Cam Timing Guru Needed

[DransportGarage]

Q: If my intake open @ .006" is 26 degrees with 0 degrees (standard) camshaft timing, what should it be with +4 degrees camshaft timing? (The cam is a Comp Cams XE268H-10.)

I know this sounds like a stupid question, but I have a Zoom roller chain, and I can't determine which tooth to align when using the +4 keyway. The first picture below shows the obvious alignment using the 0-degree keyway. The second pic shows one possible alignment using the +4 keyway, but it results in 16 degrees. If I rotate the crank gear one tooth clockwise I get 30 degrees.

Thanks,
Bob

[Speedbumpauto]

If you're going to open it 4 degrees sooner(advance) then at .006" it should be 30 degrees.? I do my cams by intake centerline, personal preference. I've heard stories about timing set problems recently, but haven't experienced one yet.

[DransportGarage]

Originally Posted by Speedbumpauto

If you're going to open it 4 degrees sooner(advance) then at .006" it should be 30 degrees.? I do my cams by intake centerline, personal preference. I've heard stories about timing set problems recently, but haven't experienced one yet.

I thought 30 made more sense than 16, but your "?" worries me. I'm in the process of using the intake centerline method, so I'll post what I find.

I'm really disappointed in this Zoom product. It's "Made in China". It should have much better marks than it has. It is possible that some detailed instructions had been lost since I bought it in a swap meet, but judging by the instructions on the cardboard insert, I probably got all there is. They do a wonderful job of describing the obvious (block clearance, what advance and retard do, that there are 3 keyways, etc.), but don't say ANYTHING about how to align the sprocket markings!

[DransportGarage]

I checked my cam using the intake lobe centerline method and came up with 106 degrees on the money. I don't want to go past 106, so I'm going to NOT adjust the cam timing. For me the initial question on this post is moot, but it's still disappointing to see a well-known brand like Zoom putting out a product with a setup that I can't interpret.

Bob

[Speedbumpauto]

That cam should work well at 106 ICL...as a matter of fact, it could have 4 degrees built in as many sbc's put the intake lobe at 110. You really have to be careful with stuff like timing sets any more, especially small block chevy stuff since it fits so many years. It's an "offshore" dream.

[parkwood]

No matter what marks you line up, check them twice.. we tried to start a motor "built by a race car guy" and this is what happened the first time we turned it over... didn't know it at the time but also had two bent valves.. after a tear down and valve job and new push rods it ran great.. just take your tiime and check things out.

[tmoble]

you should always install straight up unless you've got the time and tools to degree it in. Don't ask how I know this......or how much was the "fee" for that little lesson.

[DransportGarage]

Originally Posted by parkwood

No matter what marks you line up, check them twice.. we tried to start a motor "built by a race car guy" and this is what happened the first time we turned it over... didn't know it at the time but also had two bent valves.. after a tear down and valve job and new push rods it ran great.. just take your tiime and check things out.

Oops! Yeah, I'd like to avoid that.

Thanks also for reinforcing my thinking, SpeedBumpAuto. (Lord knows I need it.) When you only do one engine every 4 or 5 years you have a tendency to screw up.

Besides that, I had a heck of a time getting things to go well today. My dial indicator is older than I am and it only has about .150" travel. I'm surprised it doesn't have roman numerals on it. At first my test springs were too long (bottomed out) so I cut 'em down. Then they were a little weaker, so the valve would stick due to friction on the guide and seal. The indicator would stop when closing. Then the base on the indicator would rock when I least expected it.

I didn't have a solid lifter, and wouldn't you know it, the hyd lifter I picked was the only one that wasn't pumped up. Then, without the head gasket the retainer would bottom out on the seal at 1 turn in. I thought the valve was hitting the piston. Naturally, the rings were all installed, so it was a bummer to turn evenly. At one point the indicator would reverse direction while closing, like there was dirt on the lobe. I pulled the cam out, but no dirt. Tried again and all was OK. I had the head on and off about 20 times, clayed the valves, couldn't find my play dough so I had to use plumber's putty.

What fun! All in all, I screwed around for about 4 hours, but I know the measurements I took are good. Tomorrow I'll button her up on the bottom end, torque the heads down, set the valves, bolt on the intake and bag her.

[DransportGarage]

Originally Posted by tmoble

you should always install straight up unless you've got the time and tools to degree it in. Don't ask how I know this......or how much was the "fee" for that little lesson.

I did my GTO 3 years ago. Ended up advanced it 4 degrees with no problems. Everything went perfectly. This time it was a humbling experience. Had lube all over the tools, even on the head gasket. I think I'm getting old...

[JumboAMONGus]

just go dot to dot ,and drive it ,,

[DransportGarage]

Originally Posted by JumboAMONGus

just go dot to dot ,and drive it ,,

After all the fun that's where I ended up, but for some of us building a truck is a journey, not a destination! I learned a lot this time.

[Speedbumpauto]

I built lots of engines in my younger days that were just "dot to dot" and maybe knowledge is a slavemaster, but I never put one together now without doing a cam degree check. With the junk being passed off as auto parts, or even better, performance parts, I don't trust the dots. It's such a miserable event when it's all pretty, installed in the vehicle and it doesn't run right, if at all, and you're really not sure if that cam is where you thought it was. JMO.

[tmoble]

>>> "My dial indicator is older than I am and it only has about .150" travel. I'm surprised it doesn't have roman numerals on it."

That's officially stolen, fair and square. "My dial indicator is so old it has Roman numerals on it." LOL.

[DransportGarage]

Originally Posted by tmoble

>>> "My dial indicator is older than I am and it only has about .150" travel. I'm surprised it doesn't have roman numerals on it."

That's officially stolen, fair and square. "My dial indicator is so old it has Roman numerals on it." LOL.

I should have asked Santa for a new one. Here it is. You can see the plastic lens warping out of the retaining ring on the 2nd pic. (And yeah, I know I should be indicating on the retainer, but I did the best I could.)