STP Synthetic 10W30 - 300 mi - 1967 Camaro RS/SS

[SirSpeedsAlot89]

Looking to get some knowledgeable input regarding this report. While I know it says no immediate maintenance needed, there are some flagged levels. I am rebuilding this Camaro and trying to get every discrepancy fixed as I find it. Chromium being my only real concern if its my piston rings are going.

I've done cylinder pressure tests in the past and they were all about 150 psi. I have seen very small cylinder wall scoring with a borescope cam so that would be my only culprit so far, that or maybe its just from the coolant? I have noticed the engine does burn a little oil but nothing I'm worried about, esp with the oil separator on it. So again maybe there is some wearing of the piston rings? Is there any other thing that can introduce small amounts of chrome into the oil?
This is a rebuilt high compression 350 SBC gen 1 87 and up engine with profiler 195 aluminum heads, lots of Lunati and comp cam parts, scat crank, howarsd lifters, ARP everything, etc. Engine has 2,000 miles on the rebuild. Oil changes usually have a very small bronze like glitter but never any debris. This oil sample was from the oil filter. Engine had coolant leak at the intake manifold gasket in the past so this was the first sample from the second oil change and filter. Engine did also get a bit hot (260) at one time so will be checking the cylinders again. Recent test for a head gasket leak also came negative. Will be putting in AMSOIL 10W30 after this and taking another sample at 1k miles. I have added Torco Accelerator as well but I dont think that has any chrome in it. Thanks for any feedback!

 

[burbguy82]

so this is the first oil change since rebuilt?

 

[RDY4WAR]

Which camshaft exactly?

My only concern is the 2.4% fuel, a significant amount relative to sample runtime. This reflects the KV100 value teetering on the 20/30 grade border. Whether the fuel is exclusively during this runtime or residual from previous oil is unclear since we have no prior data. The engine could be running rich and/or at insufficient temperature.

You stated the engine is recently rebuilt. Do you know, or have access to, the rod and main bearing clearance? Other specs would also be helpful to include piston-to-wall clearance, ring material / coating / thickness / tension / gap, cylinder hone profile, fuel choice, valvetrain lash/preload, compression ratio, sump capacity, etc...

Torco Accelerator contains methylcyclopentadienyl manganese tricarbonyl (MMT) as an octane booster which is the source of the manganese in the sample. If the piston rings have a coating of chromium nitride, that's the source of the chromium. The value isn't alarming given the mileage. I expect this to disappear with future samples.

 

[fantastic]

Yeah, that Chromium is elevated & from everything I've learned over the years it's from the rings but it sounds like you've already done dug up that information. I'd say just keep testing to see if it comes down. This appears to be the first sample after a 150 mile run?

 

[SirSpeedsAlot89]

Which camshaft exactly?

My only concern is the 2.4% fuel, a significant amount relative to sample runtime. This reflects the KV100 value teetering on the 20/30 grade border. Whether the fuel is exclusively during this runtime or residual from previous oil is unclear since we have no prior data. The engine could be running rich and/or at insufficient temperature.

You stated the engine is recently rebuilt. Do you know, or have access to, the rod and main bearing clearance? Other specs would also be helpful to include piston-to-wall clearance, ring material / coating / thickness / tension / gap, cylinder hone profile, fuel choice, valvetrain lash/preload, compression ratio, sump capacity, etc...

Torco Accelerator contains methylcyclopentadienyl manganese tricarbonyl (MMT) as an octane booster which is the source of the manganese in the sample. If the piston rings have a coating of chromium nitride, that's the source of the chromium. The value isn't alarming given the mileage. I expect this to disappear with future samples.

Hi,

Its a Lunati Voodoo Camshaft 20120711. I have been adjusting the carb to run leaner and it is now generally in the 12.5-14 range. The AFR can sometimes run on the rich side at WOT around 10-11 and I am still trying to get it dialed in. My theory on the fuel dilution is I believe there is a small amount of fuel seeping through the intake gasket and getting into the lifter valley and contaminating the oil. Engine oil temperature may not be reaching high enough levels to burn off the fuel, as I have my electric fans to turn on at 180 degrees coolant temp with a 170 degree TStat. It is a 10.9:1 compression engine so I was told by the engine builder to not let it get too hot due to detonation and to keep it under 190. We only have 91 in CA so I have been playing it safe on the temps. I may try to increase the fan temp trigger and run it a bit hotter to see if that helps with the residual fuel and even install an oil temp gauge.

The specs I have on the rebuild are:
Bore: 4.030, Stroke: 3.48, Cylinder head: 60 cc (was milled from 64cc), dome volume +5, Deck: .025, head gasket thickness: .015. I do not know the main bearing or other bearing clearances but I was told the main bearings are "tighter than spec". My oil pressure is close to 75 at cold startup so I believe it. Idle is 40 psi at 800 rpm. Fuel is normally chevron 91. valvetrain preload is zero lash + half turn (roller cam/rockers). Sump is 7 qts but I normally fill it to 6.

Thanks!

 

[SirSpeedsAlot89]

Yeah, that Chromium is elevated & from everything I've learned over the years it's from the rings but it sounds like you've already done dug up that information. I'd say just keep testing to see if it comes down. This appears to be the first sample after a 150 mile run?

Engine has around 2k miles on it now since the rebuild and at least 6 oil changes. I kept changing the oil due to a coolant leak into the lifter valley from the intake manifold. It has since been fixed but I suspect some fuel is getting past the gasket as I normally see a wet look around the intake ports after a drive which is likely fuel. I port matched the IM but I think its still not perfectly aligned due to the heads being milled down.

 

[RDY4WAR]

Hi,

Its a Lunati Voodoo Camshaft 20120711. I have been adjusting the carb to run leaner and it is now generally in the 12.5-14 range. The AFR can sometimes run on the rich side at WOT around 10-11 and I am still trying to get it dialed in. My theory on the fuel dilution is I believe there is a small amount of fuel seeping through the intake gasket and getting into the lifter valley and contaminating the oil. Engine oil temperature may not be reaching high enough levels to burn off the fuel, as I have my electric fans to turn on at 180 degrees coolant temp with a 170 degree TStat. It is a 10.9:1 compression engine so I was told by the engine builder to not let it get too hot due to detonation and to keep it under 190. We only have 91 in CA so I have been playing it safe on the temps. I may try to increase the fan temp trigger and run it a bit hotter to see if that helps with the residual fuel and even install an oil temp gauge.

The specs I have on the rebuild are:
Bore: 4.030, Stroke: 3.48, Cylinder head: 60 cc (was milled from 64cc), dome volume +5, Deck: .025, head gasket thickness: .015. I do not know the main bearing or other bearing clearances but I was told the main bearings are "tighter than spec". My oil pressure is close to 75 at cold startup so I believe it. Idle is 40 psi at 800 rpm. Fuel is normally chevron 91. valvetrain preload is zero lash + half turn (roller cam/rockers). Sump is 7 qts but I normally fill it to 6.

Thanks!

It's good to see it has a roller cam. The rich condition at WOT explains the fuel dilution. The coolant temp, while less than ideal, is warm enough to not be a significant cause of dilution. Ideally, it would be closer to 200°F, but I wouldn't attempt that on CA-91, even with MMT. Your oil pressure is good. Note, the fuel dilution is not at an alarming level. I tend to not give it much attention until >5%. It was just significant to see with such low miles on the oil. I'm 95% confident this is due to rich AFR and thus will go away with more carb tuning.

If the AFR goes rich when you roll in the throttle and leans back out with rpm, go bigger on the idle air bleeds and bring the idle mixture back (if needed) with the screws. If it's rich across the rpm range at WOT, but has a good AFR at cruise and part-throttle, I would lean out the secondaries.

It's unlikely that fuel would seep past an intake gasket. Most of the time, the intake is under vacuum which would want to suck crankcase air into the runner. You would know if this was happening as it could lean stutter. At WOT, the mixture is riding pulses to fill the cylinder and unlikely to be collecting at the gasket. I'm not saying it's impossible, it's just unlikely.

It sounds like a healthy engine and fun to drive. I would continue to use a synthetic 5W/10W-30. I recommend High Performance Lubricants Bad @ss 5W-30, (I'm biased) but realistically, any synthetic 30 grade off the shelf will do fine. You just may need to change it more often.

 

[thastinger]

Did you go with gapless or low tension napier rings? Or maybe a chrome top ring for nitrous later? Big ring gap for later forced induction? "Race motor" with a bit extra piston to bore clearance?

 

[SirSpeedsAlot89]

It's good to see it has a roller cam. The rich condition at WOT explains the fuel dilution. The coolant temp, while less than ideal, is warm enough to not be a significant cause of dilution. Ideally, it would be closer to 200°F, but I wouldn't attempt that on CA-91, even with MMT. Your oil pressure is good. Note, the fuel dilution is not at an alarming level. I tend to not give it much attention until >5%. It was just significant to see with such low miles on the oil. I'm 95% confident this is due to rich AFR and thus will go away with more carb tuning.

If the AFR goes rich when you roll in the throttle and leans back out with rpm, go bigger on the idle air bleeds and bring the idle mixture back (if needed) with the screws. If it's rich across the rpm range at WOT, but has a good AFR at cruise and part-throttle, I would lean out the secondaries.

It's unlikely that fuel would seep past an intake gasket. Most of the time, the intake is under vacuum which would want to suck crankcase air into the runner. You would know if this was happening as it could lean stutter. At WOT, the mixture is riding pulses to fill the cylinder and unlikely to be collecting at the gasket. I'm not saying it's impossible, it's just unlikely.

It sounds like a healthy engine and fun to drive. I would continue to use a synthetic 5W/10W-30. I recommend High Performance Lubricants Bad @ss 5W-30, (I'm biased) but realistically, any synthetic 30 grade off the shelf will do fine. You just may need to change it more often.

Yes I wish we had easier access to higher octane fuel out here. Further tuning of the carburetor (Holley Brawler 650 mech secondary) I'm hoping will produce a more stable AFR and less dilution, will have to conduct further oil tests to see. I will take a look at the air bleeds, I haven't touched them yet I normally change the jetting and PVs.

The engine sounds very healthy and I'm told it produces over 400 hp so I'm very happy with it and yes it is fun to drive! I was not expecting this level of analysis and feedback with this post, I very much appreciate the help and tech tips! I will be putting AMSOIL 10W30 in it once I finish the transmission rebuild and run it.

 

[SirSpeedsAlot89]

Did you go with gapless or low tension napier rings? Or maybe a chrome top ring for nitrous later? Big ring gap for later forced induction? "Race motor" with a bit extra piston to bore clearance?

The builder did say he built it for racing and street. He said it was ready for nitrous so I would like to assume he used chrome/manganese rings with the speed pro pistons he put in it.

 

[thastinger]

The builder did say he built it for racing and street. He said it was ready for nitrous so I would like to assume he used chrome/manganese rings with the speed pro pistons he put in it.

So there is your high chromium and fuel dilution. Chromium from the piston rings and fuel dilution from the big ring gaps.

 

[addyguy]

It sounds like it is ‘built enough’ that a racing oil would be in order, something like Dominator 10W-30, or VR-1 10W-30.
Yes it’s a roller cam so it doesn’t need high zinc, but it sounds like once it is dialed-in it will see some hard use, so a stronger oil is not going to be a bad idea.