Lobe Separation
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Senior User
Joined: Jun 2003
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From: Ousley, GA
Lobe Separation
I've noticed that most rebuilds for the 390 recommend the Crane 343901/343941 (and similar). These seem to have the 112 degree separation. I've noticed that the Crane 343904 and 343902 have similar specs Dur 260/ 272, Lift .501/ .533 but differ in the lobe separation. The 902 has 110 degrees of lobe separation while the 904 has 112. It's my understanding that the lower the separation degree the sooner low end power is developed. Is that correct? Would this 2 degree difference help or hurt in my 390 stock rebuild (except for the KB150 pistons and cam)? I'm looking for a daily driver with good performance and better mileage than I'm getting in my 360.
Post Fiend
Joined: Jan 2003
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From: Iowa
Originally Posted by scottlane
I've noticed that most rebuilds for the 390 recommend the Crane 343901/343941 (and similar). These seem to have the 112 degree separation. I've noticed that the Crane 343904 and 343902 have similar specs Dur 260/ 272, Lift .501/ .533 but differ in the lobe separation. The 902 has 110 degrees of lobe separation while the 904 has 112. It's my understanding that the lower the separation degree the sooner low end power is developed. Is that correct? Would this 2 degree difference help or hurt in my 390 stock rebuild (except for the KB150 pistons and cam)? I'm looking for a daily driver with good performance and better mileage than I'm getting in my 360.
Go to http://www.cranecams.com and type the cam numbers in the "Cam Timing Spec Card" box on the right. Compare the valve events. They're identical, and as such the cams are identical.
Thread Starter
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Senior User
Joined: Jun 2003
Posts: 286
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From: Ousley, GA
Y'all are right. I was looking at these specs on the Crane Cams somewhere else and they had the different lobe separations. Never would have asked the question otherwise.
On a side note, why do these cams carry different part numbers if they are identical cams?
On a side note, why do these cams carry different part numbers if they are identical cams?
Post Fiend
Joined: Jan 2003
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From: Iowa
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FE "Freakin Expensive"
Joined: Dec 2003
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From: Smith Mountain Lake, VA
Its been my experience that the wider LSA..give's you a broader TQ band and well idle better than a closer one...It may not give you as much Peak TQ that a shorter LSA. by a few lbs...
My new roller is on a 112* LSA....with a .640/650" lift ...240/248* duration..I thought this cam maybe a little to much for my build..But after Talking too KC..He said no problem.. JMO..
RJ
My new roller is on a 112* LSA....with a .640/650" lift ...240/248* duration..I thought this cam maybe a little to much for my build..But after Talking too KC..He said no problem.. JMO..
RJ
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