I have searched but can't find an answer to my question.

I have a mildly built 350 in a 79 GMC short stepside pickup. I intend to build the engine further but am already experiencing trouble with wheel spin off the line.

My setup is as follows:

Weight is 3630 with driver.
12 bolt rear with limited slip and 3.73 gears
350 tranny with shift kit
28 inch tall, 9 inch wide tread tires
I don't want to add slicks.

What modifications do I need to help eliminate wheelspin without adding weight?

I have been advised by someone I don't really trust to move the battery to the rear, remove one rear leaf from the springs. Then add long (4' to 4 1/2') ladder bars while free floating the springs on the axle.

Please give your best advice. Thank you.

You don't say if your problem is wheel hop or just a nice spinning tire without wheel hop.

If it is wheel hop, you should look at some slapper bars or Caltrac's to control the spring wind up.

If both wheels are spinning without hopping, you need to move weight to the rear and lower overall weight, increase tire size or soften tread compound, experiment with lower tire pressures in the rear, increase weight tranfer to the rear, decrease shock damping in the front and rear. Ladder bars will put you in a different NHRA class if this matters to you.

Wheel hop is not a problem, just the tire spin.

What are ways to help weight transfer?

Class rules are not a problem at all. This is a street ride that only hits the track on occasion.

Thanks again for the help.

F1 already said some ways to help with wieght transer, like moving all weight on the truck to the rear as possible. You can move the battery to the rear, along with a fuel cell in the rear (I think they are behind the seat or behind the cab. Also, you can get some racing springs up front that spring the font up upon launch. F1 said a lot of great tips that you should try.

Trust me you have wheel hop. Try some slappers. Of course this is difficult unless you have done a spring flip on the rear. A set of lift bars of some sort would be better option and could be made to work with the top spring mount, but you might have to make your own.

The ladder bars would also do the trick.

Chris

You can use the old MOPAR tire trick, put the biggest tire possible under it, if it spins let out air, if it grabs too hard add more air, with a solid axle pickup you are going to spin, short of putting another engine or two in the bed!

Two things to try...
Lower the rear, and take a couple leaves out...
Helps the rear end squat....
Raise the front, with the loosest shock you can find
Helps the front raise and transfer weight to the squatting rear...

Decreasing pressure on radials actually will give you less traction. Try it for yourself.. let 10 lbs out of the tire and lay a nice set of marks you will see that the tire looses it's footprent when it turns another words the middle of the tire isn't getting any traction it's just folding up and going to the sides.. You will gain traction if you add 5-10 lbs.. Also heating up street tires makes they hook up worst. All you need to so is get them clean and not heat them up. Drag tires and street tires are the exact opposite.

http://www.hotrodsandhemis.com/traction1.html

http://www.hotrodsandhemis.com/Traction.html

That is the link I was thinking of. I just could not find it. Should be a very effective traction control device.

Chris

S15, that is one clean looking set-up!
What if it's a coil spring? Is a slapper bar necessary?

Its definitely not mine,I found the link while surfing one day.I will be make a set once my hand heals up.

http://www.hotrodsandhemis.com/traction1.html

Just for clarity, what they are doing is copying the Caltrac design.

I have also built a modification of this basic design, and instead of putting the rotating stop against the spring leaf, I terminated mine by having the rotating lever contact the underside of the frame. This puts less torsional stress on the spring mounting.

As you can see from the website, the design is adjustable so that you can have anything from no limit of windup to a preload and no windup. You still have spring travel which is necessary. You will find that slapper bars will bend in the middle if not strong enough. This design pulls the bar and there is not fulcrum to bend as long as all the pieces are built with good solid materials.

http://www.calvertracing.com/
Try cal tracs. Juveteach is trying to get an 84 c10 to hook up and he came across this set up. It is simular to Shelby style traction master bars but supposed to work better and are adjustable.

Is there any way to increase anti-squat on that truck? Maybe raise the front pivot point on the rear springs?