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Need a little help diagnosing oil burning SBC

 
akorcovelos
V-6 Camaros rule!
Posts: 27
Joined: 03/10
Posted: 03/01/10 10:07 PM

So I recently acquired a '72 Chevelle with a custom built small block paired to a built TH350. So far I have found that the block casting is a 14093638 that the PO said if from a '91 Corvette, which seems plausible based on my research. The heads are Vortec cast iron based on casting number 10239906. When I put the car away for its winter make over it was burning oil pretty badly on the driver bank of cylinders, and it has been running pig rich since I got it last year. I ran a compression test (dry) and got decent numbers of 190-205 on all cylinders (see pics), and I took some pics of the plugs. The engine has a Demon 650 carb on that I have not been able to get dialed in yet, which is likely why its running so rich. Any help reading the plugs would be great, I'm pretty savvy mechanically and have done everything from bolt-on mods to complete engine builds, just haven't done much with carbureted American V8s so no need to dumb it down.

Here are the plugs and cylinder compression readings.
IMG00411 20100228 1852

here are some pics of the casting numbers I found on the block and heads.
IMG00432 20100228 2001
IMG00433 20100228 2002
IMG00439 20100228 2012
IMG00440 20100228 2013
IMG00442 20100228 2018

and here is the carb.
IMG00430 20100228 1904

and finally here are all the plugs with the cylinder they came from.

cyl 1
Cylinder1

cyl 2
Cylinder2

cyl 3
Cylinder3

cyl 4
Cylinder4

cyl 5
Cylinder5

cyl 6
Cylinder6

cyl 7
Cylinder7

cyl 8
Cylinder8 1

so based on the plugs it seems to me that cyl 1 is the oil burning culprit, but how do the others look? Any help diagnosing if the problem is in the rings or head would be great.  

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waynep7122
Everything in my driveway’s a Chevy
Posts: 556
Joined: 08/09
Posted: 03/02/10 02:03 AM

start with fresh plugs...

looks like number one is down on compression a ***  


have you checked the valve lash...

can you hook a vacuum gauge to the intake manifold.. let it idle.. see if the gauge is steady.. use a short  large size hose.. not a tiny one.. and one of the fuel pump vacuum gauges that are not damped..

how much vacuum do you have also... at idle...   and running down the road at a steady rate..


i did not see your cubic inch.. what jets do you have in the primarys and secondaries..   what power valves..

is it possible that you have blown a power valve?????? so fuel is being pulled directly into the intake.. ???  

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akorcovelos
V-6 Camaros rule!
Posts: 27
Joined: 03/10
Posted: 03/02/10 06:08 PM

Icon Quotewaynep7122:
start with fresh plugs...

looks like number one is down on compression a ***  


have you checked the valve lash...

can you hook a vacuum gauge to the intake manifold.. let it idle.. see if the gauge is steady.. use a short  large size hose.. not a tiny one.. and one of the fuel pump vacuum gauges that are not damped..

how much vacuum do you have also... at idle...   and running down the road at a steady rate..


i did not see your cubic inch.. what jets do you have in the primarys and secondaries..   what power valves..

is it possible that you have blown a power valve?????? so fuel is being pulled directly into the intake.. ???




ok, picked up new plugs today, and #1 cyl is at 190. cyl 8 is at 190 and cyl 7 is at 195, all others are at 200.

I have not checked valve lash, I'll take a look at that tomorrow.

I can also pull vacuum at idle tomorrow, but vacuum cruising will be a problem since I live in the rust belt, and there is too much salt to drive it at the moment.

According to the block it's a 5.7l (350ci), but the PO said it was bored to 400.

no idea on jet sizes, I'll take a look and let you know. I doubt the power valve is bad since the PO had the carb rebuilt just before I got the car, but I'll take a look.

Thanks for the help!
 

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gettnlarge01
Everything in my driveway’s a Chevy
Posts: 545
Joined: 01/10
Posted: 03/02/10 06:14 PM

350s cant be bored to 400  
luck is when skill and opportunity meet

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redneckjoe69
Everything in my driveway’s a Chevy
Posts: 612
Joined: 02/10
Posted: 03/03/10 05:42 AM

i think your motor is a roller 350. maybe someone stroked it. you can tell by the external balancer or flex plate. compression readings within 5% arent bad. looks to me that someone has been adding alot of octane booster or fuel additive by the white, gray crustations on the plug tip. try going to a cooler plug,[ less tip sticking out], like an r43ts. are those 45s? go beat on your car and have a buddy watch, blue or black smoke? blue is oil burning, black too rich. usually the back 2 cylinders [7&8], will have the worst looking plugs if your seals are bad, do to good old gravity. so i dont know why #1 is so bad. if you want to clean the inside of your cylinders, get the motor up to temp. keep it running and slowly pour a cup of water down the carb,try to get it evenly on both sides. then go beat the crap out of it. guarantee you will literaly hear stuff flying out the exhaust if its dirty. been doing this for 20 yrs. never had a problem. you probly just got some heavy build up,& throw those miracle additives in the trash where they belong. good luck.  

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my69
I love my Chevy Chevette!
Posts: 3
Joined: 02/09
Posted: 03/03/10 02:48 PM

Are you sure they don't mean the bore is 4.000"?  
1969 Camaro, a work in Progress

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gettnlarge01
Everything in my driveway’s a Chevy
Posts: 545
Joined: 01/10
Posted: 03/03/10 04:56 PM

+1 joe  
luck is when skill and opportunity meet

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akorcovelos
V-6 Camaros rule!
Posts: 27
Joined: 03/10
Posted: 03/03/10 08:37 PM

ok, spent some time in the garage today gathering info for all you experts. Grin After decoding the carb part number I found that it is a Speed Demon 750.

waynep7122,
I checked valve lash and and all 16 valves where good.

I pulled vacuum at idle with the engine at operating temp, and got a steady 13Hg. As I stated earlier, can't get a reading cruising until the snow/salt is gone.

I pulled the carb apart today and found the following:

The primaries are 76, the secondary jets are 83 (correct my terminology if I'm wrong)

I'm not 100% on what number my power valve is, but as you can see in the pics there is a 5 and a 6 o the back side.

redneckjoe69,
I have found mention of a factory roller motor based on the block numbers, but don't know for sure, and I'm not too sure about the balancer/flex plate maybe you can tell from the last couple pics I took of the motor (don't mind the rust, the PO let the car sit for 7 years in a cold wet garage).

the plugs I pulled out are ACDelco R42LTS, and I replaced them yesterday with Champion RS12YC.

I can't take it out and beat on right now, but I do remember the smoke when I got on it was black.

No idea what additives the PO ran, but I know they are all snake oil so the engine won't see any more of that.

Is it bad to do your water trick if I can't drive the car right now?

my69,
I am sure the PO said the engine was a 400, but I also know that is not necessarily true, though most of what he told me seems to be checking out through my research.


I reset the carb setting to what it came from BG with, per the Speed Demon User Manual, so I'm ready to start from scratch on tuning this thing.

Here are the pics I snapped today.

Secondary side float was set at nearly .75, manual calls for .40-.50 so set it back to .40.
IMG00445 20100303 1851

set back to stock.
IMG00447 20100303 1907

found a nicely stripped float adjustment nut, I'll be ordering another one tomorrow.
IMG00449 20100303 1908

secondary metering block, looks pretty good.
IMG00450 20100303 1909

Primary float was also way over manual spec.
IMG00451 20100303 1917

set back to .40
IMG00452 20100303 1921

primary metering block, and power valve, only numbers I saw was a 5 and a 6 on opposite sides of the valve on the back side.
IMG00454 20100303 1927
IMG00455 20100303 1928
IMG00459 20100303 1929
IMG00461 20100303 1930

a number I found on the side of the primary metering block.
IMG00460 20100303 1929

and a couple shots of the front of the engine, I assume this is the dampener that was mentioned?
IMG00462 20100303 1956
IMG00463 20100303 1957
IMG00464 20100303 1957

Let me know any more info your all need to help me get this thing running right.
Thanks for all the help so far!  

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redneckjoe69
Everything in my driveway’s a Chevy
Posts: 612
Joined: 02/10
Posted: 03/04/10 05:06 AM

sorry, i cant really tell by your pics on the balancer.it does look aftermarket with the timing marks.maybe you can get a part num off it. i wouldnt do the water trick till you can drive it. ive heard of old guys using tranny fluid instead of water, but it will smoke like a pig. yea, that float adjustment nut looks bad. i was lookin at your pics of the jets. is it the camara or are those 2 different jets in there? your carb looks pretty clean.i want one now.l.o.l. them plugs sure look like extended reach. not sure on the number though. maybe an m.s.d. box is in order to make sure you get complete combustion. might keep your plugs cleaner also. hey, whats the rust belt? philadelphia? man, its times like this im glad i live in florida.ill probly get yelled at for this one but, if you keep fouling plugs, try dissconnecting your pcv & breathers from your intake/carb. are your valve covers baffled? o.k. im ready for the hate mail.  

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akorcovelos
V-6 Camaros rule!
Posts: 27
Joined: 03/10
Posted: 03/04/10 02:03 PM

Hey Joe, I will try and find a PN on the balancer. I'll hold off on the water trick until spring. The rust belt is the midwest and most of the north east, anywhere there is snow part of the year. They use a mixture of sand and salt on the roads to keep them from freezing over and it will destroy your car. I wish I lived somewhere warm all year, though it's kind of nice getting a mandatory 4 months of dedicated garage time to fix what I broke over the summer. Smile The carb is really clean, and the PO said he had it rebuilt just prior to me getting the car, but I don't get why the floats where set so high. It looks like the one of the jets is new and the other is older, hence the difference in color, but I checked them both and they are the same size. My guess with the plugs is that the PO ran the car for a while with it running crazy rich. I'm going to leave the new ones I just put in there to see what happens to them after I get the carb dialed in.

Any advice on tuning at idle?

I should also mention, the drivers side muffler has a big hole in it that I will be patching, don't know if that affects any of my issues.  

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redneckjoe69
Everything in my driveway’s a Chevy
Posts: 612
Joined: 02/10
Posted: 03/05/10 05:58 AM

yea, your float being set too high will definetly do it. as for tuning , id follow b.g., or go to a holley web sight. make sure to set your timing first. i like using a vacuum gauge when making small adjustments to a carb. usually im shooting for the highest vacuum reading when adjusting the mixture screws.  didnt mean to sound dumb about the rustbelt thing. that must explain why my wifes minivan is rotting away. the frame looks to be made out of a beer can, always crackin and breakin. she bought it in n.j. im a welder by trade but its hard to weld rust to thin sheetmetal. lol. but my florida camaro has never even thought about rusting since 87. night & day difference. i dont know about tuning with a blown muffler, could make a diff on backpressure. id weld or change it first. what kinda car are you puttin her in? i think it sounds like you got a good motor, just needed a tune-up. the only true way to know your cubic inch is to pull the heads & measure bore& stroke.its supposed to be 60 to 70 for the next few days here,so i can finaly work on gettin my car ready for her new paint job.i so hate body work!!!peace bro.  

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akorcovelos
V-6 Camaros rule!
Posts: 27
Joined: 03/10
Posted: 03/05/10 04:06 PM

I'm actually relieved to hear the floats could cause it to run so rich. I set all the idle mixture screws to 1.5 turns from bottomed out, I think thats about where they would be from BG.

What timing should be at? If I remember correctly last time I checked it was set right at 0 TDC, I'm thinking it likely needs some advance, right?

yeah NJ is definitely in the rust belt, and your wifes van is just like every other daily driver around here (Chicago), which is why none of my toys go out in the winter.

The motor is in my 72 Chevelle, which was a southern car so the only rust is surface rust from sitting in the PO's unheated/wet garage un-used for 7 years.

I'll weld up the muffler before I throw the carb back on just to be sure.

Once I get her running decent I'll pull the heads and see exactly what I have. It's been really warm this week, like 40-50, lol. Lucky for me I have a heated garage. Smile

I hate body work too, just finished prepping my AutoX car for paint, and once I get the Chevelle running right I'll be fixing all the rust and prepping it for paint too, hope to shoot both of them late May.

Thanks for all the help man!  

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gettnlarge01
Everything in my driveway’s a Chevy
Posts: 545
Joined: 01/10
Posted: 03/05/10 09:21 PM

set the initial timing at 10degrees BTDC to start with and total at 32. thats a good place to start at.  
luck is when skill and opportunity meet

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redneckjoe69
Everything in my driveway’s a Chevy
Posts: 612
Joined: 02/10
Posted: 03/06/10 06:50 AM

you wont believe this but i got a 72 malibu up in n.j. i sold it to an old italian guy i used to make wine for. for 100 bucks 20 years ago. 2 years ago i was up there and saw him. i asked if he still had the car. he said yes & that so many people tryed to buy it, that he had to hide it out back in all his junk. said hell never sell it to anyone but me. so i went to look at it. you can imagine what 20 years have done to it outside. sad sight for a chevelle lover. so we bought that stupid mini van {a ford none the less,...ouch}. one day i gotta go get it, the price is right, still 100 bucks. i bought the car cause my wife was born in 72,& we had just got married. she didnt want a "hotrod", at the time. maybe that old guy knows something.last car i had delivered from n.j. to florida was only 400 bucks. hmmm.....got me thinkin again. should i?  

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akorcovelos
V-6 Camaros rule!
Posts: 27
Joined: 03/10
Posted: 03/06/10 11:43 AM

man, for 500 bucks delivered you can't go wrong! You should quit wasting time helping me and get that guy on the phone.  Grin  

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