Intake Duration at 050 inch Lift 212
Exhaust Duration at 050 inch Lift 216
Flowtech 1 5/8 in full length headers
MSD Street Fire Distributor
Stock mufflers
Edelbrock 1406 carb (600cfm)

Thanks

 

Not a silly question. All your statements are correct. Oil mist is caused by not running a PCV (pressure builds up in the engine and needs to go somewhere). You most likely did suck oil into the intake and fouled the plugs.

How did you clean the plugs? Only thing I've had work was a spark plug "sand blaster" that hooks to shop air. Just spraying carb cleaner on them will not do it.

You need to verify you really do have baffles installed. You should also get a PCV valve with less flow. 2 applications for low flow valves: 89 Chevy S10 PU 4-cyl, 95 Camaro LT1 V8.

After market covers often have very poor baffles. You may need an external oil separator (it will have to be emptied every oil change or so).

 

110%. Also...due to crankcase pressure due to not having a PVC system in place....oil leaks can develop.

110% again. For what this is worth to you: I prefer to replace them. And using a solvent like gas or carb cleaner can seriously effect them. Also. I hope that they are A/C Delco plugs..(personal preference...but i do use other name brands in certain circumstances when the car is on the dyno going through testing.) Making sure that you PROPERLY gap them is also important. Electricity travels the path of least resistance. So making sure that the tang is level and parallel to the electrode is IMPORTANT to achieve the largest spark cone possible.

I agree with the valve covers needing the baffles so oil is not sucked inot the PCV....and thanks Zwede on the low flow PCV's you mentioned. That may come into play in the future at one time or another in my shop.

YEP...aftermarket stuff is often crap and will more times than not require some modifications to make work as like an original factory part.

Many more things can be causing this:

Make sure that the vacuum hose that supplies vacuum to your headlight s and HVAC system is plugged off also. You do not need it to drive during the day and for testing....unless it is raining and I doubt you would be doing serious testing during the rain when you need to have your lights on.

Make sure your spark plug wires are not all "zip-tied" together. They need to be separated at least 3/16"+.

Are they NEW spark plug wires. Often times using a KV tester will allow you to find an ignition issue fast. Mine has pin-pointed a problem more times than I can count...even when parts were NEW.

Will wait to hear a response...before I add any more.

DUB

 

I cleaned the plugs with a wire brush. Looks to be running a touch rich, huh?
Before


After


Thanks for the tips on the alternate valves. I believe the one I have now is just a regular spec'd 75 PCV.

The plugs are Autolites, which were recommended by Trick Flow. They are gapped to .050...I can't find in the literature what they should be, but for some reason they are .050.

Other vacuum operated systems were not disconnected for testing... good suggestion.

Plug wires are not new timewise, but have less than 1,000 miles. They are not zip tied together, they are routed through factory looms. They may contact each other at some point...will need to investigate.

Not sure what is meant by "kv" tester. I have a multi meter if that is what you are referring to.

Thanks for the help so far.

 

Another question...would fouled plugs require more timing advance? Out of curiosity, I tossed the timing light on it today. With vacuum advance disconnected and plugged, in order to get a smooth idle I had about 35* initial timing. Seems a little high to me. I recall setting initial around 12* when the heads and cam were installed.

 

I'm honestly surprised it runs at all with those plugs. When you wire brushed them you embedded carbon in a nice shiny layer on the electrode. Conductive carbon.

You need new plugs before doing anything else (and set timing back to where you had it).

Yes, it is running rich. Hard to see if there's oil there also, but most of it is definitely soot (rich).

 

Before you change or do anything else, listen to these guys and put in a new set of plugs. $20.00 could save you a lot of grief. Then after that's done, make your pcv changes and see what happens. It's usually the simple things that screw up and not the complicated, expensive things that we come up with. Good luck!
Duane

 

I'll pick up a set of plugs for it. I'm a little concerned that these will foul very quickly as I have not found (or corrected) the cause. Should I continue to run without PCV until I it running normal again, and then introduce the PCV?

Thanks for the help

 

Yes, take it back to what you had originally (capped PCV) and new plugs. Drive it for a bit and look at the plugs. Create a baseline, and then introduce one change at a time. I think you'll find it runs rich with the PCV capped also.

 

KV= Kilo-volt tester. It is a way to read the kilo-volts that get to a plug. Snap-On sells them and they are not that expensive and are useful.

.050" for a plug gap is kinda wide. I know you have a MSD distributor...but regardless of that...I would gap a set of A/C Delco plugs to .035" and see what the plugs look like after some miles on them. And then if you feel that they need to be opened up to .045"...you can do that also. I prefer A/C Delco plugs...because in the past i have installed numerous other brands and seemed to have failure almost immediately.

Is your harmonic balancer new??? If not...how do you know that what you are reading is correct if you do not know for a FACT that the notch on the balancer is correct for timing. Outer rings of harmonic balancers can spin...thus using a timing light and relying on that is says kinda frustrating. Just a thought.

DUB

 

KV= Kilo-volt tester. It is a way to read the kilo-volts that get to a plug. Snap-On sells them and they are not that expensive and are useful.

.050" for a plug gap is kinda wide. I know you have a MSD distributor...but regardless of that...I would gap a set of A/C Delco plugs to .035" and see what the plugs look like after some miles on them. And then if you feel that they need to be opened up to .045"...you can do that also. I prefer A/C Delco plugs...because in the past i have installed numerous other brands and seemed to have failure almost immediately.

Is your harmonic balancer new??? If not...how do you know that what you are reading is correct if you do not know for a FACT that the notch on the balancer is correct for timing. Outer rings of harmonic balancers can spin...thus using a timing light and relying on that is says kinda frustrating. Just a thought.

DUB

 

AC Delco, gapped to 0.035 for starters. I run an MSD dizzy with 6AL and that works just fine.

 

Harmonic balancer is not new...so I have reason to believe my 35* initial is not accurate. I am going to find TDC and verify/remark the balancer to get a more accurate reading. The reason for the Autolites is simply because that is what Trickflow recommends (Autolite, NGK, or Champion).

My current plan is to:
- verify/find TDC
- Re-time engine
- Replace all plugs
- Clean carb (if needed)
- Run engine (without PCV) and get baseline reading from new plugs
- Adjust A/F ratio as necessary from plug readings (possibly get/use O2 sensor)
If I can get it to run well again with the above, I will re-introduce a new PCV with added baffles in the valve covers (already has one, but will add another).

 

adust idle mixture

 

Good plan.

And get the wideband O2. Tuning a carb without one is painful.

 

I failed to find TDC because the piston stop tool was too short to contact the piston. I am assuming this is due to the angled plug heads. I suppose I could pull out the header and get a longer stop in there. Probably just go with a new damper. Anyone know the difficulty of replacing one while the engine is in the car?

I did, however, find that I had a slight fuel leak on the top of the carb. Turns out the accelerator pump had fallen apart in the bore, and would only supply a shot of fuel at WOT...not tip in. I reassembled the pump and installed, and the bogging went away (with the old plugs installed). Still have the new plugs to put in, but I thought I would use the old (cleaned) plugs for testing. I haven't driven yet due to not knowing where the timing is, but I am pretty sure that was the stumbling problem. Our driveway was just repaired, so it is stuck in the garage for a few days now.


Maybe it was a coincident that the pump broke the same drive as the PCV was connected? I don't like coincidences.