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In addition to setting the choke t the optimal setting, you need to tune the engine . This includes checking jetting, test when the secondaries open if its a vacuum secondary carb, and testing timing to see if it is optimal for your setup.
Below is one of the things I would do.
SETTING TIMING CURVE
Before you start driving it normally, I would set the timing curve so it is optimum for your particular setup . Below is just one way to do that.
1. Disconnect and plug the vacuum hoses to the dist if you have any and leave them plugged permanently or until further notice.
2. Start your timing at 8 degrees BTDC.
3. With the engine warm and idling, advance the timing 4 degrees . Listen for an increase in rpm and irregular/rough running.
4. If the rpm increases and it still runs smoothly, reset the idle speed then increase the timing 2 more degrees and check for the same things.
5. Retard timing back to 8 degrees btdc.
6. Reset the idle speed.
7. Increase the rpm to around 2000 then advance the timing 4 degrees . Listen for an increase in rpm and irregular/rough running.
8. If the rpm increases and it still runs smoothly, reset the engine speed to 2000 rpm then increase the timing 2 more degrees and check for the same things.
POST RESULTS
TEST DRIVING
After setting the timing curve you can do the following test to see if you have too much advance.
Get the engine up to operating temp.
Drive at around 20 mph in second gear for a few seconds then floor the gas pedal as fast as you can until you reach around 30 mph and listen for even the faintest pinging sound coming from the engine . If it pings, you have too much timing for the octane gas you are using . You can either reduce the timing some or use a higher octane . The highest timing level you can run without it pinging and/or running erratic will SAFELY provide the most power.
It may ping in hot weather even if it does not in cold weather . If you find this to be the case, the easiest thing to do is reduce the timing until it stops or try higher octane gas . If it still pings with the highest octane gas, you can reduce the timing then.
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CARBURETOR GAS LEVEL
Set gas level so it is just below the inspection screw holes or just 1/4 of the way up on the clear sight glass with the engine idling or just after you turn it off.
If your carb has screws in the inspection holes, put several paper towels next to the carb before you remove the screws because it may drain a bit of gas out.
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IDLE FUEL MIX SCREWS
1. With the engine off, turn both screws in until they just barely stop turning and count the turns as you turn them in.
2. Turn them both out equal amounts to where they previously were . If they were turned out different amounts, simply split the difference so they are both turned out the same amount.
3. With the engine warm, turn both screws 1/8th turn at a time until the highest idle is achieved then turn them both in 1/16th turn . You may have to try turning them in both directions to find which way provides the highest idle.
Step 3 should be repeated after all other changes are made.
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