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Unread 08-12-2011, 01:47 PM   #1
pezz
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1977 CJ7 
 
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amc 401 HP question

hello i have a 401 bored .60, rv cam, headers, no emitions, fuel injected. Does anyone know what the hp might be? i need to get it kinnda close so i can map the fuel injection. Thank you

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Unread 08-12-2011, 02:27 PM   #2
Hajihunter
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What kind of work have you done with it besides boring and what are the spec's on your cam?

Mine has 11:1 compression with a custom ground Lunati cam and polished heads and matched intake with a 750cfm carb,FL headers and MSD ignition. Mine was dyno'd at 355/410. I suspect with Fuel injection you could get somewhere similar especially with a good tune.
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Unread 08-12-2011, 03:03 PM   #3
pezz
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i trully dont know the grind on the cam, just know it was an rv cam, its mostly stock, rv cam, .60 over. alum intake, HEI style distrib, headers projection3 fuel injection.
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Unread 08-12-2011, 08:27 PM   #4
TomCombo
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There are mainly two stock versions:
1971 "high" compression (9.5:1) - 330 hp / 430 tq
1972 and later low compression (8.25:1) - 235 hp / 345 tq

71 was gross and the later ones were net hp. Net hp is much closer to the hp as installed in the vehicle (accessories, air filter, exhaust system, etc). So if you have a typical mid 70's 401 with the deep dished pistons, boring it 60 gets you about 10 cubic inches (6 hp), rv cam gets you 20 hp, headers and good flowing exhaust gets you 15 hp, *good* alum intake and FI gets you 15 hp.....so 235 + 6 + 20 + 15 + 15 = 291 hp......round it to 300 and I bet you will be in the ball park.
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Unread 08-12-2011, 09:52 PM   #5
madjeepist
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dont forget that WE are at a higher altitude. doubt that you can get to 300 hp, but maybe.
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Unread 08-13-2011, 10:59 AM   #6
pezz
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thanks you guys very much, so now i just need to find out what year the engine is, any ideas on how to find out?
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Unread 08-13-2011, 02:25 PM   #7
TKFireman
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Check the valve cover, if it has a little tag on it, you can use that number to find out a lot about the engine.
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Unread 08-13-2011, 03:00 PM   #8
levergun
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My 401 is .030 over with a comp mutha thumper cam (287), scorpion roller rockers, ported heads w/ stainless valves, edelbrock performer manifold, Holley 770 truck avenger, DUI distributor, Hedman headers w/ dynomax exhaust.. Dyno'ed at 475.. And that was a conservative estimate.. It's been tuned and tweaked since then..
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Unread 08-13-2011, 05:05 PM   #9
kw89425
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there are no estimate with a dyno. so either it did dyno 475 or its a guess at 475. dont mean to offend but 475 sounds more like a guess from what you say is done and has that sound a bit of a stretch. thats almost a 100 hp more than Hajihunter.


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Originally Posted by levergun View Post
My 401 is .030 over with a comp mutha thumper cam (287), scorpion roller rockers, ported heads w/ stainless valves, edelbrock performer manifold, Holley 770 truck avenger, DUI distributor, Hedman headers w/ dynomax exhaust.. Dyno'ed at 475.. And that was a conservative estimate.. It's been tuned and tweaked since then..
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Unread 08-13-2011, 05:31 PM   #10
levergun
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it dynoed that with a different set of heads so i don't know whether the power went up or down or what. also it was a previous owner who built the engine and had it dynoed.. after getting it tuned and dynoed he sold it and i got the fun of installing and finishing it. also I'm not sure if nos was used while dynoing or not. all i have is the dyno sheet and the po said he had a different set of heads on it. It really all depends on the cam though. with a rv cam you'll have a lot of torque but very low hp compared to an aggressive grind. and rv cam like the op has will probably be good for 350-375 or so hp. the same exact engine with a 287-295 grind cam will probably do 450-475..
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Unread 08-13-2011, 07:24 PM   #11
kw89425
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ive never seen a 100 hp gain with just a cam change. if everything isnt matched a big cam will hurt more than help it may sound wicked though
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