Premature Valve Guide Wear

[VFR750]

8/29/15 Update

This is NOT the problem.

My very reputable head guy has confirmed the heads/guides/seals/clearances are OK.

He is awesome. He disassembled, cleaned, inspected, rebuilt with new seals. Did an oil analysis, and researched possible causes. I have the heads in my possession and they look like new.

Pointing back to the rings. I will post separate questions on that subject.


8/1/15 update
Still puffing smoke on start. And ~1qt per 500 miles. See my start video on today's post.


Updated 7/9/15: after this post, and discussion I decided the concern was the engine was not yet fully broken in. The very next start was virtually free of smoke. I am not going to do anything, except drive the car and complete the break in. At this point in time the heads are ok.




Please comment on the pictures. I think my valve guides have worn out (or seals have failed) in less than 400 miles.

First picture is of #1 intake which was open when I pulled the carbs off yesterday. Note the odd polishing of the valve stem. What I see is linear ridges that are polished. The unworn surface is not polished, but slightly rough.



#2 and #3 have puddles of oil



Was noticing oil smoke on sucessive startups, and oil consumption.

Backgound: Heads rebuilt by widely recommended shop. New guides, new valves, new seals, new springs. The whole deal.

First fill was with SAE30 oil. After 20 minutes break in, drained and changed filter. used 20w-50 VR1.

At 38 miles I pulled the engine to fix my cam timing problem. I noted the plugs had oil wetting on them, but thought is was due to rings not being fuly seated. New oil filter and another 11 qts of 20w-50 VR1.

Had issue with ignition failure (stranded), traced to corroded fuse and old plug wires. Replaced wires, plugs, cap and rotor at ~250 miles. There was oil on the plugs. Again, though this was due to rings not fully seated. Started car and ran fine, a little smoke on start, but went away after 15 seconds. Went on long drive.

Last start was not very nice. Oil smoke, one cylinder acting a little wonky (fouled plug?). Pulled out of driveway to get on the road to warm up the engine. Smoke cleared after 2 minutes, and all cylinders cleared out. 70 miles later came home, noted I was down almost 3/4 qt after only ~300 miles. Parked car for five days.

Decided to pull LHS carb and found, unfortunately what I half expected, the oil puddles.

So it would appear my valves are already worn out after 400 miles.

I did a search and found some posts on poor valve stem surface finish. My old ones (133K miles) are smooth & polished. The new ones are kinda rough looking.

Thoughts??

[cabmandone]

Mike,
You have a oil catch can that connects to the breather tube that once went to your throttle body right?

[VFR750]

Originally Posted by cabmando

Mike,
You have a oil catch can that connects to the breather tube that once went to your throttle body right?

Yes. The crankcase is vented. Why do you ask?

[cgarr]

What seals were used? You running a high lift cam or stock? That oil could be from the breather, rings not seated etc.

[cabmandone]

Originally Posted by VFR750

Yes. The crankcase is vented. Why do you ask?

I believe the ccv is another tube that ran to the oil tank and that should still be there IIRC on carbs. There would have been another tube that ran from the tank to the throttle body that I think goes to the catch can. My thought is that you're too full on oil. I've never put over 10 quarts in my engine for a oil change with the only exception being when I did a complete tear down to replace my head studs. I could be wrong but that sounds like a lot of oil even for our cars. I run my car at half way up the stick which is where a lot of guys recommend running the car.

After doing some reading on other threads it seems 9.5 to 11 quarts is the norm. I suppose it depends on how full you run it on the stick. I was thinking maybe you pulled some oil from the tank back to the engine.

I'd think the lines you're seeing are machining lines on the valve and the guide. That oil would seem to indicate the seals went. I read the first post again and the first time missed the mention of the oil on top of the valves. I thought I was looking at a shadow from the camera angle.

[Steve@Rennsport]

Hi,

There are many reasons why you can see oil puddled in the intake ports. Here are some of those in order:

1) Too much oil in tank (VERY common)

2) Incorrect or worn guide seals (should be using Viton ones)

3) Improperly fitted or worn guides (talk to the machine shop and ask what clearances they used). Even the soft (& crappy) factory ones will last 40K-50K if they are properly honed and fitted.

4) Ring sealing issues (occurs in the intake with long duration, narrow LC cams causing reversion). You can check this by doing leakdown testing.

Hope this helps,

[VFR750]

Thanks for the replies. This is exactly the type of questions/information exchange I am looking for. I will try to answer your questions.

BTW, I am not throwing my head guy under the bus. He did the right things:

• manganese-bronze guides
• new valves installed and honed
• new Viton seals

Steve's comments on how long I should expect them to last is the kind of information/experience I lack; I just don't know what make of this oil or what to do next.

More background info: I am running Zenith Carbs with 34mm venturis and small port SC heads. JE 9.5:1 forged pistons with Nikasil plated Alusil cylinders.

I have the breather line going from the engine to the tank, and a second line going from the tank vent to a catch tank with a filter on top. Nothing goes from the tank to the intakes.

I put in 11 quarts in this order: Drain tank and sump. Replaced filter. Add 10 quarts on the refill. Start engine, get hot enough to open the external thermostat and get oil into the front cooler. With hot engine idling I checked the dipstick and found I needed a quart to get it back to 1/2 way between the marks. Which equals 11 qts. I do not believe I overfilled the engine.


Steve,

WRT the cams, I have a custom DRC cam. DC-20/19 with 110 lobe center, timing set per John at 2.4mm. I have DRC valve springs.

There is more duration and overlap, such that both valves are open at TDC. This is not a CIS compatible cam.

I expect there is reversion. Does reversion make it harder to seat the piston rings?

Does that explain the darker color of that oil? The oil sitting on the valve is darker than a sample taken directly from the tank.

I was hoping for some things to do next: First thing I can do is to remount the LHS carburetor, get the engine warmed up, and do a leak-down check and confirm the state of the rings.

Thanks for the possible explanations.

[cabmandone]

You're spot on with filling/checking the oil and at half way on the stick. With the oil being on top of the valves I think you'll be wasting your time with a leak down test but I could be wrong. I suppose if the cam opens the valve more or keeps it open longer if you had enough oil blow by it could get that much on the top of the valve. But it would seem like the engine would barely run if there was that much oil getting past the rings and it wouldn't clear. I think I'd focus on the top end but again, I could be wrong.

[cgarr]

Your cam is not that high a lift, if you can find out what the installed valve guide height is? On higher lift cams sometimes you have to shorten up the guide otherwise with the valve spring compressed it can hit the valve seal and destroy it, I don't think that's your problem unless the guides were set way too high?

[Lapkritis]

Originally Posted by VFR750

I did a search and found some posts on poor valve stem surface finish. My old ones (133K miles) are smooth & polished. The new ones are kinda rough looking.

Thoughts??

Plausible. Rough stem will chew softer things up. Assumption may have been made by builder to trust surface finish of stem as provided by valve manufacturer. This is historically a valid assumption... It all falls down when valve manufacturer cuts finish time for more profit. Everyone else assumes the position and takes it in the mouth.

[Josh D]

I've had a valve stem seal come off the guide and cause oil consumption (exhaust side). It will bounce up and down the valve stem and pump oil up the guide. You'll probably have to pull the valve spring to diagnose, but then you can also check guide wear at the same time.

[Lapkritis]

I can't help but notice the wide range of surface finishes within the port... a side note but they're all quite different tool marks. Did the same shop do port work as who did the guides etc?

[VFR750]

Head number 2 is from another engine. It was from a car that had flood damage so there is some pitting. I knowingly gave this head to my guy, to replace the ruined number 2.(Blown head gasket and resulting trenching on the sealing surface) The other two are factory original. No modification; as they came in 1982.

Spoke to head guy. He did fit each valve individually and honed them to fit. We talked a while and it was a good conversation. We agreed the engine may not be fully broken in. The next step is to run it some more and touch base in a month. I'm ok with this.

[Steve@Rennsport]

FWIW,....leakdowns will show you when the rings are seated so by monitoring those values, you'll be able to determine where that oil came from.

[VFR750]

Steve, it's a great suggestion.

I did a cold engine leak down after the first 38 miles when I fixed my cam timing. All were within a couple of percent. The leakage was in the green zone on my harbor freight gage.

In retrospect, doing a leak down before the first start is a great idea. You could catch a broken ring, or set the baseline for the first "hot" leak down.

I think I will run a cold leak down now, then follow it up after the engine is warmed up.

I would I expect a big difference cold to hot? I wouldn't think so if the ring gaps are the primary source of leakage on a good engine.

[VFR750]

Status,

Cold leak down was close to the same as when I did it at 38 miles. Numbers 1&5 looked worse but not by much. Plugs 1,4-6 were wet with some oil.

2-3 seemed the best, number 2 plug was dry , 3 was "moist"

Cylinders Leaked to the breather. This leads to the conclusion the valves are ok and the rings have not yet seated. I will drive it some more and check again in a month. I will keep a special eye on number 1&5.

Thanks all who commented, provided guidance, and acted as a sounding board. This is what makes the BBS great.

[tharbert]

Have you done any of the prescribed break-in routines? I think Wayne's book devotes a whole chapter to breaking in a rebuilt motor.

[VFR750]

Yes, I did follow it, except During the 20 minute cam breakin cycle I had an oil leak that forced me to shut it down after 5 minutes. I fixed the leak and completed the. 20 minutes, then drained the oil. Varying rpm, plenty of deceleration and acceleration to work the rings.

[BURN-BROS]

What valves did you use?

[VFR750]

Yesterday started the car with very little smoke. Interesting.

Also had to refit the harbor freight leak down tool. Apparently it was leaking and not sealing properly. Giving wildly varying results. After fixing the leaks, I now get repeatable results. And everything looks pretty even on leak down.

As I agreed to, just going to drive it.....