Where's has the oil gone - Team Camaro Tech
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post #1 of 25 (permalink) Old Mar 28th, 01, 04:07 PM Thread Starter
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69 camaro (plain jane) recently overhauled 307cid converted to 350 w/new trw flat top pistons, original block drilled 0.125" over to accomidate the 4"piston,(to keep original casting in car) 350 crank and harmonic balancer replaced the 307 crank and balancer. In all, the block and rods are the only original parts used in the rebuild. All other parts are high performance parts including the S/R 67 cc #4266 heads. after 15000 miles the car runs great, plugs show a little dry darkness on thread area, the electrodes are tan yellow but built up a bit, but all appear the same. However, the car still consumes approximately 1 quart every 1000 miles. the car does not leak a drop, but darkness (not dripping oil) appears at the head/block interface (head gasket area). Is that much oil consumption normal in a high performance small block. Could a leaky head gasket(due to insufficient torgue) result in oil consumption while running normal. THe rebuild was professionally done by a reputable machine shop. ANy Ideas on wher to look?
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post #2 of 25 (permalink) Old Mar 29th, 01, 06:12 AM
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Thousand miles for one quart -- Not bad!

This is an acceptable amount, you know eveything is getting lubed, (stem seals, rings, etc.). If you can find a borescope, remove a plug and check the combustion chamber for oil wetness around the edge of piston head. This will tell you rings are not sealing.

Check inside of tailpipes. Since there is no ECU/O2 sensor, the color inside should be a very light gray to white if fuel jetting is correct and no (heavy) oil burning.

Otherwise, its a good reminder to change oil on the third quart.

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post #3 of 25 (permalink) Old Mar 29th, 01, 07:41 AM
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what you are seeing is possably an intake or vavle cover leak. also if you have a high pressure oil pump you can get this and the motor might use oil as too much is getting caught up in the head's and there is no valve seal that will keep oil out if it is under oil all the time.

also are the thred's of your spark plug's oily? if so i would look at the exaust vavle seal's for the minor leak.

some time's when a shop dose a hi-pro rebuild they do not put exaust vavle seal's on. it is an old trick to keep the exaust valve's cooler. IMHO it is a joke and realy is not a fix. it just causes oil consumption.

also if you have teflone vavle seal's you can get this as well i feel thay are not very good and just cost you $. a good set of P.C. type seal's, like what G.M went to with the votec/LT1 head's work great.
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post #4 of 25 (permalink) Old Mar 29th, 01, 02:12 PM
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I would be concerned about blowby...it may not show up in the tailpipes but a .125 overbore on a 307 block? Man, those cylinder walls have got to be paper thin! You might check into getting a leakdown test to make sure your rings are sealing.

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post #5 of 25 (permalink) Old Mar 29th, 01, 09:33 PM Thread Starter
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<BLOCKQUOTE>quote:</font><HR>Originally posted by travis:
.125 overbore on a 307 block? Man, those cylinder walls have got to be paper thin!

<HR></BLOCKQUOTE>
an old small block, is a small block, is a small block, is a small block. There all the same except for bore and crank set up.
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post #6 of 25 (permalink) Old Mar 30th, 01, 02:39 AM
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My first thought was the cylinder walls are flexing I have never tried boreing a 307 that far but you said a good shop did the work I assumed they had done it before. All small blocks don't have the same cylinder walls. Gm saves money by making them to a min. spec. I know it sounds stupid not to just cast them all the same but that is not what they do.

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post #7 of 25 (permalink) Old Mar 30th, 01, 05:40 AM Thread Starter
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<BLOCKQUOTE>quote:</font><HR>Originally posted by oger:
I have never tried boreing a 307 that far <HR></BLOCKQUOTE>The .125" bore takes the block to a std. 327 bore(3.85" to 4.00") and the crank shaft provides the additional stroke to take the bore/stroke set up to a std. 350 CID. It is essentially the same as taking a 327 (w/new std cylinders) and adding a 350 crankshaftw/ std 5.7" rods. I chose this option because i was going to put $$$ into a 350 anyway, and thought that keeping original castings would be easier to convert back to original(kept orig. top engine components inc 2bbl carb/manifold and ****ty heads) should i ever sell it. It was a tough decision because i know the plain jane camaro is not worth much, but shes a beauty and is all original exterior and interior w/ the 307 emblem proudly displayed on the front fender. I think this taunts the hell out of 5.0mustangs and rice rockets. The new engine set runs really fast (especially w/ the new posi track set up (yes original casting 8.2 10bolt)and is very reliable. The oil consumption is the only less than desiriable end result.Although I could complain about the excessive gas consumption, but I won't talk about that. I only rive the car during spring and fall (too hot summer and too cold winter) so, 1quart /1000 miles is not a problem. The car does not leak any fluid, does not smoke and is fun to drive hard. I think i'll keep it a while and keep changing the oil every 3000miles. By the way the rebuilder recommended strait 30 wt.castor, havoline or shell oil, this is what i use. and reccomendations????

thx joe c.

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post #8 of 25 (permalink) Old Mar 30th, 01, 06:37 AM
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I think a quart every 1000 is excessive, 1qt every 3 would be acceptable. You should be able to go oil change to oil change without adding oil in a healthy engine. You may want to check your compression and do a leak down test as well.

GM is is telling the LS1 owners that a quart per 1000 is normal and the book recomends 7000mi oil changes. Would you want to add 7qts between changes on a new car?

Your car is old but 15K on a rebuild is it should still be tight... I have owned 22 new and old cars & trucks and never had one burn more than 1qt in 3000-4000 miles. 6 of them have been GM V8's...

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post #9 of 25 (permalink) Old Mar 30th, 01, 03:37 PM
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See any blue smoke after setting a while on first start up? If so suspect valve guide and or seal problem.If not check pcv system for proper operation.if ok.My gut feeling on this one is its probably cylinder sealing.If all 8 cylinders are leaking a little oil by it probably wont smoke unless your on it really hard.compared to one leaking bad which cannot burn off causing smoke.good luck.

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post #10 of 25 (permalink) Old Mar 30th, 01, 11:49 PM Thread Starter
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<BLOCKQUOTE>quote:</font><HR>Originally posted by gene stills:
See any blue smoke after setting a while on first start up?
No smoke noticed, However i will observe the car tonight when son runs it @1/4 mile at track.
If not check pcv system for proper operation.
IS a standard PVC able to handle a hi pro 350 @ &gt;300hp?

My gut feeling on this one is its probably cylinder sealing.If all 8 cylinders are leaking a little oil by it probably wont smoke unless your on it really hard.

Would'nt the oil have traces or smell like gasoline if all cylinders leaked?

compared to one leaking bad which cannot burn off causing smoke.
this would be evedent by spark plug inspection.

<HR></BLOCKQUOTE>

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post #11 of 25 (permalink) Old Mar 31st, 01, 12:25 AM Thread Starter
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<BLOCKQUOTE>quote:</font><HR>Originally posted by DjD:
I think a quart every 1000 is excessive,
Your car is old but 15K on a rebuild is it should still be tight
<HR></BLOCKQUOTE>

DJD, the oil burning characteristics are the same today as the day it was rebuilt (during break-in). THe car never exhibits smoke cold, or at temp. The rebuilder claims &gt;300hp (guesstimate) and i wonder if the std. PVC is able to keep w/ the vacuum charateristicis that the HP cam/valve combo create.
When i asked the the rebuiler about the oil consumption, he wanted to know the oil pressure (don't have oil pressure guage) so i don't know.
Hi pro oil pump installed at rebuild always used the recommended straight 30 wt oil.
Would excessively high/low oil pressure result in excessive oil consumption?
should i try a 5/30 multi oil to decrease oil pressure/consumption.

This rebuild cut new standard holes in a well seasoned block w/new TRW flat pistons, w/ 67 cc heads , should not be much greater than 9:1 compression. How can i correlate a compression reading to a cylinder sealing problem if all were to have the same reading. or should i just go straight for the leak down check, and how is a leak down test performmed;equip,guages pressure source? I'm not a total mechanical idiot, but i don't do much internal engine work either....thinking about that ....maybe i am a total idiot....ha.

thx
joe c

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post #12 of 25 (permalink) Old Mar 31st, 01, 08:20 AM
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Joe,

The compression test can help determine if the problem is in the heads or the rings. and can isolate if it's just one cyl or more. If you have low compression in a given cyl by squirting a bit of oil in the plug hole and testing that cyl again the compression comes back up you know it's the rings. If it didn't make a difference it's the head.

With the leak down test you would hear air leaking out of the crankcase or intake or exhaust valves if they were leaking. You would be testing condition of the top piston rings and valve seats.

Find the number for a PCV from an L-48 (350ci 300hp) or another engine making the same hp as yours.

I really am a shade tree mechanic so maybe someone that does it for a living will pitch in!

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[This message has been edited by DjD (edited 03-31-2001).]
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post #13 of 25 (permalink) Old Apr 2nd, 01, 07:35 PM
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Joe About traces on the plugs.1000 miles a quart if each cyl is giving up oil equall thats not much oil per cyl per 1000 miles probably wouldn't read on plugs enough to see,compared to a few cyls leaking which would be easy to read.About pcv system stock system is fine I have stock system on my 55 chev with 375 hp 350 but use breather cap on oposite side valve cover.If the engine suits you other than the consumption I believe i could live with 1000 miles a quart.

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post #14 of 25 (permalink) Old Apr 3rd, 01, 06:04 PM Thread Starter
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<BLOCKQUOTE>quote:</font><HR>Originally posted by gene stills:
Joe About traces on the plugs.1000 miles a quart if each cyl is giving up oil equall thats not much oil per cyl per 1000 miles probably wouldn't read on plugs enough to see,compared to a few cyls leaking which would be easy to read.About pcv system stock system is fine I have stock system on my 55 chev with 375 hp 350 but use breather cap on oposite side valve cover.If the engine suits you other than the consumption I believe i could live with 1000 miles a quart.

<HR></BLOCKQUOTE>

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post #15 of 25 (permalink) Old Apr 3rd, 01, 06:15 PM Thread Starter
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Gene, took the car to the track and ran the @#$$! out of it.I watched iot carefully for smoke: absoulty none! I did have a previous oil leak in the strangest place. The leak was from a few bolts in the intake manifold ,the bolts (that bolt) to the heads. The oil would pool in the manifold low spots. I thightedthem an it still leaked. I eventually removed the bolts and applied sealer, re-tighted and the oil stop leaking. Weird because the bolts are exposed to oil at the top part of the heads. I wonder if too much oil is reaching the heads an not exiting the heads as fast as it receives it. THe heads are world part S/R 4266 w/ 67cc chambers. Ever hear of anything weird with these heads and oil issues.
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