Vortec Heads Suck...

[SunSoaked]

oil past the valve seals?

Here's the deal:

Noticed a misfire at idle. Started pulling plugs to look for clues. #1=good. #3= oil fouled! Bingo. But the question is why?
This is a new gm crate motor with about 2k miles on it. I swapped new GM Vortec heads on it 1000 miles ago.

So I cleaned the plug with acetone and a wire brush. Swapped plug #1 with plug #3. Drove it for two days. Today I pulled the plugs and #3 is getting oil fouled again (originally plug #1).

Concluded it's not the plug. Inspected and ohmed the plug wires (new Moroso 8 mm low ohm). Wires are good. Swapped in a brand new spare cap, rotor and coil.

Gonna drive it a few days and pull the plugs again. If #3 us going south again I can conclude it's not the ignition.

Therefore, I'm assuming it can only be the valve guide seals or piston rings?

What say you all? I never even looked closely at the valve guide "umbrella" seals. I'm just assuming they have them?
Am I missing something here? I'm having a hard time believing that a new engine would have this condition.

I was hoping I just had a plug go bad but the problem didn't follow the 1-3 cylinder swap.

[Ziegelsteinfaust]

Vortec heads are a great bufhet option. But you could have a cracked guide or umbrella seal.

The only inherent weakness Vortecs have are they are on a bit of an thinner casting.

This a bit of a oem cost savings vs aftermarket bragging on thickness

[Dead Parrot]

Could be a bad or damaged during install or even missing seal from the factory.

Is the leak enough to be causing exhaust smoke? Any oil in the coolant? Or coolant in the oil?

PCV system installed and working?

#5 plug OK?

[MySons68C20]

Oil level changing?

[garyd1961]

I understand your frustration but your title is misleading. You don't even know the problem yet but you are trashing vortec heads.
It may be the heads but still what caused the problem. Could be a lot of things including the head gasket. Even if it is the heads it doesn't mean all vortecs are bad, just that the ones you have are bad.
Maybe you should check the compression on that cylinder.
How much h lift does the cam have?

[SunSoaked]

After swapping plugs 1-3 around and driving it for 2 days, the plug is beginning to foul again...so I can rule the ignition system out. I'm left to believe that the only way oil is getting in the cylinder is the rings or valve guide. I will pull the valve cover and see what I can. I'm assuming that these OEM GM heads use an umbrella seal? I doubt they would be machined for the posilock type seals?

I also pulled all the plugs to see if any other plugs are oil fouled. One thing because obvious quickly- carburetors on Vortec intakes do a lousy job when it comes to air/fuel distribution! The outer cylinders are a little lean while the inners are a little rich.

To further back up that statement, the temp dropped to 38 degrees here last night. I had a hell of a time getting the truck started this morning. I know the 160 t-stat needs changed out for at least a 180. I was just surprised how lousy a combination of the intake/carb was in the cold.

There is no smoke out the tailpipe and no oil in the coolant.

The ME Wagner PCV is working great. 20 inches of vacuum and a smooth idle...except for the occasional miss due to the fouling plug that just cropped up.

[OutlawDrifter]

What carb and intake setup are you running? I've never had any issues with fuel distribution on Vortec heads and carb setups. I've used Q-Jets, Edelbrocks, and Holleys. Cold start issues can be fixed with correct tune and choke settings. That's definitely cold for Yuma. I lived there 86ish-92, saw it snow once.

I understand being frustrated with an issue, but sometimes you have to step back and take a look at the whole picture. You never did mention if it is smoking...on startup? under a load? when letting off the throttle?

[kwmech]

Never liked the 'vortec' castings from the factory-- light weight and prone to cracking. Cheap bolt on power, but I was never really impressed with them. One of those too good to be true things

[Tom]

Not sure why you'd think ignition issue for oil on plugs. Ignition or not there isn't supposed to be any oil on the plugs.
Yes, vortecs have a normal umbrella style valve seal. Its never been an issue and your the first person I've heard complain about them failing so quickly. They are just normal small block heads like any other except the intake bolt pattern is different. That's literally it.

[SunSoaked]

First off-

No "noticable" smoke from the exhaust. It's true duals so it's a little easier to know which bank it's coming from.

Intake is Edelbrock Performer for Vortec heads.

Carb is Edelbrock 1406.

I wanted to rule out the ignition system as I wasn't sure if a dead plug, wire or otherwise would cause oil to accumulate in the cylinder.

Regarding the distribution, let me ask a question:

Did the Vortec heads ever come factory with TBI?

Lacking a heat crossover, the air/fuel mixture hits the bottom of the manifold, comes to a sudden stop, tries to change direction, falls out of suspension and puddles. The colder the temp, the worse the problem. In summer, when it's 110, it's a benefit. If it were a dry manifold, e.g. TBI, this wouldn't happen.

Moving on. Tonight I did a compression check on cylinders 1,3 & 5.
All were right at 120 psi. I tested the suspect #3 cylinder wet and dry. NO change in psi between dry and wet so I conclude it's not a ring sealing issue.

I appreciate the feedback.

[Captainfab]

No the Vortec heads did not come on any TBI engines. A TBI would still have fuel in the intake manifold. The Vortecs were only used with CPFI in automotive applications. The Performer RPM Vortec has provisions for running coolant under the carb for cold climates with a carb.

If you have a L31 crate engine, why did you change the heads 1K miles ago? What was wrong with the original heads?

[SunSoaked]

Originally Posted by Captainfab

No the Vortec heads did not come on any TBI engines. A TBI would still have fuel in the intake manifold. The Vortecs were only used with CPFI in automotive applications. The Performer RPM Vortec has provisions for running coolant under the carb for cold climates with a carb.

If you have a L31 crate engine, why did you change the heads 1K miles ago? What was wrong with the original heads?

It's not an L31. It's a Goodwrench gen 1 crate engine. I was less than impressed with the power so I swapped heads and put in a 448 lift comp cam.

[OutlawDrifter]

Originally Posted by Captainfab

No the Vortec heads did not come on any TBI engines.

I have heard rumors of 1996 GM Vans with TBI on Vortec engines. Whether this is true or not, I'm not sure...but they were never in the mainstream vehicles for sure.




Sunsoaked...the 1406 comes tuned fairly lean from Edelbrock. Have you had the top off and made any adjustments? They will run out of the box, but perform much better when they've been calibrated better.

My biggest gripe with the Edelbrocks is they love to boil this garbage ethanol fuel off, that doesn't help with starting period, cold or hot.

[Ziegelsteinfaust]

Since 88 GM's gas truck engines in the gmt400 series have been called Vortec. So people see the tbi trucks and think they have the "Vortec" heads.

[PGSigns]

The oil can be coming from the intake gasket, a weak spark from a bad plug wire can give you the oil issue. Based on dyno results on circle track crate engines with that head and a dual plane intake the vortec head engines suffer from some lean holes. My race engine builder used to do a lot of em and when I was having a lot of vapor lock issues with my L31 and the same intake and carb you are running he suggested a change based on dyno results. We switched to a Super Victor intake and a Holley 670 street avenger carb. The intake is not huge and the runners are a perfect match for the heads. Vapor lock gone, better all round performance and the vapor lock issue is gone.
Jimmy

[garyd1961]

Originally Posted by kwmech

Never liked the 'vortec' castings from the factory-- light weight and prone to cracking. Cheap bolt on power, but I was never really impressed with them. One of those too good to be true things

I don't know where you are coming from but Vortecs work, they are not a too good to be true thing. There are many many thousands of them on the road right now running great. I have seen quite a few with 250,000 or more miles and still running good. Being light is a good thing as long as they work.

[rsavage]

120 Lbs compression seems pretty low to me even if they are even. Normal is at least 150 lbs.

[SunSoaked]

Originally Posted by PGSigns

The oil can be coming from the intake gasket, a weak spark from a bad plug wire can give you the oil issue. Based on dyno results on circle track crate engines with that head and a dual plane intake the vortec head engines suffer from some lean holes. My race engine builder used to do a lot of em and when I was having a lot of vapor lock issues with my L31 and the same intake and carb you are running he suggested a change based on dyno results. We switched to a Super Victor intake and a Holley 670 street avenger carb. The intake is not huge and the runners are a perfect match for the heads. Vapor lock gone, better all round performance and the vapor lock issue is gone.
Jimmy

Exactly! I agree with what you're saying 100%.

IMO, if the outer cylinders are lean while the inner ones are rich, that is NOT a tuning issue you can adjust out of the carb. It's poor design characteristics of mismatched parts. I firmly believe that Vortec style intakes were designed to be used with port injection not TBI. That's why I asked the question regarding GM using TBI with Vortec manifolds.

Like you, I believe a weak plug or wire can cause oil buildup and eventually lead to a misfire. That's why I went thru the ignition system first.

Regarding the 120 psi readings. I thought that was low too. I don't know what my compression ratio is (Goodwrench engine with Vortecs)? I'm guessing somewhere around 9:1? However, I only pulled the plug on the cylinder I was testing. Had I pulled them all and cranked it over 4-5 revolutions, I suspect it would be up in the 150+ range. Since all three had the same reading, I'm not concerned with the numbers.

A leak at the intake manifold is plausible. I had not thought about that.

[OutlawDrifter]

Originally Posted by PGSigns

The oil can be coming from the intake gasket, a weak spark from a bad plug wire can give you the oil issue. Based on dyno results on circle track crate engines with that head and a dual plane intake the vortec head engines suffer from some lean holes. My race engine builder used to do a lot of em and when I was having a lot of vapor lock issues with my L31 and the same intake and carb you are running he suggested a change based on dyno results. We switched to a Super Victor intake and a Holley 670 street avenger carb. The intake is not huge and the runners are a perfect match for the heads. Vapor lock gone, better all round performance and the vapor lock issue is gone.
Jimmy

I'm not a Holley fan at all, but switching to the 670 Street Avenger probably solved 95% of your vapor locking problem. Look at how the two carbs store fuel and you'll see why.

Originally Posted by SunSoaked

Exactly! I agree with what you're saying 100%.

IMO, if the outer cylinders are lean while the inner ones are rich, that is NOT a tuning issue you can adjust out of the carb. It's poor design characteristics of mismatched parts. I firmly believe that Vortec style intakes were designed to be used with port injection not TBI. That's why I asked the question regarding GM using TBI with Vortec manifolds.

Like you, I believe a weak plug or wire can cause oil buildup and eventually lead to a misfire. That's why I went thru the ignition system first.

Regarding the 120 psi readings. I thought that was low too. I don't know what my compression ratio is (Goodwrench engine with Vortecs)? I'm guessing somewhere around 9:1? However, I only pulled the plug on the cylinder I was testing. Had I pulled them all and cranked it over 4-5 revolutions, I suspect it would be up in the 150+ range. Since all three had the same reading, I'm not concerned with the numbers.

A leak at the intake manifold is plausible. I had not thought about that.

Your cold start issue is definitely in the tune, this is fact. All intakes carb'd or otherwise will have lean/rich spots. If you put individual O2 sensors on the headers of my Z28(LS swapped), you could see that even the LS6 intake will do that.

What is your max RPM? You could probably get by with a smaller carb, have better velocity for fuel distribution, and a crisper throttle response.

Not trying to split hairs with you on this one, but comparing a max effort circle track engine to a DD isn't even in the same ballpark. Single and dual plain intakes work better at different RPM ranges.

[burnin oil]

I think the point on the heads was that yes they are cheap power ladders that they really arnt. Heads are cheap but the intakes are not. Add the costs and you have a decent factory head but you are now getting into the lower end costs of aftermarket. These will outflow the vortec and have a better deck surface. Vortec have raised ports on the intake and exhaust sides. I have tried to hook them to rams horn manifolds and that is a no go. There is not enough material to actually make the ports match even though they can be bolted on. Then you have the cam limitations. Valve spring swap helps this but still not great. After all that you end up with a thin deck, 170cc runner head, that doesn't accept alot of cams. Am I against them, no, but there are just better options out there.

Now if you are going to run them i say go with the autolite 606 plugs. I had the best luck with them and they are cheap. 605s are hard to find but a slightly colder plug. I too liked the victor over the performer intake for them. As mentioned there is no heat crossover so there is your cold weather issue for puddled fuel. Double check your exhaust manifolds/headers. I had about an 1/8 " lip on the manifold side. Nothing kills performance like the outgoing exhaust gasses hitting a wall of cast iron.

[mattfranklin]

Originally Posted by Tom

Not sure why you'd think ignition issue for oil on plugs. Ignition or not there isn't supposed to be any oil on the plugs.
Yes, vortecs have a normal umbrella style valve seal. Its never been an issue and your the first person I've heard complain about them failing so quickly. They are just normal small block heads like any other except the intake bolt pattern is different. That's literally it.

Just sharing a quick observation. When a cylinder isn't firing the ring pack doesn't work properly and crank case oil comes up past them into the cylinder. Have seen this on the dyno.

[SunSoaked]

Originally Posted by mattfranklin

Just sharing a quick observation. When a cylinder isn't firing the ring pack doesn't work properly and crank case oil comes up past them into the cylinder. Have seen this on the dyno.

Exactly!

Followed by a compression test to rule out damaged or broken rings. The oil scraping rings are there for a reason.
Thanks for the info.

[Tom]

Yes the vortec motor came with TBI in mexico only.

[SunSoaked]

Originally Posted by Tom

Yes the vortec motor came with TBI in mexico only.

Lol. Go figure.

[bloo]

Where is the PCV hose connected? The carb should have a dedicated port for it. If it is connected somewhere else it will screw the fuel distribution all up.