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Mud Drag Modifications

80' 427

80' 427

1/2 ton status
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Nov 14, 2006
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NEBRASKA
Hey I am new here and think this is a great site. I wanted to put your expert minds to the test in attempting to build a winning mud drag truck. I am buying a 84 K-10 from my cousin. I built the truck and all of the current mods were my ideas. The truck has a mildly built 350 with 9 to 1 compression some pocket ported heads, edelbrock eps, holley truck avanger, headers and a mild retro hyd roller cam. The engine runs well and really doesn't really lack power but could always use more. The rest of the truck is a 2" superlift New 33 12.50 Trxus mt and front and rear 10bts that now have 4.11s and a detroit in back and a front trutrac. The trans is a stock 84 700 and a 208. The truck was built to be a daily driver and a colorado forestry road truck. Now it will be my Nebraska daily driver/farm truck and a weekend mud dragger. I was thinking it needed more power but now I think 33" Boggers will be first. I was also thinking of rear wheel spacers to help the rear follow the front (why are they narrow any way?). These are my class rules.
Stock Class
Tires 34" or less and must have a DOT. stamp and can not be cut
Must be street leagal
Headers OK but must have full exh. to rear end with mufflers
May have aluminum intake OK, but must be dual plain and no air gaps
Must pull 17" of vacume at 1000rpm at intake manifold only
Must have factory or factory like bumpers front and back
Must have all lights in working order
Must be corporate matching
No more then 6" total lift
Must be naturally aspirated
No aftermarket heads, must be factory production head
Must have full dash and interior
Must Have bench seat or two buckets
Must have stock ignition system
Stall ok but on bigger then 2000RMP

Any suggestions would be of great help.
Thanks ahead of time.
 
It would be easy to start a huge list of things to do but most would not agree with a daily driver / farm truck.

Imo, the Boggers are a good idea for the rear but I'd suggest a similar height, skinnier tire for the front. No more lift and that will only make the truck feel more unstable when running fast.

Weight can play a huge factor in drag racing. The rules and usage of the truck prevent gutting it but you can control some of the weight by removing unnecessary stuff (tools, toolbox, spare, tailgate, etc) for race day.
 
was thinking about this last night... i'm thinking 10bolt or Dana 44 front, 12 bolt rear (due to the 10 bolt's weak carrier) welded up. 350 or 383 with lightened rotating assembly. 350/241 35 x 10.50 Boggers, and gut everything that you dont need. passenger side wiper, window mechanisms, heater/ac, radio. hell, all you really need is a tach, an oil pressure gauge, and a temp gauge.

IMO, a "winning" mud truck isnt anywhere near something you'd want to drive every day.

also, are you dealing with a LWB K10, or a short wheelbase?
 
The plan it to buy 33 10.50 boggers to dig instead of float but of course I could buy 10.50 for the front and 12.50 or 13.50 for the back. You see the problem, as do I with the dual usage of the truck but I still think it is possible to do OK. Depending on the traction of the truck I have been thinking of a ord traction bar and a 2000 stall to help the hole shot since it has a lock up converter and wouldn't effect highway travel. I now have a 90 K1500 that I have gotten a 2nd with in the factory stock class with just stock size mudders. To get it too do well I ran in 4 lo and in drive by the end of the pit it was right at 5000 rpms and worked really well. I plan to do the same with this truck and I have bought a vette transmission govener to allow a 5000 rpm automatic shift. And of course as the old drag racers say "light makes right". It is a LWB but some of the fastest trucks in this class are long. I think it helps them stay straight when going fast. I can't strip the truck in this class but, I can if I move up later. The fastest trucks leave like they have a transmission brake, they leave super hard, bearly spin. Also when traveling down the track there body stays flat while the suspension takes up the bumps instead of bouncing all around like some others in the class.

Thanks again for the help.
 
beater_k20 said:
IMO, a "winning" mud truck isnt anywhere near something you'd want to drive every day.
Click to expand...


+1

You take a truck like this and play and have a good time but don't expect to really be competetive unless you can retire it to racing only.
 
This is the web site for the circuit the STOCK class I want to run in is one of the more mild classes. Of course I might not win but some of the other entrys are less than steller. A good running truck with traction may really do pretty good.

http://www.geocities.com/midstatesmuddraggers/mud

The guy that wins this class all the time drives his truck to and from events. It is a really bad a-- 81 ford f-150 LWB. I don't like fords but it runs hard.
 
i'll agree, a LWB truck seems to do better in the mud. all of the big dogs around here run K20s or K30s.
 
How about a big block? Must be corporate matching. To me that means big block swaps are ok. A 454 with oval port heads and a mild cam would pull the required vacuum, and make more torque than a 350/383 could dream about.

Ditch the 700 for a built th350.

And a 9 inch rear with a spool. Lighter than a (at least I think it should be) 10/12 bolt and stronger too.

Get rid of the ac, heat, radio, and anything else that doesn't help it go. Replace the side and rear windows with lexan. Ditch the spare, tailgate, doors whatever they will let you take off. Replace the bench with a pair of drag racing seats. Replace the gas tank with a fuel cell or a plastic gas tank. Preferably with less than 10 gallons in it.
 
and mounted as far back in the bed as possible.

big block = weight on the nose. it'll stick right in the mud with short tires like that.
 
True, true. I forgot about the little tires.

Then my vote goes for a 6.0. Would be corporate matching, and has factory aluminum heads.
 
If it gets anything it willl be a a 454 but that is some day. Right now it will be very similar to the street trim. The ford that wins runs a small block. I think sticking is more important than horsepower right now because there is 2 ramchargers with 440s and they may come in 2nd 3rd but it is usually a distant 2nd and 3rd to the ford. The 350 in it is pretty stout and will get a set of ported heads to help the hp. I don't konw how strong the axles have to be I have seen 38s on 44s with big block run for 3 seasons with no problems. Plus a 9" would hang lower and drag more. The rear 10 has a detroit other than the need for axles wouldn't it live a while?
 
If ya ain't getting any traction, then all the power in the world ain't gonna do ya no good.............................:D

Interco-Boggers.jpg
 
Thats kinda what I have in mind. I was going to spend money on better heads to up the hp but since I am going to run in 4 lo anyway I don't think power will be the problem, it will be traction in the mud. I still wonder what size boggers to get (was thinking 33 10.50s) and if spacers would help cause all the wheels would be in the same track. You guys think a 2000 stall torque converter would help? It would put me in the fat of the torque curve.
 
first thing is first, you need to figure out if the rear "detroit" is a full carrier unit or not. if its a lunchbox locker in a stock open carrier, ditch the rear as a whole. the carriers are known to be weak.

as for winning with "sticking", over power, i'm going to guess you're young and dont have much experience with mud. the more wheel speed you have the better the boggers will clean out. the more they clean out, the better they'll take the next bite. to get the wheel speed, you need power. another thing to consider is you're only dealing with a 33" tire, which doesnt leave much for ground clearance, so you're going to want to spin them to stay on top of the mud, rather than digging in alot. again, you need wheel speed...

running 4 lo with a 700R4 isnt a good idea, because it just makes the already bad gear spacing that the 700R4 has worse. the 700 will want to bog going into 2nd gear, which breaks momentum, and ends your run. furthermore, running in low lowers the gear ratios, and slows wheel speed, which in turn hurts your run. i would really look into a TH350.

personally, just judging from what you have written in this thread, you dont have much experience with trucks, or mud, but want to be a weekend warrior. if that is the case, take your truck in its current form, and run it as it is. figure out its weak points, and fix them as you go.
 
It is a full carrier detroit I built it. I am young, just 30. I am a service manager at a chevy dealership and I drag race a 80 camaro with a 427 running in the 11s. You are correct I haven't spent a lot of time in the mud just messing around in the fields and mud roads/trails and a little mud drags in the stock class. I understand the concept of needing wheel speed and clean out. I guess my thought is like in the drag racing you attempt to have your engine "tach out" at the finish line, with the low range allowed by the 208 and the 4.11s with a ultimate redline of 5500ish this should put me right at the finish line. Mostly the people who run in this class are running nearly stock trucks with a lift, or headers. They only have one mod that moves them into this class. There are a few heavy hitter but for the most part they don't have the package working together. I know it isn't the strongest truck right now but do you really think the 10 bolts will break with just 33s? My dad overloads a 81 k-10 with a 10 bolt and 2.73s every harvest and planting season with a 35000lb trailer and we have yet to break that axle. I do have plans to pump up the motor more but right now it is making 275 to 300 hp pretty easy. I guess what I ment about hooking it I mean on the starting line some trucks spin bad before they leave and some just go with no spinning. In drag racing hole shot is everything so the harder you leave the better you do over being fast up top. Do you think a narrow tire or a wide tire or both on different ends are the answer? I figured there may be some suspension mods that would help it hook.
 
Just a couple more things. In our circuit the pit is 100 ft long and it starts shallow to race 4 wheelers in and is dug out between classes to get it deeper. It is still pretty shallow for this class but starts getting lots deeper afterword. In my few experences with mud dragging I tried it in 4 hi and 4 lo. 4lo had a better hole shot and because of the amount of gear reduction and actually the typical 700 gear split problems were less apearent. In 4hi it seemed like it couldn't get on top of the revs and dogged the whole way though.
 
hmm i guess my 350 acts different than a 700?:confused: if im sitting on level ground and punch it in 4 low it sits there for a second spinning before going, in 4 high it starts immidiatly. when its deep (at lower speeds)it seems like i move slower in 4 low than 4 high.. when i typed that out it seemed arsebackwards but idk. i guess the transmissions have a big effect on the way it runs though mud. :crazy: ...4 low has gotten me out of some sticky stuff though with my lack of power.. guess that doesnt apply to what your doing though.
 
First I want everyone to know that I think this is a great B.S. session. It does spin a bit but since the gear is so low the intial wheel speed doesn't go supersonic like in 4 hi. When the pit is only a 100 foot long you accelerate the hole time and though the 4 hi tops out higher the low seems to acclerate faster. It may be my crutch for low power but it seemed to work in my 90 K1500. I just held my foot on the floor and steered. With the added traction of boggers I might need all the crutches I can get.
 
80' 427 said:
I guess my thought is like in the drag racing you attempt to have your engine "tach out" at the finish line, with the low range allowed by the 208 and the 4.11s with a ultimate redline of 5500ish this should put me right at the finish line.
Click to expand...

We have a winner! :wink1:


Running in 4hi will never keep the motor spinning hard in high gear. At best, running in hi will have the tranny hunting for the correct gear because it hates the load resulting in inconsistent tire speed and eventual tranny damage.

Here's a trick that worked good for me, running in 4lo and starting with the tranny in 2nd gear. Launching hard in 1st really just causes the truck to sit and spin while hitting the redline making you want to shift immediately. Starting in second (a suggestion originally given to me by J.W. Perf. Transmissions) will help avoid wasting time spinning in place and it's also easier on the tranny.

Since this needs to remain street worthy I would take advantage of whatever weight reduction you can control and bring some of your drag racing tech over to the truck. Stuff like line locks (or trans brake) and a two-step box will be things the other guys aren't even familiar with. They also aren't addressed in the rules you posted. :wink1:

Give some serious thought to the narrow front tires. I ran 11x38 Boggers in front and 18x39's in the rear and for the most part the truck ran straight while others with 4 wide tires tended to "snake" there way to the finish line.

Another item that made a lot of difference for me was an electric fuel pump. I never realize how much the fuel pressure fell over at wide open throttle until I installed a pressure gauge. Replacing the Edelbrock "hi performance" mechanical pump with a Holley blue pump and a quality regulator made a noticable difference (motor wasn't as rpm lazy afterward).
 
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