I have a rebuilt 327 in my 51 chevy. it has about 650 miles on it now. over the weekend while cruising the GG show it would generate alot of smoke after cruisingthe fairgrounds at idle for 30 minutes, (like when I went to back up and gave it some gas). someone said it could be the vaccuum modulator on the T350 trans is bad and allowing ****** fluid to pull into the engine manifold at high vaccuum (idle). This is new to me. a little smoke at idle on the driverside. I have a vac*** line running from the modulator directly into the intake (at the back between the carb and distributor. The trans was a unknown condition when I got it (no clue how many miles were on it or it if even ran before I put it in.. I took a chance.. it seems to shift fine). I figured it could be a valve not seating right?, or one of the rings is letting oil byp*** or possible the trans modulator someone recommended.?? The car runs good, no strange noises.. I pulled the plugs and they look good (no wet plugs). could it be the modulator or something else. what should I look for.
white smoke is trans fluid, (thru the modulator), blue smoke is oil burning, white smoke that dissipates quickly is water vapor.
Remove the modulator line, see if its wet inside . Now plug it and see if its still smoking. Rig up a small section of clear hose and see. Do you have a good pcv system in place
I only have a front filler tube.. no other PCV set up. it is a vintage edelbrock intake and vintage script chevrolet valvecovers. no smoke or fliuds out of front filler tube I did pull the vac*** line a few days after the car was sitting (no sign of fluid) but it had been sitting for 2 or 3 days... I pulled the line and started the car, got a little smoke but it was on start up and it went away quickly and there was some moisture coming out of the pipes (again after sitting for 2 or 3 days) the smoke coming out of the rear after cruising at idle was I think more white and it hung around for a few seconds.
Smoke at idle or during decelleration (high manifold vacuum conditions) is often the result of a bit of oil being pulled past the intake valve guides into the combustion chamber. The valve stem seals could be damaged or installed improperly, but they can usually be readily fixed with the heads in place. You might want to pull the valve covers to see if the valve seals are in fact in place. Also look to make sure that the oil drain-back p***ages in the heads are clear so it's not trying to hold excessive oil up on the heads instead of letting it drain back into the oil pan. Also look into getting some sort of real crankase ventilation system put into place. This will help reduce blow-by and keep ypur oil cleaner longer.
327 up to 66 had no PVC just a draft tube on them then in 66 or 67 they added a PVC from the carb to the draft tube fitting on the top back of the block.
Californina required them in 61 NY in 62 most US cars had them by 64 I had a 300 hp 64 impala with a factory pc valve.
Without a Pcv system or road draft tube you will have trouble and smoke or an oily mess. Is there a breather on the filler tube or a grommet stopper.
a little more info. I am running a new edelbrock 600 carb. the filler tube has a breather on it. the back down draft location has a freeze plug (by the dist) How do I tell if a valve stem seal is bad (if I pull the valve cover?) I had to put on other valve covers with access for PCV but will if that is causing some of the problem. I have run engines with this combo and not had issues (it is basically a stock spec rebuild)
I had a similar problem and I replace the new valve seals with Fel pro seals and used the GM orings and it fixed my problem.{ I think my seal where for over size valve steams}
In my recent experience with my 350 running an early intake with the tube and closed valve covers. There was alot of condensation, white milky crud under the valve covers after a very short amount of run time. You really need to put on the road draft tube to allow it to function as designed. Or use a pcv valve at that location. The oil fill tube is not meant for a vent, it is meant for a way for air to come into the crank case and ventilate and exit thru the draft tube. This may or may not be your problem, but it is my experience. ASK TOMMY, he'll tell you!!!!
but will opening the draft tube in the rear stop the smoke. I find it hard to believe that is what causing it.. maybe adding it to. I have to replace the valve cover gasket since i have a leak from when we adjusted the valved after break in so I will just add different valve covers (old ****py edelbrock finned ones I have, just have to find them.)
I had an Edelbrock like yours and after I junked it, I installed a Holley and the smoke disappeared. I tried everything on that damned Edelbrock carb to get it from running rich at idle. Ditch it!!
Boonies, you can run those covers. You just put the PCV valve in the hole where your freeze plug/road draft tube is. There needs to be a baffle in there
If the trans condition is unknown, it could be the vac modulator, like others have said (but if they leak, they usually wont hook up top gear due to loosing vacuum). My inlet manifold worked loose on my 350, and ****ed oil in from the valley. All I did was tighten the bolts and the problem was fixed..
Are you loosing any coolant -at all-? I had a 350 one time that had a small crack in the head between thr exhaust valve and the exit port into the exhaust manifold...... It would only drizzle a tiny bit when warming up causing slight smoking. as soon as it warmed up it stopped,also as it was seperate from the combustion process it did not foul a plug or other symptoms usually ***ociated with a coolant leak.... it used a very small amount of coolant if driving a distance and used a bit more on short three block commutes..... casting flaws are very common in the late 80's sbc heads, mainly the light duty re-design with the irregular cast edges near bottom boltholes of heads......
If the smoke is coming out the tailpipes??? it is originating in the combustion chamber. If it is blue, it is oil, if it is white, it is water and if it is black, it is fuel. If the valve seals are bad, it will puff out a little blue smoke when you first start. If the blue smoke continues, it is blow-by. If you have chrome moly rings, they are probably not yet seated. If the smoke is white, you probably have a problem with a head gasket. If the smoke is black, the carb is probably loading the engine with fuel during low rpm operation. If you are puking oil out the dipstick tube, or smoking out the oil filler tube, you probably need additional crankcase venting. If oil is coming from the transmission thru the modulator valve??? I would suspect that the diaphram was ruptured and the ****** wouldn't shift properly???
chopt top, thanks for all the variations. I will have to do some checking this weekend to lock down the color. The trans kickdown is not hooked up to the carb (need to get a new bracket built). so I am manualy kicking it down. When I am in drive... I think it is upshifting as I accelerate (but now I need to double check that) there is about 650 miles on the car. 1st drive was a 250 mile drive since then it has been shorter 50 to 75 miles drives at a time. No oil or smoke from dipstick or oil filler tube As for what is in the motor, the builder could not find any recepts but said it was a stock rebuild.. It came as a package with a 35 ford a buddy bought.. he needed some money so I bought the motor. it did look rebuilt and fresh when looking at it. (it was really tight during first crank over (could not turn with a bar off the crank bolt)
The part about the engine being tight is kinda scarey, but if it runs ok and doesn't make any weird noises I would try a PCV system on it before I did anything else. You'll probably have to pull the intake to install the cannister, use the factory PCV adaptor and an in line PCV valve. I'll bet that (along with putting some miles on the car) will take care of the problem. Unless it's the vacuum modulator. Did the car have the same transmission in it before you changed engines? Did it smoke then?
Ken, if you checked the vacuum mod line and it was dry thats not the problem as ATF is opl and their would be residual,use a Q-tip inside the line and that will confirm it. How long did this engine sit after it was said to be rebuilt? The valve guide seals could have even been damaged during install or could have even been some that had been sitting around on a shelf for a extended period. how long does the initial smoking last, 2 minutes,10 minutes.... Taking the risk of somebody's second hand info on "it was rebuilt" is well... i state this from my experience working for a major engine rem. back in the 80's when i was shipping 128 motors a DAY out the door meaning until the last onewas in the trailer you didn't go home. I also worked close with the warranty guys and i did see some **** that most likely the direct result of over consumption of alcohol or drugs the previous evening or finding out your old lady was screwing your co-worker! good luck.
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