Good thing 350 engines are inexpensive. You can have a remanufactured long block put in at reasonable prices. You will at least have to pull the heads and scrape the crud off the intake valves. The problem is that if you do that and you have a stuck oil ring, you’ll wish you just got the long block put in. Then you won’t have to worry about all the other old engine problems that could crop up later. If the body is good, go with new stuff.
On deceleration, when the vacuum is peaking, I would absolutely agree.
At idle, I suspect that’s only part of the problem.
It also occurs on start up when oil has leaked past the seas and in to the combustion chambers. My 1984 Impala emitted some smoke just after start up as well.
I agree with you
But . . . unless I’m forgetting something, I believe OP only mentioned smoke upon startup?
If this engine has remained untouched since 1979, I’m guessing you are right, and it is worn, causing multiple problems. Hooking up a compression tester and vacuum gauge would tell you a lot about the condition
True, but wear applies there too.
That’s my thinking. The engine is 37 years old. I’d be reluctant to make any assumptions without first checking it out. The tests are easy and definitive. And the engine is old.
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You’re probably onto something
it might have rotten valve stem seals, stuck oil control rings, and low compression
If that’s determined to be the case, a long block might be in order, as has already been suggested
There’s only one way to know for sure!
If the compression tests out ok, I’d just fix the valve stem seal problem and see if that fixes the oil consumption problem. Tester above implies the valve stem seal job isn’t overly complicated. Engine remains installed, head remains on I presume. I’m not sure what the nylon cord is for, when my VW Rabbit had valve stem seal replacement the dealership – warranty job – used pressurized air to keep the valve from dropping into the cylinder.
This may or may not help you. I have a lawnmower that smoked badly out the exhaust and used copious amounts of oil. I had been using straight 30 weight heavy detergent. For an experiment, I bought a bottle of 10W-30 full synthetic oil at my local Rural King store. The oil was $ 2.79 a quart under the house brand RK label. The 30 weight oil I had been using was $ 1.79 a quart. The synthetic oil reduced the oil consumption by 75%. I think the oil is now sold under the Harvest King name. This may or may not help your truck.
I had a similar problem to your situation with 1971 Ford Maverick with a 250 cubic inch 6 cylinder engine. The oil consumption was 1 quart every 300 miles. I had the valve stem seals replaced and the oil consumption rate dropped to 1 quart per 1250 miles. The cylinder head did not have to be removed. Compressed air was fed into each cylinder while the seal was being replaced. My total bill for the work was $ 42 50. This was back in 1974.
I seem to recall the rope trick Tester referred to above. If I have it right, you don’t need an air compressor to hold the valves closed while you’re changing the stem seals; you fill a cylinder bore with rope via the spark plug hole while that cylinder is down; then turn the crankshaft. The rising cylinder compresses the rope, which presses the valves open. Works even better if you leave some of the rope hanging out the spark plug bore.
Of course you mean “presses the valves closed.”
;-]
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I always used a piece of vacuum hose soaked with transmission fluid to hold the valves up when needed. But soft flexible rope sounds like a good alternative.
I recommend not using the aftermarket umbrella seals. they can starve the exhaust stem of oil and cause it to wear quickly.
Yes, valves closed. And I meant to talk about the piston (not the cylinder) rising!