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radioman Samba Member
Joined: April 15, 2004 Posts: 430 Location: Irmo, SC
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Posted: Fri Aug 27, 2004 4:47 am Post subject: Thing Timing? |
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I have become confused - again. On my 73 stock engine Thing, there is a dimple in the REAR crank pulley half that I assumed was TDC. Looking at the pulley, about 3/8 inch to the LEFT of the dimple is a "v" cut in the FRONT pulley half - that I assumed was the timing mark. What is the timing susposed to be? If the "v" is the timing mark, doesn 't that place the timing "after" TDC? Eventhing I seem to find talks about the timing mark at (*) BTDC. Where (*) is anywhere from 5 to 71/2 degrees. These are the only marks on my pulley. Please someone set me straight. _________________ It's a Southern Thing, 73, stock.
Bill |
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mattt Samba Member
Joined: January 20, 2004 Posts: 1143
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Posted: Fri Aug 27, 2004 10:13 am Post subject: |
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Timing on 73 & 74 Things is 5 ATDC. This is based on having the stock dual hose vacuum distributor and a 34 PICT carb. Your eyes are not deceiving you. The notch is on the side of the pulley closest to the case. I dont know what that other notch is you mention on the other side of the pulley.
If you have any other distributor or carb, its all out the window. |
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radioman Samba Member
Joined: April 15, 2004 Posts: 430 Location: Irmo, SC
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Posted: Fri Aug 27, 2004 10:55 am Post subject: |
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Matt: What you say is what I understood. I am running the dual vac. hose distributor and the 34 PICT 3. Muirs book (How to...) lists the 73/74 engine at 5 degrees After TDC. I can only assume that the dimple in the rear pulley half MUST be TDC since it is before the timing mark by the correct amount (by extrapolation. Do you happen to know if I should stronbe time with the hoses on or off? Both? One? Which? This AE?AH engine is clearly different that others w/ regard to timing. _________________ It's a Southern Thing, 73, stock.
Bill |
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mattt Samba Member
Joined: January 20, 2004 Posts: 1143
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Posted: Fri Aug 27, 2004 11:14 am Post subject: |
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Where is this "dimple" you mention?
Where is the "timing mark" you are using?
When using the dual hose dist. and 34PICT, Ive always read to leave both hoses connected during timing check. Line up the notch with the case 1/2 split and go.
I run a dual hose distributor, but I have the retard line disconnected. It seems to run better that way. My initial timing is somewhere around 5BTDC and I get a bit more pep off the bottom. The only safe way to do this is to set total timing at 3500RPM to 30 deg. and let the initial(idle) timing fall where it will. The retard hose pulls the timing down so low that it takes a long time for all the timing to come in when driving. The retard line goes to the back side of the distributor(facing front of car), and to the back port(facing rear of car) off the carb. |
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radioman Samba Member
Joined: April 15, 2004 Posts: 430 Location: Irmo, SC
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Posted: Fri Aug 27, 2004 1:46 pm Post subject: |
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Mattt: the dimple is in the rear crank pulley half ( Front is front, rear is rear as I stare at the engine.) The "V" is about 3/8 to the left of the dimple but on the FRONT crank pulley half. Understand that the Thing runs OK....I just want to be sure I am right. If I understand , you are running about 5 degrees BEFORE TDC>>>>even though the books say 5 degrees After TDC???? You drive with the retard hose plugged...at the carb and the distributor both? zI don't understand "total timing". I only have a regular timing strobe. Can you give me advice on seeing "total timiing?I see the 28 to 20 degrees advance written up but I don't know how to get there. Perhaps I am already there but don't know it. _________________ It's a Southern Thing, 73, stock.
Bill |
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mattt Samba Member
Joined: January 20, 2004 Posts: 1143
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Posted: Sat Aug 28, 2004 1:11 am Post subject: |
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There are two ways to see total timing. Either you need to have a pulley with timing marks on it, or you need to have a strobe light on which you can adjust for advance or retard. If you go to a Kragen/Checkers/Schucks auto parts store, they carry one like Im mentioning. I bought mine there, they are around $100, but worth it.
The way to "see" total timing is to rev up the engine to around 3500RPM, and watch how much timing you have once up at that RPM. With the aftermarket pulleys, they are labeled all the way around with timing marks. You want about 30 degrees total. What that means is you want no more than 30 degrees of total advance at your highest RPM. Make sense?
In regards to your pulley, I dont know what the dimple is. Id work off the V notch in the front half of the pulley.
I am running somewhere around 5 BTDC. I dont know EXACT because Im not concerned with idle timing. I only set my total timing to 30 degrees, and I let the idle timing go where it wanted. You can run this way, yes, you need to plug the port on the carb for the retard line. I dont have the retard port plugged on the distributor, it doesnt matter. When you setup a dual hose stock distributor like this, its really close to an SVDA style distributor in performance. If you cant set total timing, in order to be safe I would run both hoses, and time it to stock spec, 5 ATDC. |
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