Fresh 383 SBC fouls one plug in 500 miles. Leak down is 6% (very good). After a few checks, i remove the intake and find OIL all up the intake gaskets and into the ports. I reseal the intake with better gaskets. Now, 700 miles later she fouls a different plug. Pull the intake. Bitchen seal around all ports this time around. BUT, the silicone ring that's pushed towards the ports are soaked with oil. Oil's coming from the ports outward. Also, the NEW Performer, dual plane intake is soaked with oil on the half plenum floor closest the lifter valley. The other side's like new. Thoughts? 383 9.8 Hyperneurotic pistons, with NEW SR Torquer heads, NEW Performer intake, stock exhaust, Holley 3310, Comp mild solid stick (.495 lift minus .022 lash, 222(?) @ .050, and 110 lobe centers. Too mild for any crazy reversion. Scroll for pics
Shot in the dark here. On the torquer heads,is the rocker arm stud hole open into the port? If so clean and liquid teflon the stud to seal the leak. I've seen other aftermarket heads pull oil through rocker stud holes.
Do you have adequate crankcase ventalation? Running a PCV valve? If so, is it possible the PCV valve is sucking oil? If no, then check the valve steam seal on that cyl to see if its come loose or is bad and check the valve guide for excessive clearance.
Check to see where your PCV is hooked up. It's possible that you have your PCV hooked up to the rear of a valve cover and are picking up oil during hard acceleration. You will also see smoke from the oil burning on those cylinders that draw from that plennum of the intake.
No studs in ports, PCV bone dry, on the ring gaps-6% leakdown! I've had 20% leakdown without a flood of oil in one half the intake manifold
Hard excelleration drops the vacuum signal. This is the least likely time for oil to get sucked into the PCV circuit. Decelleration and idle would be more likely. But the PCV is dry
ive seen em burn oil without smoking noticebly like a couple of qrts in 500 miles or less because of no baffle under pcv ......and rocker lined up under it, ???
RTV sealent? i disagree, but im voicing pure opinion... if you are messy with it and not careful during assembly, then ya you'd probably get a leak. groucho.. did you assemble the motor? i know the heads and intake are new, but perhaps check those mating surfaces for straightness along the ports?
Silicone impregnated bead on gaskets both times. 1st time, just silicone around water jackets. Result-tons of oil past the gaskets into the ports from what appeared to be sucked from lifter area. 2nd time, silicone around every opening. Result-great seal around all. Only thing was, this time oil was around the little bit of silicne that oozed past the gasket towards the port. So the oil's coming from the port, not the lifter area as in the 1st time around. Also the big puddle throughout half the dual plane intake that's unexplained. From plenum floor, to the intake ports where they meet the head
Oil on plenum floor???? Hmmmm....weird.... I'd pull the intake one last time and check it for cracks....ya never know man.... Got another intake to try????
That's where I'm at. I pulled it this AM, and taking it to Edelbrock tomorrow. I was kinda waiting to see if someone else thought that. What else guys? I need another way oil could get where it's at in case the intake tests OK. Lemme see if i can get a pic. Hang on a sec
The intake floor is obvious. The black rectangles are the silicone that oozed inboard of the gasket, and was the only part of the gasket with oil this time around
Hey Grouch....just thinkin' out loud here but......IF the intake had a SMALL crack, once the engine warmed up, that crack would 'open' and engine vaccum would suck oil through it. Never seen it happen with an intake, but have seen it many times with hydraulic manifolds........
Well, that's exactly what i'm hoping to find. In the off chance it's not porous/cracked, i'm looking for a Plan B here
Groucho....is there any trace of oil in the intake runner of the cylinder head? In the past couple months I've had a set of sr torquers and platinum series iron eagles that did the same thing...it was cause from oil past the valve guides. Both sets were brand new not used...found the torquers to have a little bit too much clearance on the guides to stems, and the iron eagle actually had the wrong valve guide seals. I've also ran into crackis in itakes...usually they were old used ones not new...but sh*t happens and you just might have gotten a friday afternoon set!!!
my friend had this problem & it was that the angle on the heads intake surface didn't match the angle on the intake manifold!! Its kind hard to follow but try 2 intake gaskets & silicone the shit out of the ends.I do think they make a thinner intake gasket set for this reason, i guess its common when ya mill heads or shave a block. JimV
well if the intake is pulling oil and your Pcv is dry its sucking oil through the valves. im thinking bad valve stem seal. either that or a bad milled surface on the intake or head causing oil to be sucked into the intake from the lifter valley. always a possibility.
I did upgrade the valve seals the 1st time i fouled a plug 4 months ago. Yes, oil in the ports. I believe the oil's source is from above the guide
Read all posts. That was an issue the 1st time, but resolved the 2nd time around when oil was discovered uphill of the area in question
if your intake pulls 18-20 in. hg. it will pull that much oil into the intake that quickly. if you have a high volume oil pump it will do it even quicker. its being pulled by intake vacuum, im almost sure its pulling past the valve and into the intake not through the intake itself. if it was cracked you would have a breneling mark arounf the crack in the intake where hot oil is pulling through.
is the bottom of the carb(venturis) wet with oil also? and if so,is it just on one side? just bare with me....
Well, i know it's being pulled "BY" vacuum. I just don't know from "WHERE". It's only affected by half the intake, and it's got good seals on the valves i put on just for added insurance. Besides, if it were coming past the guides, the incoming fuel/air mix would sweep it right into the combustion chamber, not uphill into the plenum.As far as a witness mark on the oils source, it sat overnite before i pulled the manifold
first and foremost which plug is it fouling, is it one in particular or does it foul different ones. if its only fouling one then the intake is leaking around that cylinder, or the valves are leaking on that cylinder. the cylinder with the leak will foul plugs faster than all the others eventhough the oil in the intake will be sucked into all cylines evenually. check the intake for flatness on the mating surfaces.
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