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427 SO with Lunati 20501 Cam
I'm wondering if the collective knowledge base here may be able to shed some light on possible estimates for me on HP and torque.
My ERA has a '68 Side Oiler with stock bore/stroke. It has 390 heads (c1ae-6090-a) and dual Holley 600 CFM carbs. The rear is 3.31:1 and has a wide ratio toploader. The Cam is a Lunati 20501. Autolite #45 plugs (.035 gap), valve adj: .24 in, .26 exh., 10 degrees initial timing. The car runs fantastic - idles smoothly at around 800 RPM and seems to have tons of torque. Very easy to drive on the street (which I like) and I usually find myself wanting to shift around 3000 RPM through the neighborhoods. I've never had it over 4200 RPMs as the car is new to me and I don't know what the engine can take. Any estimates of what kind of HP and TQ I might have and when the best shift points may be as well as red line to stay away from? I can only imagine what it sounds like at 5000 RPM as I don't want to destroy this beautiful engine. Thank you in advance for sharing your knowledge to assist me. Troy http://customshowboards.com/era446/sale/0025.jpg |
Maybe 450-possibly less. From a performance standpoint, you have mediocre heads and cam and too little advance. Your compression is probably in the 9.5 range. I'd guess you have the stock iron rockers and shafts.
It was probably a rebuild, certainly not built for serious HP. Use maybe 5200 as a redline; that's probably your HP peak-you don't go there anyway. Don't change a thing. It's perfect for the way you apparently use it. Sounds like you're not used to big power. |
Chas, you are correct. My Shelby has a supercharger with 500 horsepower and it's too much for the street. I much prefer this laid back street setup. I can't imagine needing more power unless you are racing, which I'm not interested in doing with a Cobra. My life is too precious (:
Personally, I think too many of these Cobras are built with too much power and become downright scary and unusable for most of the inexperienced drivers who buy them. Many are for sale with a mere 1000 miles (: It's pretty cool that we live in a time where we can build these cars exactly the way we want to. Love it! |
I would have to check later when I'm at home but I think those may be the same heads I'm running - 390 hi po or police interceptor heads used on the mechanical cam 390s. What you have will depend greatly on what, if anything, has been done with them. Keith Craft ported, polished and installed 427 valves in the ones I have and from what I can tell they are probably roughly equivalent to 427 LR or 428 CJ heads. What intake is on there - a medium riser or a low riser?
But, Chas guess is probably as good as any and would seem to line up with mine pretty well. Mine is built pretty mild with 9:1 compression and a 4.25 crank for 459 cu inches. I'm using the 427 LR intake which from the Great FE Intake Manifold Shootout book is a big torque maker. It made 470 HP and somewhere around 535 ft lbs of torque (torque had already peaked when he started his pull). It seems like a well assembled, stock 428 CJ will often make around 420 HP so I would guess you are around that or maybe a bit higher. |
the stock rockers are fine up to and over 6500 rpm. its high spring pressures that get you in trouble, which you probably don't have with that cam.
from the top view pic, it looks like a low riser intake, it will make power up to 6200..... the C1AE heads make a nice street head. don't worry about going north of 5000 rpm now and then, it will be fine |
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You could guess all day long, but find yourself a dyno and you'll know exactly how much HP you have.
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there is not much out there that as fun as a 427 at 7,000 rpms!
Dwight |
Personally, I think too many of these Cobras are built with too much power and become downright scary and unusable for most of the inexperienced drivers who buy them.
Given the number of these things that end up in ditches and wrapped around poles etc, I'd say you're right. And don't let these he-men tell you to twist your motor higher than you're comfortable with, they don't have to pay for a new one. |
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