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Old 01-30-2008, 10:43 AM
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sbc timing problems

I am trying to time chevy 350. I brought to TDC #1 and checked the distributor position and it is at 3 o'clock i got it to fire up, but it is missing a little. I rotated the distributor until it ran ok. but reving it up I still have a miss in it. I have looked around and found that the position of the distributor on TDC #1 should be at 6 o'clock. I pulled the distributor out with #1 on TDC and pointed the distributor at 6 o'clock. I tried to start it but didn't want to fire in that position. So I took out the distributor again and repositioned it to where it was before. I checked over the firing order and that was all fine. Anyone have any ideas?
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Old 01-30-2008, 02:22 PM
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If you got it at TDC "firing" (now keep in mind there are two TDC's,TDC firing and TDC exhaust) you can have the pointer anywhere you want, but you must start at that point wiring the firing order. Lots of times it easy to cross # 5 & #7. You are correct the #1 cylinder on the cap is normally located about 5-6 o'clock looking down on dist cap.

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Originally Posted by Hobbster
I am trying to time chevy 350. I brought to TDC #1 and checked the distributor position and it is at 3 o'clock i got it to fire up, but it is missing a little. I rotated the distributor until it ran ok. but reving it up I still have a miss in it. I have looked around and found that the position of the distributor on TDC #1 should be at 6 o'clock. I pulled the distributor out with #1 on TDC and pointed the distributor at 6 o'clock. I tried to start it but didn't want to fire in that position. So I took out the distributor again and repositioned it to where it was before. I checked over the firing order and that was all fine. Anyone have any ideas?
Thanks
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Old 01-30-2008, 02:38 PM
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Basically you have to bring the motor to TDC on the Compression stroke and the rotor should be pointing at the stud that the #1 spark plug wire should be attached to. If not then you could be having these types of problems.

But if that is all good then you need to start looking at other potential ignitition problems
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Old 01-30-2008, 03:41 PM
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sbc timing problems

If #1 is at top dead center on the compression stroke both the intake and exhaust valves will be closed. Check your rockers to verify. I suspect the inside of your rotor cap, or rotor is oily or dirty. Have you checked your coil and verified that it fires blue out of the coil. If your coil fires yellow it could be the problem. How old are your plug wires and are they burnt or damaged in any way. Hope this helps.

Bob
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Old 01-30-2008, 05:28 PM
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If you just moved the rotor and didn't move the wires as well its not going to start. Generally #1 is somewhere between 5 and 7 o'clock. Once you get the distributor set properly and pointing at the tower you want to be the #1 wire tower you will need to start putting in the wires in order, 1 8 4 3 6 5 7 2 clock wise. Be careful with #5 and #7 as they are real easy to mess up as they are next to each other on both ends. If you have a skip it is most likely not timing. I would look for in this order;

1 Wrong firing order
2 Bad or mis gapped plug
3 Broken or bad wire
4 Bad cap or rotor
5 Poorly adjusted valve

If it is a hard skip the easiest way to pin it down is to pull each plug wire one at a time with the engine running to see if there is a cylinder that doesn't seem to change the RPM of the engine. You need to use a well insulated pair of pliers or a spark plug wire tool or you will get zapped. Once you have identified the faulty cylinder you can look for the reason. Pull the plug and see how it looks. Swap it with another one and see if the problem moves with the plug or stay with the cylinder. You can usually do the same with the wires, make sure you move both ends. A good visual inspection of the inside of the cap and rotor should tell the tale there.
Good luck, you will find it

Chet
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Old 01-31-2008, 12:59 PM
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Quote:
Originally Posted by Quarter Flash
If #1 is at top dead center on the compression stroke both the intake and exhaust valves will be closed. Check your rockers to verify. I suspect the inside of your rotor cap, or rotor is oily or dirty. Have you checked your coil and verified that it fires blue out of the coil. If your coil fires yellow it could be the problem. How old are your plug wires and are they burnt or damaged in any way. Hope this helps.

Bob
I have new plugs and wires. I also changed out the module is side the distributor. When I put to TDC #1 I had the valve covers off to make sure I was on TDC #1 and not on #6. I guess my question is that #1 on the cap doesn't need to be at the 6 o'clock position. I have checked over the firing order on the cap to make for sure and everything looks in order. But still have a miss in it.
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Old 01-31-2008, 01:46 PM
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Timing Problems

No it does not make any difference what *** on the cap you plug the #1 plug wire into. It is sometimes more convenient to have the wire positioned on the left side of the distributor, but not necessary. More than once I have had a new plug or wire be bad, but not often. Electrical is usually a sharp quick miss and mechanical or fuel is usually more of a flutter or rolling miss. Fuel and mechanical can be repetitious or have a rhythm. Electrical tends to be more sporadic. Nothing is 100% but I hope this helps.

Bob
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