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Old Nov 25, 2006 | 02:00 PM
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Default Camshaft Comparison

Similar camshaft comparison between:
#1: 238/240 112+2 --> 64 degrees of overlap
#2: 238/242 114+4 --> 61 degrees of overlap

What differences would there be when installed in 402cid engine, great flow through heads (71% 'exhaust/intake' ratio), M6.

Looking for info like: "area under the curve" differences, fuel economy, low rpm highway cruising. Which one would be more desireable, why?
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Old Nov 25, 2006 | 03:31 PM
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Originally Posted by squealingtires
Similar camshaft comparison between:
#1: 238/240 112+2 --> 64 degrees of overlap
#2: 238/242 114+4 --> 61 degrees of overlap

What differences would there be when installed in 402cid engine, great flow through heads (71% 'exhaust/intake' ratio), M6.

Looking for info like: "area under the curve" differences, fuel economy, low rpm highway cruising. Which one would be more desireable, why?
hmm for overlap 238+240=478 478/4=119.5 119.5-112=7.5 overlap
238+242=480 480/4=120 120-114= 6 overlap
now the cam has built in advance and i don't know how much that changes things. most gurus do not like anything more than +2 built into the cam. good luck. maybe Predator or Patrick G. will help you.

Last edited by mullenh; Nov 25, 2006 at 05:15 PM. Reason: spelling
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Old Nov 25, 2006 | 05:07 PM
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Originally Posted by squealingtires
Similar camshaft comparison between:
#1: 238/240 112+2 --> 64 degrees of overlap
#2: 238/242 114+4 --> 61 degrees of overlap

What differences would there be when installed in 402cid engine, great flow through heads (71% 'exhaust/intake' ratio), M6.

Looking for info like: "area under the curve" differences, fuel economy, low rpm highway cruising. Which one would be more desireable, why?
PRETTY CLOSE CALL, I WOULD USE #2 MYSELF, I THINK IT WOULD GIVE YOU THE BEST OVERALL TRQ CURVE.
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Old Nov 25, 2006 | 06:49 PM
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238/240 with 112 lsa = 15* overlap

238/242 with 114 lsa = 12* overlap

those are small cams for use in a 402 cid engine. i would opt for the 238/240 - 112 lsa because it would offer a better tq curve (more "under the curve" and it would come in sooner) and more potential for upper rpm power. both cams would provide excellent low rpm driving manners and when compared on a dyno, would be very similar.

if it was me, i'd be using a 25x/26x cam with a 108+2 lsa in that 402, but we obviously have different goals.

overlap calculator: ... [ indur+exdur / 2 = N. N - LSAx2 = overlap ]
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Old Nov 25, 2006 | 09:39 PM
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238/242 110+0

Basically like a 228/232 in a 346.
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Old Nov 25, 2006 | 10:45 PM
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Originally Posted by s346k
238/240 with 112 lsa = 15* overlap

238/242 with 114 lsa = 12* overlap

overlap calculator: ... [ indur+exdur / 2 = N. N - LSAx2 = overlap ]
Good call, had to check my math because in my original post I ignorantly copied the values from Pat Kelly's DCR calculator. I calculated the advertised duration for .006". Should overlap always be calculated at .050" instead?

[(287+289)/2]-112*2=64* -->good
[(287+291)/2]-114*2=61* -->good

I think either of these are gonna be great for a DD car. DCR is way up there at 8.882:1. However it is calculated the overlap difference is 3*, so would camshaft #2 have better off-idle torque? Would fuel consumption be noticable on 1 tank of gas between the two of these (highway miles @70mph)?

Originally Posted by s346k
those are small cams for use in a 402 cid engine.
Think these cams are small. You'd never guess what's in it now...the '02+ LS6 -->204/218 117.5 LSA it's a little torque devil
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Old Nov 26, 2006 | 10:28 AM
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They will be nearly identical but the 112+2 is going to make slightly better power throughout. Not enough difference to tell if you drove both i'd say.
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