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Cam decision |
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DoughertyAMX
Supporter of TheAMCForum Joined: Sep/20/2016 Location: Washington, Ind Status: Offline Points: 519 |
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http://www.lunatipower.com/Product.aspx?id=1482&gid=287 The Lunati Voodoo cams were designed by Harold Brookshire, who was one of the industries most respected cam grind designers of all time. He also designed most of the Comp Cam lines including the Xtreme Energy series. One other key factor about the Lunati Voodoo series is they are ground on .904 lobes which is what our lifter diameters are. Many cam grinders grind the AMC cams using an .842 lobe. The other Lunati I was considering was the next step up, which is this cam: http://www.lunatipower.com/Product.aspx?id=2585&gid=287 With AC and auto trans, I decided the 262/268 cam was a better fit for my application (which I have not completed). |
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90islander
AMC Apprentice Joined: Aug/27/2017 Location: flora il Status: Offline Points: 31 |
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https://youtu.be/RX96Kl24Bc4
I currently have then same lunati cam u went with in my 304 |
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90islander
AMC Apprentice Joined: Aug/27/2017 Location: flora il Status: Offline Points: 31 |
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https://howardscams.com/i-24080225-howards-cams-mc312481-11-max-certified-1966-1991-american-motors-290-401-hydraulic-flat-tappet-1200-to-5200-camshaft.html
This is the cam I'm kicking around also, it'sfor a 360 that will be running in my Jeep with 37s and 4:10 gears with Granny low tranny if that is more helpful in knowing the application |
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gremlinsteve
AMC Addicted Joined: Dec/16/2008 Location: houston Status: Offline Points: 884 |
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Use the lunati
Never look back... |
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Greyhounds_AMX
AMC Addicted Joined: Nov/14/2009 Location: Kansas City Status: Offline Points: 1268 |
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The Howards Max Certified uses a middle range hydraulic intensity of 61 in order to ensure they minimize the risk of lobe wear issues. That's slightly less aggressive than the Crane HMV hydraulic lobes, which are 56.
The compression ratio is a huge factor though. If you have the stock 8.25:1 CR the Comp 270H would probably be a good choice, though it's a pretty aggressive lobe with a hydraulic intensity of 48.
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1968 AMX 390 w/T5
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90islander
AMC Apprentice Joined: Aug/27/2017 Location: flora il Status: Offline Points: 31 |
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So with that being said we
Which would be the more behaved on a Jeep trail, I would assume the Howard or the crane and they would also have a lower powerband if in understanding it all correctly |
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Greyhounds_AMX
AMC Addicted Joined: Nov/14/2009 Location: Kansas City Status: Offline Points: 1268 |
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Ok, for an off-road application you'll want to target a lower overall operating range. I don't think the 270H would be such a good fit then. Let's check some things though: 1) Stock 8.25:1 compression ratio? 2) Stock (unported) dogleg heads? 3) Stock stamped rockers? 4) Power brakes? |
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1968 AMX 390 w/T5
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90islander
AMC Apprentice Joined: Aug/27/2017 Location: flora il Status: Offline Points: 31 |
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1)I have speed pro pistons so should be stock but may be different idk.
2)they look to atleast have the runners cleaned up since there is not flash in them but I haven't checked them against the gaskets yet. 3) yes 4)yes and power steering other things u might want to know I have a granny low trans, with 6.72:1 1st and 4:10 gears in the axles. I also already have a performer intake and holley 600 vacuum for it off my 304. I also already have duals on it with free flowing exhaust and no AIR tubes in the manifolds either. |
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Greyhounds_AMX
AMC Addicted Joined: Nov/14/2009 Location: Kansas City Status: Offline Points: 1268 |
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Your pistons are probably the L2380F, which is the 27.5 cc
dish version. They are more common as they stopped making the L2381F
earlier. The static compression ratio with stock combustion chambers will be on
the order of 8.7:1.
It looks like the Howards Max Certified MC312481-11 would be a really good candidate for you, with a DCR of 7.00 and overlap factor of 1.37. You could probably squeak by with 87 octane fuel, but premium if you want to run a lot of spark advance. The 1.37 overlap factor is just below the point that a 360 starts to show a noticeable lope at idle based on what other people have seen, so that's a good indicator that you won't be overcammed for off road work. The cam also provides more intake flow area under the curve than any other off the shelf middle intensity cam that would work with pump gas and provide an overlap factor of less than 1.5. |
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1968 AMX 390 w/T5
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tached_out
AMC Nut Joined: Feb/08/2008 Location: Vancouver, BC Status: Offline Points: 328 |
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The additional information you posted about your Jeep helps a lot.
This guy's setup isn't far from your's. Take a look at this video and listen to his description. https://www.youtube.com/watch?v=RKmWTLcn3Uw
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