lowering 60 foot time

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green67cuda

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OK....i was pulling 1.87-1.89 60' with the old worn out springs.
I switched to 3000# S/S springs, and only gained a few 1/100. i think maybe there is maybe some engine tuning that needs to be done, but i don't remember what factors affect 60' the most....there is a list of things for each section of the track that change the characteristics for that section.

I am running 275/50-15 drag radials and have zero tire spin off the line. also have been playing with launch speed....seems to like higher staged speed, like around 3000 rpm

ALSO...something different from the old springs to the new springs is i ran about 10# more pressure because i was wearing the outsides of the tires off and haven't begun noticeable wear in the center yet

i am trying to find a way to post a video so you can see the current launches
 
is it bogging about 30 foot off the line? what gears you running? can you launch any higher rpm?
 
I seem to have forgot your full combo. Also what convertor and gears are you using ? Ron
 
oh yeah....it has 3.91s and a B&M Holeshot 3000 converter.
I can't tell it's bogging if it is. i only got a few runs on it because none of the tracks near me have any test & tune days...they are all race nights of some sort and the staging lanes are always packed.
 
green67cuda said:
still have to teach the GF what i want
Click to expand...


Dont we all. :evil4:

I still say try a bigger squirter. 35s or 37s. When it noses over you went to far.
 
The video tells me you have a very soft launch...lol. What is your current tune up? Snubber, or no? You dotn seem to have any body movement, so either there is too much stiff in the new spring, you arent transferring much weight, or it's just not making a lot of power when you start to move. What's the rest of the setup?
 
With 8.39 1/8 mile times, you can't expect much better on the 60' than you're pulling. Your trap speed is right about where it should be for those kind of ETs, so you probably won't see much more of a gain, unless you launch it harder to get up in the power band better.
 
launch harder as in stage at a lower speed to give the converter more hit?

moper:
the car is 3200 or less with me in it.
it's a 72 400 with about 8.5-9:1 CR
452 heads, some porting
windage tray, deep oil pan
Torker intake
770 cfm vac sec holley street avenger (jetted 72/75or76, bare sec spring, .031 squirter)
K&N 14x3 filter
aluminum WP/housing/radiator
5" aluminum lower pulley, 6" stock WP pulley
battery in trunk
B&M Holeshot 3000
TF-2 kit in trans
3.91 sure-grip
275/50-15 BFG drag radials
3000# S/S springs
Gabriel mid-price range truck shocks
 
This is a pic of mine launching. Basically the same setup as yours, same carb even. Except mine is a stock piston 400, no porting and approx 100,000 miles on it . I bring it up to about 3000 on the convertor. 60 ft is the same as yours, Mine went 13.7 in 1/4 .I think I could have shaved a bit mor off with more tuning , but replaced the 400 with a 383 this year. I have 90/10 shocks up front and some leaf springs in the rear from 20 yrs ago, not even sure what the heck they are. And NO snubber. Note , air under drivers wheel ( battery is still in the front and I weigh 275lbs)

up50du.jpg

track11gm.jpg
 
hmm...must be the suspension setup....
i have .920 bars in front and regular parts-store shocks.

to me, in the video, it doesn't seem to be lifting very much on the line. i need to get it out in the driveway and put it up near the stall and have the GF measure the rise in the rear. i may be able to help that by puting spacers in the rear shackle hangers to give them a better angle. right now, they're vertical, so that could possiby prevent adequate rise.

I was thinking about some 90/10s, but am not sure if that would be a good idea for a street car. seems like they would be bad for the drive to the track or to shows.

i am also needing to tune the squirt and the jetting on the carb, but like i said, there are no test/tune nights here....just race nights and they are always too busy to get a good series of runs.i think i'll get out on a back road and run a few WOT tests and check the plugs.
 
I really couldn't see much in the video it was to dark. I would agree with Adam and go with bigger squirters. What do the plugs look like after the run?

I had the same problem for a while with a soft launch. Had to go with a 3600
convertor. Then play with the suspension. I have Cal-Tracs and QA-1's in all four corners. What I did was bring the adjustments back to where I would slightly spin off the line and adjust it from there. Time consuming but it works.

Now this may sound wacked but I got it to where the tires would just move on the rim on launch. Then I screwed the tires to the rims and worked with air pressure and shock adjustment from there. She launches pretty hard now without any spin. It took me a long time to get it there. About 1 season.

The qa-1's run pretty good for me on the street. I back them off (soft ) for the street and at the track soft in the front so she flies up and stiff (50/50) in the rear. More than that and she raised up and down in the rear on launch.

I will try to attach a video after I post this.
 
ok....looking at the timeslip page, i see that there are some people running low 12s with a slower 60' than me.....
guess that just means they're making more topend HP than i am, or not getting a good launch.

i just figured the S/S springs would be an easy 1/10 or 2 off my 60' and ET

i will get some squirters and run it up til i get black smoke on take-off and back off a size or two. then i can play with jetting, after an initial plug reading.

should i adjust for secondary opening before or after i get the jetting right?
 
I think the biggest problem with your combo is the cam. The .509" like alot of compression,gear and converter. Your actually 60fting pretty good for you combo. I would swap cams to something more like the XE274.
 
everything in the rear has to work together. SS springs were designed to raise the rear slightly for tier clearance, and tighten the front sections, so they plant better. I'm a firm beliver in using a snubber properly. For me, that means setting the ride hieght (i dont like a lot of rake, I want the front end easy to rise, not slammed down), then set pinion angle, then set the snubber to be 1/4" below the floor pan with a race load in it (me and fuel) . When I load the convertor, my car begins to rise. when I launch, there is around 4" of space above the tire, and the nose comes up so the car is level. I can leav at 3500, running 3.91s and street tire QTimes(the full tread, not the Pros). Thats with a 12.5:1 solid cam 440, my car is 3300 or so with me in it. If the nose is too low, there is very little transfer, shocks or no shocks.
 
i haven't made my adjustable snubber yet, and i figure a stock one will be too far from the floor, so i'll have to set that up after I get a snubber made.
 
I would use the vacume secondary carb as they will leave harder than a dbl pumper, try a shorter tire, we have a 360 that uses similar setup and runs 1.55-1.57 60ft times with 26" tires and a 3.91 gear 750 vac. carb with some minor mods. The car weighs in at 3510 lbs. The worst 60 ft we've had is 1.68 and this was spinning.

BJR Racing
 
When we had the 383 in my sons Dart its best 60 was a 1.77 on the old springs and air shocks. It did hook and had a Turbo Action 10" tight 3000 convertor and 3.91's with 26" McCreary tires. Its best et was 12.31 @ 110 and 7.86 @ 88. We never really worked on the 60's much but yours aren't all that bad for a mild street car. Also check the pinion angle as that can help some. Ron
 
I cant "relook" at the video..my work's firewall wont let me go there...lol. but, lookig at the stance of the car in your pic..The nose is very low..Try raising up the T bars a turn or two. Your launch is very soft (that much I remember) for a big block with 3K stall and 3.91s. You have the plain spring in the secondary? Id try the purple and tall yellow in that order, and see if it bogs..If it does, go a little bigger on the squirtor to see if that fixes it. Also, as Ron said, check pinion angle. When you can get the car to move on launch, then you can set the snubber if you run it.
 
I think Adam may have hit the nail on the head with the cam in your combo. That cam really likes to see a high final compression ratio and lots of rear gear, along with the high stall converter. Changing the cam might be a little drastic in the search for a better launch, but you could try using a 4 degree advance key to bring the engine torque down a few hundred RPM. If you know what your piston to valve clearance is right now, it would really help in deciding if you should try this or not. The other thing that might help, and might be worth a try at the strip, is smaller torsion bars. Good luck and keep us posted on your progress.
 
I agree with Adam and Oldvart on the cam versus compression theory. But as for the larger squirter, you
might want to try moving or changing your pump cam
a bit first. You may be half way through the shot when staging.
As for cranking up the torsion bars, I would recomend against it. I think that would worsen things. My theory is that you want your front end to rise, thus transfering weight to the rear tires. (Things in motion,.... so forth.)
Try 6cyl bars like oldvart suggested.

good luck.
 
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