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Can I adjust cam timing without pulling the oil pan?
https://slantsix.org/forum/viewtopic.php?t=67912		 Page 2 of 3
Author:  Charrlie_S [ Fri Sep 13, 2024 11:06 am ]
Post subject:  Re: Can I adjust cam timing without pulling the oil pan?
If the cam timing is not correct, and the timing chain is not sloppy, I wouldn't bother with a rollmaster, or a offset crank key. Just get a set of chevy offset cam bushings, drill the cam sprocket "pin" hole over size, and use the offset bushing to adjust the cam timing.
Author:  doubleclutch [ Fri Sep 13, 2024 2:08 pm ]
Post subject:  Re: Can I adjust cam timing without pulling the oil pan?
Quote:
If the cam timing is not correct, and the timing chain is not sloppy, I wouldn't bother with a rollmaster, or a offset crank key. Just get a set of chevy offset cam bushings, drill the cam sprocket "pin" hole over size, and use the offset bushing to adjust the cam timing.
Will do. Once I tear into it and figure out how to get it degree'd, I'll post some pictures of the situation before deciding how to move forward.
Author:  Rick Covalt [ Fri Sep 13, 2024 5:24 pm ]
Post subject:  Re: Can I adjust cam timing without pulling the oil pan?
Quote:
I did and "glued" three lifters together and put these in the #1 intake lifter hole the dial indicator on these.
I have degreed the cam several times as well with the head on. Charlie's 3 lifters works. But I just bolted a piece of scrap metal to a valve cover bolt that has a hole drilled in it the size of the push rod. Then drop the push rod through the hole and into the lifter on #1. Set your dial indicator on top of the push rod and go to town. :D :D
Author:  doubleclutch [ Fri Sep 13, 2024 6:22 pm ]
Post subject:  Re: Can I adjust cam timing without pulling the oil pan?
For future reference and future readers, this is really cool.

A web site that let's you build your own degree wheel (using your specific timing values, etc).
You can also print timing tape to wrap around a pulley, etc. It also has functions to print a myriad of other things too (protractors, clock faces, etc).

I played with my printer scaling to get a 7" diameter wheel, which is apparently the size of my pulley...I haven't taken it out to my engine yet, but that's the size it says in my Dutra rebuild manual. I'm going to try the timing tape, as well - it may be easier to use with the engine in the bay.

Degree wheel:
https://www.blocklayer.com/degree-wheel

Timing tape:
https://www.blocklayer.com/timing-tape
Author:  MadScientistMatt [ Sat Sep 14, 2024 5:19 am ]
Post subject:  Re: Can I adjust cam timing without pulling the oil pan?
Nice, I used that site myself when degreeing my cam.
Author:  doubleclutch [ Fri Sep 27, 2024 5:34 pm ]
Post subject:  Re: Can I adjust cam timing without pulling the oil pan?
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I obtained a dial indicator and then experimented with ways to find actual TDC and to measure cam movement with as little disassembly as possible. I'm optimistic that I finally have this cam degreeing thing understood at an apprentice level, or at least it isn't the occult ritual I perceived it to be just a few weeks ago. I'm looking for some confirmation from you guys to make sure I understand properly the information I now have before I plow forward and pull apart the front of the engine to make the adjustment I think I need to make. I've attached pictures so you can see yourself the results of verifying my intake cam lobe position. To explain, here's what's in the pictures:
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Dial indicator reading the intake cam opening at .020. From all my research (my Haynes manual, info I've read on this forum, etc), the stock rocker arm ratio is 1.5 and the ONLY place I could get a reliable reading without taking apart the rocker assembly is on the retainer. So, the indicated .030 opening reflects .020 x 1.5.
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My actual TDC was found to be dead-on and the "pointer" is the yellow mark on my factory probe tube. With that being said, I turned the engine clockwise until I achieve the valve opening of .030 and my effective crank measurement is 16 degrees BTDC. I perceive this is my issue, since the cam card indicates it should be 24 degrees BTDC. This suggests to me, if I'm not mistaken, that I'm likely off a tooth on my cam gear.

Does anyone see any problems with my methods or diagnosis? If not, I'll tear into it and see if this fixes my rough running!
Author:  Rick Covalt [ Fri Sep 27, 2024 6:04 pm ]
Post subject:  Re: Can I adjust cam timing without pulling the oil pan?
Did you remove all the valve lash before starting? No your rockers are not exactly 1.5. They could be 1.45 or 1.55 or somewhere in between.

I do my measurement off the Intake Centerline number on your cam card. Yours is 106 degrees. Once you are sure the TDC mark is correct. Make a temporary pointer to point to TDC on your paper wheel. Rotate the crank until the camshaft reaches the highest lift on the intake valve retainer. Turn the dial indicator to zero. Then go to .020 or .030 on either side of that zero and write down those two readings.(It doesn't matter what number you measure at as long as you do the same before and after the peak) Add them up and divide by two and that is your installed intake centerline. Double check your work. If it turns out to be 100 then you are 6 degrees advance and if it is 110 you are 4 degrees retarded. Adjust accordingly. Honestly if you are withing 1 or even 2 degrees of where you want to be, you are probably fine.
Author:  doubleclutch [ Fri Sep 27, 2024 6:20 pm ]
Post subject:  Re: Can I adjust cam timing without pulling the oil pan?
Quote:
Did you remove all the valve lash before starting? No your rockers are not exactly 1.5. They could be 1.45 or 1.55 or somewhere in between.

I do my measurement off the Intake Centerline number on your cam card. Yours is 106 degrees. Once you are sure the TDC mark is correct. Make a temporary pointer to point to TDC on your paper wheel. Rotate the crank until the camshaft reaches the highest lift on the intake valve retainer. Turn the dial indicator to zero. Then go to .020 or .030 on either side of that zero and write down those two readings.(It doesn't matter what number you measure at as long as you do the same before and after the peak) Add them up and divide by two and that is your installed intake centerline. Double check your work. If it turns out to be 100 then you are 6 degrees advance and if it is 110 you are 4 degrees retarded. Adjust accordingly. Honestly if you are withing 1 or even 2 degrees of where you want to be, you are probably fine.
Yup - the valve lash was removed from the rocker. I did read about others using your method to confirm timing so I'll try that as well - if it comes out the same and confirms my initial results, I'll be confident the cam is off. Thanks much!
Author:  doubleclutch [ Sun Sep 29, 2024 10:22 am ]
Post subject:  Re: Can I adjust cam timing without pulling the oil pan?
I did measurements on intake centerline and found that I am off by four degrees. I measured twice and I'm consistently coming out to 110 degrees. That seems to confirm my measurements on intake timing, suggesting I'm off a tooth. It looks like it's time to grab my favorite barley pop and get the wrenches out and adjust my chain.
Author:  Rick Covalt [ Sun Sep 29, 2024 11:25 am ]
Post subject:  Re: Can I adjust cam timing without pulling the oil pan?
I think one tooth will be a lot more than 4 degrees. You will need to drill the gear and use offset bushings.
Author:  Charrlie_S [ Sun Sep 29, 2024 1:40 pm ]
Post subject:  Re: Can I adjust cam timing without pulling the oil pan?
I don't remember exactly how many degrees is one tooth, but it is more than 10 degrees.
Edit: Just checked a stock cam sprocket. 38 teeth 360 degrees equals 9.47 degrees per tooth.
Author:  doubleclutch [ Sun Sep 29, 2024 3:07 pm ]
Post subject:  Re: Can I adjust cam timing without pulling the oil pan?
I was wondering how big a change one tooth would be. Sounds like the project is getting more involved!
Author:  Charrlie_S [ Sun Sep 29, 2024 6:37 pm ]
Post subject:  Re: Can I adjust cam timing without pulling the oil pan?
Quote:
I was wondering how big a change one tooth would be. Sounds like the project is getting more involved!
Not really. Just remove the cam sprocket, and drill the dowel pin hole over size, and install a offset bushing. They come in a set of even numbers, or a set of odd numbers. You can buy them for either Mopar or Chevy. Same part. The directions for the bushing will tell you what size to drill.
Author:  doubleclutch [ Wed Oct 02, 2024 5:16 pm ]
Post subject:  Re: Can I adjust cam timing without pulling the oil pan?
Quote:
Quote:
I was wondering how big a change one tooth would be. Sounds like the project is getting more involved!
Not really. Just remove the cam sprocket, and drill the dowel pin hole over size, and install a offset bushing. They come in a set of even numbers, or a set of odd numbers. You can buy them for either Mopar or Chevy. Same part. The directions for the bushing will tell you what size to drill.
Just so I don't order the wrong part, I'm assuming this is what you are describing?
https://www.amazon.com/Competition-Cams ... B000CIS8G8
Author:  Charrlie_S [ Thu Oct 03, 2024 3:28 am ]
Post subject:  Re: Can I adjust cam timing without pulling the oil pan?
Quote:


Just so I don't order the wrong part, I'm assuming this is what you are describing?
https://www.amazon.com/Competition-Cams ... B000CIS8G8
That's correct
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