Dear 402 Engine Gurus…

Sorry for this long thread, I just want to give you all the info you need to help me!

My new \LS2 402 11.2 compression engine usually has blueish oil smoke out the back at WOT and immediate Decel, but then, sometimes it does Not!

It made 492HP/478TQ RWHP a few weeks ago on the dyno, through the Y pipe. I know this engine can make more but that seems pretty good with the heavy MCL clutch and 4:10 Moser.

Of note, the Valve cover Baffles had been machined off to fit in the T&D rockers on the RHS heads - so they do sling oil. I put a large air compressor type oil separator between the PCV and the TB - and sure enough it IS collecting oil.

But it still smokes after installing the filter, so there must be other problems.

I'm doing Compression tests with rounds of 10 strokes, (fuel relay pulled out/ spark wires off, cold engine)

I saw a PO308 misfire code on #8 code, so I started there and compared to cyl. #1. (I will test the rest of the holes later)

#1 cyl. psi goes like this:
FIRST TRY AND ALL SUBSEQUENT TRIES:
80 100 120 150 190 190 190 190 190 190 –
(30 seconds to bleed back down to zero. Does that matter?)
Is this good compression?

#8 cyl. psi goes like this: ( I had to rig up a 90 degree quick-fitting to get it into the tight hole there)

FIRST TRY
50, 80, 100 100 100 100 100 100 100 100 -
(Bleeds down to zero in 2 seconds. but maybe my rigged-up 90 degree quick connect fitting is leaking air?)

SECOND TRY, hangs low then jumps up late!:
80, 100, 100, 100 100 120 150 190 190 190-
with a 3 sec. bleed down to zero.

THIRD, FOURTH, FIFTH tests: similar to #1 cyl.:
80 100 120 150 190 190 190 190 190 190 –
(6 seconds to bleed back down to zero. Again, maybe leaking quick connect on my gauge?)

Questions and Notes:

1. Is 5 strokes pumping up to 190 good? (11.2 compression 402)

2. Does the leaking down time matter? ( I know I'll probably need a leakdown test)

3. What do ya think about sticking low - then going high on #8 on the first two tries?

Maybe a slightly bent, sticking valve - sometimes it sticks and sometimes not, as it rotates? And for some reason leaks oil by the valve seal?

Maybe on first try it smears the cylinder walls or the valve stem with some oil and then it finally "seals up"?...

4. I saw smoke coming out of the oil filler neck with engine running warm at idle. But, It does NOT "Puff-Puff" smoke like a choo choo train out of the oil filler neck , like my Vortech Z28 did when it had broken ring lands.

It looks more like a cigarette in an ashtray, multiple streams rising straight up.

I felt a pretty good vacuum (for a big cam) when I put my hand on it.

5. What else...the plugs are dark reddish-brown, rather than the usual tan. It was set rich while breaking in but was recently dyno tuned for correct A/F, so could be left-over color: They were not gunked up with oil.

6. These new RHS heads recently went back to Comp Cams for a full freshening (4 new 921 springs, seals, all valve seats, all locks,) after a couple rounds of broken rings during break-in.
It was discovered the WRONG springs had been ordered and were collapsing the lifters, breaking springs.
Hopefully they didn't miss a bad seal or slightly bent valve at Comp.

7. I do want to say that Comp Cams was great about this. Red Obert is a straight up super guy! They do want to make you happy and are MORE than fair.

8. I did wrap it up to 7000 rpm on a missed shift afterwards, but my equipment should be built for that. (see sig)

Next steps...Trying to figure out if I should plan to pull the heads or just try to replace valve seals with the heads on...

THANKS FOR ANY ADVICE GUYS!
Sorry for the long winded explanation!
Rambo

 

With the parts you have I wouldnt think the rings but the low compression in the one cylinder is definatly not good. I have heard of putting a bit of oil in the cylinder then turning over the motor and seeing if the compression rises any more than before. If so its the rings or ringlands if not start looking other places like the valves.
sorry I cant give you more but that is where I would start personally.
Good luck
Brian

 

When you say new, how new? How did you break it in? Have you checked the obvious? Some times we tend to over look small things like teflon on the rocker studs. Oil can seep down those. Have you pulled the intake to see if you have oil sitting on top of your valves? You may not believe it but, push rod lenght! have you checked it. Could cause a problem and cause a low reading on your leak test. Good luck, I hope there's a simple solution to your problem.

 

Thanks Guys...

nvmy2000s,
Yep I am on that next. I read that in the manual too. At least rule the rings out.

1999vetteroo,
2,000 miles on the motor, broken in carefully, babied it for 1000 miles. Found some oil in the intake but not like puddles, I really don't want to take the intake off If i can help it...I do have a scope though, maybe i can snake it up in there and look down on the valves.

The Mechanic said he definately put teflon or sealant on the rocker stud threads.

You may be on to something here..I was told by Chris Straub who sells Morel Lifters, that with my Morel lifters and T&D rockers combination...."no more than 1-2 turns out on the adjuster...any more WRECKS the geometry and will be noisy." (and it is!!!)

In other words, any more than that...we must get different length pushrods. And Pre-load must be 0.30 -0.45.

So, 1999vetteroo, Does this sound like it could be pulling oil in if the pushrods were wrong length and adjustment over compensated? If so, That sounds encouraging, like maybe I can have another mechanic just go through valvetrain and adjust/ replace seals and pushrods.
COuld that explain the smoke too?

Do you think would I need all new seals since maybe they got worn funny if geometry was wrong? (I am not a mechanic) Just sounds like it makes sense.

Thanks again!
Rambo

 

Your compression looks good, but I would get a leak down gage to really find out what's up. I bought one last year and now never use the compression gage.
What kind of rings are you using? Try some different things on the PCV system, if nothing changes, it probably is rings, or valve seals. I have a LS6 that has good compression, but the oil rings are not working. It smoke bad on decel.

 

racecar,

I'll do that on the leak down tester. Sold at auto stores?

Those are DRP File-Fit rings. What do you think about them?

OK, I will try what Matt at TTP is suggesting on the PCV system. TTP built my short block and Matt says he has never had any oil burning problems with 402s other than the oil slinging in the vc's which they fix with a dual valve cover breather setup linked together.)

Thanks for your advice.
ram

 

R'car is correct - - do a leak down test ASAP. That will rule out rings for sure but not seals. Usually if it is seals the leak down will not be effected.

My drag motor was built WITHOUT exhaust valve seals at all and I get NO smoke at all upon lifting. At times, I will get just a touch upon a cold start for about 5 seconds.

Pushrod should not effect 'smoke' without effecting the car's running to my understanding.

Lastly, do you have a PVC system? if so, why? Two K&N breathers will release the crankcase pressure and not draw huge vacuum and oil from the system.

 

Hey olddog,

Thanks for checking in...wow, how about that, no seals on your drag moto!

Yes, I have the PCV system still on, but agree no need per TTP matt too. I'll do something like you and he suggest.

Seems like you doubt Valve seals? If that's not the case then I hope its all PCV sucking oil. Hope Not rings! But is some smoke normal out the oil filler?

OK, I know I owe you guys more information after squirting a little oil in #8 and leakdown tests... but just too damn hot in St. Louis to do anything about it.... and the Beer is colder inside!

I'll post more test soon results in a couple days....thanks again!!!!

Ram

 

Rambo,
I went through the whole, pushrod thing try to get rid of valve train noise. I tried a 7.425 and the noise was still there. Not only that but, I dropped 20rwhp! So then I tried a 7.45 pushrod, still had the noise and was down another 20rwhp. So, at this point I'm down to 380rwhp (from 420rwhp) and I've learned my lesson. Should have listened to all the guys saying just live with the noise. So I put the stock lenght 7.4 pushrods and everythings back to normal right! No, now I'm buring oil. In my garage, I have black marks behind each exhaust pipe from starting my car. After thinking about is for a while, I pull my intake and found a pool of oil sitting on top of each intake valve. My theory is that when i put the longer pushrods in, it increased seat pressure with each change. (Your spring seats ride on top of your seals) Then I turn around and backed it off when I went back to 7.4. Some people by this and some people don't. Thats fine with me. All I know is I now have new seals, Rocker arm studs are teflon coated and my car is no longer burning oil.

Hope this info is helpful.

 

This is very informative! Yes it helps a whole lot and ties in with what Chris says about messing with the geometry.

I have the same black marks too. I'm going to scope my intake valves later in the week, I have a fiberoptic "snake" I can go in through the TB with. .

It is encouraging though...instead of rings, it's more likely that more likely seals/ wrong pushrods / make sure studs are teflon coated....

I still have not gotten to putting some oil in the cylinder but I did pick up a fresh compression tester today to try instead of my leaky one.

I'll do some more tests and snooping, then when I get out of "bankruptcy" I'll hire the best guy in the area to do a real leakdown test and if it agrees, probably redo the heads with all these notes.

Thanks VERY much. Everyone. This is all is very helpful.
Ram

 

I hope that you are kidding about bankrupcty, and that this moror did not drive you to it. Borrow a leak down and check it out. If all is good, then replace the intake seals. Yes, some drag racers don't even run seals on the exhaust. It is pretty common on these motors to have oil in the intake, they seem to blow it up the PCV due to the low tension oil rings.

 

As long as you have a scope, try to get into #8 and look at the cly walls. It is possible and not unheard of to have scuffing which scores the cyl walls. This would give you the symptoms you describe.
I hope this is not the cause but if it is you want to address it before you continue with other trouble shooting.
No baffles in the valve covers is not good if you are using the unbaffled vents.
You probably need to rethink the whole PCV, catch can, vent issue but not before you find out what is going on (above).

 

If your that low on compression in one cylender you have a bad leak. You could have a cracked ringland or a cracked ring or a burnt or bent valve. You should do a leak down and listen for where the leak is comming from. Listen at the tailpipe, intake and oil fill cap you will get results fast some noisy is normal fom filler cap but not alot.

George Benson

 

Thanks for teching in with me guys!!!!
I'm obviously in the right place.

Racecar, Ummmmmwelllll... LOL....in the racecar dept. at least, yes. It's a matter of shutting off funds to send the boys to school, so, priorities rule! Your notes are very encouraging and I will follow through!

See5, Pardon my ignorance but what are baffled vents? something I can retrofit? Will do on all your other advice. BTW, I saw 4 tiny scratches so far in #1, which I also saw when the heads were off. Will check the others...it's hard to point the damn scope in the cylinder, I am trying bendy wire taped to the fiber optic cable but it's not paying attention to me! thanks man....

07BlueDevilZ06...now there is a user name from hell! Well, not sure you noticed but the compression ends up at 190psi, just took a little while to wake up on #8, or you are right, something is not sealing...but then sealing. Also didju mean some "smoke" is OK at the oil cap but not a lot? Thanks man. I mean brother! (benson)

Best to all ya.
ram

 

[QUOTE=

See5, Pardon my ignorance but what are baffled vents? something I can retrofit? Will do on all your other advice.


Best to all ya.
ram[/QUOTE]

"Of note, the Valve cover Baffles had been machined off to fit in the T&D rockers on the RHS heads "

 

gotcha, I confused myself!

 

I got the new gauge and it pumped right up to 190# again but leaked right out again in about the same 6 seconds.

Then I put 3 teaspoons of oil, ( actually it was "No Leak" oil additive) in the compession tester hose and blew it down into #8 cylinder with a blast of compressed air.

Then it went right up to 215 psi (!) on the third bounce and just stayed there..... Not until I pushed the button did it drop.

So I guess this points to piston rings. Or - wishful thinking...maybe my jury-rigged 90 degree snap- on fitting finally sealed up with the addition of oil. Grasping at straws now!

Certified Performance in St. Louis was recommended by a friend so I called them, they seem straight up, nice, and knowlegable with LS race engines and Fbodies. I'm taking it there tomorrow... they only charge 40 bucks for the full leakdown test.

I'll look down the runners with my scope to see if there is oil on top of the valves while it's in there.

I'll keep you guys posted and thanks for all the help.
Ram

 

Can't yopu just pull the head yourself? That will tell you what is going on. If you get into a shop, and they have to pull the motor, then you are looking at a HUGE bill.

-Geoff

 

I wouldn't count the ring(s) out yet! You said you babied it for 1000 MILES!? Dude, you need to go out within the first 10-20 miles and build cylinder pressure and get those rings to seat properly. I'd bet that number 8's rings didnt seat much if at all.

Again, I WOULDN'T count out the ring(s).

 

White Hawk, Yes I can pull the heads and will, that way I can store it in my garage if the heads need work....but 40 bucks is worth someone else doing leakdown tests. Those plug holes are hell to get to without a lift. I'll pull them once I know what is up. Or, If it's just valve seals, correct size pushrods, can that be done with engine in the car? (Don't laugh, I'm not a mechanic! )

lilbuddy1587, Well I lied, we got on it a bit. I can't say exactly when, the mechanic broke it in, he builds ls engines all the time.


Tomorrow is leakdown day!