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502 BB Chevy Oil Use

16K views 17 replies 9 participants last post by  Bryan59EC 
#1 ·
I hope I found the right place, hi to all:

I have a question Im sure you all have had tabled before. Currently have a 502 in a 68 GMC. It has always used oil, about 1qt in every 400-500 miles. Is that normal? I did a leak test which turned out fine, my thought was the valve guide seals but was told they are not avaiable for the 502, I dont think a new motor 13000 mi should have such a problem.

Any Ideas, thanks in advance.

Bob
 
#2 · (Edited)
Things You Should Know About 502's
A) All 502's built since the inception during the mid 80's have used a unique ring combination of 2.0mm/1.5mm/4.0mm. The factory installed 4.0mm oil ring is a low tension ring. It is used to reduce frictional horsepower losses. Oil consumption is a natural characteristic of this type of oil ring. When it is time for a ''freshen up'' on your 502, we recommend the Speed-Pro High performance file fit ring set which includes a standard tension oil ring for improved ring sealing and oil control. (This info was taken from page 11 Tech. Note in Scoggin Dickey Parts Center catolog)...Hope this helps
 
#4 ·
Things You Should Know About 502's
A) All 502's built since the inception during the mid 80's have used a unique ring combination of 2.0mm/1.5mm/4.0mm. The factory installed 4.0mm oil ring is a low tension ring. It is used to reduce frictional horsepower losses. Oil consumption is a natural characteristic of this type of oil ring. When it is time for a ''freshen up'' on your 502, we recommend the Speed-Pro High performance file fit ring set which includes a standard tension oil ring for improved ring sealing and oil control. (This info was taken from page 11 Tech. Note in Scoggin Dickey Parts Center catolog)...Hope this helps
Thank you for the information it seems very common from what I gather. When the day arrives and I hope not soon to refresh it I will keep these notes for reference. I might try a 20-50 was another suggestion. Thanks again.
 
#6 ·
Does it smoke idling?

I think these big block crate motors suffer from 2 problems. The ring situation obviously, and the inadequate valve seals on the iron head motors. I went through this also...still going through it to some degree. My motor smoked bad in addition to using a qt. of oil every 2-300 miles. The factory umbrella seals IMO are too small to drape over the stem adequately, causing a smokey idle and deceleration. Also had puddles of oil on top of each intake valve. I had my heads machined for PC seal. Smoking is gone, but still uses oil. All my plugs come out w/oil on the threads still. I was more concerned about the smoking though as it was quite embarrassing. No seals off the shelf will fit the guides b/c of the dual springs. Getting valves seals will reduce the smoking but not eliminate the oil burn. I was told the low-tension oil rings were worth ALOT of power so that's why GM ran them.

Here's a pic of the factory valve seal (if you want to call it a seal)



Here's a push-on type seal, but the there's not enough clearance between the dual springs to run it. Another member suggested to take the top metal ring off of it and maybe even trim the top a bit. Shoulda tried if B4 ripping the heads off.

 
#7 ·
Bob, I had my 502/502 torque plate honed before I assembled the motor (also had it decked). I reassembled it with the same piston/rings it came with. I used about half a quart in the first 200 miles and have not used any since (~700 miles total). I drive the car hard (it's too much fun stepping into it :) ). Perhaps the torque plate hone helped the rings to seat bettter?

Vince, I had the same problem when I switched to my Lunati solid roller springs. The stock guide seals would not fit in the spring. I looked through a bunch of sites and found a teflon seal with a smaller OD (I think it was from Crane) that fit with room to spare. You may want to try that route.
 
#8 ·
Tom, you have aluminum heads right? They are machined for the smaller seals from the factory. The iron motor have unmachined guides (.625).

Unless they have a small o.d. push on seal for .625 guides...that would be a godsend.
 
#11 ·
I'm not sure this will get to evryone who has had a hand on my question, but just wanted to say thank you, what a great group.

With the information you ALL have offered I have decided its "normal" for this power plant, when it's time to refresh I have some good information.

Thanks agian

Bob
 
#12 ·
do the new ZZ's with alumninum heads have the same problems as the HO's? I really want to put a ZZ in my 67, but no way am I going to pay the big bucks for an engine that burns oil.....very shameful! guess I will have to go with another engine choice....anybody hear anything about the new Edelbrock 502?

thanks
 
#16 ·
do the new ZZ's with alumninum heads have the same problems as the HO's? I really want to put a ZZ in my 67, but no way am I going to pay the big bucks for an engine that burns oil.....very shameful! guess I will have to go with another engine choice....anybody hear anything about the new Edelbrock 502?

thanks
I can only say that the zz502 crate motor with what looks to be Eddy performer rpm rovals is no oil burner.Maybe we got lucky.It uses 1 qaurt of oil between 5k mile changes.Aside from the weeny HR and the economy 850 VS..we are ok with it.A quick carb swap to a 850 DP and 6 degrees added to the initial timing helped it.It is a tire fryer for sure..and no valve float at 5800 rpm shifts out of the crate.So far so good.
 
#13 ·
my 454 HO (build date=07-04) had the rings in upside down

Light hone--machine heads for new valve seals--new rings
(had this done by a builder)

Engine has not been back in the car long enough for me to get a grip on it yet.

Tailpipes were litterally dripping with oil
Even had an oil spot on the garage floor under the mufflers while the car was sitting w/o motor.
Also---the valley baffle is designed so that the 'tabs' that support it, rest on a intake/head mating surface.
I trimmed the tabs in the center off-----double the vacuum.
Chimps are building these motors
 
#15 ·
I know some will say garbage but here's what I've seen with my 454HO. After initial breakin it blew smoke on startup like crazy. Was only running on 6 or 7 cylinders and would take 5 minutes to burn up all the oil in the cylinders and start running on all 8. This was consistent, every startup.

I swapped the valve covers that come with the engine for the short chrome covers from my 396, no more smoke and starts on all 8. Also moved PCV valve hookup from intake to carb. Oil consumption is way down as well. Still less than 1000 miles on engine, maybe the rings have seated more. All I know is the change was dramatic. Wouldn't cost much to test this yourself. Remove PCV valve and replace with breather.
 
#17 ·
lets see, many of you bought the motor from GM with a warranty, but don't use it? Not a wise move if I may say so myself.... if I buy something, ANYthing, with a warranty, I'll by God use it :yes:

Independent shops can do warranty work on GMPP motors. since 3-1-07 they come with a 2 year 50,000 mile warranty.

any concerns should be taken to a local dealer or independent shop. No luck with one dealer, go to another.

Just my take on things though
 
#18 ·
lets see, many of you bought the motor from GM with a warranty, but don't use it? Not a wise move if I may say so myself.... if I buy something, ANYthing, with a warranty, I'll by God use it :yes:
I bought my engine long before I started it, let alone put any miles on it.
Bought it in March of 2005, was not even set between the rails for six months---I finally registered the car in June of 06 with only 5 miles on the odometer-----By this time the warranty was long gone.

Do not even think for a minute that I did not argue with GM performance parts AND GM warranty people----They pretty much told me "tough chit"
I bought it thru Summit Racing and installed it myself so the warranty was not worth the paper it was written on (as I gathered from what they told me)

When I finally pulled the engine and got it repaired-----I called them to let them know what the builder found-----They pretty much said, "We don't believe you as a GM technician did not have the opportunity to look at it".

Also having braking issues with a new Ford Ranger and dealing with their warranty people (3 times for brake repairs in 90 days), you can bet I was not very polite to these twits.

Building the 59---I bought parts as I could afford them and in a logical order---when doing the frame and powertrain--the engine to be used is kind of necessary.
 
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