Thread: Help tuning my SBC!

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I have just finished a 1927 Track T Roadster with a mild SBC that runs a tri-power Offenhauser manifold and 3 Rochester 2 carbs. The few small goodies on the car are Dart aluminum Pro-1 heads with a roller setup.

Here's where I stand.....

The car stalls while trying to idle. Even when driving for a while and coming to a light when I push the clutch in.....

Also, I have a fair amount of smoke from the headers, but I did fog the motor and have only run for about 20-30 minutes since then.

I feel the electric choke conversion is working well, and am unsure as to where to start looking to solve this issue.

On the carb, I opened up the idle tubes to .032" on the bottom and .041" on the top, an adjustment recommended to me to compensate for today's fuel versus the old stuff. This seemed to help a bit, but with the rain I only ran it for about 1 minute.

Lastly, the dipstick I am using with the motor doesn't seem to work too well, and I was told that I may have 1 quart too much oil in the engine....could this lead to the smoking?

Thanks. Tom

this is a good place to look for your answers i will
give my opinion,first i would drain the oil put in 5
quarts if that is what your oil pan recommends,then
i would sribe a line on the dip stick,the smoking and
stalling could be its running to rich,on a sbc 600 cfm
is plenty unless you are putting out 350-400 hp

You can tell if you are burning oil by taking out your sparkplugs--if they are black and mucky then you are burning oil. If they are black and sooty, the timing is off. I had the same problem with my 454 with black smoke coming out of my exhaust. I simply drained the oil and refilled it with the correct amount. (I got overzealous and poured in some Lucas Oil when I had 6 qts in the motor already.) I also replaced the plugs; now it runs much better.

tom, you need to get the oil right in you motor but 1 qt. over shouldnt hurt anything. black smoke is fuel, white smoke is oil. sounds like to me you might have a carb. problem, but if you dont know anything about that set up you need to carry it to someone that does.

Well, I have spent a bunch of time chasing the problem....here's what I did and where I stand:

Drained 1 qt. of oil out of the car.

I chased down a few vacuum leaks in the center and front carb. After I solved those, the left side of the motor was strong and smoke free. The right side still smoked black smoke, and I found a vacuum leak at the midpoint of the intake / cylinder head joint. For details, I am running an Offenhauser aluminum intake with modern Pro-1 aluminum SBC cylinder heads.

I took apart the top end on the motor, bought new gaskets with a slightly different shape, and closed the motor. Upon trying to refire, I couldn't get the engine to catch. Thinking I was 180 out, I redid the timing and it made it worse. I took everything off again....

Looks like I had a major vacuum leak again! This time on the left side of the motor.

Question: If there is a large enough opening, could this cause the motor not to ignite? My thought is yes. When I removed the plugs, the right side plugs were very wet with gas, whereas the left sides were basically dry. My thought is I was getting no sucking to the left side of the motor due to the vacuum leak, and that I drowned out the right side.

I plan of buying a better set of gaskets or a blank piece of gasket material and making my own to best fit the odd combination of intake and head.

You might wanna try using Permatex "The Right Stuff" instead of gaskets. It'll make a great seal even if there's a misalignment problem. It comes in a pressurized can and makes a nice even bead. It's expensive, but compares with using purchased gaskets. Sometimes the angles between the heads and the intake can be slightly off depending on the heads, milling, decking, etc. It'll drive you nuts trying to get a good seal.