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| degre wheel and stock cam https://slantsix.org/forum/viewtopic.php?t=27634 |
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| Author: | gato [ Tue Mar 04, 2008 5:46 am ] |
| Post subject: | degre wheel and stock cam |
i understand that a degree wheel is used to set up the cam. i don't know how to use it. can any noticable improvements be had on a stock block/cam? i super sixed my 225 with headers. i still need to reaseal the oil pan and timing cover. since i'll have it open. . . . . is the stock timing chain adjustable? D~~~! |
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| Author: | slantvaliant [ Tue Mar 04, 2008 6:28 am ] |
| Post subject: | |
Instructions are all over the 'net. HERE'S one set, and ANOTHER. The stock gear is not adjustable. CAM DEGREE BUSHING THREAD Here's a FREE DEGREE WHEEL for you. |
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| Author: | Doc [ Tue Mar 04, 2008 8:49 am ] |
| Post subject: | |
Degree your cam! The simple version: Find true Top Dead Center (TDC) and adjust your timing tab for accuracy. Check the overlap event at TDC Exhaust stroke. The overlap event (the number of degrees that both valves are open) should be centered over TDCEx. (sometimes called "splitting the overlap") DD |
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| Author: | Reed [ Tue Mar 04, 2008 10:06 am ] |
| Post subject: | |
While you are messing with degreeing the cam, another VERY useful thing to do is to check if your timing mark on the vibration dampener has slipped. Last year, my brother had me tune up his 83 Dodge van that has a 225 in it. The motor had been rebuilt and had under 10,000 miles, but it was getting 8 mpg. Among other problems, I found that the vibration dampener (which had not been rebuilt when the rest of the motor was rebuilt) had slipped, making the timing mark read 8 degrees advanced. This resulted in the timing being set 8 degrees retarded from where it should be. Checking the timing mark is VERY easy. The only special tool you need is a TDC stop tool, such as the one sold HERE To check your timing mark, remove the #1 spark plug and thread the tool into the hole. By hand, rotate the motor counterclockwise until the motor won't turn anymore (the piston has come into contact with the bottom of the TDC tool). Using whiteout, mark the vibration dampener next to the 0 degree or TDC line on the timing tab. Now rotate the motorclockwise until the mtor stops turning. Mark the vibration dampener again at the TDC mark on the timing tab. Ideally, the two marks on the vibration dampener should be equidistant from the timing mark cast into the dampener. If the two marks are not equidistant, you need to measure the distance between the two, divide it by two, and make a new mark equally distanced from each whiteout mark which will be your new timing mark. Alternatively, you can use the timing tab as a ruler and measure how far each whiteout mark is from the cast timing mark and then figure where the timing should be. Checking this helped me tune my brother's van to get 18 MPG highway with a Super Six and a non-lockup 727 tranny. If a van can get 18 mpg, then a Dart or Valiant should be able to as well. |
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| Author: | gato [ Tue Mar 04, 2008 10:34 am ] |
| Post subject: | Ok. . . |
i get it, get 'er done! while i'm in there i'll probly replace the timing gear. is there any real advantage to upgrading to an aftermarket model that is adjustable as opposed to a stock version? D~~~! |
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| Author: | Reed [ Tue Mar 04, 2008 10:44 am ] |
| Post subject: | |
Beyond being new and not stretched and having the ability to fine tune the cam, there is not advantage to replacing your current timing set (cam gear, chain, crank gear). |
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| Author: | gato [ Tue Mar 04, 2008 12:11 pm ] |
| Post subject: | |
Beyond being new and not stretched and having the ability to fine tune the cam, there is not advantage to replacing your current timing set (cam gear, chain, crank gear). is there any substantial gain to be had in fine tuning the stock cam? is it worth the effort? |
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| Author: | Reed [ Tue Mar 04, 2008 12:53 pm ] |
| Post subject: | |
Fine tuning the cam for the sake of fine tuning the cam probably won't be too noticeable in a stock daily driver. However, if you replace the timing set, you need to remember a few things: (1) Replacement timing set are notoriously manufactured with incorrect cam indexing. THis means that replacing your timing set can change the relationship between the cam and the crank. (2) A few degrees makes a difference. When people talk about advancing or retarding the cam, they are talking about changing the cam's relation to the crank by 2, 4, 6, or 8 degrees. If I were to be replacing the timing set on any engine, I would take the time and do it right. I would go ahead and degree the camshaft (1) to make sure that the cam is properly indexed in relation to the crank and (2) to optimize power and fuel efficiency. Given the age of our motors, I would also go ahead and check the timing mark on the vibration dampener. Unless you have a low mile motor or the timing set has already been replaced, your timing chain is probably stretched (factory timing sets used nylon coated gears which wore out, further degrading the timing accuracy) and needs to be replaced. I am a firm believer of doing a job once and doing it right. Considering all this, I say replace your timing chain and gears, degree the cam back to the specs Doc mentioned, and check your vibration dampener timing mark. |
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| Author: | slantfin [ Tue Mar 04, 2008 2:57 pm ] |
| Post subject: | |
Don't forget a cam stop. DD Mod. |
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