Has anyone used a line lock with a two step in the rear brakes? Do they come off quick enough? It would be like a poor mans trans brake if it worked.
And has anyone used a MSD two step at low rpm? Around 2000 rpm. My back fires bad. Even with open headers. Tried it once with mufflers, that was a mistake. I just wanted to know if that is how they work or if something is wrong my rev limiter. Thanks

 

Brian,

The first year I started racing in our tracks "street class" it was all footbrake aside from using a line lock for the burnout...the old school basic but simple way to drag race-grass roots if you will.

The second year I knew at some point I wanted to step up and start running our Mod class/No Box where transbrakes are the norm, so getting the car set-up to leave off a button to aquaint myself prior to jumping in with the big fish was a priority. Back then our class rules allowed using a button/2 step so long as we did not run a delay box and did not have a transbrake. So that spring I updated and installed a MSD 2 step with the adjustiable pill (the little red one where you can adjust from 0 rpm to 3000 rpm) since I was going against the convertor and esspentially footbraking, my brakes did not have the ability to hold the car any higher than 3000rpm at that point with that convertor. Early in the year I started noticing that every once in a great while the car would want to push, so naturally the next step was installing a rear line lock to work with the front line lock once I pressed the button for staging.

This set-up was very consistant and worked very well, R/T's were right there all the time and any poor performance was me missing the tree-not the fact I had 2 line locks working to hold the car and the theoritical drag one might assume to happen.

The next thing I discovered very quickly was my rpm had to be set at least to 2800 to stay juuuust green on the tree, but what I also found was every once in a great while the car backfired and stalled...happened maybe 3-4 times that year, but after talking with many others with the same results we came to the conclusion anything lower in staging rpm with this set-up and you get the back fire and/or cat stalling/dieing like your experiencing. I think most of it is since the car is rotating at such a low rpm, the added fuel that is not getting burnt off due to that fact loads the car up and the back firing begins causing problems and lost rounds. If at all possible step up staging rpms after you hook up a rear line lock and see how that treats you, but from experience with my old set-up, just try to stay above 2800rpm when staging.

Josh

 

A starting line enhancer would be better than using a 2 step on these slower vehicles but takes a bit more to set up. If a 2 step is allowed, they can't refuse a simple SLE either. If it's only activated by a driver pushing a button, it's not electronics any more than a 2 step would be. It's just a way to launch at the same rpm every time.

What the SLE does is it controls the throttle position. When the button is pushed and your throttle is pushed to the floor, an electric or CO2 cylinder changes the throttle position to bring the throttle down to a launch rpm. Your foot is to the floor but the engine is only at 2500 rpm and isn't banging and popping like on a 2 step. When the button is released, the throttle goes to WOT and you launch never having to move your foot on the throttle. You could have it wired into a line lock also just to keep from rolling on the start line.

A third option is to buy a good tach. I use an Autometer 3966 playback tach. It's a good inexpensive ($240 from Jegs) playback tach. It also has a launch light feature which I don't use since I use a transbrake, 2-step and a delay box. A shift light will blink at different sequences until you reach your preset launch rpm. Just takes a bit more practice but it could never be classified as electronics. Just before prestaging, you bring the rpm up to your launch rpm as indicated by the shift light. You then bump into the prestage then stage lights all the time keeping your rpms the same. Not as high tech as line locks, 2 steps or transbrakes but may give a slight edge over someone with nothing and you're racing in a class that allows nothing but the tach. The tach has up to 5 shift points so a 5 speed tranny can shift at 5 different rpms. It records 40 seconds of a pass so you can watch everything including your burnout. Playback is in real time or 1/3 time to see the fine details of the rpms during a run.

 

Thanks Guys . I guess there is nothing wrong with my rev limiter I just have to get the rpm up a little more on the line. I can bring it up to about 2400
now . It is a 3500 rpm converter , 10"body with a 12" lock up clutch . We are running the 7004 with a 4.56 gear. Jumps off the line ok. (shifts at about the 40' foot mark though) We still drive the car on the street and to and from the track , about 1 1/2 hour each way. A local guy here runs b/fia stocker and he has a pressure gauge in the rear brake line ,said he worked with the pedel to get the pressure up to 1500 psi. I might try that with bigger wheel cylinders. If can get her up to about 2900 rpm I will try the line lock . Sure be nice to leave off the button. If not I will try the light idea, never thought of that. Thanks again guys.