Gearing Opinions
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Gearing Opinions
I'm building a mud bog truck with my Dad, and we're to the point where we need to make a decision on gearing (has stock 3.55 right now). I posted a thread in the 79 F-150 section as a basic intro and noobie zone (I being the noobie) if you will. I received a lot of good advice in there, and thought I'd try to expand some opinions on more specific things.
It's a 79' F-150 with a 466. Est HP 450-500 range. C6, 31 spline 9'' rear, D44 front. We'll be running 2 different sets of tires, 1 being 4x 35x14.50, the others being 38.5's with the front 11 wide and the rear 15 wide. It has a NP203 as well, and as far as I know both the transfer case and transmission are stock. I'm not sure what other info you'd need, I'll gladly get it for you if you need more.
Here's a picture of the cam card for the cam that's in the block. Don't know if this'll help any:
http://sphotos-b.xx.fbcdn.net/hphoto...42572967_n.jpg
The truck: It has a 4'' suspension lift, and probably won't get any more.
http://sphotos-a.xx.fbcdn.net/hphoto...36441770_o.jpg
The brothers who built the engine seem to lean towards 4.10/11, and so far I've gotten mostly 4.88/5.13 from here. Would 4.56 be a good compromise? I am currently in the pitch-black dark on the matter.
Thanks guys.
It's a 79' F-150 with a 466. Est HP 450-500 range. C6, 31 spline 9'' rear, D44 front. We'll be running 2 different sets of tires, 1 being 4x 35x14.50, the others being 38.5's with the front 11 wide and the rear 15 wide. It has a NP203 as well, and as far as I know both the transfer case and transmission are stock. I'm not sure what other info you'd need, I'll gladly get it for you if you need more.
Here's a picture of the cam card for the cam that's in the block. Don't know if this'll help any:
http://sphotos-b.xx.fbcdn.net/hphoto...42572967_n.jpg
The truck: It has a 4'' suspension lift, and probably won't get any more.
http://sphotos-a.xx.fbcdn.net/hphoto...36441770_o.jpg
The brothers who built the engine seem to lean towards 4.10/11, and so far I've gotten mostly 4.88/5.13 from here. Would 4.56 be a good compromise? I am currently in the pitch-black dark on the matter.
Thanks guys.
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Critter, and Karl both have alot more engine than you or me, and both run 5.13 and + gearing. and like i mentioned to you threw PM i aswell run 5.13's. that way in deep pit's you wont have to pull back to first to keep your tire's moving.
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My concern with such a big gear is with 3 possibly 4 of us driving it, I'm worried about our total (100%) inexperience with using any sort of shifter. This first season the shifter has been on the column and we just put it in drive and hit the floor with the gas pedal.
We'll be switching to a B&M floor shifter, but still have no experience with shifting it. We have a MSD box that stops us at somewhere between 6500-7000 RPM's, won't the 5.13 make us hit that limit too fast, especially if we don't have the experience to shift at the right times? The tranny and transfer case also being stock, I don't know if that plays into it any or not I'm assuming the tranny will be under some serious stress.
To me, it sounds like some seriously stupid questions but that's really how much of a grasp I have on the topic.
We'll be switching to a B&M floor shifter, but still have no experience with shifting it. We have a MSD box that stops us at somewhere between 6500-7000 RPM's, won't the 5.13 make us hit that limit too fast, especially if we don't have the experience to shift at the right times? The tranny and transfer case also being stock, I don't know if that plays into it any or not I'm assuming the tranny will be under some serious stress.
To me, it sounds like some seriously stupid questions but that's really how much of a grasp I have on the topic.
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Stick the 5.13s in there really.
I had 5.38s in my wheeler and a doubler, I was able so slap gears fast enought to keep from over reving.
Get a shift light, set it for 500 or so rpms below your ideal shift rpm, that way I will give you a bit of time to react to shift if your worried about it.
I had 5.38s in my wheeler and a doubler, I was able so slap gears fast enought to keep from over reving.
Get a shift light, set it for 500 or so rpms below your ideal shift rpm, that way I will give you a bit of time to react to shift if your worried about it.
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From: Springfield, VA
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i ain't rite
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it is only seriously stupid if you do not ask the question.
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From: Springfield, VA
What mad box do you have? If you are spinning that 466 to 6500-7k like you are and know little about what it's built for, then you have bigger problems than gearing. You need to (or someone running that truck) know the whole combo and what's works together. A stock c6 isn't going to last very long behind a healthy big block running those rpms. Plus you need to shift it through the gears to make it fast. Seat time and practice runs will help
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What mad box do you have? If you are spinning that 466 to 6500-7k like you are and know little about what it's built for, then you have bigger problems than gearing. You need to (or someone running that truck) know the whole combo and what's works together. A stock c6 isn't going to last very long behind a healthy big block running those rpms. Plus you need to shift it through the gears to make it fast. Seat time and practice runs will help
We haven't had any opportunity to test the new motor out, and probably won't until Good Friday. The guys who built the motor put the MSD box on it because when asked how we drive it, the answer was "to the floor until we don't move". Of course, that was with a stock motor that had little to no threat of blowing.
I know experience will probably help the most when it comes to these things, but until that experience is gained you guys, along with a couple friends who bog here, are my "experience". When our new carb comes in the guy who built the motor offered to come tune it in for us, so when he does that I can ask him if he thinks we'll actually be running those 6500-7000 RPM's. Do you have any more things in mind I should make sure I get a definite answer about?
What kits would you recommend to beef up the C6? I read at work that a shift light will just plug into the MSD box, is there any truth to that?
Appreciate all the help guys.
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Yes, the box is the 6AL (PN 6425). Ran out into the shed and took a picture to make sure I remembered it. We don't have a tach, that I'm aware of, in the truck.
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Post Fiend
Joined: Jan 2001
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From: Springfield, VA
Stinking auto spell! MSD box, not mad box. Is the cam hydraulic or solid? Flat tappet or roller? That, along with the spring package in the heads will tell what rpm you should be running. I'm betting your setup with the cam you showed, would be probably end up around the 6000 rpm range. Just hope the rest of the drivetrain is up to the task.
How familiar are you with the internals of a c6? Some upgraded clutches/steels with a Kevlar band would help hold everything better at your hp range. Also a good manual valve body will help hold the 1-2-3 shifts better. Has your motor been dyno'd or are you guessing the hp numbers? A converter setup for your motor will go a long way and doesn't cost much more than a shelf converter. Just food for thought
How familiar are you with the internals of a c6? Some upgraded clutches/steels with a Kevlar band would help hold everything better at your hp range. Also a good manual valve body will help hold the 1-2-3 shifts better. Has your motor been dyno'd or are you guessing the hp numbers? A converter setup for your motor will go a long way and doesn't cost much more than a shelf converter. Just food for thought