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Offline bad bean

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blow by
« on: September 21, 2014, 10:51:08 PM »
 :'fresh rebuild on sbf motor v-8 conversion having blow by issues pushing oil out different places.does anyone have any advise.

Offline Wittsend

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Re: blow by
« Reply #1 on: September 21, 2014, 11:35:39 PM »
Do you have a PCV system hooked up? Sometimes aftermarket valve covers will be installed without openings for crankcase ventilation.  If the rings were installed backwards they will not seal correctly.  Lastly, until the rings are broken in (assuming correct installation and a PCV system) you may get added crankcase pressure.

Offline bad bean

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Re: blow by
« Reply #2 on: September 22, 2014, 01:09:57 AM »
Yes new pcv, drive it around getting out kinks. Saw that valve cover had pushed gasket out in one spot. What is best way to get rings to seal faster. Don't want to blow out rear seal.

Offline amc49

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Re: blow by
« Reply #3 on: September 22, 2014, 08:09:56 AM »
Uh, if block honed correctly for ring type then any ring seal pretty much mostly done in the first 30 minutes of engine running. A bit more will occur over time but really very little. Most happens in the first 5 minutes. If any rings installed upside down forget it, not going to happen. Same if block was worn and no hone or a simple 'glaze-breaker', sometimes it can work but if top of block worn deeply from top ring land the hone job will not touch that. Time to bore.

Put more breather on it............ .....

Offline Wittsend

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Re: blow by
« Reply #4 on: September 22, 2014, 10:15:37 AM »
I'd run the engine with as many openings as you can get for the crankcase ventilation (filler cap off, PCV plugged at the intake, but open to the atmosphere etc.) . If, after that you have the problem I'd be concern the rings got installed backwards.  Is it possible the PCV is installed backwards? Thread ins are difficult to get wrong, but some of the slip in type are similar on each side.  I've also heard of rags etc. to keep debris out during assembly being left behind in the head drain back holes.  While not your problem I've heard of wood blocks used to prevent crank rotation during assembly being left behind. So, don't discount anything from happening.

Years ago I had an early 80's Honda Civic with the CVCC engine. By 100K miles it was getting 50 miles to a quart of oil.  Strangely it never really smoked nor leaked.  I honed the cylinders and put new rings in it (A poor man's rebuild).  That motor smoked like crazy for the first few hundred miles and I never got better than 500 miles to the quart.  I'm 99% sure the rings got installed backwards. There were no instructions with the ring set and I was dependent upon the kid at the store for directions as Al Gore had yet to invent the internet - enough said.

Offline bad bean

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Re: blow by
« Reply #5 on: September 22, 2014, 10:37:50 AM »
I don't think ring installed wrong they are Molly rings.what are thoughts on evac system car has thrust turbo mufflers.I read that you should not run mufflers. Collectors have fittings for evac.

Offline 65ShelbyClone

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Re: blow by
« Reply #6 on: September 22, 2014, 03:22:32 PM »
Wait, is your crankcase ventilation system connected to the collector evacuation fittings?

Turbo mufflers are not the best-flowing designs out there, so it's possible that exhaust is pressurizing the crankcase.
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Offline bad bean

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Re: blow by
« Reply #7 on: September 22, 2014, 04:30:33 PM »
No not yet it has pcv and valve cover breather right now,pcv connected to carb plate.was thinking that putting a evac system on to help with blow by.

Offline amc49

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Re: blow by
« Reply #8 on: September 22, 2014, 06:31:42 PM »
Exhaust evap only works at higher rpm, why it must be combined with intake evap to work. A pcv system is NOT intake evap, the motor must be sealed specifically for it.

Moly rings mount correctly as far as side facing up like every other ring, rings are designed to twist upward or downward depending on the design and backward makes for a bad problem. You make all ring manufacturing marks face upward at rebuild time. A few are not marked and a problem there, most are though, as it is in makers best interest to do so or risk bad press about quality of product. Only oil ring pretty much doesn't matter but even some of them do now.

You are trying to mask an engine problem with fixes that are not going to work, you fix the basic engine there. Brand new rebuild already blowing by a lot is not going to get better. Do you have oil baffle before the pcv as OEM? If the pcv just pulling off anywhere could be a problem. Pcv entry is always baffled to the max.

Offline dick1172762

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Re: blow by
« Reply #9 on: September 22, 2014, 08:21:16 PM »
Easy way to fix it will be sealing up the motor the best you can, then running a hose from the valve cover to the air cleaner. Use car lots have been doing this fix since Henry Ford was a pup. If you use a piece of water hose, paint it black so it doesn't show so bad. Sucking the blow by down the carb will work great for a while. After that your on your on. Look on the Vega web sites as they had lots of blow by and blow ups as one will follow the other.
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Offline bad bean

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Re: blow by
« Reply #10 on: September 22, 2014, 10:40:09 PM »
Rings had bevel on top ring and second ring had dot.Not trying to mask just looking for advice before having to tear it down. Pcv is just hose from carb to pcv no baffle. I'm running high compression about 12.1, cam is 284/544 hydraulic flat. Intake is Parker funnel web.

Offline amc49

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Re: blow by
« Reply #11 on: September 22, 2014, 11:01:01 PM »
You cannot run pcv straight out of engine unbaffled if it is in an oiled spot, it will blow oil right into intake. The baffle is usually at/under the pcv takeoff point wherever it may be as long as the OEM point.

Bevel on ring CAN go on the bottom side if a reverse torsional twist ring.......... .but usually those are on second ring. The dot is the thing there. Or a letter or somesuch.

Moly rings need to finish block with a fairly fine hone finish, too rough will eat the moly out almost instantly. Bore quality figures in there greatly too, it is getting so hard to find competent people to run boring bars any more. Here in north Texas they used to be coming out my ears, now I'd be terrified if I had to get it done. Last two I had done were both messed up by those who talked a whole lot more than they worked and high dollar shops with big reps too.

Offline bad bean

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Re: blow by
« Reply #12 on: September 22, 2014, 11:36:59 PM »
Not sure about the baffle can you give me little more info. Guess I'm not that smart about baffles :-*

Offline Wittsend

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Re: blow by
« Reply #13 on: September 23, 2014, 01:20:32 AM »
The valve cover will have a baffle (usually a piece of metal, sometimes stuffed with a steel wool like substance). The purpose is to prevent direct oil splashing of a PCV that sits in the valve cover. Sometimes they are removed for rocker arm clearance.

Offline bad bean

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Re: blow by
« Reply #14 on: September 23, 2014, 01:29:13 AM »
Valve covers don't have that for pcv or breather. What is a way to correct it or just buy new covers.

Offline Wittsend

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Re: blow by
« Reply #15 on: September 23, 2014, 11:12:18 AM »
For all the wonders of the Internet sometimes there are things that are hard to find pictures of, and valve cover baffles seem to be one of them. Here is an article that shows baffles that have been cut down, so it will take some creative thinking to imagine what they originally looked like. http://forums.vintage-mustang.com/vintage-mustang-forum/509142-build-your-own-valve-cover-baffle.html

To some degree this post seems to be running off track. Your issue is crankcase pressure that is weeping oil at the gaskets and seals - correct?  If your PCV system was sucking oil up directly (yes, that would increase crank case pressure) but you would also be pumping oil into the intake and fowling plugs severely.  And, I didn't read that as your problem.

As I said above run the engine with as many openings as you can. PCV hose removed, filler cap removed (sorry, it can get messy) and see if there is excessive pressure coming out. If there is then I'd still have to say it is a ring issue. I say that because what else would be pumping air???

Offline bad bean

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Re: blow by
« Reply #16 on: September 23, 2014, 04:31:30 PM »
That is my issue, I did pull breather and pcv couldn't tell if pumping air. Oil was hitting header so smoke was coming off them. I'm looking to run evac system instead of pcv.I read that mufflers create problem. They are thrust turbo. Will installing evac not help to stop crank pressure or reduce it as well as sealing rings against wall.

Offline amc49

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Re: blow by
« Reply #17 on: September 23, 2014, 07:15:41 PM »
Crankcase evacuation will not work. It has to have a sealed up engines with reversed seals, I also ran no valve stem seals at all on mine as you stick the valves in the guides when it works right. Exhaust alone won't get it there, the exhaust has too little effect and only works past about 3K rpm. There is ZERO evac below that. You balance the no exhaust flow with intake too, the intake covers low rpm and exhaust takes up when the intake vacuum drops. Only works though with crank end seals reversed, they leak like hell in normal position since they were made to seal pressure not suction like that. Under suction it's like no seal there at all. Full evac like that demands short exhaust system, almost impossible to do it with full to rear of car exhaust, the stackup of gases stops the venturi effect in pipe. It works best on open header but I drove street cars around with it and simple header mufflers only and was able to keep crankcase at around 10-15 inched Hg most of the time. Everything's gotta be perfect to do it though.

What else could be pumping air? Dead cylinder walls passing lots of gases around side of piston. Hole melted or punched in piston from detonation if ran pump gas with 12/1 compression, impossible, the motor will last five minutes like that.

Offline Wittsend

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Re: blow by
« Reply #18 on: September 23, 2014, 07:50:08 PM »
...Or broken piston rings on install. Do a compression test (or leak down test if you have that available) and report back.

Offline bad bean

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Re: blow by
« Reply #19 on: September 23, 2014, 08:09:37 PM »
Info on motor so we all have the same thoughts.306ci, 12.1 piston,284/544cam,aluminium heads with 205/160,parker funnel web intake, Holley 650 double pumper.trans with 3500 stall, reared 5.38 gears.thrust turbo mufflers 2 ft off collector.I'm going to do compression check to see if all's well on that end.Will report findings.just didn't want to rebuild again.car only going to run to some shows and strip few times.guys I want to thank you for things I'm learning here.just looking for way out before rebuild on fresh motor.

Offline bad bean

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Re: blow by
« Reply #20 on: September 25, 2014, 07:25:16 PM »
Checked compression psi not sure but 90 psi was what it read.that seems light for that motor unless rings are not seating.not sure that it's not leaking at the valve and could that cause the blow by.just stumped at this point.

Offline Reeves1

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Re: blow by
« Reply #21 on: September 25, 2014, 07:53:03 PM »
Way low.
Pull it & tear it down before you damage it beyond repair.
Gaskets are cheap.

Offline Wittsend

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Re: blow by
« Reply #22 on: September 25, 2014, 08:10:39 PM »
Not sure what you should be seeing given your cam, but that "seems" low. Is your 284 duration gross or @ .050?  In a gas powered engine there is a limit to cylinder pressure. As you get a cam with more duration you both increase overlap (typically - but not always) and have valve events occurring earlier.  All that tends to lower cylinder pressure hence the need to increase the compression ratio to compensate.  How much pressure you get at cranking speeds as opposed to operating speeds could also factor in.  I assume they are all at 90PSI? That kind of rules out a damaged head gasket leaking into the intake valley.  You speak of leaking seals and gaskets..., is there smoke too?

I've never built engines such as yours. Hopefully AMC49 or others with this type experience will chime in.  But, if you want my guess I'm still thinking rings.  All the air should enter and exit the manifolds, not wind up in the crank case. The only other option would seem to be a clogged exhaust system and lots of exhaust valve stem clearance.

 Do you see the actual pressure, or only the results of it. Remove the PCV hose, but make sure it is still attached to the valve cover, crankcase or wherever you have the other end of the hose attached. Hold a rubber glove around the hose and run the engine. Use care because it might rupture.  Report back what happened to the glove and how fast.

Offline bad bean

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Re: blow by
« Reply #23 on: September 25, 2014, 08:52:05 PM »
Cam is 240/246@.50 110 lobe separation.one cylinder was at 75 psi.not sure if gauge was any good AutoZone rental.when running just pulling the pcv out of cover it has a slight pump of air just enough to feel.you made mention of head gasket.not getting oil in water, water in oil or plug Fouling with oil or water.having one heck of time with this build.

Offline bad bean

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Re: blow by
« Reply #24 on: September 25, 2014, 08:59:27 PM »
Motor not smoking. pulling this motor is going to be frustrating.th ings not going well, waiting on heart transplant and building motor has me sick at the stomach.

Offline Wittsend

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Re: blow by
« Reply #25 on: September 25, 2014, 09:42:53 PM »
Is there any possibility that gas worked its way into the crankcase at some point and then ignited causing a spike of pressure that caused the seals and gaskets to leak?  Once I did a compression check with the plugs out and the wires dangling. The car was jacked in the front and that caused the float bowls to over run. Gas ran past the rings and accumulated in the crankcase - as well as shooting out the spark plug hole.

At some point the dangling wire lit the external fuel in a WOOF! And about a second later BANG!!! The crank case vapor went off. I had the valve covers just placed, but not bolted. Everything flew and it was all quite startling.

Offline bad bean

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Re: blow by
« Reply #26 on: September 25, 2014, 11:30:27 PM »
Just a update on motor build.to start eagle crank and rods,trw piston, comp cam hydraulic flat tapper 284/544, comp valve springs, comp lifters, aluminum heads 205/160 ss valves, parker funnel web intake 7.5"tall Holley carb 650 double pumper.motor break in normal run time 20 minutes@2500rpms.no leaks at driveway running.only when getting it out on

Offline amc49

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Re: blow by
« Reply #27 on: September 26, 2014, 06:16:26 PM »
Motor is dead, engines with less than 100 psi will never run correctly, not enough heat (from compression) generated to keep plugs running clean. The limit we used when I built engines was 100 psi, you need well over 200 if cam timing like said and 12/1 compression. Afraid you got a serious issue there.

Forget the d-mn car for a bit if facing heart surgery, or at least let what will be be, it ain't worth the extra stress I'm tellin' ya. I had double bypass and did that, you gotta give it all up to realign your head for it. Enjoy working on the car, not turn it into a millstone.

Assuming you did compression test correctly..... .....warm engine and throttle held wide open while spinning engine with ALL plugs out of it and using a decent screw-in gauge, crap push-in compression gauges cause a LOT of unnecessary trouble. Do more than one spin on each cylinder as backup, I usually do at least three.

A small possibility that you have washed cylinder walls down enough with raw fuel to kill compression, I've heard of it but don't necessarily buy the idea. My view is that if oil cut back that much the engine will scar the walls anyway to make permanent damage. I've heard other skilled guys talk of it though, that the engine can lose almost all compression to then get it back later and run fine, the part I have trouble with but you never know.......... .............

Offline bad bean

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Re: blow by
« Reply #28 on: September 26, 2014, 11:08:00 PM »
Just realized that motor has to be at 180 or above correct not just run for a few moments maybe the person doing test is problem.c guess that was my problem.

Offline amc49

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Re: blow by
« Reply #29 on: September 27, 2014, 10:50:46 AM »
It very easily can be. The gauges and getting them to seal properly to get repeat numbers over and over can be problematic, why you always pull multiple tests. Numbers varying are an indicator of doing something wrong. Done right the numbers will fall in line pretty much. You crank until gauge quits moving on every cylinder, not a certain number of spins on each. Lower reading cylinders take more spinning but the numbers will still not come up, telling you something wrong. You repeat to verify it. I even go so far as to tear down the setup, i.e., unscrew the gauge and then screw it back in again, the sealing o-ring sometimes does not seal, a repeat can show you that as well. I keep extra o-rings on hand, they tear up easy doing that.