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Smoke at the valve covers

Vortec heads, steam holes for 400 Eng? Head gaskets with steam holes?
Cracked head or bad head gasket would have milky colored oil and or white
Smoke from exhaust generally. Is your rad being pressurized and bubbling in overflow bottle?
Blow by pressurizing crankcase is compression getting past the rings or a cracked cylinder. 400's are Siamese cylinders and don't like overheating
(Steam holes) a must have.

I have not had noticeable blow by with any engines I have put together.

Misadjusted valves and blow by doesn't sound right to me.

U have an internal upper end problem in my Opinion. Pull a head on
The #7 side or give it back to the shop.

Is this a driver? 11:1 comp, why? With that cam what is your actual running compression . Plus 1.94 valve steel heads.

Something has failed. IMHO.
 
Who did the machine work?? I had all my stuff done by
http://www.carpartsmachineshop.com/ there right downtown on Texas

I built a 400 destroker a few years back with Vortec heads and it ripped , but I had them drill the steamholes when they decked the heads and milled down the valve guides.
 
chulisohombre said:
Anything over 150 psi can't run on pump gas. .
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El Paso is pretty High elevation, when I lived in Alamogordo NM, (about 90 miles north of the OP ) we could usually get a full point of compression more then what you sea level guys could. I routinely ran 10-1 on the street running pump gas with "normal" timing and it would't ping
 
yellowK20 said:
El Paso is pretty High elevation, when I lived in Alamogordo NM, (about 90 miles north of the OP ) we could usually get a full point of compression more then what you sea level guys could. I routinely ran 10-1 on the street running pump gas with "normal" timing and it would't ping
Click to expand...

Ill give you that. Lol. But normal applications won't allow for it with the extra compression. If he ever drives it down the mountain problems will get bad again though unless you can do something before going to lower elevation. Correct?
 
Yep, but he would have to drive a few hundred miles to really find a low enough elevation to start hurting him . 11-to 1 is higher then I would run on tue street with Iron heads down there
 
Gonna take a stab at this and say the detonation took off a chunk of piston and that's why you have the blowby and smoke coming out of the valve cover.

Do you know if the pistons are forged or cast?
 
Keith Black Pistons are all Hypereutectic cast , but there super tough
 
Thats KB's big claim to fame as tough as a forged but lighter . Alot of the stock car guys I use to build motors for ran KB psitons and buzzed the crap out of them never seen one fail. I think they have a thermal coating on them as well.



I agree its possible but I would be surprised
 
i was taking a breather. The machine work was done at carquest, i've known the machinist for a several years and he does excellent work. The KB pistons are Hypereutectic cast. When the machine work was done we made sure to drill the steam holes onthe heads. the heads checked out good and the springs were also changed, the only things i did not replace were the valves themselves as they were good. The 11:1 compression is high but i figure since its not a DD and only gets used on flat trails and steep hill climbing, i figure it would be okay. Either way, i checked the cooling system pressure and its good. No water in the oil, inside the valve covers is clean, I'm building alot of pressure in the crankcase because i noticed a nasty oil leak around the front of the oil pan that wasn't there before, oil is also coming out the breather and into the air filter. I'm thinking since the machinist is willing to warranty all the parts and labor, why not just do that the K5 will only be down about a week or so.
 
And yes, as i mentioned, the heads have the steam holes, the gaskets have the steam holes, the radiatior is pressurized, no smoke at the exhaust (i can feel the pressure, but no smoke) the exhaust gases are getting into the crankcase because the smoke coming out smells like gas. all good points here, i'll take out the heads first and have the machinist check em again, if they are good, then go and pull everyting out then.
 
If your running a stock intake,maybe it has failed internally at the heat riser passages,I have seen a few do that,it will let exhaust gasses get into the crankcase and pressurize it..
 
Intake is a brand new aluminum edlebrock. when I built the engine, all internals parts (except crank), all external parts and accessories were replaced. Something had to give because the engine was running great, no problems whatsoever until that day with the blow by pressure incident.
 
Still sounds like rings are bad to me. Should have bad compression though. Maybe it just has wrong ring gap onbthe pistons. Maybe not sealibg good enough with not enough pressure. Sucks because its new. If its free id just pull the engine and see whats up. When you pull the heads you can check cylinder walls and see whats up. And if he's in there maybe drop the compression a little. Just a couple more thoughts.
 
I'm betting you are going to see the problem when the heads come off.
That much blow-by should be obvious. Non-seated rings are just not enough for that much leakage unless they all stopped sealing at once.

I'm thinking a hole in a piston. Not sure why you still have compression though, unless its an awfully small hole.

A crack in the cylinder wall way down low would do it. Once the piston moved above the crack, you would have normal compression, but when it moved below it, the remaining pressure would shoot out into the crankcase.
 
Hope you can post some photos of the tear down and hopefully find the cause and post it up. This can be a great learning point for a lot of people and I'd be grateful for the info.
 
Well, back again fellas, I finally got a break from the shop. Hard to believe my baby has been sitting for six months, well I have driven it here and there in hopes that the rings will seal and all will be good. But that was a big negative. I noticed that the needle and seats of my Holley carb gave out and was constantly dumping the gas inside the intake.

Anyhow, I proceeded to do a cylinder leakdown test and #1, #3, #4 and #5 had about a 70% loss as soon as I hooked up the air line. No bubbles in the radiator or air via the carb or exhaust pipe which showed everything else was good, but more than likely the rings were broken.

So, the engine came out and as I tore it apart, all the rings look good :angry1: WT$. I noticed the bearings were scarred and washed off with all the gas that had gone inside the crankcase. Further inspection of cylinders 1,3,4 and 5 showed me the problem. Those pistons were broken between the top and 2nd rings which explains all the blowby I was getting.

My guess is that the carb was leaking gas internally into the intake, washing the cylinder and preventing the rings from being lubricated thus creating more friction. Or maybe I got a bad batch of KB pistons. Either I will post up some pics on Monday of my findings then its time to go to the machine shop.
 
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