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I swapped the stock 305 for a 350 4bbl that i pulled from an 86 blazer but i didn't have any time or money when i did it so i didn't rebuild it, i just took it out and dropped it in my trans am. The engine only had 30k on it but i guess it had been sitting for a while and it burned oil.
It burned oil at startup and WOT so i pulled the valve covers and put new valve stem seals on and that solved that problem, but it burns oil from the engine.
At first, I had hoped that would be solved with changing the valve stem seals, but apparently not. It burns a pretty good amount of oil out of the passenger's side valve cover breather, and it's enough to get noticed when i stop and sit at stoplights. Not only that, but I have to top the oil off all the time.
Anybody know what the issue is, and can anyone tell me how to fix it?
Re: 86 350 4bbl Burning Oil From Valve Cover Breather
There's no oil burning from the exhaust. The oil dipstick line doesn't smoke and the driver's side valve cover (where you top off the oil) doesn't burn, even when you take the cap off
Re: 86 350 4bbl Burning Oil From Valve Cover Breather
Sounds like you have blowby on the pass side of the engine. Do compression tests on all your cylinders - bet one on pass side is much lower than others.
You can take out the breather and install a PCV valve in the hole, running the vacuum line to the carb (or whatever) to reburn the smoke through the exhaust to temp get rid of the embarrasing smoke and keep the engine bay from getting so greasy.
Re: 86 350 4bbl Burning Oil From Valve Cover Breather
i'm doing a compression test and a leak down test tomorrow after work, but i'm pretty sure what the results are gonna be
when i replaced the valve stem seals and had the compressor hooked up in the spark plug inlet, cylinder six was letting air by
but could you please explain a little bit more to me about this pcv valve? what is it, what does it do, where would i get one, and how would i hook it up?
Re: 86 350 4bbl Burning Oil From Valve Cover Breather
PCV = positive crankcase ventilation - it's a check valve that hooks to vacuum source, plugs in the valve cover, and reburns oil that blows by the rings. All cars have some blowby - yours is worse than most. Most cars have a fliter in one valve cover, and a PCV in the other. I myself have a tad bit of blowby, so I run a PCV in each valve cover, the vacuum source sucks the smoke out of the valve covers and runs it through the carb, exiting the smoke through the exhaust instead of into the engine bay where it makes a greasy mess.
Re: 86 350 4bbl Burning Oil From Valve Cover Breather
Well - it might not be a PCV, but it is a crankcase ventilator - just run a vacuum line from that to the carb - you'll probably have to get a T fitting to connect it inline with whatever else you have connected to the carb (like an HEI distributor).
Re: 86 350 4bbl Burning Oil From Valve Cover Breather
I don't have a pic of mine - sorry. But maybe this will help...
See the large vacuum port dead center on the front of this Edelbrock? I have 2in vacuum hose coming from that, to a "T", then to a PCV valve on each valve cover. This sucks all the smoke and whatever out of the valve covers and reburns it through the carb. Most carbs have a port like this on the front, and another on the rear (for the brake booster).
Most cars have a breather in one (that draws fresh air in) and a PCV valve in other valve cover (to suck out the gunk) - but since I have some blowby, I use the PCV valve in each valve cover to suck gunk out of both sides.
Re: 86 350 4bbl Burning Oil From Valve Cover Breather
Alright, i checket out my carburator, and I have two seperate vacuum hookups. One is on the back and it runs straight to the brake booster. The other is on the side and it runs to what appears to be the distributor.
Where would you recommend inserting a t-joint? I don't want to risk ruining my engine if i hook it up to the distributor vacuum, and I don't want to risk losing my power brakes...
Re: 86 350 4bbl Burning Oil From Valve Cover Breather
Besides the two larger vacuum ports, there should be one or two smaller ones - these smaller ones are where I have my distrubutor plugged in. What carb do you have?
Re: 86 350 4bbl Burning Oil From Valve Cover Breather
i could only find one of the smaller outlets you were talking about (see attached piture)
it split into two: one was quickly drawn into a closed wiring harness and the other ended at the corner of the engine bay closest to the windshield on the driver's side (see attached picture). i don't even know what this is to be honest