Installing my Crower 50232 cam and have confused myself. It seems to be retarded 3 deg based on crankshaft. It should open the intake at -1 deg ATDC. It's actually opening at -4 deg ATDC. Should I advance it 4 deg or do I have this all wrong? When I check the Lob Center method of degreeing I get 111 when it should be 108 which I think means I have it retarded also since it's opening later. Timing set has +/- 4 deg key ways.
Thoughts? Know others were recommending I advance it from straight up, now I could only get it to straight up.
Mike, Try advancing it 4 degrees and see what you get, if 1 degree either way I wouldn't worry about it. I think the specs for that cam is 112 lobe center and is supposed to be advanced 4 degrees which would be 108. Is it a new timing chain? Could be slop if that's not the case. When you are at TDC, timing mark dots on gears lined up, rotor pointing at #1?
Jim's correct...112 degree lobe centre.....Crower cam spec here:
http://www.crower.com/buick-215-340-compu-pro-hydraulic-cam-278-hdp.html
Thanks guys. When I say Lob Center that's not LSA. The cam card does show LSA 112, which is center of intake lob to center of exhaust lob. They also talk about the "Lob Center" means of degreeing cam which is 108 for the center of the intake lob. That's the one that is coming out at 111 not the LSA. If the LSA was off then Crower would have made a mistake in the manufacturing.
Will try advancing 4deg and see if I get closer to straight up spec.
Sounds like you're on the right page Mike.
In this case I would err on the advanced side as that will move your torque peak down a little.
A retarded setting will get you more peak torque in theory, but with the crappy heads that we have, moving it down to a lower rpm will get you a faster car.
Of course if you used the mighty "B" cam you wouldn't even have to hook up the timing chain.
As a matter of fact if you just throw one in the trunk, the world is your oyster.
Cheers
Fred
Got the cam dialed in now perfectly! 4 deg advanced put it right at straight up conditions. LSA 112, LCA intake 108 as per cam card. Now to see how it handles the FI. But seeing as we have snow again that looks to be some time away.
Some manufacturers set them up that way. I had that cam years ago in a 215 with 300 Buick heads. In that small motor it was too much and kind of like you flipped a power switch on at over 2000 rpm. In a 4.6 it'll be just right. Did you use the 4.0 pistons to raise compression, mild porting?
Jim,
Compression was left at 9.35 plus a tab more from a very minimal cut to the heads for clean up. Very mild porting is just being finished next week at the machine shop with a proper valve job. Stock job left just a bit to be desired.
You are going to be amazed at the difference!
QuoteI had that cam years ago in a 215 with 300 Buick heads. In that small motor it was too much and kind of like you flipped a power switch on at over 2000 rpm.
Sounds perfect! ;)
Well first impressions of the new cam are great. Did not change to FI yet as I was concerned with cam brake in and FI teathing issues. Runs great with the carb, no lope and good pull over 3000 rpm. Only done a few miles and lots of gravel still on our lovely roads so hard to get a full idea of the change. More details,to follow soon and FI will be installed in a month or so.