So as I finished up a load of repairs and upgrades I noticed some white smoke coming out of the passenger side valve cover which has a breather on it. I'm not quite sure what it is but I'm doing some research and searches. Any ideas? Here is a bit of background info Engine: 305 Carb: Demon 625 Fuel pump: Micro something, puts out 7 / 8 psi, didn't use the return line, figured it would drop fuel pressure Recent related repairs; > Smoked before here and then from the exhaust months later so I replaced the valve seals, no smoke after that > Prior fuel pump put out way to much pressure and caused alot of issues, blacked the spark plugs which... might still be black :/ I was hoping that a clean run would clear them off. I'd hate to pull them all off again. > Timing on Accel HEI set to 12, tried 10, still smokes > Air / Fuel Ratio was set to Stoich, idled a lil rich after the test drive ( Guage stopped stopped working today, maybe the oxygen sensor became fouled, it was in operating temp to work, just no lights anymore wires are good ) > Idle screw set to idle at 1,100 > No strange noises or pings > Cant determine vacuum due to cheap vac guage. It reads 5 pressure when disconnected and 5 vac when reved so.. I'm guessing 10lbs of vac? I dont trust it. The test drive yesterday was awesome! The car never responded so well. I really dont feel any lack of power, its a 305 so I wasnt even expecting that much. I'm just hoping that it might be burning something due to me being in the middle of adjusting the timing and tuning the carb but something makes me think that its gonna be some type of internal water or oil leak... bad gasket or something.. which doesnt seem right cause all those gaskets are new. Unless I fat fingered the install but it all seemed pretty straight forward to me. The car didnt immediantly smoke after I replaced the valve seals but the engine did get to hot with to much fuel pressure. I swear I saw a light flame burning from where the AIRS system goes into the cat.. that part did get red so.. makes me wonder. Maybe the heat jacked something up. Whatever it is, I hope its an easy repair. I reaaally dont want to take that engine apart again lol. If I do I'll end up upgrading parts and keeping the thought in my head that I should be spending this money on a 350 swap. I'm just trying to keep it alive till then. If the timing, a/f ratio and idle speed seem fine, and the guage kicks on saying I'm burning at a stoichiometric range... does the white smoke still spell a critical failure issue that is about to happen? I dont want to test drive it to much or mess with timing / carb tuning to much if the smoke is telling me that the engine is being damaged. Any thoughts would be great

Maybe this engine is just worn out. Could be one of the cylinders with lose rings, blow by? I dug these up from google. If this is the case then I don't think its going to pass emissions. An overhaul seems pricey for a 305 when that money really needs to just go to a 350. This kinda sucks cause I spent 11 days working on it every night to find a smoke issue.

"You can still drive your vehicle despite the blow by problem, just make sure the oil is always topped up. Blow by occurs when the compression rings can no longer seal the combustion process and it leaks by into the crankcase. Their is usually a fresh air intake for the pcv system to function properly, this creates a loop in the crankcase so that the gases can be cycled through the engine and back into the the intake to be burned properly. Check to see if the fresh air intake, pcv valve, and all the hoses are hooked up properly and not plugged. Then pull the oil fill cap off if there is still excessive blow by then it's time for an overhaul."

"blow by is when the clearence between the piston rings and cylinder wall get to big. Oil from teh crank and pan is going up past the rings and burning in the combustion chamber. Also, the smoke from the burning gas and oil leaks back into the crank case causing the smoke to come out of the breathers. If you smell it, it should smell like exhuast. You need to get a ring job. Bore and hone out the cylinders and put new rings and if you bore it, you need new pistons. You will continue to lose compression. I know about blow by cause i natually have blow by since my engine has loose rings."

Actually, I poped the oil cap off and found that smoke is coming from both valve covers so.. it sounds like that top end has to come off again to figure out or repair anything. Lol sucks cause I just got the timing and a/f mixture perfect. Runs great with the exception of the smoke... :/

HA! I think I just pulled a noob move. I looked at my new Demon carb and noticed it didnt have a large vacuum port on the front like the old holly did. Keep in mind that this car has been in storage for 2 years, I have not had a chance to hook up most of the top end components above the intake manifold until 13 days ago. So I start tracing hoses and find that the one connected to the pcv valve is just kinda laying behind the engine. I believe this hose went into the front of the old holly so the engine could cycle unspent gases and burn them for cleaner emissions. Poped the hose on a different vac port as I dont have one on the front and the engine stopped smoking from the valve covers.

My guess is that without that vacuum then these gases cannot properly be removed from the crank case or burnt efficiently so they just rise up through the valve covers. I'm not sure if that normally appears in the white smoke / steam as it did or as much as it did. Still cant be sure if it was really smoke or steam, it did smell like exhaust but.. I mean its coming from the valve cover, what else is it going to smell like to me? lol I might bring it in for emissions testing to see what the numbers look like then come back to that smoke / steam mystery thing if it fails. Umm thanks for the help? I hope all this info helps someone somewhere. Maybe I just had my hose routing all jacked up with the new carb.

One last reply cause I just found a pic that I remember seeing years ago. Screw this up and you just might see some smoke. Not sure how much is abnormal but.. yeah

http://z.about.com/d/autorepair/1/0/8/B/41921072.gif