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Cam Questions????
https://slantsix.org/forum/viewtopic.php?t=50988		 Page 2 of 3
Author:  John Brayton [ Sun Feb 03, 2013 2:28 pm ]
Post subject:  Cam Questions????
Thanks everyone for responding! Charlie, the question I was hoping to get answered is "has anyone drilled out a keyed gear"? I ended up ordering another gear/chain set and hope to have it in by the end of the week. Erson, to their credit, did offer to regrind or replace my cam....and while I appreciated their offer the month wait time was too much.

Regards,
John Brayton
Author:  Fopar [ Sun Feb 03, 2013 2:34 pm ]
Post subject: 
You don't drill out the crankshaft gear just the cam gear.

Richard
Author:  Charrlie_S [ Sun Feb 03, 2013 4:21 pm ]
Post subject: 
That's right. The crank gear can have several keyways, which allows you to adjust cam timing, by using a different keyway. The cam gear has a "drive pin" hole. This hole gets drilled out to (if I remember correctly) 13/32 of an inch, and the offset bushing is installed. Using different offset bushings allows the cam timing to be adjusted. Normally you would do one or the other, not both. I have always used the bushing. I did try a multi keyway timing set, but found the crank gear fit so tightly on the crank, I was afraid of doing damage trying to remove it to change the cam timing. So I drilled the cam gear, and went back to using the bushing, and left the crank gear alone.
Author:  Sprag [ Mon Feb 04, 2013 1:00 pm ]
Post subject: 
OK, simply for clarification I'll kick the dead horse here :lol: I'm not real smart so I need pictures most of the time too!

It's a one or the other deal, you can drill the cam gear index hole to use the offset bushings or purchase a timing set that has an multi-keyway (adjustable) crank gear.

An adjustable crank gear allows for numerous cam/crank relationships by simply removing the chain and gear, moving the position on the crank key and reinstalling:

Image

Same goes for the offset bushing option for the adjusting cam gear. Here's one of unknown manufacture but you get the idea, the offset bushing is now controlling the position of the cam relative to the crankshaft. When you use the offset bushing, you change the cam's timing so it is just ahead of or behind the crankshaft (advance/retard).

Image
Author:  John Brayton [ Mon Feb 04, 2013 5:30 pm ]
Post subject:  Cam Questions????
Sprag,

Thanks for taking the time to "kick the dead horse again"..... photos really help! The Comp cam gear does not have a round locater pin as in your photo...instead it has a skelaton key hole shaped locater pin. The shape of this locater pin creates issues with drilling for offset bushings. We've ordered a new gear and chain set with the locater pin as shown in your photo.

Regards,
John Brayton
Author:  DusterIdiot [ Mon Feb 04, 2013 5:52 pm ]
Post subject:  Lol...
Quote:
The shape of this locater pin creates issues with drilling for offset bushings.
Since you are using the offset bushings you can use a straight edge to strike a line right through the middle of the gear using the skeleton 'slot' as a reference, and drill your new hole 180 degrees from the slot using a bit the width of the slot to start with, place on cam, if it all lines up, redrill for the size of the bushing....Worried about the bushing coming out, or other cataclysmic issues, Install the gear on the cam, drill a hole on the 'slot' side and use an engine dowel to act as a secondary pin for hte gear.

-D.Idiot
Author:  Charrlie_S [ Mon Feb 04, 2013 6:13 pm ]
Post subject:  Re: Cam Questions????
Quote:
Sprag,

Thanks for taking the time to "kick the dead horse again"..... photos really help! The Comp cam gear does not have a round locater pin as in your photo...instead it has a skelaton key hole shaped locater pin. The shape of this locater pin creates issues with drilling for offset bushings. We've ordered a new gear and chain set with the locater pin as shown in your photo.

Regards,
John Brayton
Boy, Comp cams must be using a really cheap gear.
Author:  Sprag [ Mon Feb 04, 2013 7:15 pm ]
Post subject: 
I'd like to see a picture of this key slot thing, it sounds stupid and depressing. I do like D.Idiot's solution though, nothing beats using what you got.

Now I sorta don't feel so bad about the basic $29 Cloyes set I bought for my turd :(
Author:  John Brayton [ Thu Feb 07, 2013 4:19 pm ]
Post subject:  Cam Questions????
We received and installed the new gear/chain set. The adjustments built in to the crank gear allowed us to get 106.5 degrees. We called Mark and he thought 104/105 is optimum. This is a street car with 4 speed tranny... will 1 to 2 degrees make a noticeable impact? If so, it's time to drill the cam gear for a bushing......if not, we can move on with the assembly. Your advise and thoughts are appreciated!

John Brayton
Author:  madmax/6 [ Thu Feb 07, 2013 7:54 pm ]
Post subject: 
Like I told you,Lou would KNOW the right answer.I am just going by what I think he told me.I dont even trust my memory.Guzzi Mark
Author:  DusterIdiot [ Thu Feb 07, 2013 9:21 pm ]
Post subject:  Yes...
Quote:
This is a street car with 4 speed tranny... will 1 to 2 degrees make a noticeable impact?
It will make a slight difference on a street car(a few HP, a little bit of torque there),it will be much more if the engine is a performance build...if the LSA ordered is 108, 104 would put the useable torque band lower for best use light to light and passing on the highway (especially if using a street gear instead of say 'drag' gearing an an 833OD). If you go too much your power will 'eel over' sooner limiting the top end, and you may get pinging problems as the DCR is pushed higher...

One other item, did you request the cam to already be ground with advance in it? (Erson shows this on their cards as the LSA+the advance...IE 110+4)

-D.Idiot
Author:  John Brayton [ Thu Feb 07, 2013 10:20 pm ]
Post subject:  Cam Questions????
Hi DI,

No, did not order the cam with advance..... yes, the lsa is 108.....AND I'm using an OD tranny. This is a mild "performance" engine with .060 over, oversized stainless valves, and ported head. If I understand your comments you agree with Mark that 104/105 is preferred?

JB
Author:  DusterIdiot [ Fri Feb 08, 2013 7:22 am ]
Post subject:  yes...
Quote:
If I understand your comments you agree with Mark that 104/105 is preferred?
Yes, I would. On bigger cams I've had better success with more than that (closer to 102/103...)

What rear ratio are you handling with that gear box?

-D.Idiot
Author:  John Brayton [ Fri Feb 08, 2013 11:15 am ]
Post subject:  Re: yes...
Quote:
Quote:
If I understand your comments you agree with Mark that 104/105 is preferred?
Yes, I would. On bigger cams I've had better success with more than that (closer to 102/103...)

What rear ratio are you handling with that gear box?

-D.Idiot
The rear end is a 4.56.....

JB
Author:  DusterIdiot [ Fri Feb 08, 2013 1:17 pm ]
Post subject:  Lol...
Quote:
The rear end is a 4.56.....
I run that ratio in my duster and at a 3.31 final ratio it works great for the fat car, but after daily driving with it in OD and 25.6" tire diameter and dual exhaust the drone gets to you after a while...Either way I've never had to get it into OD at the track (shift comes about 50' from the finish line if recovering from the 2-3 upshift and keeping a 5K shift point...my typical track run is launch at 6000 rpm, launch drops the rpm to 4500...run it to 5500 rpm, 2-3 loses about 800-1000 rpm, leave it in 3 for the rest of the track and recover to 5500 rpm...the 3-OD shift is about a 3-400 rpm drop if it could be made.)

-D.Idiot
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