topher_csr

so last night i ran my 65 mustang at a local drag strip, i ran it 4 times and the best i could run is a 16.02. at first i was running 16.5's, but i bumped my timing up a bit and ditched the water pit and cut it down to 16.020. so what i am after now is a way to make my car half way respectable in the 1/4. it still has the stock rear end in it, a four speed, and a 289 with a mild cam, holly 650 carb, 4 barrel edlebrock dual plane intake, and long tube headers. so with all that i figured i would run a little faster than a 16.020. i was having a hard time hooking up off the line. i would either spin, or bog down. once i got going it went pretty well, but it seemed like i was running out of power towards the end and had to shift. so any tips form the drag racing guys out theres.

also im still running points in teh distributor. think that switching to electronic would help a lot?

racin66coupe

what are you running for suspension/tires in the back?

topher_csr

stock suspension, with new air shocks. just normal summer tires. i dont think that the tires are really hurting it all that much but the rear suspension is weak

Starfury

Ditch the air shocks. The upper supports are not designed to take any portion of the vehicle's weight. Doing so will eventually punch the shocks through the upper supports.

I'm assuming the air shocks are there because of sagging leaf springs. Old, worn out leaf springs will allow lots of axle-wrap, which leads to lots of wheel hop. Get some good leaf springs to get the ride height and performance you want. Traction Masters will help prevent any further wheel hop.

Jonk67

I wouldn't trust the air shocks they are basically solid with any amount of air in them and supporting the wt. of the car. The upper mount is just a single plate of thin steel not meant to support the wt. of the car either and may eventually spider crack or punch through, happened on my '70 20yrs. ago and many others have posted pics of the same results. Get new leaf springs, a decent set of shocks and fix the problem vs. putting bandaid on it.

Decent springs (4 1/2 leaf) will help your launch and then you can add caltracs if you're still slipping. A good set of road legal slicks like MT ET streets will make a big difference in your launch, I've seen guys run .5 faster with just adding MT's.

Don't get in the water trap with street summer tires drive around it, just spin your tires to clean them then stage.

Disconnnecting your front swaybar will allow the wt. to shift to the rear when you launch. Your launch is key, the first 60 ft. is where most races are won/loss.

The electronic ign. may help a little but it won't be a huge jump, will get you a more consistent spark but unless you're points are miss adjusted or you have missing I don't think you'll feel a seat of the pants change.

The stock rear gears are really hurting you also, they're probably 2.79:1? even 3:25:1 would make a difference you would feel but you'll loose some top end on the highway.

Any idea what cam you have? you may be running it past it's RPM range, what RPM are you shifting at?
Just my .02
Jon

andrewmp6

A 16 for a 289 is kinda normal the rear end kills its take off.

Aussie66Fastback

+1. Lowering your rear end is relatively cheap bang for buck. I'd change to 3.55 rear end or even 4.11 if 1/4 mile is your thing. 3.55s are still ok on the highway unless you are doing a long daily commute.

kudos to you for having a go at the track.

kalli

well that's great to hear. means anything lower than 16 is an improvement.
i'd start as well with the rear suspension to get quicker off the line. do you have 60' times or a complete timesheet?

urban_cowboy

Yeh...post your best time slip.

If you are slipping the tires in the first 100', switching to a drag radial like Mickey Thompson ET Street Radials will help a bunch. You do not want to run them on the street because they are very soft and will wear quickly. They also do not have a bunch of groves so they are near slicks so they suck in the rain. I run a set at the track and have a set of MT Sportsman S/Rs I run on the street and on the front.

Once you start planting power, you may run into wheel hop. That is normal. You then need to think about a traction device like 4.5 leaf springs and/or Cal-Tracs or Slide-A-Links. These help limit the amount your rearend can twist thus helping with Pinion angle and wheel hop.

At what RPM did you shift each gear and what RPM did you launch from? Did you side step the clutch or let it out so it could slip some? The idea is for you to shift when the applied torque to the ground (flywheel torque x tranny gear ratio x rearend gear ratio) is less in the gear you are in than the next higher gear at that same speed. This will insure you keep the most possible power and torque to the wheels that you can. Depending on the tranny gear ratios for each gear, for most engines, this is basically at the redline. In a 289, your redline is probably about 6200-7200 rpm given that the piston speed for the 2.87" stroke at that rpm is 3000-3500ft/min. You may not can spin that high depending on your valve train, springs, connecting hardware, etc. The stock cast crank and rods should handle 3000ft/min ok, but other things may not. Your particular setup may also not make power that high. In that case the formula and concept above would dictate at what rpm for you to shift.

I would suggest getting some drag tires, switching to electronic ignition like MSD, and installing a shift light connected to the ignition box. You can then play with shift rpm settings to see what you setup like best on the track.

2+2GT

New GT springs will allow you to ditch the air shocks. Traction Masters will do a great job at an economical price, and you should consider a limited slip diff., although the TM's will help an open diff hook up a lot better. As others have said, if the car is street/strip, get 3.55 or 3.79 rear. If it's just a fun car, get the 4.11.