Fidanza cam pulley degreed and found retarded

[4 l-bodies]

Guys,
I just thought I would pass along my findings after degreeing in my camshaft using a new Fidanza cam pulley. BTW this is round tooth variety. I know very few people take the time to degree their camshafts in, so I'll let you know what I found in my case. In comparing the Fidanza pulley to two different 557 pulleys, my Fidanza pulley when centered at it's zero mark (so it has 12 degrees advance and retard) was 2-2.5 degrees retarded. In other words I had to advance the pulley 2-2.5 camshaft degrees to read the same intake installed centerline as the stock pulley. That would be 4-5 crankshaft degrees. I am NOT saying they are all like that, I'm saying don't assume zero is really zero.
In my case on a fresh motor that has had it's deck and head milled, slightly thinner head gasket, then adding in the Fidanza pulley retard, my camshaft C/L was well lets say... quite retarded. Lots of little stacking, all going retarded, made for one very retarded intake C/L. I've been reading how many people are finding their motors seem to like the cam advanced, or on the flip side can't believe how hard it pulls in upper RPM's. Wonder why?...;)
Todd Nelson

[iTurbo]

Does the scale on the Fidanza refer to cam or crankshaft degrees? IOW, if you put it at the 12' advanced mark on the sprocket, would your intake centerline change by 24 degrees in relation to the crankshaft?

Your experience sounds very similar to when I installed the TIII adjustable sprockets on my Spirit R/T. I'm fairly certain the head has been resurfaced a couple times at least. Sure enough, with the stock sprockets, my intake/exhaust centerlines were both retarded from stock specs. Installing the adjustable sprockets at '0' advanced the cam 1-2 degrees (on crank degree wheel) bringing them both a little closer to stock specs but not much. I had to advance both cams quite a bit to regain driveability.

[turbovanman²]

Well my Gary D unit was out 6 deg, :wow1:


http://www.turbo-mopar.com/forums/showthread.php?t=10042

[Clay]

maybe the fidanza/GD units are right by factory specs and the factory cam gears are off? ;) (not out of the realm of possibility!)

[4 l-bodies]

maybe the fidanza/GD units are right by factory specs and the factory cam gears are off? ;) (not out of the realm of possibility!)

Yes I that is a possibilty. That is why I checked it against two different factory 557 pulleys. They were .5 degree of each other. That is why I had .5 degree variances in my readings.

[4 l-bodies]

Does the scale on the Fidanza refer to cam or crankshaft degrees? IOW, if you put it at the 12' advanced mark on the sprocket, would your intake centerline change by 24 degrees in relation to the crankshaft?



Your experience sounds very similar to when I installed the TIII adjustable sprockets on my Spirit R/T. I'm fairly certain the head has been resurfaced a couple times at least. Sure enough, with the stock sprockets, my intake/exhaust centerlines were both retarded from stock specs. Installing the adjustable sprockets at '0' advanced the cam 1-2 degrees (on crank degree wheel) bringing them both a little closer to stock specs but not much. I had to advance both cams quite a bit to regain driveability.

Timing marks on pulley refers to cam degrees, so yes 12 degrees would equal 24 crankshaft degrees.

[turbovanman²]

maybe the fidanza/GD units are right by factory specs and the factory cam gears are off? ;) (not out of the realm of possibility!)

That could be but I am really too lazy to measure my cam with a dial indicator, :o

[iTurbo]

Something that has always confused me is why people even refer to 'cam degrees' in the first place. Everything is in relation to the crank, so why not just use crank degrees to describe cam timing?

For example, my TIII adjustable sprockets have 6 marks to the left and right of the '0' mark. I have been told each mark is worth 2 cam degrees. However, when I centerlined the cams (via degree wheel and dial indicator), I found that my exhaust cam centerline was at 100' BTDC at '0'. If I want the exhaust cam centerline at 104' BTDC (stock spec), should I move the sprocket 1 or 2 marks advanced to achieve 104'?

Basically I just don't understand why people refer to cam degrees at all, when everything is in relation to crank degrees. When I degreed the cams, it appeared to me each mark on the sprocket would change cam centerline 4 degrees on the degree wheel. I also don't understand why they put so much adjustablity into the sprocket; way more than would ever be needed.

[Garret]

Or you know cause you had your head milled and your block decked it will change your base cam timing