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Old 01-31-2012, 04:41 PM
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How to Choose RPM range

Hello, I'm at the point where that I want to tackle rebuilding my engine. It's a SBC 350 I pulled from a donor van with 100k+ miles and I figure itís a good time to replace all the seals and gaskets before its in the vehicle. The more I thought about it the more I figured I might as well see if I can build the best engine for the application that I plan to use it if leaving it stock isn't the best choice. It'll be going into a 1954 Chevy truck (weighs about 7000 lb) and will be in front of a 700r4. I'm not opposed to changing the rear end gears later if I have to.
As I was searching previous post I found the following info
"Pick the rpm range where you want the powerband to fall based on how you will use and drive the vehicle. Then you pick the duration of the cam that will put the powerband in that range."
This is the first place that I got lost. How do I choose the rpm range where I want the powerband to fall. It will be a daily driver but I live 3 miles from work. On those days I normally get up to 35-40 mph tops. There are 3 stop signs and one light (that I NEVER catch) but I don't think I do a lot of idling. However, I do make occasional trips (usually once a week) on the interstate at 75-80 mph for distances of 30 - 150 miles at a time.

This is not going to be a racing vehicle just one that gets up to speed enough to drive. I realize that with the weight of the vehicle I'll need sufficient torque but unsure of where to begin with deciding on leaving the engine stock and just 'freshening up the engine' or building the engine up for better hp/torque. My main goal with the vehicle is gas mileage but I'm not looking for something unrealistic. Right now I'm driving an Expedition and it's mileage is not great.

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Old 01-31-2012, 05:34 PM
How fast is fast enough?
 
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Compared to your expedition your mileage will be dismal, expect 15mpg's and be prepared for 10mpg's.

Your powerband is as low as you can get it. You'll want a near stock cam with less seat duration, slightly tighter lsa, and more lift.
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Old 01-31-2012, 07:18 PM
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Im pretty sure your truck weighs a lot less then 7000lbs.I wouldn't go much over stock with your combo.Your rpm range should be off idle to 4500 or 5500.Go to comp cam site and download there cam selector program,it may be some help.If you have never set up a 700r research this sight for info.The 700r can be a ***** to tweak .

good luck and keep wrenching
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Old 01-31-2012, 07:42 PM
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Dammit! I type 3 paragraphs of advanced engine theory, then the cat manages to delete it. So here's the short answer:
I'd do a TBI 350, from an '88-'95 C1500. I wouldn't do any mods to it, at all. Then I'd choose axle gearing and rear tires to give a cruise RPM of 1550-1600 at 60 MPH. Expect better than 20 MPG on a regular basis. 210 HP isn't amazing, but it will do the job you described.
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Old 02-01-2012, 08:23 AM
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Quote:
Originally Posted by jmsaunders
Hello, I'm at the point where that I want to tackle rebuilding my engine. It's a SBC 350 I pulled from a donor van with 100k+ miles and I figure itís a good time to replace all the seals and gaskets before its in the vehicle. The more I thought about it the more I figured I might as well see if I can build the best engine for the application that I plan to use it if leaving it stock isn't the best choice. It'll be going into a 1954 Chevy truck (weighs about 7000 lb) and will be in front of a 700r4. I'm not opposed to changing the rear end gears later if I have to.
As I was searching previous post I found the following info
"Pick the rpm range where you want the powerband to fall based on how you will use and drive the vehicle. Then you pick the duration of the cam that will put the powerband in that range."
This is the first place that I got lost. How do I choose the rpm range where I want the powerband to fall. It will be a daily driver but I live 3 miles from work. On those days I normally get up to 35-40 mph tops. There are 3 stop signs and one light (that I NEVER catch) but I don't think I do a lot of idling. However, I do make occasional trips (usually once a week) on the interstate at 75-80 mph for distances of 30 - 150 miles at a time.

This is not going to be a racing vehicle just one that gets up to speed enough to drive. I realize that with the weight of the vehicle I'll need sufficient torque but unsure of where to begin with deciding on leaving the engine stock and just 'freshening up the engine' or building the engine up for better hp/torque. My main goal with the vehicle is gas mileage but I'm not looking for something unrealistic. Right now I'm driving an Expedition and it's mileage is not great.
I'd take your engine.. and reseal it..
order an rv cam for it.. get a alum q get intake (82-86 t/a camaro, or same years monte/caprice, it'll flow better than the iron one on the van engine
your 7004r low first gear will help get that 7000lb moving just fine..
you can get crazy spending money.. but this is cheap. and will do what you need.. with that much weight to lug around.. a 396 would get you better mpg as it not have to work as hard..
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Old 02-01-2012, 08:54 AM
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i would think something like this edelbrock cam , (or any brand with similar specs) would be what you want to use
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Old 02-01-2012, 09:48 AM
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I would also do all the usual work, port matching, clean up all casting flash and de-burr everything that looks like it needs de-burring.
All you need is a cheap die grinder and a carbide burr or two (Dremel is a waste of time, unless you have several weeks to grind stuff )
If your not using it a lot, Harbor Freight Tools has electric die grinder for about $40.00 and air for about $10~$15
You will need a couple of Carbide burrs, Enco (www.useenco.com) is about the cheapest in the country
Your not building a race motor but anything that makes it more efficient is going to be beneficial.
I like building motors so I usually go a bit overboard on my own stuff

Last edited by crazypj; 02-01-2012 at 09:53 AM.
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Old 02-01-2012, 12:59 PM
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Does that truck really weigh 7000 lb or is that the GVW? 7000 lb is extremely heavy. Is it just a regular pickup or a flat bed? Dump truck? I've found that people often seem to overexaggerate the weight of their trucks.

Is it one of these?

http://chevy.oldcarmanualproject.com...esto/54060.htm
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Old 02-01-2012, 01:03 PM
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my 71 long bed 2wd is 3900 lb
v8 a/c auto
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Old 02-01-2012, 02:45 PM
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Hey jmsaunders,
Quote:
Originally Posted by jmsaunders
Hello, I'm at the point where that I want to tackle rebuilding my engine. It's a SBC 350 I pulled from a donor van with 100k+ miles and I figure itís a good time to replace all the seals and gaskets before its in the vehicle. The more I thought about it the more I figured I might as well see if I can build the best engine for the application that I plan to use it if leaving it stock isn't the best choice. It'll be going into a 1954 Chevy truck (weighs about 7000 lb) and will be in front of a 700r4. I'm not opposed to changing the rear end gears later if I have to.
As I was searching previous post I found the following info
"Pick the rpm range where you want the powerband to fall based on how you will use and drive the vehicle. Then you pick the duration of the cam that will put the powerband in that range."
This is the first place that I got lost. How do I choose the rpm range where I want the powerband to fall.
Excellent question. I hope to tackle a similar first-build myself some time soon. This thread may help clear away some confusion about RPM ranges: "Engine Building: Horse Power vs Torque-Oriented Configurations".

Good luck!
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Old 02-01-2012, 03:36 PM
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Quote:
Originally Posted by Blazin72
Does that truck really weigh 7000 lb or is that the GVW? 7000 lb is extremely heavy. Is it just a regular pickup or a flat bed? Dump truck? I've found that people often seem to overexaggerate the weight of their trucks.

Is it one of these?

http://chevy.oldcarmanualproject.com...esto/54060.htm
No it actually weighs closer to 3000 lb. I had accidently read to far over on the chart I was using and read GVW. Well its good to know that I should be able to tow anything not nailed, cemented and super glued down .

Quote:
Originally Posted by crazypj
I would also do all the usual work, port matching, clean up all casting flash and de-burr everything that looks like it needs de-burring.
All you need is a cheap die grinder and a carbide burr or two (Dremel is a waste of time, unless you have several weeks to grind stuff )
If your not using it a lot, Harbor Freight Tools has electric die grinder for about $40.00 and air for about $10~$15
You will need a couple of Carbide burrs, Enco (www.useenco.com) is about the cheapest in the country
Your not building a race motor but anything that makes it more efficient is going to be beneficial.
I like building motors so I usually go a bit overboard on my own stuff
Yes, I do plan to do all of that also as I plan to send the block off to be tested etc before reassembly.
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