oil leak

I recently built up a 383 and I am having trouble with a oil leak I hope you can help me with.   When  I "get on it"  traveling down the
highway with  revs over 3500 I get a oil leak out the front seal in the timing cover.  I have replaced that seal once but it still leaks. The engine build up includes a Comp Cams XE268 cam, Scat 9000 Series 383 Cast Crank with 6" rods,  internally balanced , KB 164 pistons , CR of 9.6, Fluidampr #712430, and a stock oil pan .   The heads are modified Vortec with a PCV valve on one side and a breather on the other side.  Under the timing cover the 2 galley plugs are drilled with a #30 drill along with a #30 drill hole in the boss under the cam sprocket, Are these 3 drill holes pumping too much into the timing cover area ?   The transmission  is a Bowtie Overdrive 700r4 and a rear end gear of 3.36. It cruises in 4th at 2 grand on the tach and 70 mph on the speedo ,  a real nice gutsy setup, other than this oil leak out the front seal around the crank.
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Not knowing which kind of block this is, I don't know if this applies..When you put the oil pan on did you use silicone, or a sealer on the end rails of the oil pan... After drilling the holes in the galley plugs you may be be putting more oil in the cover than can be drained out the bottom of the cover.. There isn't a lot of room for drainage.....now put a little sealer in the way and you may have a problem.... Have you tried free revving the engine in neutral/park to see if it leaks then??? Is the fluiddamper old or new.. have you checked the seal to make sure it matches the balancer??? not trying to give you too much simple information, just trying to jog you to see if something comes up... Bobo
P.S. I forgot .. I have seen some leak oil through the keyway of the balancer.... a little silicone helps here.....

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From personal experience with KB slugs:
Silv-O-Lites carry ominous warnings about top ring seizure and breakage from thermal expansion; they recommend astronomical top ring end gaps. (In my case, an .032 recommendation, when I usually set about .018 for a warm street motor.) I'd never used SOLs (appropriate abbrev?) before, so I followed the recommendation, and blowby was pretty atrocious. Look around that breather--if there's evidence of oil mist being ejected, blowby is pressurizing the crankcase and the front and rear seals are definitely plausible locations for this pressure to vent (along with oil). This sounds especially possible since you state it only happens when you lay the hammer down.
The already mentioned things are also good places to check; in particular, ensure there are no burrs on the damper hub where the seal rides. And I'm certain there's no need to ask, but the seal is facing the proper direction, correct?
FWIW, I personally wouldn't drill the galley plugs to oil the timing set on a street motor; drain back from the valley is pretty sufficient to keep a timing set lubed up, and the holes are bleeding off oil that I'd rather have on the bearings. I *might* do this on a race only motor where acceleration forces keep oil in the valley sloshed aft, but only if the sucker displayed a tendency to eat timing sets. Race motors get torn down frequently anyway, so impending bearing failure stands a better chance of being caught before bad juju occurs, whereas a street motor might not get yanked for years.
Best of luck, Mark
On Mon, 24 Nov 2003 17:55:46 -0700, Bobo wrote:

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I am sorry, but I just couldn't see him complaining about an oil leak from the front seal without mentioning oil spray from the breather... There would have to be a build up of pressure before he would blow it out the seal.The amount of smoke and oil going out the breather would have to be so amazing I think that would have been mentioned..One thing comes to mind.. Do the holes for the breather and pcv actually connect to the inside of the valve cover.. I had a show set once that were sealed.... Now that would either blow out the dipstick or a seal...... Bobo

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You've responded to your own comment; if the breather grommet is solid (seen it) or the oil baffles in the valvecover are sealed up, pressure can't vent that way. I don't expect to be taken for gospel, especially when I've never seen the motor, but if it leaks only when the motor's under hard load, it's definitely a point to be considered. I've seen engines do this, and while the dipstick usually is blown out, as you've mentioned, and oil almost always is ejected from a breather, it doesn't always make an incredible mess. Add in the restriction imposed by the drainback holes in the heads before blowby gets into the valvecovers, and front/rear seal venting is a real possibility, particularly if some of the other factors you mentioned, such as a worn hub or way off balance motor exist. I don't mean to offend anyone, just contributing some experience of conditions of I've personally seen, identified and rectified.
Cheers, Mark
On Tue, 25 Nov 2003 16:37:02 -0700, Bobo wrote:

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