I just got back from trip out of the garage with my newly rebuilt 350. In 120 miles, it burnt a quart for every 25 miles, and was no better at the end than at the beginning. Most, if not all, of the smoke comes out on deceleration.

I'm using 10W-30, and fullowed the correct cam breakin procedure. It smoked some then too.

Any ideas?

Are you using synthetic? If so switch to dino oil. If you are using dino oil already then pull the plugs and see how many cylinders show signs of oil burning, the cylinders that are burning oil will show ashey deposits on the center part of the plug.

A quart every 25 miles, someone forget the rings (installed incorrectly)?

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Oil burning on deceleration is almost definitely something wrong with the rings.
Did you break them in, seat them by accelerating hard then decelerating 3 or 4 times? If you did, then maybe someone did not scatter the joints in the correct pattern. If you did that, then depending on what rings you have, some take almost 1500 miles to even get them to start seating right.

All of the plugs show ashy deposits, some more than other.

I am using regular, non-synthetic oil.

I did not rebuild this motor myself, and was told that ring break-in was not a big deal. Run it at variable rpm's, and not a lot of idling, but mainly don't worry about it.

I Have the SAME PROBLEM. I have been chasing this for a while and although I'm 90% sure of the ring gaps and such, I am ready to pull the engine and build again. I didn't allow too much time for the rings to seat before I started romping it really hard. Do you guys think the rings will seat after a while or should I just bite the bullet and re-ring?

<font face="Arial,Verdana" size="2">Originally posted by rustbucket79:
A quart every 25 miles, someone forget the rings (installed incorrectly)?

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I would have to agree. The rings must be installed incorrectly or broken. Do you know if the motor was bored or was it just a ring job?

LS1: It was bored 0.40

even though it may be the rings,i dunno if i would say its because they werent broken in properly..each time ive had my 327 apart it was ran 20-30 mins for the cam breakin then ran hard as soon as the cam checked out...ive had other problems with the motor,but never bearings/rings doing it this way...

my guess is something went fubar in the build,like was said here..i.e broken(or missing ring(s),something along that line

LS1 eh? Might try some ring sealer off the shelf, or some GM EOS.

I agree, could be rings, but could be valve seals, or head gasket too. Check this proper break-in proceedure: Prelube by spinning the distrib. shaft to fill the oil passages and prevent unlubed surfaces on startup. Start and do not allow to idle,...bring the engine up to 2000 rpm immediately and run for thirty minutes, varying rpm's between 1500 and 2500. Stop the engine and re-torque head and manifold bolts. Take the car out and accelerate under load from about 20 mph to 40 mph about 3 to 4 times. Then drive normally for the first few miles, and check all bolts you can get to externally for tightness afterwards. Drive the car normally for the first few hundred miles avoiding constant engine speeds and not to exceed about 4000 rpm. After 500 miles change oil and filter. Check compression. And I don't get on the engine until after about 1000 miles. Are there any steps in there that were missed? If so that may lead you to the problem. Never had an engine go through oil like that! Good luck, Todd.

I once had to pull an engine out of a Astro van for oil consumption and found one cylinder with no oil rings. A ring could have been forgotten.

I did some checking in the 3-D world, and came up with two more things; both of which are easy to check:

1) Aftermarket valvecovers with no baffle under the PVC. This could be allowing oil splashing off the rockers to bounce into the PVC valve. I did notice a lot of smoke once when taking a (left turn) corner hard.

I'll install a stock GM valve cover with a factory baffle and try that.

2) Intake manifold gaskets leaking and allowing oil to be sucked up from bottom. Seems to me that if this was happening, the engine would be running lean and rough. It's not. But, if the above 1) does not fix the problem, I guess I'll yank the intake and replace the (fel-pro) gaskets.

Note: This is not an LS1, my reply was to LS1 1971.

[This message has been edited by BSchroeder (edited October 17, 2005).]

<font face="Arial,Verdana" size="2">Originally posted by BSchroeder:
I did some checking in the 3-D world, and came up with two more things; both of which are easy to check:

1) Aftermarket valvecovers with no baffle under the PVC. This could be allowing oil splashing off the rockers to bounce into the PVC valve. I did notice a lot of smoke once when taking a (left turn) corner hard.

I'll install a stock GM valve cover with a factory baffle and try that.

2) Intake manifold gaskets leaking and allowing oil to be sucked up from bottom. Seems to me that if this was happening, the engine would be running lean and rough. It's not. But, if the above 1) does not fix the problem, I guess I'll yank the intake and replace the (fel-pro) gaskets.

Note: This is not an LS1, my reply was to LS1 1971.

[This message has been edited by BSchroeder (edited October 17, 2005).]</font>

If you try all that and nothing changes, try doing a compression check. That should tell you weather or not your rings are sealing.

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Mike T. 71 RS/SS

another very remote possibility (whithout knowing what heads) is oil pump. I did hot rebuild/beef-up with a high volume oil pump, and a set of double hump heads, broke in properly, and after 2500 miles it still looked like i was fogging mosquitoes. upon dis-assembly i found crusted burnt oil on top of every valve. machine shop told me intake gasket. since that wont crust exhaust valves i installed regular oil pump. and now it doesnt burn a drop. i suspect the older heads didnt have the drainage capacity for the HV oil pump so the top end filled up with oil and seeped down thru valve guides. for what it's worth

Zack

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Going fast never killed anybody, it's the sudden stops that hurt

[This message has been edited by my76rally (edited October 18, 2005).]

Hey I know how you feel, I rebuilt mine and it burned oil. I thought it was the valves, well I knew it was at one point, but I got new/rebuilt heads froma machine shop but it is buring oil. I pulled the plugs and I found that cyl # 3 & 6 are buring oil. I rebuilt my own engine and I am about 99% sure the rings are set right, but you never know anything can happen. My problem is it smokes on acceleration, when I let off it goes away, or at least dies down.
I am planning on pulling the motor this winter to make sure everything is right, I just have not done that yet. Any other ideas would also be great.