Anyone know where I can download instructions on how to degree a cam? My comp cam shows the info at .006 on the cam card. My Summit instructs talk about everything at .050. I'm so confused.
Camshaft Degreeing Instructions
- Thread starter jefflock
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I found this link when I did mine.
http://www.carcraft.com/howto/116_0701_how_to_degree_a_camshaft/top_dead_center.html
http://www.carcraft.com/howto/116_0701_how_to_degree_a_camshaft/top_dead_center.html
AdamR
Big Member
moper
Well-Known Member
There are a few ways to do it. The reason most use the "@ .050" method is to remove any possibility of the take up ramps on the lobes from skewing the measurements. Plus, now there are asymmetric (means the opening side of the lobe is a different shape fromt he closing ramp) lobes being used that can make things interesting.
340 Dart
I don't know ****.
If you get the Mopar Performance degree wheel, it is printed on the wheel.
Thanks for the help guys I finally got it figured out on the how to. After many attemps I finally got down to 107.5. It's supposed to be at 106. Is that close enough?? Those cams keys ought to be labeled.
Comp cams 20-225-4 XE 284H grind. Going in a 70 340 10-1 motor,Airgap, 750 holley. In a 68 Dart some street mostly strip and show. 727 rev man with 3200 to 3600 stall race gas and premium blend.
moper
Well-Known Member
I'd bet your measurements might be a hair off. I have yet to have a Comp that was not dead nuts on it's designed installed centerline. I would not advance it, leave it where it is.
With the normal (straight key) it was at 109. I checked it several times even again later after trying some of the offset keys to check myself. The cam could be right on the money and the timing set that is off. I pulled out a Lunati bracket Master 2. It's specs are 230 duration 480 lift with advertized duration of 292. I could never get the car to run like I thought it should. I never degreed in the Lunati cam and always suspected something was up with it. I have kicked myself hundreds of times for not doing it. Best time was around 14.00 flat. I'm reusing the timing set maybe I shouldn't.
lilcuda
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I disagree. If anything, you want it to be a little more advanced than specs, because as the chain stretches, it will retard. I'd advance it to 106, if not 105.
340sFastback
Well-Known Member
Soak that chain in a container of fresh oil too before installing. That way it won't be dry on initial start up.
moper
Well-Known Member
lil, Comp grinds thier cams with advance in it. That's whay it's in at 106, yet the camshaft centerline listed is 110. Just my opinion of course.. One can advance the installed centerline, but advancing a cam that is properly chosen, and designed as the XE line is for making cylinder pressure, can put you over the pump gas threshold pretty easy. Also, if he's running a tensioner and/or a good chain, the stretch means virually nothing. It's there of course, but it will not make any difference. 2° is barely measurable/feelable, 6° is huge.
moper: I picked up a new timing set. (Cloyes) I run the Mopar tensioner. With the straight key I'm at 107. I checked and rechecked it 4 times. I'm assuming that I'm supposed to install it as close to 106 is that correct? I think I'm good to go.
Thanks!
Thanks!
340sFastback
Well-Known Member
I used a Cloyes with my new Comp cam and I had to retard it 1 degree to get the center line just right. I messed with it for a few hours both before and after I retarded it just to be sure. Probably could have left it 1 degree off but I figured why not have it right on.
Congratulations on getting it right on the number...you will find out that following instructions to the "t" is the best way....If you need any help just PM me I know a few people around there or I might be close.
Close is only good enough, for government work..when they round your taxes to the next highest dollar...:cheers:
Close is only good enough, for government work..when they round your taxes to the next highest dollar...:cheers:
Thanks Guys for all your help. I went back out to the shop today and got it down to 106. Maybe a hair under. Anyway got started on putting her back together. The cometic head gaskets won't be in till next week so I'll finish it up when they arrive. (By the way I don't work for the government.)
moper
Well-Known Member
Jeff, For each engine I always degree it 3 times...lol. Eight times out of ten, the last two times I get the same final result, 10 out of ten the first result is different than the last two...lol.
lilcuda
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Moper,
Yes, I understand that Comp grinds their cams with advance in them. I'm not a noob. I built engines for 10 years professionally. The issue is that you don't know if the crank keyway is machined in exactly the right place in relation to the rod throws. There could also be small errors in the machining of the timing set, the block, etc. If you get a few of these errors in the same engine, it's called stacked tolerances.
The goal is to get the cam installed exactly at the recommended centerline. Typically, Comp recommends that their cams should be installed at a 106 centerline, even though the centerline of the intake lobe (aka point of maximum lift) is at 110 degrees ATDC. That's your ground-in advance.
What I'm saying is that if the cam is at 107 from the day it's assembled, it's starting out 1 degree retarded from where it should be. Tensioner or no tensioner, the chain will stretch some. I've seen both Cloyes and Rollmaster chains stretched quite a bit after only a little time in an engine. What happens when it stretches? The cam retards! So if it's at 107 with a straight key after checking and re-checking several times, I would use whatever key is needed to get it to at least 106. If it gets a little more advanced than that, no big deal. In no time it will be right where it should be. Long term, it will keep the motor running better for longer. Even the best chains stretch!
340sFastback
Well-Known Member
And the chain is going to stretch more if you don't soak it in oil before installing it.
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