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Old 08-13-2003, 07:15 PM
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Blowby! need opinions before new motor

I just wanted to dress up the engine on my driver El camino, so I put on a set of new aluminum valve covers, used holley intake and a rebuilt holley carb. It ran fine with no problems for a short while , then it started to push a little oil out of the front seal and a place on the dipstick tube that the PO had punctured with a screwdriver. So I replaced the dipstick tube and now it blows the dipstick out about two inches and pukes oil all over the engine compartment. By that I mean its getting worse very quickly. I just checked compression and only had one cyl that was low it was 110 and came up to 120 with oil the rest were 145 to 150. I'm just wondering if there's anything I could have done on installing these parts that would cause this excessive blowby. If the collected knowledge here can't help with this problem I guess it's target engine time. By the way its not burning any oil and the plugs are a nice coacoa brown and it seems to run good. HELP!!!!

Mnardo

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Old 08-13-2003, 07:36 PM
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Mnardo
How are you getting the blow by out of the crankcase ? Did you change the PCV system when you put on the new valve covers ?
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Old 08-13-2003, 07:37 PM
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Are your replacement valve covers vented properly? is the P C V system hooked up properly? this seems to be the problem if all you did was chg the covers and intake.
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Old 08-13-2003, 09:56 PM
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I used a new pvc valve and installed a chrome breather on the other valve cover. At the present time I've got a hose on the oil dipstick tube into a jar to collect the oil so it dosen't get on the exhaust. there is no oil blowing out of the breather. It seems to be only the bottom end that is under pressure. I'm at a loss for explainations on this one. One more thing is that it only does it under load but I think that's to be expected. It didn't do this with the original equiptment 500 miles ago. I'm thinking that the extra equiptment maybe jacked up the HP enough to put a strain onthis old horse.
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Old 08-13-2003, 10:07 PM
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the same thing happened to me when i converted from a 2 bbl to a 4 bbl intake. my problem was due to the positive crankcase ventalation (pcv). once i reran the pcv hose to the intake and the other side to the carb all was well again. this should work for you. just make sure that the carb or intake is pulling all the pcv out of the block.
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Old 08-13-2003, 10:22 PM
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I installed a new pvc and it is hooked to the full vac port on the front of the carb and it is working. By the way the carb is a holley 84011 spreadbore on a holley street dominator manifold with the EGR valve to the rear of the carb, also its on a 74 350 in an el camino with 115000 miles, but the PO did some work because the heads have been off of it before I got it, don't know if it went any further than that. I have even pulled the manifold off to check if the exhaust crossover was leaking but it wasn't. I'm really at a loss to explain this one!!
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Old 08-13-2003, 10:29 PM
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If u have access to a leakdown tester see what ur leak is. sounds like the 1 cylinder with the low comp is going by the rings and going in the pan causing the pressure u r experienceing. U can also put air in the cylinders with an adapter and listen at the dipsick tube to see if that is the prob,but a leak test will confirm as a well sealed engine fresh should have no more than 1 to 5 % if everything was machined properly and the rings and seats have seated.

Oops didnt see the 115000 miles if the heads were done and nothing else that will cause the pan pressure to be worse than if it wasnt touched at all,causing a worn ring to really show up because the heads will seal and all the pressure has to go somewhere so it goes in the pan.
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Old 08-13-2003, 10:46 PM
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A Holley Street Dominator intake with an EGR valve?
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Old 08-13-2003, 10:54 PM
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I also think its that one cyl but I have a hard time with one cyl pushing that much oil out and only out the bottom end. Its not pushing any oil out the valve cover breather or around the pvc valve. and like I said it doesn't seem to run bad its just blowing oil, I would think it would be sucking oil into the cyl as much as its blowing out but it dosen't smoke at all.

Its an old street dominator single plane with a split plenum and a cross over tube around by the distributor I forget what the numbers are I got it because I wanted the EGR to be kind of hidden behind the carb. Makes the engine compartment a little cleaner looking.
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Old 08-13-2003, 11:10 PM
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Not at all, its compression going by the ring and causing the pan pressure. If uve ever seen what its like in the pan area with an engine running it looks like a thunderstorm so its real easy for the aereated oil to go out the dipstick hole.
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Old 08-14-2003, 12:20 AM
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mnardo,

The only thing I can think of is that maybe you didn't put a large enough hole in the breather side rocker cover or on the pcv side. So the your pcv system is getting vacuum from the carb at idle and it can pull the pressure out because the vent allows clean air in. But when you put the car under a load manifold vacuum drops to zero and you then build pressure in the crankcase and the end result is oil coming out the easiest way it can. Check the hole sizes.

Good Luck
Scholman
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Old 08-14-2003, 12:57 AM
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OK Lets get thiis straight its not blowing any oil out the valve cover ports(breather) and the pvc valve is working so I should not see any blowby but it is there and it has gotton worse as time goes by. I would like to know if one cyl can cause enough blowby to blow out the dipstick?
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Old 08-14-2003, 01:12 AM
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YES!!!!!!!! see it all the time with irrigation engines after a few yrs. Like i said leak cylinders and u will get answer by listening.
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Old 08-14-2003, 05:30 AM
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Do you think that you may have over filled with oil? most stock pans are 5 qts with filter.
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Old 08-14-2003, 09:54 AM
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Good Guys meet in Pleasenton week after next . I guess I'll be shopping for a crate motor. The wife even said to go buy one ,I guess she's tired of my nasty mood over this. Thanks everyone who replyed, this is one of the best places to go if you have problems, everyone is so helpful.
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