New engine troubles. Need help.

[Nick88]

Hey guys, I just recently rebuilt the LT9 350 in my GMC. It is now a 383 stroker with flotek heads, eagle rotating assembly, howard roller cam (originally a comp flat tappet that wiped out on break in but I aggressively flushed the motor and the bearings looked good when pulled) edlebrock performer intake, and a holley 770 street avenger with a pertronix flamethrower distributor. So far, I just got the carb dialed in to the max vacuum and idle, but I'm having an issue where the exhaust is blowing blue smoke noticeably and worse when revved, a blue gray smoke. It shouldn't be running super rich but it has that look. The intake manifold gasket is slightly large but I lined it up so it's not peeking into the lifter valley and sucking oil. All 8 spark plugs were oil fouled after around 5-6 hours of running time, bad too. The breathers have a noticeable about of steam coming out of them. Haven't done any compression tests, but could this be because of the rings not seating yet???? I dont think valve seals because they are brand new heads and I doubt every single seal is a dud. The engine is bored 30 over and the original machine shop did a pretty poor job, the top of the cylinder is wider than the bottom by a bit. Could this contribute??? Any ideas help. I dont think it's intake gasket because smoke is coming out breather, not like it's in a vacuum, either way I will tighten bolts a bit to make sure. Any help is GREATLY appreciated!!! Driving me nuts this motor.

 

[Ricko1966]

Hey guys, I just recently rebuilt the LT9 350 in my GMC. It is now a 383 stroker with flotek heads, eagle rotating assembly, howard roller cam (originally a comp flat tappet that wiped out on break in but I aggressively flushed the motor and the bearings looked good when pulled) edlebrock performer intake, and a holley 770 street avenger with a pertronix flamethrower distributor. So far, I just got the carb dialed in to the max vacuum and idle, but I'm having an issue where the exhaust is blowing blue smoke noticeably and worse when revved, a blue gray smoke. It shouldn't be running super rich but it has that look. The intake manifold gasket is slightly large but I lined it up so it's not peeking into the lifter valley and sucking oil. All 8 spark plugs were oil fouled after around 5-6 hours of running time, bad too. The breathers have a noticeable about of steam coming out of them. Haven't done any compression tests, but could this be because of the rings not seating yet???? I dont think valve seals because they are brand new heads and I doubt every single seal is a dud. The engine is bored 30 over and the original machine shop did a pretty poor job, the top of the cylinder is wider than the bottom by a bit. Could this contribute??? Any ideas help. I dont think it's intake gasket because smoke is coming out breather, not like it's in a vacuum, either way I will tighten bolts a bit to make sure. Any help is GREATLY appreciated!!! Driving me nuts this motor.

Who put the rings on the pistons? Did they understand the orientation of everything as in which ring faces up which faces down and not to overlap the oil ring expander. And put the right intake gaskets on it.Im assuming you have pcv setup correctly with the correct valve covers,not after market.

 

[Nick88]

Just some more info: the rings are plasmamoly rings, on hypereutectic pistons. The guy who honed it is a machinist that has been machining for forever so it is professionally honed. The engine has been up to operating temp but only driven maybe twice for less than a minute each time since there is no plates on it and I live in a residential area, not really any load on it. Truck is dual breathers no pcv at the moment, and I checked the vacuum line is not sucking trans fluid through trans modulator.

 

[Nick88]

Who put the rings on the pistons? Did they understand the orientation of everything as in which ring faces up which faces down and not to overlap the oil ring expander. And put the right intake gaskets on it.Im assuming you have pcv setup correctly with the correct valve covers,not after market.

I put the rings on, made sure they were all oriented correctly and I made sure they were all clocked correctly. Intake gasket is a bit large but towards the top, not the bottom. No pcv only breathers on aftermarket deep valve covers for roller rockers.

 

[xm20k]

Check the oil does it smell like gas or is it thinner than before it was ran, does it show higher on the stick?

 

[Ricko1966]

Quit letting it run no load. Get the pcv hooked up and drive it. The rings aren't going to seat with no load,and possibly end up scoring the cylinder walls or pistons from fuel wash.

 

[Nick88]

Check the oil does it smell like gas or is it thinner than before it was ran, does it show higher on the stick?

Original oil i used for break in smelled a bit like gas, which i figured since I tuned the carb with that oil, I since changed it to fresh conventional 15w40 but it still started smoking immediately with fresh oil and the carb tuned good.

 

[Nick88]

Quit letting it run no load. Get the pcv hooked up and drive it. The rings aren't going to seat with no load,and possibly end up scoring the cylinder walls or pistons from fuel wash.

I was originally running it for a while to tune it, ran it for a while tuning a quadrajet that ended up being junk then I switched to the holley the other day and was working for a while to really dial it in to rule that out. Its really tough to put it under load since I'm in a residential area with no plates and the truck is very loud, also it's rained non stop recently and I have no wipers. But tomorrow I plan on fixing a valve cover leak then I'll probably partially depress the parking break to load it and give it some aggressive pulls up and down my block to really heat the truck up try to seat them.

 

[Ricko1966]

Or finish doing it right,get some some exhaust and tags before you do damage. Why are you so against pcv. Your fuel mixture is artificially richer in the throttle without the pcv,contributing to fuel wash and fouling. PCV helps seal the rings,that's why the big guys put vacuum pumps on their engines.

 

[Nick88]

Or finish doing it right,get some some exhaust and tags before you do damage. Why are you so against pcv. Your fuel mixture is artificially richer in the throttle without the pcv,contributing to fuel wash and fouling. PCV helps seal the rings,that's why the big guys put vacuum pumps on their engines.

It has an exhaust on it brand new stainless but it came out much louder than id like, im gonna add on some small resonators to try to help it soon. Im not against pcv. I actually plan on putting one on very soon, I just want to thoroughly research first since it's a stock setup, I dont want to toss on a pcv valve that's not gonna work correctly or drink oil, if it helps to seat rings I'll definitely get one sooner rather than later, any suggestions?

 

[xm20k]

Original oil i used for break in smelled a bit like gas, which i figured since I tuned the carb with that oil, I since changed it to fresh conventional 15w40 but it still started smoking immediately with fresh oil and the carb tuned good.

Engine can consume oil in a few ways

Manifold gaskets are allowing the intake to suck oil from the valley.
Cylinders glazed and rings are washed out (posable depending on how rich the carb was and for how long)
Valve seals leak (new heads so unlikely)
PCV failure (breathers)

My guess as you stated the gaskets were a bit large compared to ports would be its sucking oil from the valley first mechanical thing I'd look into (Felpro 1205 I believe is the gasket size I used on a 350 with flotek heads) Add a PCV at least until things are sorted

 

[Nick88]

Engine can consume oil in a few ways

Manifold gaskets are allowing the intake to suck oil from the valley.
Cylinders glazed and rings are washed out (posable depending on how rich the carb was and for how long)
Valve seals leak (new heads so unlikely)
PCV failure (breathers)

My guess as you stated the gaskets were a bit large compared to ports would be its sucking oil from the valley first mechanical thing I'd look into (Felpro 1205 I believe is the gasket size I used on a 350 with flotek heads) Add a PCV at least until things are sorted

Intake gaskets were a bit large but before I swapped cams I had smaller ones that fit perfect that had the same smoke, albeit with a quadrajet that was untuneable but still. Also it doesnt seem like the breathers are pulling vacuum at all. Is there an easy way to test it before i rip apart the motor? If the cylinders are glazed, is there a way to deglaze them? My main thing is what PCV valve should I run??? Considering it's all different from stock i doubt I can run a stock pcv without problem.

 

[Ricko1966]

You can check for intake gaskets leaking to valley by plugging the valve cover vents and putting a vacuum gauge on the dipstick tube if you are pulling vacuum at the dipstick tube,it's from the intake. Intake gaskets were my first thought as well but you said you had smoke coming out of the breather which would indicate peessure,not vacuum. My thinking the crankcase is under pressure is what's leading me to rings. BUT as simple as it is to check for vacuum at the dipstick tube go ahead and check,it will be one more thing verified. Leaving less to diagnose.

 

[Ricko1966]

Intake gaskets were a bit large but before I swapped cams I had smaller ones that fit perfect that had the same smoke, albeit with a quadrajet that was untuneable but still. Also it doesnt seem like the breathers are pulling vacuum at all. Is there an easy way to test it before i rip apart the motor? If the cylinders are glazed, is there a way to deglaze them? My main thing is what PCV valve should I run??? Considering it's all different from stock i doubt I can run a stock pcv without problem.

Read this.

Crankcase Ventilation–Yes, it’s Important

Positive Crankcase Ventilation (PCV) can easily qualify as the least interesting aspect of a gearhead’s inventory of hot rod romance parts. Many people think that this system’s only benefit is to keep oil vapors from escaping valve cover vents that create that annoying oil mist that coats your...

digital.allchevyperformance.com

For now run a pvc valve for a 400 sbc with a 4bbl

 

[Nick88]

You can check for intake gaskets leaking to valley by plugging the valve cover vents and putting a vacuum gauge on the dipstick tube if you are pulling vacuum at the dipstick tube,it's from the intake. Intake gaskets were my first thought as well but you said you had smoke coming out of the breather which would indicate peessure,not vacuum. My thinking the crankcase is underdressed is what's leading me to rings. BUT as simple as it is to check for vacuum at the dipstick tube go ahead and check,it will be one more thing verified. Leaving less to diagnose.

That's been my thinking, the rings because of the smoke from breathers. I will definitely do that with a vacuum gauge on dipstick see what it shows if it's pressure or vacuum. Might point to something also if it's pressured pretty good. If I have basically stock vacuum could I run a stock pcv? My motor makes basically stock vacuum since it's higher lift lower duration truck cam.