Cam degreeing help me understand!

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Where you'll be running into a math issue is because MrGasket is not exactly describing their product correctly! That very same 988G is used on SBC crank applications and other applications, yet is still called a 4 degree key. It can't change 4 degrees on a chev crank AND change 4 degrees on a Mopar camshaft, and then expect the same result of change (in crankshaft degrees) on the Mopar crank.
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Very interesting. As you stated. Looks like the 988G is used on the Chrysler cam whereas it's on the Chev crank. It lists Chrysler 354-392 engines. I guess that is why I had to grind to get it to fit down far enough into the can groove. Good info.
 
Back at it again this morning. First thing was to install cam gear straight up and advance the crank gear +4 degrees with my 3 way 3103 timing set. Found TDC and measured intake lobe. Shows 107.5. Odd that it does not match my original 106 value in post 144 and it's also +4 from yesterday's dot to dot 111 measure. A 4 degree crank advance should be 2 degrees at the cam. Unless Comp uses cam degrees. Doesn't specify on their website. Summit says both. Pushing forward on my way to 106 I retarded the crank gear -4 degrees and installed the offset cam keyway advanced (it was adding 10 degrees yesterday). Set TDC again and now I am measuring 105 degrees on the intake lobe. I am happy with that and will now measure lift, duration and cam timing open/close on intake and exhaust but I wish I understood why these numbers are not following what you would think to be logical. I would also like to know if it is OK to run installed -4 crank and +10 offset key at cam getting me where I want to be. YES I understand that this is not the textbook way to do it so no lectures please. Just want to know if I will break parts.
Thanks.
 
All measurements just about spot on the cam card using offset cam keyway advanced and crank timing gear retarded -4 degrees.
Cam timing appears to be good.

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I would also like to know if it is OK to run installed -4 crank and +10 offset key at cam getting me where I want to be.
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It doesn’t make any difference how you get there.

However, looking at your figures the numbers don’t add up.
The intake events at 3 & 35 @.050 work out to 218*, in at 106.
The exhaust events of 47 & 1 @.050 work out to 228*@.050, in at 113.
If the “1” for the exhaust is really a “-1” then it’s 226*@.050, in at 114.
 
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Thanks PRH. I figured since the timing events were good then I would be OK. Will definitely be using a 9 way timing set next time.
Lesson learned. Actually lots of lessons learned in this thread. Thanks to @dartfreak75 for letting me jump in on this but I figured it will help others down the road.
 
PRH said:
It doesn’t make any difference how you get there.

However, looking at your figures the numbers don’t add up.
The intake events at 3 & 35 @.050 work out to 218*, in at 106.
The exhaust events of 47 & 1 @.050 work out to 228*@.050, in at 113.
If the “1” for the exhaust is really a “-1” then it’s 226*@.050, in at 114.
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Yeah...it's -1. I wrote that down wrong.
 
JoePole1 said:
Back at it again this morning. First thing was to install cam gear straight up and advance the crank gear +4 degrees with my 3 way 3103 timing set. Found TDC and measured intake lobe. Shows 107.5. Odd that it does not match my original 106 value in post 144 and it's also +4 from yesterday's dot to dot 111 measure. A 4 degree crank advance should be 2 degrees at the cam. Unless Comp uses cam degrees. Doesn't specify on their website. Summit says both. Pushing forward on my way to 106 I retarded the crank gear -4 degrees and installed the offset cam keyway advanced (it was adding 10 degrees yesterday). Set TDC again and now I am measuring 105 degrees on the intake lobe. I am happy with that and will now measure lift, duration and cam timing open/close on intake and exhaust but I wish I understood why these numbers are not following what you would think to be logical. I would also like to know if it is OK to run installed -4 crank and +10 offset key at cam getting me where I want to be. YES I understand that this is not the textbook way to do it so no lectures please. Just want to know if I will break parts.
Thanks.
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I would duplicate that several times to be sure you get the same thing each time. If you do, send it.
 
RustyRatRod said:
How are you trying to find TDC? Use a piston stop. That's the best, most positive way.
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I was thinking the same. I am no expert and I usually run mine dot to dot, but I did this in tech school many years ago and I remember using a piston stop that bolted over the bore. I suppose you could temporarily bolt the head on and use one in the spark plug hole also.
 
JoePole1 said:
I used piston stop and dial indicator. Verified both ways.
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Like I said, I would do it multiple times. When I set one up, when I "think" I have it where I want it, I always begin again and verify five times. When you're talking about degrees, there's a lot of room for error. That's why "to me" duplication is key. Sounds like you've got it zeroed in.
 
Roger that. I feel like I have done this twenty times but not with this configuration.
I put some playdough in a cylinder and starting my pushrod measurements.
I have more questions but that is for another post after I search the site.
 
JoePole1 said:
. A 4 degree crank advance should be 2 degree but I wish I understood why these numbers are not following what you would think to be logical. .
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A 4 degree off set key is not an exact amount! It completely depends on the diameter of the shaft that it's used on! For example the MrGasket key part # 988G (see picture and applications in post 176) may be used on a small block chev crank with a snout diameter of 1.2510, take the 988G key and measure the step, it's .050 thou, convert that into "radians", you get .079936, multiply that by 180 and divide by pi= you get 4.5799 degrees. Now stuff that same 988G on a mopar cam snout with a diameter of 1.0625 thou and final answer is 5.3925 degrees! Now double that (2-1 drive ratio to get crankshaft degrees instead) and you can see how that stupid little key amplified the change to end up with a posable 10.785 degree of change in your cam timing!
 
Max1196 said:
A 4 degree off set key is not an exact amount! It completely depends on the diameter of the shaft that it's used on! For example the MrGasket key part # 988G (see picture and applications in post 176) may be used on a small block chev crank with a snout diameter of 1.2510, take the 988G key and measure the step, it's .050 thou, convert that into "radians", you get .079936, multiply that by 180 and divide by pi= you get 4.5799 degrees. Now stuff that same 988G on a mopar cam snout with a diameter of 1.0625 thou and final answer is 5.3925 degrees! Now double that (2-1 drive ratio to get crankshaft degrees instead) and you can see how that stupid little key amplified the change to end up with a posable 10.785 degree of change in your cam timing!
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Thanks Max!! That right there is some really useful information. MrGasket should have that on their website for reference.
 
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