273 smoking

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my273mopar

my273mopar

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The 66 Dart 273 that I have owned for about 2 months I have noticed that after a few minutes of driving when I get on it a little the blue smoke rolls out. My first though was valve stem seals. Pulled the valve covers it has new springs and seals. Next pulled the spark plugs they looked great. Did a compression test , every cly. has 125 pounds. Bad rings ??

Mike
 
If it smokes when you give it gas it rings.
If it smokes when you let off the gas it is valve guides.
 
Blue smoke on acceleration surely points to the rings giving up.....But, what carb are you running? Could you just be a little rich with the tune? The color of smoke out the rear view mirror is not always reliable. If the bumper is coloring blue, or you have a friend/helper following you and can confirm it, then yes, she's getting tired. But if that's not the case, don't rule out a carb/tuning issue...
 
It's possible the previous owner pulled the heads and went through them. Often times if you freshen the heads and not the bottom end, the rings will be the next to go. The weakest link in the chain is next to break. tmm
 
I'll just add that if your initial timing is pushed up a little for performance and you got a bad batch of fuel, a little knock/rattle on the pistons will break the ring seal enough to smoke a hair.

As far as your compression test, if those numbers are across the board, I don't see a issue with a low comp 273 with some miles on it.
 
I would pull the intake and check the intake runners in the head for oil ,also 125 psi is low for that engine should be in the 160 range ,unless it has a bigger cam then stock installed but having the same compression on all cylinders shows a good balance. also the oil rings could be stuck on the pistons if it is the factory engine. how many miles on it?
 
There aren't any NO SMOKING signs along the sides of the roads ( yet ) LOL
Some of the tests ( like compression ) will suggest a rebuild but you don't have to anytime in the near future if you don't want to.
Equally low compression on every cylinder simply means "well worn". It doesn't indicate about to come apart.
Monitor the oil pressure ( and temperature ) with a real gauge. If you suspect the oil pick up is clogged, by all means dig in there and fix that.
Check oil loss. If you loose more than 1/2 quart in 900 miles, change to single viscosity 30W HD and monitor oil loss again.
Temperature is as important, even more with worn bearings. DO NOT allow it to run hot. A new radiator might be the best investment you could make ( I cant know if the original is still in use ).
Old engines in vehicles are a lot like our own hearts. It's never to late to start paying closer attention to it. Taking the right smaller steps now can get many more years of use from it.
 
I have an old Atlas tune up guide that give a compression range between 120 to 150 psi for 1966 2v 273. The 4v range is 150 to 180 psi. I'd say a combination of cylinder and rings. Although it is good if they read all the same. How much oil does it use between changes?
 
A little oil smoke at high vacuum, idle, coasting in gear, could be a leaking intake gasket.
 
Thanks for all the input. I my have found some of the problem. When I am sure I will post it.

Thanks Again

Mike
 
You can also recheck your compression after squirting a small amount of oil into each cylinder and if there is a substantial increase in compression you have worn cylinders/rings Also not questioning your competence but did you have all plugs out and throttle jammed wide open when doing the compression test initially
Another good indicator of motor health is a vacuum gauge
 
Just to add to what I know I did a leak down and it is 17 to 18 % speedo states the mileage is 60,243 miles. Going to pull the intake on monday
 
teringer said:
I would pull the intake and check the intake runners in the head for oil ,also 125 psi is low for that engine should be in the 160 range ,unless it has a bigger cam then stock installed but having the same compression on all cylinders shows a good balance. also the oil rings could be stuck on the pistons if it is the factory engine. how many miles on it?
Click to expand...


I pulled the intake and the gaskets had oil on both sides and oil on the intake runners. I installed new gaskets and used sealer as suggested by the directions. Have not had time to drive the car yet.

Mike
 
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