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summit 8601 |
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matty 401
AMC Addicted Joined: Jul/06/2007 Location: Iowa Status: Offline Points: 1728 |
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Posted: May/26/2018 at 8:16pm |
well i got my 401 running with the Summit 8601 cam it has a very smooth idle i think my old cam was more lumpy lol anybody else running this cam how does it sound ?
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72 matador 401 the beast
79 concord 2 door 72 matador 304 grasshopper 68 Rogue 406 93 Cherokee 4.0 5 speed |
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69 ambassador 390
Supporter of TheAMCForum Joined: Nov/22/2009 Location: Peoria, AZ Status: Offline Points: 3539 |
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The 8601 is a split pattern and actually idles like a smaller cam. It's a great all around cam and will run better than cams with a single pattern and lumpy idle. I use them all the time in 400 to 425 hp builds.
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Steve Brown
Algonac, Mi. 69 Ambassador sst 390 84 Grand Wagoneer 69 Cougar XR7 65 Fairlaine 500XL 79 F-350 Super Camper Special |
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matty 401
AMC Addicted Joined: Jul/06/2007 Location: Iowa Status: Offline Points: 1728 |
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std bore 401 60119 eldo heads and a torker intake just was expecting more lope out of it with the 304 duration
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72 matador 401 the beast
79 concord 2 door 72 matador 304 grasshopper 68 Rogue 406 93 Cherokee 4.0 5 speed |
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jpnjim
AMC Addicted Joined: Nov/25/2007 Location: New England Status: Offline Points: 2752 |
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Big advertised duration with moderate .050 numbers, and a wide centerline = plenty of gross overlap but not much overlap at .050" lift and beyond.
What Std pistons are you running? I'm also putting together a Std 401 with Eddy heads, but I went with a smaller, fast acting cam (278 gross, 228 @ .050")with a narrower centerline (108*) to try to boost dynamic compression ratio with the stock low compression pistons. I'm thinking the 108 CL will probably give a healthy lope with the 228 net duration. I'm leaning towards the R4B for an intake with Dougs 103 headers. |
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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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https://www.summitracing.com/parts/sum-k8601
.050" numbers: 224 intake 234 exhaust 114 lobe seperation =1* net overlap (59* gross overlap w/282 & 292 gross) ^it shows 300/304 gross numbers in the description and 282/292 in the specs my smaller cam .050" numbers 228 intake 228 exhaust 108 lobe seperation = 12* net overlap (62* gross overlap w/278 & 278 gross) Edited by jpnjim - May/27/2018 at 12:42am |
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71 P-code 4spd Javelin/AMX
some Jeeps and some Fords |
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PHAT69AMX
AMC Addicted Joined: Jul/07/2007 Location: West Virginia Status: Offline Points: 5888 |
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If I may ask, if I'm understanding correctly, it's Overlap at .050 Lift that gives a Cam Lope?
Is it the 1* Overlap at .050 that the Summit 8601 Cam has that gives it so little Lope?
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matty 401
AMC Addicted Joined: Jul/06/2007 Location: Iowa Status: Offline Points: 1728 |
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72 matador 401 the beast
79 concord 2 door 72 matador 304 grasshopper 68 Rogue 406 93 Cherokee 4.0 5 speed |
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matty 401
AMC Addicted Joined: Jul/06/2007 Location: Iowa Status: Offline Points: 1728 |
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car has 456 gears stick a stock converter lol i know get that changed hope to take it out for a test run later today
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72 matador 401 the beast
79 concord 2 door 72 matador 304 grasshopper 68 Rogue 406 93 Cherokee 4.0 5 speed |
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jpnjim
AMC Addicted Joined: Nov/25/2007 Location: New England Status: Offline Points: 2752 |
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I'm not claiming to be a cam expert, but I would say yes. My non-expert thoughts: There's a lot going on with overlap, and it varies throughout the RPM range of the engine. You have the exploding gasses escaping out the exhaust valve, as the piston is rising, then towards the end of the exhaust cycle, when air is speeding up past the closing exhaust valve, the intake starts to open. Hopefully, at certain RPM's (depending on the rest of the combo) the exiting exhaust actually pulls air into the chamber at this point. That's the benefit of cylinder filling you hopefully get from overlap (some people have called it the 5th cycle). At lower RPM's, the escaping exhaust gasses use the opeing intake valve as another escape path. That's when you get the lope from exhaust gasses entering the intake. My thoughts are, even though the exhaust gasses are under pressure at this point, how much is going to escape the intake valve at under .050" lift? If you crack open your welding tank .050", a lot of gas comes out, crack your window open .050" and you're just breaking the seal and not much transfers, so everything is relative. If you think about it, the factory cams were rated at 266* advertised originally, then later (emission) cams went to 263.5* intake 293.32* exhaust and the 1971 401 cam's advertised duration was 296.32*/303.55* ^that was not a rip snorting cam by anyone's defintion so the advertised duration (under .050") seem to have a much smaller effect than the fatter part of the curve, past .050 and further. I picked a cam that was as wide as possible at .200 lift, but tried to keep the advertised number well under 280* (278*), and the .050" lift under 230* (228* in my case) to have the cam flow well, but still have some manners with the a lobe centerline thats slightly tight (108*). I have the same low-ish CR as the original poster here, so I did the above because I wanted an intake valve that closed early to maintain Dynamic CR. We'll see how it works out when it's finally together |
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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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You're doing a lot better than me, mine is an assembled short block on the stand and I'm moving at a snails pace. Did you do anything to the heads? What head gasket did you use, and what do you think you compression ratio is? I'm leaning towards using the (not recommended) stamped steel gasket to get the slightly thinned compressed height, but even with that I think compression ratio will be in the 8.9:1 range (I haven't done the formula yet, but think that's close). I'm leaning towards the R4B because the divided runners help isolate that exhaust gas that enters the manifold at low RPM, and should give a slightly better idle. We'll see what it actually idles like when it's where your build is at now, a Torker would be my next choice as well. By the way, I'm heading on the opposite direction as you gear wise, I took out the 3.91's and went to 3.15's for this build But going from a 2.23 first T-10 to a 2.64 first with a shorter tire makes first gear a wash. |
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71 P-code 4spd Javelin/AMX
some Jeeps and some Fords |
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