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Discussion Starter #1
I have a 66 auto with a rebuilt 289, which i have had terrible transmission problems. After taking it to a transmission shop and gettin the problem fixed, the mechanic told me that the 7th and 8th cylinders were not working as good as the others. (he checked them by looking at the temp of the headers).

When i get the car home i remove the spark plugs to find pretty bad oil fouling on the 7th and just a little bit on the 8th while all the others were carbon fouled. This is the first time i have started it in a long time. I am guessing that i have the wrong type of spark plugs for the car (Bosch Platinum) or the carb needs to be tuned a little bit.

Does any one have any advice on the OIL FOULING on the 7th adn 8th plugs? I have turned the car over manually (with a breaker bar) many times with out it starting would that cause some oil to leak on the spark plugs? I have heard of trying a leakdown test, but should i be trying to do that myself? How difficult is it to check the piston rings or a leak in valve guides? Any help is appreciated, Thanx.
 

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Oil consumption per 1K miles?

Smoke on cold start? Warm start? Acceleration? Deceleration?

Nothing wrong with Bosch plugs. I've used them for a long time with great success. Carburetor model? Last rebuild? FWIW, a carb issue can lead to oiling issues, if the carb runs rich for any length of time, or if the choke sticks.

A leakdown test will include/exclude rings.

Is it possible that the intake manifold gasket is leaking oil (to vacuum)? How's the vacuum reading on the back manifold runners (like at the power brake takeoff)? Where does the PCV valve hose enter the manifold?

That's it for now...

Pat
 

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I would try putting in new plugs and drive it again. If they foul again possibly step up one temperature range (hotter spark).

Oil fouling on the cylinders 7 and 8 is usually due to overheating the engine. The passenger side water/coolant flow (from most water pumps) is (unforturnately by design) not as good as the drivers side (certain water pumps out there are equalized like Edelbrock).

I would also check compression on those cylinders.

Could be the head gasket, valve guides/guide seals, intake gasket or rings. Compression test will tell a lot.

I doubt it is your PCV valve as that would cause fouling across all cylinders.
 

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Some folks mistakenly route the PCV hose to the PB tap on the back of the manifold. If routed correctly, to the carb or carb spacer, effect should be equal.

Pat
 

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I don't like the Bosch series spark plugs. My exsperience is that Auto Lites work better in American made cars... (my exsperience, don't take verbadom [sp?])....

military_stang
:track:
 

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Discussion Starter #6
I have an edelbrock 500 cfm 4 barrel that i put on myself but never touched the tuning screws.

My Mechanic did mention that he thought the brakes were not getting vacuum and that i should check my brake booster. Why would that cause the OIL FOULING on the 7th and 8th cylinders?

I have not actually driven the car yet and it is open headers still (cant decide on exhaust). Should i still look for smoke on startup?

So far i havent put any anti freeze in the radiator, just water.

The PCV Valve is routed to the carb. Should i replace the Spark Plugs and start it again or will the result be the same?

How do i perform a leak down test? Can someone post a link or tell me a breif description? Thanx for all your help so far i really want to get this engine to 100% it has taken me FOREVER had sooooo many problems, but im determined!
 

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Try spraying brake cleaner, or carb cleaner around edges of the intake manifold. Had the same problem and the intake gasket was bad on one side.
 

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Discussion Starter #9
Does anyone know of where i may be able to get a leakdown tester? Or has anyone built their own? I have have access to an air compressor.
 

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You can use a compression tester for a leak down test. You have to bottom out the cylinder you're testing ( both intake and exhaust valve must be close on that cylinder) Then you fill the cylinder with air, and see if air is hissing out somewhere. If it leaks from your exhaust, it's an exhaust valve. If it comes out of your carb, it's an intake valve. If it comes out somewhere else, then I guess you found your problem. A compression tester is available at any parts place, like autozone. ( if you don't already have one) Do a compression test on each cylinder, then if all looks ok, then do a leakdown on each cylinder. That should narrow things down at the very least. Good luck.

Jason
 

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Discussion Starter #12
I was told that i wasn't getting a good vacuum to my brake booster, and possibly not to the distributer either, could that have anything to do with the oil fouling on the 7th and 8th plugs?

What would spraying brake cleaner on the intake manifold do? How would that allow me to determine if i have incorrectly seated my intake gasket?

Could an oily plug still fire a spark? If it could then doesnt that mean that i have a problem with my distributor or ignition system as the oil isnt burned off?
 

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http://mackrafab.com/vmf/images/PlugChart.JPG

Yes, an oily plug will still fire. In fact, with a MSD box, a plug with no side electrode will still fire. Ask me how I know this ;)

You need to get some mufflers on the car and put a load on the engine. You have a very good background now in what to look for and how to diagnose the issue. Take a deep breath and dig in :)

Pat
 

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Don't sweat the little stuff. What would you do if you learn you have oil control problems on these two cylinders? Would you yank the motor and fix it? If the car runs ok, then put in new plugs, fix all your other stuff, and when your ready to start making big power, hunt down and fix this problem.

A little oil control issue is not going to hinder your performance significantly nor will it make your car unreliable.

Good luck,
 
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