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Smoky startup and acceleration,'72-350

F

fc3

Guest
right side smokes on start up and acceleration. then stops smoking till accelerated again. doesn't smoke (can't see) going down highway. I bought the car 1 mo ago. Had been driven 300 mi in last 3 yrs. any thoughts.
 
R

RalleyRed

Guest
fc3,

Someone will be along to help soon. Alot of these guys know their $hit.

I'm thinking valve seals or possibly rings.


Rick
 

MoeJr

Well-known member
Joined
Jun 7, 2002
Messages
797
Location
Londonderry NH USA
Corvette
Vetteless
From looking at the amount of mileagethe car has gone the last few years I would say your valve seals have dried up. Not expensive to buy the seals but can be a royal pain in the arse to do in the car.
 

AKRAY4PLAY

Well-known member
Joined
Oct 14, 2001
Messages
584
Location
Wasilla, Alaska, U.S.A.
Corvette
'77 L-82, black on black. Full mod 406 small block
SOUNDS LIKE MOEJR IS ON THE RIGHT PATH. YOU MAY HAVE ALSO HAVE A SLIGHT CYLINDER WALL RUST ISSUE. IF THE CAR WAS STORED IN A DAMP ENVIRONMENT FOR THREE YEARS, IT IS POSSIBLE. RUN THE CAR FAIRLY HARD FOR A COUPLE OF WEEKS AND KEEP THE OIL FULL. IF IT IS THE RINGS LOOSING SEAT DO TO RUST, THEY WILL RE-SEAT AND LIFE WILL BE GOOD, IF SMOKING CONTINUES THEN LOOK TO THE VALVE GUIDE SEALS AFTER A COMPRESSION TEST. THEY CAN BE REPLACED ON THE CAR, TUFF BUT NOT IMPOSSIBLE. IF THE SEALS ARE BAD, YOU WILL NEED SOME ROPE, PLUG WRENCH, VALVE SPRING COMPRESSOR AND A COUPLE OF HAND TOOLS. YOU WILL NEED TO DO EACH CYLINDER ONE AT A TIME. GET PISTON ON COMPRESSION STROKE AND PULL THE PLUG. THEN FEED SOME 1/4IN. ROPE INTO THE PLUG HOLE. THE ROPE SUPPORTS THE VALVE AND MAKES PULLING AND INSTALLING THE SPRING RETAINERS MUCH EASIER. ONCE THE SPRINGS ARE OFF, THE SEALS ARE A SNAP. IT IS NOT ROCKET SCIENCE, BUT IS TIME CONSUMING. JUST REMEMBER TO PULL THE ROPE OUT BEFORE YOU ROLL THE MOTOR FOR THE NEXT CYLINDER, MADE THAT MISTAKE ONCE WHEN I WAS TIRED. GOOD LUCK, BRIAN
 

Nut

Well-known member
Joined
Oct 15, 2000
Messages
890
Location
Bowie, MD
Corvette
Vette-less for now
fc3,

Valve seals are the likely suspect. My '72 did the same thing at about 175K miles. Though everyone that has responded is correct; and you can do this yourself, it might not be a bad time (and good excuse) to pull the heads and have the seals replaced, have the valves cleaned up and/or replaced if necessary, springs, ...etc. New head gaskets, valve cover gaskets and you'll be good to go for a long time.

Good luck............ Nut
 
F

fc3

Guest
valve guides

How much should it cost to have valve guides replaced?
 

AKRAY4PLAY

Well-known member
Joined
Oct 14, 2001
Messages
584
Location
Wasilla, Alaska, U.S.A.
Corvette
'77 L-82, black on black. Full mod 406 small block
VALVE "GUIDES" ARE SPENDY, MOST PEOPLE DO NOT HAVE THE EQUIPMENT IN THEIR GARAGE TO DO THE REPAIR. VALVE "SEALS" ARE CHEAP, JUST TIME CONSUMING. YOU SHOULD BE ABLE TO DO A VALVE SEAL JOB IN AN AFTERNOON WITHOUT PULLING THE HEADS. OR FOR $500 YOU CAN BUY SOME GM PERFORMANCE HEADS THAT ARE COMPLETE AND READY TO INSTALL. DON'T FORGET TO ADD ANOTHER $100 FOR GASKETS AND SILICONE. I WOULD CALL YOUR LOCAL GM DEALER AND HAVE THEM GIVE YOU A QUOTE FOR JUST REPLACING VALVE SEALS, AND ANOTHER FOR INSTALLING NEW HEADS. IT IS HARD TO GET HEADS RE-WORKED (TOTALLY) FOR THE PRICE OF SOME OF THE NEW ONES. SHOP AROUND AND WEIGHT THE OPTIONS. SOME PLACES WILL ONLY TOUCH HEADS IF THEY ARE GOING TO COMPLETELY REBUILD THEM. THEY DON'T LIKE REPLACING VALVE SEALS AND HAVE ANGRY COSTOMERS COME BACK BECAUSE THIER GUIDES ARE SHOT. IT WOULD NOT HURT TO ALSO GET A QUOTE FOR RE-CONDITIONING YOUR HEADS. QUOTES ARE FREE, PARTS ARE NOT! GOOD LUCK AND KEEP US POSTED ON WHAT YOU DECIDE, BRIAN
 
H

Hijinx

Guest
You should be able to get a valve job for under $200 if you take the heads off yourself. not a tough job, but if you have not done it before, you are basically taking to top end of the motor off. Heads, intake, everything has to come off. Get someone with some knowledge to help you if you have not done it before. It can be a big job getting everything back together and torqued down correctly. I just did my '73 December and went ahead and added roller rockers, new Performer intake and Ignitor II ignition. Mine is noticably more responsive after the build and no more smoke. Good luck. Let me know if you need more info, since I just did mine I can give you more detail if you want it.
 

cntrhub

Well-known member
Joined
Jun 17, 2002
Messages
390
Location
North Hollywood, Ca.
Corvette
Miss my '62 & '80 4- Sp. Vettes
Here's the oil smoke problem. I will give you one off the wall variable and the other two are basic.
The first oil smoke problem (off the wall) is a small oil leak that runs on top of a header or exhaust pipe. This will be obvious as you look under the car and find built up oil around the exhaust system.
The other two basic oil smoke problems are as follows: Smoke upon start-up. This is caused by valve guide/valve seals. The valves tend wear in their guides and loose their tolerences. Even if you replace the seals, this is only a band-aid fix. The valve will move far enough away to egg shape the new seal's lip and suck oil back into the combustion chamber when the intake valve is open and on it's "intake stroke". Worn valves/dried seals: The car sits over night, the oil will run down the vavle and trickle into the combustion chamber. When you first start up the engine, it will burn off eventually, but it's slowly sucking in oil at every stroke.
Here's the trick to know if you have a valve guide/seal problem. One is cold start up, as stated above. If you want to know how bad it really is, go down a graded hill and lift on the throttle and coast down hill. Then stomp on the gas, (if you are driving) and watch the bellow of smoke through the rear view mirror. You'll see a big puff of white smoke when you do this. What is happening is... vacuum forming in the combustion chamber. It's sucking in oil throught the guides. As you step on the throttle, it finally puffs out. This is how you detect a valve problem.
The second oil smoke test is: Oil is constantly smoking at idle and driving. This is generally worn rings.
Either way, you have to check your oil level and monitor the milage. If you top off the level now, check milage. Drive for a day or two and check the milage again. Did you have to add? If you did, time to either fix the valves, change to a fresh engine, rebuild the one that's in the car, or buy lots of cases of oil.
4play is right. If you have an air compressor, a spark plug adaptor and the mechanical skill to change the seals, I would try the cheapest way first. If it's smoking on only one side, it might be just a seal? Not sure, but just guessing at this point. There is a valve spring tool made especially for this job. Tool trucks like Snap-on usually have these in stock. You need to set the valves after replacing the seals. There is only one valve seal used on each chamber. I used to install new quad rings and seals on both intake and exhaust. I would buy two valve seal packs to do the job.
If you attempt to do this at home, there are enough gear heads here, to walk you through the steps.
 

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