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AMC 360 Limited RPM? |
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ruphianh 
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Joined: Jan/21/2018 Location: CA Status: Offline Points: 76 |
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 Topic: AMC 360 Limited RPM?Posted: Jan/21/2018 at 5:56pm |
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Hey All,
This is my first post and I'm trying to understand where my 360 should be power wise and where it reaches max hp.
I ask this because this engine doesn't really seem to make sense to shift under full throttle much past 4500-4600 rpm. I'm wondering if its just cam limited or theres something else going on. What it has: Motor: Rebuilt about w/ 10,000 miles 360 bored .030 over Edelbrock Performer Cam(its an Elgin performer grind) Performer Intake 9.2:1 pistons Some mild headwork (3 angle valve job) Ignition: Howell EFI(was previously 600CFM edelbrock. The EFI is so much better) DUI HEI Patriot headers 3" Exhaust Should this be turning more RPMs? Don't get me wrong, its strong, but its power is down low and mid. Is there anyone else thats got this same motor build that knows what power it should be making and what RPM it should be turning? Thanks all! Edited by ruphianh - Jan/21/2018 at 6:32pm |
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FuzzFace2
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Joined: Jul/05/2007 Location: Angier, N.C. Status: Offline Points: 10356 |
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Posted: Jan/21/2018 at 6:28pm |
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Welcome to the AMC Forum.
I say look up the RPM spec for the Edelbrock Performer package, cam & intake. I am going out on a limb and say that is where the Edelbrock Performer package RPM limit is. Only other thing I can think of would be everything after the headers. Too small of a pipe (1-3/4") and cheap bad muffler(s) but I don't think that is it, is it? FYI I have a torker intake and a Comp cam think 280H in my drag car with 360 and it runs out of breath at about the 6000 RPM mark and that is just before the 1/4 mile line using 4.56 rear gear. The cam working RPM is 2000-6000 RPM. The intake is think 3000-7500 RPM. Dave ---- |
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TSM = Technical Service Manual
75 Gremlin X v8 for sale 70 Javelin 360/auto drag car 70 Javelin 360/T5 Street car |
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WesternRed
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Joined: Aug/03/2010 Location: Australia Status: Offline Points: 5798 |
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Posted: Jan/21/2018 at 6:33pm |
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72 factory spec for a 360 is 195 HP @ 4400 net, you upgrades will give you a bit more but nothing crazy. Make sure you have a full 12 volts at the ignition (no ballast or resistor wires) or the HEI may fall over at higher RPM.
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ruphianh
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Joined: Jan/21/2018 Location: CA Status: Offline Points: 76 |
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Posted: Jan/21/2018 at 6:34pm |
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I updated my original post to show 3" exhaust.
Also, I checked and performer plus RPM range is Idle-5500RPM. It does not go 5500RPM lol. Someone's gotta have this cam, right?
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Sonic Silver
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Joined: Nov/23/2011 Location: East Tennessee Status: Offline Points: 7949 |
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Posted: Jan/21/2018 at 6:52pm |
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Sonic Silver
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Posted: Jan/21/2018 at 6:56pm |
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FSJunkie
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Joined: Jan/09/2011 Location: Flagstaff, AZ Status: Offline Points: 4742 |
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Posted: Jan/22/2018 at 12:43am |
I hate when people say, "This smog engine originally made a weakling 175 horsepower, but I built it up with Edelbrock this and Holley that, and it made 300 horsepower on the engine dyno! I nearly doubled my power with these simple off-the-shelf upgrades!" |
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1955 Packard
1966 Marlin 1972 Wagoneer 1973 Ambassador 1977 Hornet 1982 Concord D/L 1984 Eagle Limited |
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FSJunkie
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Joined: Jan/09/2011 Location: Flagstaff, AZ Status: Offline Points: 4742 |
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Posted: Jan/22/2018 at 1:36am |
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To the original topic: This engine of yours is not making much different power than a stock engine or at much different RPM. As it sits in the car, it makes 230-260 horsepower at around 4500 RPM if it is tuned perfectly. You will feel power decrease after that, but will still want to rev past 4500 before you upshift to get the best acceleration. With the horsepower curve peak at 4500 RPM, you will want to shift around 5000 RPM for optimal acceleration because the engine speed will drop to 4000 RPM or so after the shift is complete. That way, you keep the engine speed sweeping through the power peak as you accelerate. Drag racing 101. ...also because operation above 5000 RPM is questionable unless your valve train was upgraded and your rotating assembly balanced. Some guys here have engines with power peaks around 6000 RPM so they are shifting around 7000 RPM. They have upgraded their engines mechanically to handle that RPM. Whatever RPM your power peak is at is pretty useless if your engine explodes trying to use it.
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1955 Packard
1966 Marlin 1972 Wagoneer 1973 Ambassador 1977 Hornet 1982 Concord D/L 1984 Eagle Limited |
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Buzzman72
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Posted: Jan/22/2018 at 6:04am |
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I owned a '57 Rambler with the 250V8, the Carter WCFB 4-barrel, and factory ceramic dual exhausts. It would run 120 MPH at 6000 rpm and would do it all night without "exploding." It was a solid lifter engine, of course.
I would think a modern 360 with hydraulic lifters would run at 5500 all day. To have one that won't, I'd look at intake/exhaust restriction. Since the OP mentions he has 3" exhaust, I'm thinking the throttle body EFI just MIGHT be the bottleneck. SOMETHING is restricting the volume of air/fuel in or out...3" exhaust says it's likely NOT a matter of what's coming OUT, so the restriction almost HAS to be on what's coming in. I sincerely doubt that the camshaft is the limiting factor. After all, it's less "limiting" than the stock cam used in the Rambler 250 V8. So what else in that equation might be the limiting factor? Providing the spark is sufficient, it would HAVE to be something in the fuel side of the equation, IMHO. How many CFM is that throttle body? That might answer your question. |
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Buzzman72...void where prohibited, your mileage may vary, objects in mirror may be closer than they appear, and alcohol may intensify any side effects.
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farna
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Posted: Jan/22/2018 at 6:52am |
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Might be the EFI -- either TB size or programming. The Howell EFI is mostly aimed at Jeeps, where you want power in the low to mid range. Great for a street engine also. Unless you're planning on drag racing you might just have a great setup as is..
Typically, if you gain power at higher rpm, you're losing it at low rpm. There's about a 2000-3000 rpm power band (say 2500 for simplicity) where the engine produces its best power. So move that up to 5000 and you don't get good low speed power. That's why drag racers use higher rpm stall converters and/or lower rear axle gearing. Edited by farna - Jan/22/2018 at 6:55am |
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Frank Swygert
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