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401 street strip build |
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amx73
AMC Nut Joined: Aug/28/2009 Location: NJ Status: Offline Points: 294 |
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Sorry, I just re read my post and realized I put 1 7/8 tube. I do have a set of those but, the car this motor is going into currently has 1 5/8 tube Hedmans. And a 2.5" x-pipe dual exhaust.
I've been checking out Comps website and like the specs on the XE262H cam. |
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Red means run son, numbers add up to nothin'!
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mixed up
AMC Addicted Joined: Jun/16/2015 Location: Monroe mich Status: Offline Points: 2156 |
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take a look at howards cams they have a nice line of cams for amc
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69 amx 290 auto
65 220 290 4spd 80 ford fairmont |
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amx73
AMC Nut Joined: Aug/28/2009 Location: NJ Status: Offline Points: 294 |
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I spoke to Howard's Cams. Very nice and helpful guy named Eric. I gave him all the specs on my build and this is what he recommended:
.520/.541 lift 235/243 duration @ .050 112LSA |
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Red means run son, numbers add up to nothin'!
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WesternRed
AMC Addicted Joined: Aug/03/2010 Location: Australia Status: Offline Points: 5787 |
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That sounds better, the XE262H seemed a bit small to me.
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PHAT69AMX
AMC Addicted Joined: Jul/07/2007 Location: West Virginia Status: Offline Points: 5905 |
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Those specs look a lot like an Elgin E-981-P AMC Camshaft...
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jpnjim
AMC Addicted Joined: Nov/25/2007 Location: New England Status: Offline Points: 2752 |
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I like Howards Cams, it took about a week to get a custom AMC cam from them a couple months ago, I ordered it through Competition Products, they are in the same building as Howards and had the best prices: I'm not a cam expert, I just overthink things that I think I understand until they either start to make sense to me or I really screw them up From your description, I think these are the lobes he's recommending: 1hf235325 Duration 289@.006" 262@.020" 235@.050" 147@.200" Lift .325" lobe .520" w/1.6 rockers 1hf243338 Duration 297@.006" 270@.020" 243@.050" 156@.200" Lift .338" lobe .543" w/1.6 rockers Lobe list is here: these lobes are on page one and two "standard ramp hydraulic flat tappet" This is a pretty healthy cam, obviously bigger than the cam from the Car Craft build. with 4.10's and a decent converter he probably figured you could handle it. A few things I'd point out: 1)you have to make sure the heads are set up for over .500" lift 2)289/297 gross duration on a 112 lobe center is going to have a fairly late intake closing, which will lower your dynamic compression ratio quite a bit from the Lunati cam you first mentioned, not that it's a bad thing on pump gas, but it might be happier with 10:1 compression 3)This is what most people would call a "Chevy Grind", meaning the lift to duration is optimized for the smaller diameter Chevy lifter, not a bad thing, it tends to be easier on the valve parts than a lobe designed for our wider lifters. The faster acting cams optimized for wider .903/.904 lifters are on page 25 of the Lobe List above. What usually ends up happening (if you choose a .903/.904 cam instead) is you can pick a cam with less .050" duration, much less .006" and .020" duration, but more lift and more .200" duration. The cam can act more mild, because it isn't open as long, but because it opens and closes at such a steeper rate, it actually allows more flow in that shorter time period. Compare: HM2303541A Duration 277@.006" 254@.020" 230@.050" 150@.200" Lift .354" lobe .567" w/1.6 rockers to the 1hf235325 Duration 289@.006" 262@.020" 235@.050" 147@.200" Lift .325" lobe .520" w/1.6 rockers Much less gross duration 277 vs 289, 8 degrees less at .020", 5 degrees less at .050", but then 3 degrees more at .200, that's the "under the curve" lift people talk about. A side effect of the .904 grinds is you end up with more lift even in a smaller cam, which you'd want your head to be able to handle, and hopefully be worked to flow well at these lifts, but on the positive you may end up with an engine that idles better, pulls better at a lower RPM, and makes more power on top. (in a perfect world). The added stress on your valvetrain and added potential to wipe out the more aggressive lobes should be taken into account too, which may be why they went with a standard grind for your recommendation. Page 4 of that lobe list has "Aggressive Hydraulic Flat Tappet" lobes that are part way between the standard type grinds that were recommended, and the .903/.904's. Page 26 has Ford .875 lobes that can be slightly tamer than the .903/.904 grinds, but not always. I hope my advice didn't just muddy the waters too much, and if I'm in error in any of this I'd invite anyone to clear things up for me. Edited by jpnjim - Jul/19/2018 at 3:45pm |
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71 P-code 4spd Javelin/AMX
some Jeeps and some Fords |
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jpnjim
AMC Addicted Joined: Nov/25/2007 Location: New England Status: Offline Points: 2752 |
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One more thing, I'd be leaning away from the Performer RPM with any of the bigger cams we're talking about. I don't claim to be an intake expert either but the RPM seems to trade mid range for top end compared to a Torker. No sense going with the bigger cam if the Performer RPM will be the limiting factor when you get to where the cam really starts working. |
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71 P-code 4spd Javelin/AMX
some Jeeps and some Fords |
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6PakBee
Supporter of TheAMCForum Charter Member Joined: Jul/01/2007 Location: North Dakota Status: Offline Points: 5454 |
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Boy, do I identify with that!!
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Roger Gazur
1969 'B' Scheme SC/Rambler 1970 RWB 4-spd Machine 1970 Sonic Silver auto AMX All project cars. Forum Cockroach |
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Red Devil
AMC Addicted Joined: Jul/10/2007 Location: Canada Status: Offline Points: 1743 |
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If you don't mind setting lash and checking periodically, a solid cam is likely a better option than a big hydraulic. For a comparable rpm range, typically less seat timing, more @0.50", @0.200" duration, more lift, more stable at higher rpms ... and no lifter start-up rattle and a bit easier on the starter for a seldom-driven car.
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PHAT69AMX
AMC Addicted Joined: Jul/07/2007 Location: West Virginia Status: Offline Points: 5905 |
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Agree, I should have used a solid lifter flat tappet cam in my last build...
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