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Oil Smoke driving me crazy

General engine tech -- Drag Racing to Circle Track

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ProPower engines
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Re: Oil Smoke driving me crazy

Post by ProPower engines » Mon Jun 15, 2020 3:03 pm

On any intake I like to use .0008" to .001" clearance with a bronze guide. This is a honed guide fitted to a straight stem!!!
Remember it will grow as the head warms up but the valve stays cool from incoming air/fuel going past it.
And again if you can wiggle that intake its worn out the guide. You may disagree but if you measure the stem clearance you will be shocked. Combine that with the excess wiggle as the engine runs tearing up the sealing lip on the seals.
Also as mentioned earlier about the rocker studs. Use an anaerobic sealer on them to eliminate the possibility of the oil getting sucked down the threads after the head grows when warmed up
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Re: Oil Smoke driving me crazy

Post by Raybo » Mon Jun 15, 2020 3:34 pm

ProPower engines wrote:
Mon Jun 15, 2020 3:03 pm
On any intake I like to use .0008" to .001" clearance with a bronze guide. This is a honed guide fitted to a straight stem!!!
Remember it will grow as the head warms up but the valve stays cool from incoming air/fuel going past it.
And again if you can wiggle that intake its worn out the guide. You may disagree but if you measure the stem clearance you will be shocked. Combine that with the excess wiggle as the engine runs tearing up the sealing lip on the seals.
Also as mentioned earlier about the rocker studs. Use an anaerobic sealer on them to eliminate the possibility of the oil getting sucked down the threads after the head grows when warmed up
Yes sir I agree. I can install liners in the guides or send them back to AFR. Not sure what to do yet.

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Re: Oil Smoke driving me crazy

Post by ProPower engines » Mon Jun 15, 2020 4:01 pm

I would measure the stems and just use a new press in guide and fit the valves to them.
Liner-ing some guides can be a PITA as the section of guide that is not encased in the head will grow and spring back smaller creating a tapered area of the exposed part.
Measure and ream .0003 to .0005 undersize and finish with a hone to final size for .0008 to .001 clearance.
if the exhaust is less then .002 at this point they will be fine for a week end warrior street car.
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Re: Oil Smoke driving me crazy

Post by steve cowan » Mon Jun 15, 2020 4:38 pm

ProPower engines wrote:
Mon Jun 15, 2020 4:01 pm
I would measure the stems and just use a new press in guide and fit the valves to them.
Liner-ing some guides can be a PITA as the section of guide that is not encased in the head will grow and spring back smaller creating a tapered area of the exposed part.
Measure and ream .0003 to .0005 undersize and finish with a hone to final size for .0008 to .001 clearance.
if the exhaust is less then .002 at this point they will be fine for a week end warrior street car.
Good information right there
Thank you Dave,much appreciated.
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Re: Oil Smoke driving me crazy

Post by ProPower engines » Mon Jun 15, 2020 4:53 pm

steve cowan wrote:
Mon Jun 15, 2020 4:38 pm
ProPower engines wrote:
Mon Jun 15, 2020 4:01 pm
I would measure the stems and just use a new press in guide and fit the valves to them.
Liner-ing some guides can be a PITA as the section of guide that is not encased in the head will grow and spring back smaller creating a tapered area of the exposed part.
Measure and ream .0003 to .0005 undersize and finish with a hone to final size for .0008 to .001 clearance.
if the exhaust is less then .002 at this point they will be fine for a week end warrior street car.
Good information right there
Thank you Dave,much appreciated.
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Re: Oil Smoke driving me crazy

Post by Raybo » Tue Jun 16, 2020 6:12 am

ProPower engines wrote:
Mon Jun 15, 2020 4:01 pm
I would measure the stems and just use a new press in guide and fit the valves to them.
Liner-ing some guides can be a PITA as the section of guide that is not encased in the head will grow and spring back smaller creating a tapered area of the exposed part.
Measure and ream .0003 to .0005 undersize and finish with a hone to final size for .0008 to .001 clearance.
if the exhaust is less then .002 at this point they will be fine for a week end warrior street car.
These are 8mm stems. Does that change your final home numbers?

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Re: Oil Smoke driving me crazy

Post by BillK » Tue Jun 16, 2020 6:33 am

Raybo,
Any chance you have another set of heads that you can put on the engine just to try ? Maybe borrow a set from someone ? I am personally not convinced it is the heads and it would be a shame to do all of that work and still have the problem.
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Re: Oil Smoke driving me crazy

Post by Belgian1979 » Tue Jun 16, 2020 7:29 am

I start wondering if all of these assembled heads come with too much clearance from the factory...

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Re: Oil Smoke driving me crazy

Post by GRTfast » Tue Jun 16, 2020 7:50 am

I've always had a little bit of oil on a few spark plugs when I pull them out. My car doesn't noticeably smoke, but it uses maybe a quart every few thousand miles. From what I've seen, this isn't out of line for a mark IV big block.

Leak down is good (all cylinders less that 2%), compression is within 3% on all cylinders, valve seals are good, valve guide clearance is good. PCV system has an oil separator that is effective, engine has no external oil leaks.

I've had my intake off a number of times and never really noticed any oil in the runners. I also never put any sealer on my intake gaskets, I just used the print-o-seal gaskets. I had it off last week when putting my new cam in. When I reassembled I used some new intake gaskets and put a thin layer of "right stuff" around every port on both sides of the gasket. After driving for 50 miles or so, I pulled the plugs to see how they look. To my surprise, there is absolutely no oil on any spark plug at all. This is the first time that has happened in the 20,000+ miles this engine has been together.

Not sure if any of that info helps, but it appears that you can have leaks at the intake gaskets without seeing much, if any signs of it when you take it apart.
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Re: Oil Smoke driving me crazy

Post by ProPower engines » Tue Jun 16, 2020 1:26 pm

Raybo wrote:
Tue Jun 16, 2020 6:12 am
ProPower engines wrote:
Mon Jun 15, 2020 4:01 pm
I would measure the stems and just use a new press in guide and fit the valves to them.
Liner-ing some guides can be a PITA as the section of guide that is not encased in the head will grow and spring back smaller creating a tapered area of the exposed part.
Measure and ream .0003 to .0005 undersize and finish with a hone to final size for .0008 to .001 clearance.
if the exhaust is less then .002 at this point they will be fine for a week end warrior street car.
These are 8mm stems. Does that change your final home numbers?
No that does not really affect that at all.
8mm stems I use the same clearance but I did see a set of heads last summer that had .3418 guide with some fat 8mm valves in them.
They were bought complete assembled and that thing needed an external oil tank to feed it smoked so bad.
You may want to confirm stem and guide sizes regardless to see if it is a seal issue were too much clearance has allowed the stem to wear the seal out prematurely .
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Re: Oil Smoke driving me crazy

Post by steve cowan » Tue Jun 16, 2020 2:18 pm

GRTfast wrote:
Tue Jun 16, 2020 7:50 am
I've always had a little bit of oil on a few spark plugs when I pull them out. My car doesn't noticeably smoke, but it uses maybe a quart every few thousand miles. From what I've seen, this isn't out of line for a mark IV big block.

Leak down is good (all cylinders less that 2%), compression is within 3% on all cylinders, valve seals are good, valve guide clearance is good. PCV system has an oil separator that is effective, engine has no external oil leaks.

I've had my intake off a number of times and never really noticed any oil in the runners. I also never put any sealer on my intake gaskets, I just used the print-o-seal gaskets. I had it off last week when putting my new cam in. When I reassembled I used some new intake gaskets and put a thin layer of "right stuff" around every port on both sides of the gasket. After driving for 50 miles or so, I pulled the plugs to see how they look. To my surprise, there is absolutely no oil on any spark plug at all. This is the first time that has happened in the 20,000+ miles this engine has been together.

Not sure if any of that info helps, but it appears that you can have leaks at the intake gaskets without seeing much, if any signs of it when you take it apart.
i agree,
look at the bottom of the port on a 23 deg at the flange.
not much meat there,most of us when we zero deck the block and most people flat mill heads?? and then we dont correct the intake to suit, it might only be a degree or two but it may cause issues.i think if the clearance between the china wall and intake there could be a possibility that silicon might hold the intake up as well.
thicker trim fit gaskets and silicon :D
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Re: Oil Smoke driving me crazy

Post by CGT » Tue Jun 16, 2020 2:47 pm

My sbc in the special needs thread, I put new rings in for it smoking badly on the dyno. I was playing with very low ring tensions, so I just assumed that was the culprit. New rings, hone, bearings, everything....back on dyno...smoke is back. Put a vacuum pump on it, wouldn't really pull any vacuum.

Bottom line, it was a leak at the intake gaskets which were two glued together. Sucking oil in from the bottom and through the two layers. I reused the intake gaskets from the first go around because of the time I had in making them so the smoke followed the gaskets. New gaskets and rtv around the problems and everything cleared up.
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Re: Oil Smoke driving me crazy

Post by Belgian1979 » Tue Jun 16, 2020 2:52 pm

I suspected this for a long time. I then did a smoke test (on an ITB'd engine you can basically test each runner seperately), but to no avail. There were no leaks in the intake gasket.
I now use the felpro steel reinforced ones.

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Re: Oil Smoke driving me crazy

Post by Kevin Johnson » Tue Jun 16, 2020 8:26 pm

Raybo wrote:
Tue May 19, 2020 6:58 pm
UPDATE
Swapped to the 1205 gasket with gasgacinch under the gasket. SO far so good. Got it up to operating temp and little smoke. I think it was residual. Shut it down and let it get a good heat soak and restarted with no smoke. Thanks for all the help. I appreciate each persons input.
Going back to this post.

What exactly were the conditions that led up to smoke being an issue again?

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Re: Oil Smoke driving me crazy

Post by Raybo » Tue Jun 16, 2020 11:08 pm

Kevin Johnson wrote:
Tue Jun 16, 2020 8:26 pm
Raybo wrote:
Tue May 19, 2020 6:58 pm
UPDATE
Swapped to the 1205 gasket with gasgacinch under the gasket. SO far so good. Got it up to operating temp and little smoke. I think it was residual. Shut it down and let it get a good heat soak and restarted with no smoke. Thanks for all the help. I appreciate each persons input.
Going back to this post.

What exactly were the conditions that led up to smoke being an issue again?
Little smoke on the run stand, figured it was residual. Put engine back in the truck and once it gets a good heat soak its smoking again

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