Cam questions...

[The Donzi]

I was just about to install my 8601 Summit cam when I noticed that there was no keyway on the cam????? The timing gear is slotted to fit on a protruding keyway on the cam right??? At least that is how my old one is set up?? I called Summit and got a big fat :rolleyes: It didn't really bother me that I overnighted everyhting and now have to take a cab to work because thats how it goes but the tech guys at summit have been really arrogant and they aren't really listening to me that it may be a casting defect. They just want me to buy another one and ship back the old one?? I don't feel like playing ring around the rosey with defective cams so that brings me to my original question:

Anybody got some good numbers for a custom grind cam?? I saw that Kris and Riverbeast were either running or getting some custom grinds from engle...I just got their new catalog sheet and it is very impressive with the options.

I am looking for a strong low end and mid range with a decent idle...doesn't have to pur but I will need it to be streetable at least somewhat...bear in mind that I currently run unbalanced hummer beadlocks with runflats on SX's on the street so I'm pretty tolerant of a little racket at idle :D

I have a three angle valve job and mild port work to the heads and intake (edelbrock performer) and a truck avenger 670 cfm. Also, I have both headers and manifolds now (thanks Jared!!) and will run either dual or single exhaust with a nonrestrictive magnaflow of flowmaster exhaust, also 3.73 gears and 35's currently.

So, what are some good combinations of lift/duration/lobe center etc...I am a bit simple minded when it comes to picking the best combination as evidenced by the 8601 choice since it was the biggest they had in the summit catalog :eek:

The custom grinds can be set to just about anything I want so if anybody has some advice you have an apprentice!!!

[88GW]

Try a Crane 268 H 0r 270H or the Comp cams truck cam. I went with the comp truck cam and it works very well. The problem sometimes with high mileage motors and big lift and duration cams is they lack the compression necessary to run well because of this. I found out when I used a Lunati .488 lift and 218 duration cam on a whipped motor and it ran like poop. Just my .02.

Did you put the carb on yet?

[Al Johnson]

I think the key in the cam is a separate part that you have to install. It's not cast into the cam so as to stick out. Doesn't your cam have a slot machined into the surface where the sprocket mounts? The key goes in there. If there is no slot, then you have a defective cam.

[The Donzi]

Al, you are exactly right!! I finally got a call back from Ken at Summit and we straightened everything out. It appears that the new cam is meant to be used with the old keys that are simply popped into the machined slots in the cam. Apparently you can get these keys at any auto store or home depot for 50 cents!!! I feel pretty dumb for making a big deal out of a .50 key but I had never heard of this before?? Live and learn I guess.... Well, I retract all negative comments toward Summit, no more posting for me until I have at least an hour to calm down!!!

88GW, No I haven't installed it yet. I should be getting my heads back today and now that I have the cam problem straightened out I hope to have it running this weekend. I'll let you know how it turns out.

[JERSEY JOE]

You better degree it. Most of the cams that I have checked need to be advanced 2 or 4 degrees.
It will run much better if installed as per the timing card. If you run it in the retarded mode it will run but lack bottom end and be light on available vacuum at idle

[The Donzi]

I am probably going ot advance the cam with the 4 degree timing keyway. I really don't understand how you can "degree in a cam" anyway since the amount by which you can vary the cam/crank offset is limited by the distance of moving the chain one link on the cam gear. Unless I am totally missing something?? Ideally I would like to advance the cam 2 degrees but after checking different orientations of the chain I don't see how this is possible. The keyway on the timing gear will allow me to either advance or retard the cam 4 degree but it looks like even just one tooth on the cam timing gear equates to at least 4 degrees or more?? So, is there any way to set the cam at just 2 degrees advance??

[Al Johnson]

The roller chain timing set I got from Summit, the no-name one, was made by Dynagear. It had crank sprocket positions to give 2° advance, retarded, or straight up. Dynagear is no longer in business, so that might not be available any more.

To figure out the amount you would offset the timing by mounting a tooth off, just divide 360 by the number of teeth on the sprocket, to give degrees per tooth. Probably going to be too much.

To degree a cam, you have to get a degree wheel for the crank, and instructions. Some parts stores rent them or loan them out with a deposit. Use it to find out how the cam sits in relation to the crank with the parts you have and wherever their tolerances are, then you will decide whether or not to change anything.

They make offset keys for the crank hub to degree the cam to whatever you like. I think they come in 1° increments. I don't know if they are available for AMC, or if Chev or other make keys will fit.

Be sure your cam timing sprocket has the oil passage hole open and clear all the way thru the sprocket hub. It's a half-round slot opposite the keyway slot.

Al

[The Donzi]

Al, I did have to file out the slot opposite the keyway. I also noticed that there is another half round slot on the face of the timing gear that only goes half way down the face?? Does this need to medified as well?? I'm not sure what that one is for...

So, it seems like the degree wheel is really meant to check the slack in the entire system in order to determine the true top dead center. Then you can decide how much to advance/retard the cam based on the amount (of advance/retard)already present in the system due to increased drivetrain tolerances. Is that an accurate description??

I think I'm getting it now!! Anyway...thanks for the help guys :D

I haven't decided yet on the cam but I'm thinking .5 lift or so with 270 max duration on a 112* lobe center. Is this in the ball park for good low and mid range torque with a streetable idle and stock stall convertor??

[skid2964]

Originally posted by The Donzi:
I haven't decided yet on the cam but I'm thinking .5 lift or so with 270 max duration on a 112* lobe center. Is this in the ball park for good low and mid range torque with a streetable idle and stock stall convertor??Well, the duration measured at .050 tells more about a cam than total duration, the ramp speed could be different, I know comp cams seem to have a faster ramp than others, may have less total duration with more duration at .050 than a comparable cam. for "good low end torque" I think a cam with 209 to 215 degrees duration at .050, .450 to .500 lift and 112 to 114 deg of separation would suit your needs. Is this for a 360 or 401?

[ March 10, 2004, 08:38 AM: Message edited by: skid2964 ]

[The Donzi]

This is for a 360.

[skid2964]

The cams up closer to 214 deg at .050 in a 360 is just starting to diminish the bottom end, especially if you have large tires and stock gears. With low gears you may be ok, if you have stock gears(with large tires), dropping down to a cam with 212 or 209 deg at .050 may work better. Its all about bottom end, the more duration you have, the higher your usable power range will move up the RPM scale.

[Al Johnson]

I'm running the K8600 Summit cam in my '84 360, with 4.11 gears and 31" tires, manual trans in a Wrangler (3800-4000lb?) This engine has a 4bbl Edelbrock 650CFM, stock compression, 3 angle valves, gasket matched ports, staight-thru 2 1/4" true dual exhaust. Cam installed 2° advanced.

I have great power across the board, just off idle, say 1000 rpm, to 5500 rpm redline. The only thing I'd do differently with the same gearing is install the cam straight up. I have enough bottom end that I could easily give some up for advances in the mid and upper range. With higher gearing, I would stick with the advanced cam timing for the better low end.

In reference to the cam timing sprocket oil passage on the back face of the hub: I am pretty sure you are talking about the oil passage to lead oil from the outlet hole in the cam front surface into the large chamfer that goes around the sprocket hub hole, and then into the slot thru the middle of the hub. If you take a few moments to study where the oil comes from and where it flows in this area, it will become clear. It does go all around the barn, though! In any case, that part of the oil passage is "probably" okay, as I have not heard much about problems in that area. The biggie is the slot inside the hub, that you correctly filed out. Good catch!

[ March 10, 2004, 09:28 PM: Message edited by: Al Johnson ]

[The Donzi]

Well, I just ordered a custom grind from Engle...I used the grind that Kris on the board has its a combination of K52/ K54 grinds .489/.501 lift, but only 209/214 duration (@.050"). Lobe center is 112*. I should get it in about a week. I'll post up when its all done....Maybe I'll finally be able to break my 35's loose from a dead stop :D

[skid2964]

Originally posted by The Donzi:
Well, I just ordered a custom grind from Engle...I used the grind that Kris on the board has its a combination of K52/ K54 grinds .489/.501 lift, but only 209/214 duration (@.050"). Lobe center is 112*. I should get it in about a week. I'll post up when its all done....Maybe I'll finally be able to break my 35's loose from a dead stop :D I think that is an excellent choice! I am considering the same one, but may go a tad larger since I have a 401.