Aussie66Fastback

hi all

wheni changed out my Ford Racing rocker covers to go back to a stock look, i put a PCV valve in connected to the carb (normal setup). Now I am finding that it is sucking oil into the carb.

the result is using a lot of oil and the exhaust is black and crusty as if it were running extremely rich. Its not blow by, theres no smoke or leaks and its not running rich.

is the PCV sposed to close off when engine revs come up?
funny thing is, i always thought it opened so pressure could be relieved.

can anyone clarify this? Are the valves prone to failure??

67mustang302

Is there a baffle under the PCV valve? And how recently rebuilt are the heads?

Aussie66Fastback

there is a baffle, but its up pretty close against the pcv as I had to "manipulate" the stock rocker covers to fit over the roller rockers.

I had a crack in one head repaired about 12 months ago, so both were stripped and checked with a valve grind at the time...maybe 1500 miles since, so should be good.

67mustang302

Guides and seals are new? What do the plugs look like? Is there actually a lot of oil in the bottom of the carb(looking when you take it off)? If it is sucking oil through the PCV there are filter trap kits for that. But I'd be concerned about where all the oil is coming from, if that's what it is. Check the plugs, post pics.

Aussie66Fastback

i'm not sure the plugs are gunna tell me much if the oil is going in via the pcv to the carb...wont they be blackened regardless?

the valve guides and seals should be good...if the heads were not so well p&p'd the guy wasnt going to repair the cracked one. The repair and refurb ended up costing not much less than replacing them with new alum heads (which is prolly what I should have done anyway)

The pcv to carb connecting pipe is wet with oil and the dip stick is dropping a noticeable amount if i take the car for a "spirited" drive. I am checking the oil the following day so I know everything is drained back down.

the carb itself...why didnt i think to look in there doh

what are the filter trap kits?

67mustang302

http://www.steeda.com/products/steeda_oil_separator.php

Something like that. Check the plugs, oil deposits and fuel deposits look different. That'll tell you whether you're actually burning it off or if it's leaking someplace you haven't noticed. How much oil does it burn? Running harder = more oil consumption.

Aussie66Fastback

hahha, spanking requires lubrication!?!?

I'm with you - drive it harder will burn oil, but this is ridiculous

I went out for about an hour and went pretty hard1st thru 3rd maybe 6 orso times. Rest of the time just cruising. Dipstick was down by about 3-400mls. For it to leak that much or burn it, surely I would have to notice fresh oil underneath or the following cloud of smoke when i stand on it???

Scott H.

.....

Aussie66Fastback

ok thanks to you both.

Scott I dont have an option with the rocker covers unfortunately. So i need to try to correct the problem another way. Heres where i'm at

1) the pcv is failing - regardless of rocker oil pressures pushing in or carb sucking out, oil is passing the pcv. I will check under the carb to make 100% sure and replace the pcv.

2) if that doesnt work, I will add a second breather on the oil fill side, plumb that via a t-piece with the other side to the carb.

3) assuming at least some improvement, I can add one of those oil/air seperators if need be. jegs has them for $45.

I'll have a look at the plugs while i am about it.

Plan B is go back to a breather instead of the PCV
Plan C is a catch can
Plan D is replace the engine with one that can handle the mild spankings i dish out

thanks again guys...lemme know if ive missed anything.

Aussie66Fastback

update

so i pulled plugs. they're grey around the electrode. all looks good. bit oily around the threads, so i pulled the carb. Inlet manifold has oil all thru it.
pulled the rocker cover and had another look at my baffle. it is close under the pcv and it only has a small drain hole in in (maybe 1/8"?)

conclusion...its def sucking the oil in, not blow by etc. Theres so much of it, its not even burning off...spitting most straight out the exhaust.

solution(s)...i have to keep the stock rocker covers. i dont have to keep the pcv valve to carb thing happening.

I am thinking to keep the pcv valve for 2 reasons. (1) i havent found a breather cap small enough to fit in the stock d-shaped grommet and (2) i still want to vent gasses.

but, can you see any reason why i couldnt plumb the pcv to a small catch can rather than to the carb?

would it be worth considering adding a drain pipe from low on the firewall end of the rocker coversback to the sump? it seems this particular engine creates pretty strong vacuum but also seems to have a fair quantity of oil around the rocker covers thats not draining quite as quickly as would be optimal.

bear in mind, i am not going to spend $ on this engine. Eventually i will build another but for the time being just gunna accept this one for its limitations and enjoy it as is.

thanks
ben