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oil consumption
#1
I have a D0VE-A block w/460 crank, SCJ iron heads, performer rpm. It ran good, a little oil on the spark plug threads but didn't foul plugs. I took it apart to see what was in the engine and freshen it up. When I removed the intake, I noticed a sticky film of oil in all of the intake ports and about 1 to 2 inches into the intake manifold. The heads checked out good, I had the machinist install SS valves. The pistons and cylinder walls looked good, it was punched .030" over. The cylinders showed no taper or out of roundness. I flex honed the cylinders with 325 grit, installed Total Seal rings with gapless second. The cam that was in it was an engle. Hard to find specs for it but it looked to be 214/218 @ .050 with .500 lift, 110cl. I replaced it with a voodoo hyd flat tappet, 233/241 @ .050, .564/.582 lift, 110cl. Fired it up, broke in the cam, had a hard time trying to tune it, had a lot of fuel smell. Checked the plugs and found oil on the threads. Compression check showed 200-210 across the board and 3% leak down across the board. I drove it, had lots of power, much more than before I tore it apart. check the plugs again and a couple with oil on the insulators. Compression and leakage test showed no change. At this point, I thought the intake must be sucking oil from the valley. The Air fuel ratio looks good at 13.5 to 14, but the HC was crazy high, 4000ppm. I pulled the intake, it looked like it was sealing, but the intake ports were wet with oil. I reinstalled it, this time using silicone for end seals, and it seemed the same or maybe worse. I keep thinking it's the intake because the carb mixture screws don't respond the same from one side to the other, and if I goose the throttle from an idle, I hear a whistle sound from the air horn, all this leads me to think vacuum leak, but nothing detectable from the top side.
Not sure what to do next, the intake looks like it seals when inspecting the gaskets. My biggest worry is to tear the engine down and not find a problem.
Any suggestions???
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#2
I believe the D0OE-R heads (CJ/SCJ) have 2 valve cover tapped holes that penetrate an intake port. If the valve cover isn't leaking, it should be OK, but worth a look at the valve cover screws for oil on the threads.
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#3
I would start by looking at the PCV set up to see if that is where the oil is coming from.

Most ring manufacturers recommend a hone with a coarser grit in the 240 range IIRC, and ring gap and piston clearance could certainly account for some of it. That being said, i would not worry about this as your compression and leakdown numbers are really excellent.

I would look at the valve guides and seals if you didn't already check their condition. Knurling guides for a good fit used to be a common practice and it only works to a certain degree and it doesn't last.

If the oil pump is a high volume pump and you aren't using restricted pushrods, you could be overwhelming the oil return set up and getting valve covers full of oil-if your valve covers leak regularly, this is something to follow up on.

Blown head gaskets could maybe be a culprit, but I doubt it.

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"I love my Hookers!" and "Get some Strange" probably have a different connotation to non automotive enthusiasts!
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#4
Thanks for the reply. I don't think it's the PCV system, I have ran it with and with out, made no difference. no oil in the plenum. No blow by.
Total Seal recommended 280 to 320 grit for the hone. I do have a HV oil pump though. But no leaks anywhere. It could be possible that there is too much oil at the top of the heads but the guides were good and it has new positive seals.
One question I have, is the oil in ports from reversion, or could it be only from sucking oil from the valley? And if the oil pump volume is too much, could it be blowing oil past the rings?
I am really trying to find the best way to proceed before I get to the point of tearing the engine down.
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#5
Jeff73Mach1;289105 Wrote:I would start by looking at the PCV set up to see if that is where the oil is coming from.

Most ring manufacturers recommend a hone with a coarser grit in the 240 range IIRC, and ring gap and piston clearance could certainly account for some of it. That being said, i would not worry about this as your compression and leakdown numbers are really excellent.

I would look at the valve guides and seals if you didn't already check their condition. Knurling guides for a good fit used to be a common practice and it only works to a certain degree and it doesn't last.

If the oil pump is a high volume pump and you aren't using restricted pushrods, you could be overwhelming the oil return set up and getting valve covers full of oil-if your valve covers leak regularly, this is something to follow up on.

Blown head gaskets could maybe be a culprit, but I doubt it.

Agree, if you had the same problem before hand and still do, I'd be looking at the PCV valve more than anything. Also Total Seal recommend a grit of 400 minimum (I'll find a sheet around here somewhere from them) as that's been what I've used to hone cylinders over the years with a nice flat plane in the cross hatch without any dramas, but I really don't think this is your problem as it's exactly the same before and after the build. So replace your PCV with a correct new one of quality brand, not cheap Chinese Charlie ones and see how that goes. Hope this helps you out and let us know how it goes.
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#6
cjstaci;289109 Wrote:Thanks for the reply. I don't think it's the PCV system, I have ran it with and with out, made no difference. no oil in the plenum. No blow by.
Total Seal recommended 280 to 320 grit for the hone. I do have a HV oil pump though. But no leaks anywhere. It could be possible that there is too much oil at the top of the heads but the guides were good and it has new positive seals.
One question I have, is the oil in ports from reversion, or could it be only from sucking oil from the valley? And if the oil pump volume is too much, could it be blowing oil past the rings?
I am really trying to find the best way to proceed before I get to the point of tearing the engine down.

Ok then, check the angles of the intake manifold with the angles of the heads without the gasket fitted. With milling of heads, block over the years it may be mismatched, or as I've seen plenty of over the years, old machining practices of close enough, good enough and the angles are out a bit and can cause problems like these.
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#7
I also would start with the PCV valve, make sure it is working properly and the right one for your engine. Make sure there's a baffle where you have the PCV inserted, so oil doesn't splash directly onto the valve.

Another possibility is a porous casting on your intake manifold. A friend had that happen on a Performer manifold he had on his FE powered pickup.

And, it may be leaking around the gaskets. The manifold doesn't have to be cocked one way or another much at all for the gaskets to leak.



“If you can't explain it simply, you don't understand it well enough.”
--Albert Einstein
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#8
That was exactly my first thought. I know the engine had been rebuilt, never how many times the heads have surfaced. Prior to reassembly, I cc'd the chambers and found them to be 70-71 CC's. Spec's show volume between 72-74cc's. The manifold looked like it was fitting tight against the gaskets. With the rubber end seals it was sitting too high and had to be tightened down for all of the bolts to thread smoothly. So when I reinstalled the manifold, I did so using silicone for end seals and it all lined up nicely. The first gasket I used was a felpro 1231-S3. That gasket showed markings all around the port but very little compression. So I tried a Mr Gasket 208A, that one showed about .010-.013" compression. I checked the angles and it looks like 45* on the heads and intake, but it's a cheap gauge and it's very possible there is lots of room for error.
I've been thinking, what I have done that's different then before.
1. the heads have been re-surfaced, possibly enhancing a preexisting problem. I replaced the factory valves with Ferrea SS valves and I removed the thermactor bosses from the exhaust ports.
2. I put a Melling HV oil pump in.
3. I changed the rings. I made sure all the ring clearances were with in specs (side and back clearance). I set the end gaps a little large (.026) with the thought of running a small shot of NOS in the future.
4. I installed a Milodon windage tray and a 7qt front sump pan.
5. I installed a higher lift, longer duration cam. And I made sure there was enough clearance for the higher lift in the guides, valve springs and piston to valve clearance.

Those are the changes made. The engine runs much stronger than before. It has head snapping torque which it didn't before, and it will smoke the tires from a 25MPH roll which it didn't do before.
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#9
On the plugs with oil on the insulators, which cylinders were those from?
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#10
Did you buy the intake manifold, or did it come with the engine? If it came with the engine it may have also been surfaced to match the surfacing on the heads. Use a good carpenter's square to check that the the manifold gasket surfaces are 90° to each other.

What kind of valve stem seals do you have?



“If you can't explain it simply, you don't understand it well enough.”
--Albert Einstein
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