Hot Rod Forum banner
1 - 6 of 6 Posts

·
Registered
Joined
·
34 Posts
Discussion Starter · #1 ·
Hello all,
Have a warmed up 455 that runs great, but will take oil up the PCV valve - hose and blow blue real bad. Block off PCV to intake and it stops smoking. Has four K&N breathers (two in each valve cover) and seems to wet them with oil in a very short time. Also pushes oil out front cover seal with no PCV vacuum in place. Looking for any helpful ideas or experiences.
Thanks!
 

·
Registered
Joined
·
15,298 Posts
Sorry but it is rebuild time. Blowing oil out the breathers and building pressure in the crankcase are sure fire signs that the compression rings are not sealing. That is usually a function of wear, occasionally it is the rings are trapped by sludge buildup that prevents their movement, there are elixirs that claim to help but I’ve seen them do far more harm than good.

Bogie
 

·
Registered
Joined
·
34 Posts
Discussion Starter · #3 ·
Has less than 1,000 miles on it and it runs strong for a mild build. A few passes at the 1/8 mile track with a 323 gear gets consistent low 8 sec.
Starts and runs great on the street too. Does not use oil ,unless you hook up PCV.
 

·
Registered
Joined
·
2,260 Posts
Has less than 1,000 miles on it and it runs strong for a mild build. A few passes at the 1/8 mile track with a 323 gear gets consistent low 8 sec.
Starts and runs great on the street too. Does not use oil ,unless you hook up PCV.
Try an oil seperator on the PCV ? Make sure the PCV is baffled inside the valve cover . drill a 1/16" hole longways in a piece of 3/8" round bar ,put it in the PCV hose to restrict the vacuum , obviously you can experiment with the hole size .
 

·
Registered
Joined
·
651 Posts
Only 1k miles then you should investigate why the rings and possibly cylinder walls are not getting along and not playing well together. It is still in break in period. Anything less than tear down and repair is not going to give satisfactory results. JMHO
 

·
Registered
Joined
·
15,298 Posts
Burning oil and loosing compression to the crankcase are mutually exclusive problems. One is a failure of the oil control rings which includes the second ring the latter is a failure of the compression rings which includes the second ring. Obviously the second ring is in a critical position doing some of two jobs.

Racing is a different proposition that you didn’t bring to the fore front. There are a lot of reasons in a race engine as to why compression is lost past the rings as now this brings the high speed dynamic into the equation which doesn‘t eliminate classical wear or damage to the rings but introduces problems with sealing due to an inability to track with the velocities involved. This as usual includes tracking and irregularities in the wall both concentrically and length wise. It includes pressure build up between the first and second ring that prevents either or causes them to float over the cylinder wall or prevents them from making the alternating seal with the top and bottom of their lands, wide heavy rings have a harder time with this than narrow lighter rings. But the latter has problems with floating over the wall which requires a positive pump evacuating the crankcase which pulls the compression rings against the cylinder wall and helps reduce inter ring pressure. The current thinking is to gap the second ring a bit wider than the “legal” gap of the top ring as that helps vent out the inter ring pressure the floats these two upper rings. This, also, gets into modern piston materials where high silicon alloys run hotter with less thermal expansion (hypereutectic castings and 4032 forgings) need a little wider ring gap than low silicon casting or forgings.

Bogie
 
1 - 6 of 6 Posts
This is an older thread, you may not receive a response, and could be reviving an old thread. Please consider creating a new thread.
Top