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mstemp
Mike Stemp
Calgary, Canada
(222 posts)

Registered:
11/25/2009 07:18AM

Main British Car:
1980 MGB Rover 4.6L

Degree Cam
Posted by: mstemp
Date: March 19, 2014 09:01PM

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.


mgb260
Jim Nichols
Sequim,WA
(2461 posts)

Registered:
02/29/2008 08:29PM

Main British Car:
1973 MGB roadster 260 Ford V8

Re: Degree Cam
Posted by: mgb260
Date: March 19, 2014 09:18PM

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?



Edited 1 time(s). Last edit at 03/20/2014 07:10AM by mgb260.


ex-tyke
Graham Creswick
Chatham, Ontario, Canada
(1165 posts)

Registered:
10/25/2007 11:17AM

Main British Car:
1976 MGB Ford 302

authors avatar
Re: Degree Cam
Posted by: ex-tyke
Date: March 19, 2014 09:52PM

Jim's correct...112 degree lobe centre.....Crower cam spec here:
[www.crower.com]


mstemp
Mike Stemp
Calgary, Canada
(222 posts)

Registered:
11/25/2009 07:18AM

Main British Car:
1980 MGB Rover 4.6L

Re: Degree Cam
Posted by: mstemp
Date: March 19, 2014 10:16PM

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.



Edited 2 time(s). Last edit at 03/19/2014 10:29PM by mstemp.


DiDueColpi
Fred Key
West coast - Canada
(1365 posts)

Registered:
05/14/2010 03:06AM

Main British Car:
I really thought that I'd be an action figure by now!

authors avatar
Re: Degree Cam
Posted by: DiDueColpi
Date: March 19, 2014 10:29PM

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


mstemp
Mike Stemp
Calgary, Canada
(222 posts)

Registered:
11/25/2009 07:18AM

Main British Car:
1980 MGB Rover 4.6L

Re: Degree Cam
Posted by: mstemp
Date: March 22, 2014 11:19PM

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.


mgb260
Jim Nichols
Sequim,WA
(2461 posts)

Registered:
02/29/2008 08:29PM

Main British Car:
1973 MGB roadster 260 Ford V8

Re: Degree Cam
Posted by: mgb260
Date: March 22, 2014 11:30PM

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?



mstemp
Mike Stemp
Calgary, Canada
(222 posts)

Registered:
11/25/2009 07:18AM

Main British Car:
1980 MGB Rover 4.6L

Re: Degree Cam
Posted by: mstemp
Date: March 23, 2014 12:56AM

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.


mgb260
Jim Nichols
Sequim,WA
(2461 posts)

Registered:
02/29/2008 08:29PM

Main British Car:
1973 MGB roadster 260 Ford V8

Re: Degree Cam
Posted by: mgb260
Date: March 23, 2014 06:43AM

You are going to be amazed at the difference!


MGBV8
Carl Floyd
Kingsport, TN
(4511 posts)

Registered:
10/23/2007 11:32PM

Main British Car:
1979 MGB Buick 215

authors avatar
Re: Degree Cam
Posted by: MGBV8
Date: March 25, 2014 01:47PM

Quote:
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.

Sounds perfect! ;)


mstemp
Mike Stemp
Calgary, Canada
(222 posts)

Registered:
11/25/2009 07:18AM

Main British Car:
1980 MGB Rover 4.6L

Re: Degree Cam
Posted by: mstemp
Date: April 05, 2014 03:45PM

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.



Edited 1 time(s). Last edit at 04/06/2014 09:27AM by mstemp.


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