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Alright I have done this before, it has been a while. I want to check the accuracy of this unknown double roller timing set and my used Performer cam. I have a checker lifter with a built in dial indicator and degree wheel. I need the cam card, correct? Any tips are welcome.
The way I do it is check the opening/closing events. I drew a big lobe on a piece of paper and drew where things appx happen . This is to envision the movement. I check at .050 opening , .050 closing. I check the icl. . I even made marks of where the various methods are registered. So I just find all these numbers then compare. Sounds nuts but as long as my numbers match or are within atleast a degree I roll with it.
Sounds good, how I remember doing it, comparing events, was within a 1/2 degree last time. Curious how close this cam and timing set is, only one way to find out. The last floppy Cloyes Street roller timing set was accurate but the slop on a low mile set was ridiculous and I am not reusing it.
I made a stopper to determine TDC. The cam card shows 4 Degrees ATDC for the .050" timing event. I am getting about 15 degrees at the .050" reading. I will do some playing around to see what is up.
I have read a few methods from On All Cylinders, Lunati, Crane and Erson cams. Going to start over and make sure my TDC is set right and go from there. Erson is the easiest to follow of the bunch.
Tried my best to get an accurate TDC on the wheel. With the stopper and sitting on the floor, I can see when the piston fitst hits it. I adjusted the wheel a couple of times, I think it is close to right. Not so easy to do. Ok, so I calculated the intake centerline. I found maximum lift and put the dial on 0. Went .050" clockwise then around till it hit .050" again. I got 153 and 62, 215 together divided by 2=107.5 ICL. The cam spec is 106 ICL. I still get 10 degrees advanced on the intake opening point, cam card says 4 ATDC.
Location: Colorado Springs Colorado/Thousand Oaks Ca
Posts: 1,721
Originally Posted by olds 307 and 403
Tried my best to get an accurate TDC on the wheel. With the stopper and sitting on the floor, I can see when the piston fitst hits it. I adjusted the wheel a couple of times, I think it is close to right. Not so easy to do. Ok, so I calculated the intake centerline. I found maximum lift and put the dial on 0. Went .050" clockwise then around till it hit .050" again. I got 153 and 62, 215 together divided by 2=107.5 ICL. The cam spec is 106 ICL. I still get 10 degrees advanced on the intake opening point, cam card says 4 ATDC.
Don't adjust the wheel, use a sharpie and make your own line to TDC. Whats the lobe separation of the cam?
The dots on the timing set line up pretty much perfectly with TDC. I have no idea what brand timing set this is. I ran this cam with 9.6 to 1 and 1.72 roller rockers, cam advanced 2 degrees. The timing set was accurate, checked degreeing another cam but never degreed this cam itself. I had to limit part throttle timing a bunch on 91, sucked around town. It ran 9.4 in the 1/8 with more in it. I was adjusting the APT, gained a 1/10 and a mph with every 1/2 turn out. I did that 3 times, keeping the timing at 36 total.
Ken that is great idea if I had the head on. I used a cut non A/C alternator bracket with a bolt. I am just getting TDC, I believe. Here are the pics. I am getting 25 going one way and 40 the other way. I should adjust the wheel so they are same, correct?
I rechecked with the proper TDC with a better stopper. I got 107 ICL, in the 4 degrees advanced position, I got 112 ICL. Isn't that 4 degrees retarded?
Last edited by olds 307 and 403; January 15th, 2021 at 08:31 PM.
I need to recheck my numbers, retarding this cam 4 degrees seems counter productive. The triangle should be 4 degrees advanced, around 103 if my 107 number is right. If this is an Edelbrock timing set, like many of the Comp cam sets that others more knowledgeable than I have checked, it could be off. Multiple people had their Performer cams off when degreeing with the Edelbrock 7813 set. I have a sloppy Cloyes Street roller that was bang on checking it with a degree wheel. I also have a non adjustable single link stock replacement set as well.
Location: Colorado Springs Colorado/Thousand Oaks Ca
Posts: 1,721
Pay attention: If the Lobe Separation is 114, you want the intake lobe in at 110, 4 degrees advanced. You will set the timing chain on the 4 degree advanced position, you will then ck and see were the intake lobe center line is. Come back on this thread and tell me where the intake centerline came in at and I will tell how to get it to 110 from there.
Are you sure the intake centerline is at 103 degrees? Advancing the lower gear to +4 on a chevy moves the cam approx 8 degrees, why I have no idea. If you have a 103 its very simple to get it to 110, but first make sure you have 103.
Don't worry about the chain being off, you need to put it were you want it, the chain isn't going to do that for you.
Last edited by VORTECPRO; January 16th, 2021 at 07:06 AM.
No, Vortecpro is right, it is 112.5 in the advanced position. I was right the first time. I made the mistake the second time and listened to bad advice from someone else, not on this site. I am installing it in the straight up positiion, 107 or 107.5, done twice, supposed to be 106 so within 2.5 to 3 degrees of 110 is acceptable for a generic grind. This isn't a race car, well it might see the track IF I can get the 3.90 gears in before Summer is done. Spring and Fall are no good due to work for racing unfortunately. The timing cover is going on tonight. Thanks guys.
Last edited by olds 307 and 403; January 16th, 2021 at 04:19 PM.
January 8th, 2021, 07:53 PM
