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FE 427 Rev range
My question is with a serious build, (but max 10.1 comp) 427 engine which would be suitably cammed/manifolded etc to rev to 7000rpm, generally what would be the engines minimum cruising rpm?
This is just to give a very broad approx cruising speed final drive ratio, I also am aware that engines differ quite a bit between builders! |
Ant, in Pat Ganal's book ("Ford Performance"), he comments that the NASCAR crank (C9AZ-6303-D) is "...recommended by Ford for continuous 7000-9000 RPM use (just in case thats what you intended)." That tells me that if you build the rest of the motor right, the side oilers for sure, and probably all the 427 blocks, are good for at least 6000-7000 RPM continuous use (if that's what you intend).
Street cruising at 4000-5000 should be no problem (for the motor, not sure about your ears, etc.). |
FE 427 RANGE
mr0077,
Re: adjusting the rear end ratio to suit engines minimum cruising speed. The engine will be used up to 7000rpm on the circuit, when under pressure in a 5 lap sprint race, all other street use will generally be way down 3-4000 range, with the regular 6000 - 6500 blow out through the gears. I would prefer the engine to be getting on the camshaft at around 2800 - 3000 for cruising, but I guess thats what you have a transmission for! I doubt whether a 7000 rev engine would start running nice at 2500? |
Re: FE 427 Rev range
Quote:
Dave |
Ant, my apologies, I guess I just can't READ!! I misread the words "minimum cruising" to be "maximum cruising" (small difference!). Sorry 'bout that...
If you're going to build it to make decent power to 7000, I'd bet you'll need to keep the cruising RPM above 3000, and above 3500 even better. My power starts falling off at about 6000, and cruising below 2500 is right on the edge of the power band. It has SO much torque that it still moves out well from 2000 or so, but noticably better above 2500. |
The cam ,intake, carb ,heads all effect operating criteria.Your choises will determine where it cleans up. 2500 rpm is about 50 mph on my car.
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Gees Ant, what was wrong with the Big Chevy motor?
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427
Hey Dave, mr0077 & Bevan
I guess serious and 10.1 dont really go together but that information sounds okay, I would expect it to start going smoother at 2500rpm! Bevan, I am going to stick with the recipe that 'OL Shel" came up with all those years ago! |
Say Ant.
I am going through a build right now and I have chosen the Comp Cam #294S (605/605 lift and 246/246 dur w/110 seperation (I wish I had them cut it at 108 or 106 seperation for a quicker throtle response). I think I went with the recommended dual springs # 924. Should give me a good cruising range of about 3200 RPM @ 65 mph w/ 3.50 gears and 2800 RPM w/ 3.30 gears. Still trying to decide on rear end gears. Clois |
3.31 rear gears with the Goodrich BIG letter tires at 26.5" tall.
2800 rpm or so at cruise. I had a roller cam and the engine was good to 6500, just wastin' time after that. 2X4 intake. The point is: It BARELY liked 2800 rpm cruise. Sometimes I would cruise in 3rd just to get the rpm up a little bit! Maybe it was that 12.5 to 1 compression ratio? Going with a flat tappet, less wild, looking for 2500-2800 rpm cruise range. 6000 or so max rpm (done racing I keep telling myself, liar liar). :D Gessford is recommending the cam profile based on my new 9.8 to 1 engine. Looking back on it, I think the RADICAL center squirter drag race carbs were as much a problem as the cam profile. I switched to vac secondaries a week or so before she "blew" and it DID appear to be doing much better. In fact, it was running GREAT, isn't that the way it always goes just before they blow? :D |
FE 427 Rev range
Clois,
I am contemplating either 3.27, or 3.08 rear end on 26.5" tires, that will give me 6500rpm at 165mph. That sort of speed is not really important as it will be used on the track at a max of 150mph. Cruising speed of around 65mph at 2500 with the 3.08, 3.27 = 60mph, sounds like if you want a goer at the top end like pulling hard at 6500 it wont like cruising much under 3000! I have no idea what I need as I haven't really studied 427 parts, but I will be using roughly as below, 427 Alloy block Armandos racing oil pan Edelbrock Heads 10.1 comp Edelbrock Victor single plane manifold I have no idea on internals but would run quality forged parts, probably phone KC and ask him to supply parts and of maybe build it for me pending $$$$$ I saw a Gessford video on a blue 472 Cobra with single plane manifold etc, and I gotta admit it it didn't sound brilliant with the exhaust it had, or maybe they are big lumberers. If you can fit some sort of balance pipe to these cars it would make a difference! |
Ant, I have a TKO600 with a .82 OD and 3.54 gears. 70 MPH is 2600 RPM. I think I will get the TKO600 with the .64 OD which will get the RPMs down to 2025 at 70 MPH. 2600 on the highway gets a bit grating on your nerves after a while. With the engine your building (I imagine in excess of 500hp) high gear will still get your attention at 2000 RPM, but if it doesn't you can always drop down a gear. I know mine gets my heart rate up in any gear. The whole decision rests on the use. If your are going to spend any amount of time on the highway, there is a lot of difference between the low 2000s and 500 RPM more in high gear for an extended period of time.
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FE 427 Rev range.
thorconstr,
I suppose it depends on when the camshaft starts and the final drive ratio, and with a stroker as you mention a long long cog for cruising! Clois, Snappy throttle response is important, not so keen on to much high gearing 3.08 max! |
Ant, What transmission are you using?
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Transmission
Seriously considering a Richmond Road race five speed with 1.1 top cog!
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Ant, 3.08 gears with 1.1 final at 65 MPH is 2550 RPM. A friend has that trans and gear combo. His 427 is howling on the highway at 70 mph. He wears earplugs all the time. I personally would opt for a 5th gear OD. The TKO600 with 2.87 first is a great road race trans, and rugged also. With the power to weight ratio of our cars, I don't think that a 3.27 first gear is needed to launch the car. If your building strictly for the track it would be a different story.
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I have a 3.31 rear with a toploader (1:1 top gear), and find cruising above 70-75 (2900 to 3100 RPM) starts to get weary, and earplugs are useful, almost necessary, due to wind as much as engine/exhaust noise...the motor is doing just fine, but I'm not! Below 70, (particularly at 65 mph, 2700 RPM) it cruises fine, and engine noise is not a problem.
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Ant,
Dean Lampe is building a new 427 and he has purchased the new 600 HP TKO Trans to put behind it. His plans are to go with 3.31 gears (I think he may need to go up even higher gears since his first gear is going to be around 3.27 :1 and final drive gear will be .82 : 1). His plans are to be around 11: 1 compression on his engine. He is also buying the Blue Thunder heads (they are really sweet), Manley SS Valves, dual springs, Victor type intake, Roller Rockers, JE Pistons, with light weight rods. I guess I should let him jump in and tell you exactly what he is doing. His intentions are to keep his RPM's under 6500 and to use his Cobra in several road race venues each year plus the usual amount of cruising. Clois |
FE 427 Rev range
I dont want to start another thread on Tremec transmissions, I assume they have sorted the syncromesh problems that seem to appear when they are given a bit of a hard time.
I cant say I am enthusiastic on these transmissions, but the TKO-600 may not have these problems?????????? One CC post described the synro rings as being made out of "pot material" I think he runs a Jerico! Pending the camshaft etc going much below 2550 might be a problem, but as a friend of mine with a 428 two door Galaxie, 2.4.1 rear end keeps saying you can always change down a cog if you have enough of them.....eh! |
Ant, I've got 2600 mile on my TKO600 without any problems, and I haven't been exactly babying it! As I said before, I tend to like the closer gear ratios of the 600 with the 2.87 first gear.
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