Need engine help!! At my wits end

[Olegmbuilder]

What's up guys. Recently I built the motor in my 1986 crewcab from a 350 to a 383 stroker. The engine has an issue though that it burns a ton of oil. Originally it had a comp cam flat tappet that wiped out on break in, I believe that's when the problems started. I have tried everything to stop the oil usage. It has blow by and drinks probably almost a quart of oil from idling for an hour. It puts out constant blue smoke at idle and when revved makes a grey blue cloud. It is FAR worse without a pcv valve. Without the pcv it puts out noticeable blowby from the breather and let's out a ton of smoke at idle. I checked compression, every cylinder cold is 170-180. I checked the intake gasket, the ports line up and everything is the right angle and sealed. Truck makes 40-50 psi of oil pressure hot at idle and probably 60-70 starting on a 60 degree day. What could possibly be wrong with this motor? Cylinder 3 and 4 barely have any oil on the plug, cylinder 8 has a bunch, i also believe cylinder 8 is the one that the cam lobe wiped out. The motor makes no weird noises and idles good but buttchugs oil. Please anyone help with this, what could cause the engine to have these symptoms, im stumped. Thanks.

I see the problem. You need more beer! Jk jk ok ! Check your valve spring lifter seals. I once new a someone that got a rebuilt engine and they did not replace and upgrade the little ring seals and lifter springs to HP compression springs and seals on all the lifters. The oil blew straight threw and caused everything you're talking about. Hope this helps good luck

 

[Chevydad]

Does any bolts or studs protrude into the intake ports? Not 100% sure on a sbc if the rocker arm studs go into them ports.
I do know some of the big block aftermarket heads do need sealer for this reason.
After seeing you have flotec heads checking online. I found you have to use a thread sealer.

 

[Nick88]

Howdy yall, I'm back again, I hope this gets some attention despite this thread being vacant for a couple months. I finally got a chance to work on the truck again and narrowed the issue to cylinder 8, all other cylinders are relatively clean but cylinder 8 is covered in oil residue. Thought it could be broken ring from cam wiping out so I popped the heads and oil pan and tapped out the piston. Piston rings look relatively fine and we're clocked correctly. Top ring gap for 8 was .024, a bit large but it went in at around .022. Cross hatch still looks good so I doubt the cylinder was glazed. Next up looking for the cause I popped out the old horoscope and checked the intake/ exhaust ports of the heads on the bench. 1,5, 6,8 all have varying from a bit of oil to a pool of oil sitting on top of the valve on the intake side. Cylinder 8 is the worst with oil and a ton of residue on the top of the intake valve.

To recap the issue I've been having is it would put out blue smoke at idle, just a bit and when revved would put out a big cloud of grayish smoke. With a PCV on the truck would put out almost no blue smoke at idle but still would put out a cloud when revved.

This is where I really need help. The machine shop I use is convinced I should pull the motor and have it rehoned. (The original shop that honed it they have found does some kinda shotty work) my question is does this sound like valve seals to you guys? I would hate to pull the motor just for it to be valve seals all along, I already popped off the heads with it in the truck just to discover this now.

I would greatly appreciate any help, machine shop thinks it could be cylinder 8 rings never seated because the engine has some blow by, but the blowby only started after the cam wiped and I don't see any glazing on the cylinder walls which I would assume would happen by now, the engine also made about 180 psi of compression cold on every cylinder. Thanks ahead of time, I look forward to hearing your ideas because I'm stumped

 

[Nick88]

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Cylinder 8 ^

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Cylinder 6 next door, yup right up top that's a puddle of oil on the valve.

 

[Nick88]

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Piston 8 out of truck^

Cylinder 8 wall cross hatching still clear, piston 6 next door is nice and clean still.

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[Nick88]

Anyone?

 

[xm20k]

The oil is on the back side of the valve. So, from that either valve seals, intake gasket not sealing allowing the cylinders on that side to suck in oil from the valley, or rocker studs not sealed allowing oil to be pulled from the valve train side.

Most likely valve seals or intake gasket leak. Put new seals on the valves and before reassembly make sure the intake gaskets match the ports as close as possible, some are large enough to not seal at the bottom of the intake ports and allow oil to be pulled from the valley.

 

[TX87R10]

Evidence Pointing to Valve Seals:​

1. Oil pooling on intake valves (cylinders 1, 5, 6, 8)

• This is the smoking gun(pun intended). Oil sitting on top of intake valves is classic valve seal failure
• Cylinder 8 being worst explains why it's your problem child
• Oil seeps past worn seals when engine sits, pools on valve tops, then gets sucked into cylinder on startup/acceleration

2. Your smoke pattern fits perfectly:

• Blue smoke at idle = oil dripping past seals onto hot valves
• Big cloud when revved = vacuum spike pulls pooled oil into cylinders all at once
• PCV reducing idle smoke = less crankcase pressure pushing oil past seals

3. Compression test results:

• 180 PSI cold on all cylinders is excellent - rules out major ring/bore issues
• Good compression with oil consumption = seals, not rings

4. Ring measurements:

• Top ring gap of .022-.024" is actually within spec for a 350 (standard is .010-.020", but .024" isn't cause for concern)
• Rings clocked correctly and looking good
• Crosshatch still visible = bore is fine

Why I Disagree with the Machine Shop:​

The rehone recommendation doesn't add up because:

1. You have good compression - if rings never seated, you'd see lower/uneven compression
2. Crosshatch is still visible - indicates bore condition is fine
3. Blowby started after cam failure - suggests it's related to that event (possibly increased crankcase pressure from valve train issues), not bore/ring problems
4. Ring gaps are acceptable - not excessive enough to cause your level of oil consumption

My Recommended Course of Action:​

Replace valve seals with heads already off:

1. Use quality positive seals - Perfect Circle 214-1515 or Fel-Pro SS72323
2. Check valve guides for wear- if guides are worn, seals won't help much
   • Test: Insert valve, try to rock it side-to-side. Should have minimal play
3. Inspect valve stems - look for wear grooves where seals ride
4. Check valve springs - weak springs can cause sealing issues

While you're in there:

• Lap the valves if you see any pitting or poor seating
• Clean all that oil residue from intake ports thoroughly
• Inspect for any cracks between valve seats (common 350 issue)

The Blowby Issue:​

Your blowby likely increased after cam failure because:

• Damaged cam/lifters = poor valve control = combustion pressure escaping past valves into crankcase
• This creates excess crankcase pressure pushing oil past seals
• New valve seals should help this significantly

Test Before Reassembly:​

After installing new seals:

1. Vacuum test the intake ports - apply vacuum to intake side, shouldn't lose vacuum quickly
2. Check valve spring pressure if you have access to a tester
3. Verify valve-to-guide clearance is within spec (.001"-.003")

Cost/Benefit Analysis:​

Valve seal replacement (heads off):

• Parts: $50-100
• Labor: You're already there
• Success probability: 85%+based on your symptoms

Full rehone/rebuild:

• Cost: $800-1500+
• Downtime: Weeks
• Necessary? Probably notgiven your compression numbers

Bottom Line:​

Your symptoms scream valve seals. With 180 PSI compression across the board and visible crosshatch, I'd bet money that new valve seals will solve 90% of your problem. The machine shop may be covering for their previous hone work, but your bore condition sounds fine.

Replace the valve seals, reassemble, and report back.If it still smokes after that, thenconsider further work, but I think you'll be pleasantly surprised.

 

[Olegmbuilder]

What's up guys. Recently I built the motor in my 1986 crewcab from a 350 to a 383 stroker. The engine has an issue though that it burns a ton of oil. Originally it had a comp cam flat tappet that wiped out on break in, I believe that's when the problems started. I have tried everything to stop the oil usage. It has blow by and drinks probably almost a quart of oil from idling for an hour. It puts out constant blue smoke at idle and when revved makes a grey blue cloud. It is FAR worse without a pcv valve. Without the pcv it puts out noticeable blowby from the breather and let's out a ton of smoke at idle. I checked compression, every cylinder cold is 170-180. I checked the intake gasket, the ports line up and everything is the right angle and sealed. Truck makes 40-50 psi of oil pressure hot at idle and probably 60-70 starting on a 60 degree day. What could possibly be wrong with this motor? Cylinder 3 and 4 barely have any oil on the plug, cylinder 8 has a bunch, i also believe cylinder 8 is the one that the cam lobe wiped out. The motor makes no weird noises and idles good but buttchugs oil. Please anyone help with this, what could cause the engine to have these symptoms, im stumped. Thanks.

Replace all your valve seals and hope you didnt score or bend the valve guides. Good luck

 

[idahovette]

How in the he!! do you "bend" valve guides