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Old 03-10-2012, 06:20 PM
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Big Block Chevy oil problems

I have a 1970 454 that is blowing oil out the dip stick tube. The engine is newly built with less than 300 miles on it. It did not do this in the beginning. I just picked it up from the body shop where it sat not running since December. Oil is 25w-50 w/lucas zinc additive, 60psi cold, 40psi hot, any ideas?
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Old 03-10-2012, 06:35 PM
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Running PVC? Overfill the oil?
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Old 03-10-2012, 06:57 PM
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6qts and no pcv, valve covers are vented to air filter.
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Old 03-10-2012, 07:15 PM
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Quote:
Originally Posted by miguelitosd
6qts and no pcv, valve covers are vented to air filter.

Just wondering, why are you running 50wt.
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Old 03-10-2012, 07:29 PM
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Engine builder said to run this oil.
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Old 03-10-2012, 07:38 PM
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With only 300 miles, why don't you ask the engine builder why the dip stick is blowing out.
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Old 03-10-2012, 09:44 PM
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I will be asking on Monday, posted because I want to know the answers and I want to know what to ask the builder.
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Old 03-10-2012, 11:10 PM
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PVC plugged up the engine needs to breath. Ask builder have him fix it.
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Old 03-11-2012, 07:37 AM
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BB Chevy oil problems

I would think you would need a PVC on drivers side valve cover. Then you could vent the other valve cover through the air breather. This should stop the dipstick from blowing out. The crankcase is building up too much pressure. Like 406bug asked why so heavy oil. I assume with the zinc additive your motor has a hyd. camshaft. Royal purple, Comp Cams, etc, have excellent break-in oil that has everything needed for breaking in hydraulic camshafts. I would have used the Royal Purple break-in oil in a 10W40. Discuss the bearing clearances with your builder, maybe there is a reason he recommended the 25W50. I haven't heard of using heavy weight oil in many years.
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Old 03-11-2012, 09:53 AM
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Im running a 496 big block with no problems n no pvc,just two breathers.
I build engines for a living
So... ask the guy that built it to do a blowdown test(cylinder leakdown test)
Insist on it!
You are building a lot of cranckase pressure inside that motor.
Find a parts house that has a cranckase pressure checking gage,you take a beather off n hold it there in place of the breather,you can probly do this today(they r cheap).
The pcv deal wont help much with so hi a cranckase pressure that it blows the dipstick out.
Also make sure the crank and or rods aint hitting the dipstick,take out the dipstick,start the engine,take a breather off n see how much pressure there is with dipstick off,if there is none then the crank or something in the rotating assy.is hitting the dipstick,if you see a lot with your gage as i suggsted ,back to the blowdown test deal

I hope this helps!
Al
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Old 03-11-2012, 09:56 AM
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Add a PCV system as that's your issue.

Make sure your valve covers have baffling so the PCV does not draw the oil out of the engine.
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Old 03-11-2012, 09:59 AM
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Quote:
Originally Posted by Shaker455
Add a PCV system as that's your issue.

Make sure your valve covers have baffling so the PCV does not draw the oil out of the engine.
You can do that! But please do those tests,wont cost much.
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Old 03-11-2012, 10:03 AM
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You can do that! But please do those tests,wont cost much.
Yes Al I agree...
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Old 10-29-2012, 07:56 PM
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Quote:
Originally Posted by GMCTRUCKS View Post
PVC plugged up the engine needs to breath. Ask builder have him fix it.
I would totally agree with this. Even a new engine will have some blow by, oil consumption, and crankcase fumes. Even just moisture evaporation from the hot oil will add to these fumes. Older engines need the pcv ventilation even more. In my experience you need a breather filter on one valve cover, and a original replacement pcv valve that is plumbed to full manifold vacuum or on some carbs like my holley 670 there is a special vac port on front. The reason I say get the original replacement pcv is because they come in various sizes and the flap valve inside the pcv needs to open and close to the correct vac. For example, when at idle vacuum is plenty, so the valve opens because the engine can afford to "waste" some of its vacuum in order to suck up oil fumes. At full throttle or high load the engine cannot tolerate this vacuum "leak" anymore, the vacuum is low and not enough to pull the flap valve open, so the pcv is closed and not sucking oil fumes. Some engineer came up with the pcv system for a reason, USE IT, cant hurt.
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Old 10-29-2012, 10:59 PM
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Did they hone cylinders with a torque plate? Egged cylinders will do this or rings didnt seat. I always lead fresh engine on stand before i run it so i can see if it seats the rings or not. Most seat pretty close to right now when the cylinders are done right.
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