10 Second Club - 4.30's too much gear?

I have a 99 Firebird. I built an LS3 427 with a 3500 stall and a TH400. My diff is a Moser 9 inch with 4.30. I got 28 inch rear tires. I made my first pass this past weekend, my tach stopped working just before the runs and my tuner told me my rev limiter was set at 6800. The launch was great but I had to shift just after the 60 ft to 2nd. Into 3rd just as quick and I would hit rev limiter at about the 1000 ft. mark!! Again I had no tach my rev limit, but tuner check the file and comfirmed 6800. Does this sound right? did I over gear for 1/4 mile? By the way the track was slippery and my best was 1.63 60 ft. and a 10.79 @ 119 due to the rev limiter.

It's actually a TH350. Been so darn long since I built the car, I forgot what it had. 59 views, someone's got to have an opinion!

I think you might have, I know that most auto guys go with 3.73 so that is a big jump there.

Damn!, can anyone else comfirm this? Sux that I am running blind (no tach) to verify my rpm. I will get that fixed obviously, just would hate to go and hit a wall again.

I have a 99 Firebird. I built an LS3 427 with a 3500 stall and a TH400. My diff is a Moser 9 inch with 4.30. I got 28 inch rear tires. I made my first pass this past weekend, my tach stopped working just before the runs and my tuner told me my rev limiter was set at 6800. The launch was great but I had to shift just after the 60 ft to 2nd. Into 3rd just as quick and I would hit rev limiter at about the 1000 ft. mark!! Again I had no tach my rev limit, but tuner check the file and comfirmed 6800. Does this sound right? did I over gear for 1/4 mile? By the way the track was slippery and my best was 1.63 60 ft. and a 10.79 @ 119 due to the rev limiter.

You should not be taching 6800 with 4.30 and 28in tire at 119 mph unless your converter is slipping too much on the big end. I would raise your rev limiter to around 7200 -7300 anyway with that engine. What rpm did it make peak HP? What brand converter do you have and did you have it custom built to your complete setup? I looked at some of the claculators on Wallace Racing and with your gear/ tire/ 3rd gear ratio , you should be able to hit 130 mph@6800 and 135 @7000. Sounds like you have too much converter slip. I would raise your rev limiter to about 7200 and make some passes and see if you can make it through 1/4. I would definitely get a good tach so you can keep track of what is going on.

I hate not having all the info, I really need to go out there with my tach working. As far as my converter, it was built for the application I just can't remember who or how, been a few years and plenty of builds in between. Here is a crappy recording posted on youtube by one of the spectators. I shift to 2nd just after landing and 3rd not long after. You can hear me bouncing off the rev limiter like 6 times until I cross the finish. Tell me what you guys make of it.

http://www.youtube.com/watch?v=a8TpXiMWkdk

I hate not having all the info, I really need to go out there with my tach working. As far as my converter, it was built for the application I just can't remember who or how, been a few years and plenty of builds in between. Here is a crappy recording posted on youtube by one of the spectators. I shift to 2nd just after landing and 3rd not long after. You can hear me bouncing off the rev limiter like 6 times until I cross the finish. Tell me what you guys make of it.

http://www.youtube.com/watch?v=a8TpXiMWkdk

Well I think you just answered the question. Sounds like you had converter built and then your combo has change several times since. The gear and tire sound really close for your combo unless it has the capability of trapping higher than 135 on motor. I can tell you the rev limiter is set really low as stock bottom end LS1 usually set higher than 6800 with H/C.

Man listening to your video your converter sounds like it is blowing through and slipping alot. I would get a tach working first so you know what is going on, raise your rev limiter to 7200- 7300 and make some passes. If it is still hitting the limiter before you get hrough traps and it is not at least somewhere close to 135 mph I would pull converter and have it reworked to your exact combo.

As far as changes, none to the setup, when I said many builds in between I meant other vehicles. Do you think 7300 would do it, now I'm starting to think 7500.

As far as changes, none to the setup, when I said many builds in between I meant other vehicles. Do you think 7300 would do it, now I'm starting to think 7500.

Well I was just suggesting that because I didn't know your complete build and obviously you were already being somewhat conservative by having it set @ 6800. Aftermarket rods should be good to 7500 easy. Most drag setups usually if optimized go through the traps 200-300 rpm above shift points at least. I would think your shift points should be somewhere around 6800-7000 anyway so going through the traps around 7200- 7300 wouldn't be too far off. Like I said it all depends on where your motor made peak hp as to where it needs to be shifted and rpm through the traps. Your gear, tire size and converter should be based of of that along with other factors. All good converter companies have a tech sheet you fill out with info needed and usually the converter will be really close based off of that. Like I said listening to the video sounds like it is getting up through the converter pretty quick and may be too much slip on the big end. Google Wallace racing calculators and they have a converter slip calculator that will tell you how much you have. Usually you don't want more than 4-6% slip at most.

thanks for the input!!

Sounds like an aweful lot of slip in that convertor!

looks wrong from the launch might want to have the converter freshened up and maybe swap to 4.11 or 3.89's should be 10.5 na with a 427 or better

Your are blowing slam thru the converter from the word go......I have buddies with 430's in there Camaro's and don't have that trouble. Converter change for sure and go with a bigger stall speed.

Your are blowing slam thru the converter from the word go......I have buddies with 430's in there Camaro's and don't have that trouble. Converter change for sure and go with a bigger stall speed.

Thanks for the suggestions, I think my first step is really to bring up the rev limit to 7500 and make sure my tach is working after that I shall a better idea of how high it stalls and see if I can cross the line without running out of motor. What stall speed do you recommend?