Cam Centerline Problem...

kris

ok. My build is moving along. Installed the cam last night, its my usual Engle k52/k54 with a 112*lsa, and 112* intake centerline. On this build (for the first time) I'm using the Edelbrock timing chain with 4* adv/ret available. Ive checked the intake centerline at least 6 times and its coming up between 104.25* and 104.75*. Ive used numbers from .025"-.050" on either side of peak lift and its all the same. Is this the chain or the grind ? This isnt the first cam Ive run from them, but its the first I've checked the C/L on. Thoughts ? kris.

kris

I hope this isnt my problem...

From...
http://www.edelbrock.com/automotive_new/mc/camshafts/cams_amc.shtml
Then click on cam#2132

CAUTION: Use Performer-Link Timing Set, #7818. Do not use late model timing sets. They are machined in a retarded position and are not recommended for this camshaft installation. Edelbrock Performer-Link True Rolling Timing Sets feature three keyways for specific timing selection. Always use the “0” or straight-up timing mark when installing Performer-Plus camshafts with Performer-Link Timing Sets.

Can I interprete this to mean that the Eddy set is machined advanced, not that the others are retarded ?

Has anyone else used the Eddy set and checked the intake C/L ?

tufcj

Most emissions era OEM timing sets are machined about 4 degrees retarded for better emissions. On the Edelbrock sets, 0 is truly straight up. You do realize the lobe separation angle and lobe centerline are 2 different things? If you look at the spec card on the Edlebrock 2132, the LSA is 110, the centerline is 105. Bob tufcj

kris

tufcj wrote
Most emissions era OEM timing sets are machined about 4 degrees retarded for better emissions. On the Edelbrock sets, 0 is truly straight up.

You do realize the lobe separation angle and lobe centerline are 2 different things? If you look at the spec card on the Edlebrock 2132, the LSA is 110, the centerline is 105.

Bob
tufcj

Yes I do realise that c/l and lsa are different.
I had this Engle ground to my spec which was 112"lsa and 112*icl.

It really is out.
Ive spent the better part of the day out there checking the cam. Ive checked the intake and exhaust events at .006" and at .050" and with the timing set installed in the 4* retarded position, its still 3* advanced.

Its now at 109icl and 115ecl.
109+115=224/2=112lsa.

Either the cam was ground 7* advanced or the timing set is off. Chris at Engle told me that it would be ground 1* advanced to make up for chain stretch, which would still leave it at 6* out.

I can live with it 3* advanced, but Id like to know why its so far out.

ironman_gq

call em up and tell them. Im sure they would do the good guy thing and fix the problem for you.

kris

ok. We're good to go... I did call Engle. The centerline method of picking a point within .025" on either side of peak lift is a quickie method and will not work with an asymetrical lobe. The lobes on this cam are asymetrical, meaning they ramp up faster and ramp down slower. He did say that he would like to see an ICL with this method of around 109*, which is where Im at. I decided after my last post to triple check everything and recheck the intake and exhaust events at .050" lift. With the timing set in the 4*ret position, its within a degree of right on. Doug (Engle) walked me thru everything and decided I did everything right. He also said that it doesnt matter how the chain is installed as long as the cam is phased correctly with the piston at TDC. Makes sense... Im at 109*icl and intake events within a degree. He said its time to close the hood and drive it. He also stressed how important it is to check the cam. The 4* advance that it had with the timing set installed straight up can make a noticable difference. I bought a big timing wheel from Summit for about $20, and the dial indicator and mag base from Harbor Freight for about $30. When you think about how much you can put into a build, its cheap insurance. k.