You need to tighten the fronts up some - the car is coming straight up too hard, need to get the thing to shoot outward and not up, that's how Johnny cuts mid 1.5's.

Too much stall?

 

No question about my Vigilante and engine combination (396 stroker). I've tried every launch RPM and flashing from around 1200 RPM is the only way to get the 60 fts down in the 1.40s every time (1.48 to be exact). When I try to stall it up, the 60 fts move up into the high 1.50s to 1.60s.

WD

 

But he's running a Yank converter now that's why he made that comment.

I leave at 2400 with the Yank 4000 and net 1.44-1.53 60s depending on the weather. The 1.53s were on a 90° day. Average is 1.47-1.49
I would leave higher but at higher revs it leaves harder and quicker causing me to red light every time.

 

I’m not disputing his comment or that the Yank converters need to be stalled-up, just stating what works well for me with my Vigilante and engine combination.

Personally, now that I’ve gotten used to this type converter, I prefer to flash the converter off the line with low RPM. Then there is far less chance of pushing through the lights and red-lighting! Again, a matter of personal preference, with no right or wrong.

WD

 

I weighed the car today because the last time I weighed it, it was stock. 3480lbs with me in it, 3290lbs without me. This was with a full tank of gas. So, atleast I know weight isn't a factor.

 

I can tell you what I learned yesterday from Tyson at Performance Auto Fab (great suspension/chassis shop). We went to the track yesterday to test out the new combo for this year...We added QA1 R series fronts with 275 lb springs, QA1 12 ways in the rear with the stock springs, 4.10s, a spool, and 275 60 R15 M/T Drag Radials...Before the track session we scaled the car, squared the rear, set the LCAs in the lowest holes in the Spohn relocation brackets, set the pinion angle at 1.5 degrees negative usinga digital angle finder, and set the suspension preload....It was at this point that I fully realized the importance of the proper rear sway bar (that I don't have..I have the Spohn 1" stock style moly bar) What I need is the Spohn drag bar....Its very hard to try to set the preload with the street style bars with poly bushings...

We went to the track with the front shocks at 2 and the rears at 7 on the drivers side and 8 on the passengers, tires at 18 psi and went 1.52s all day long...We tried a few different tire pressure changes making only one change at a time, stiffened the rears to 8 and 9 leaving the fronts alone...But the first setting seemed to work the best...I was still running a 4L60E and a Vig 3600 flashing off idle...The 3 years of racing and the 7 wheels up launches were too much for the tranny, so I'm done for the year, but you may want to stiffen your rears, get a 28" tire back there, and look at a good, drag style rear sway bar...What brand of converter do you have?

--Alan

 

How do you "preload" the rear? I've got a Wolfe sway bar on the way but I'm pretty much a rookie on setting up the suspension. -1.5 deg pinion angle is where its set now. Adj tq arm, adj PHB, non-adj LCAs set on the bottom hole. 27" Hoosier QTPs 1.64 all day long for me. Inform the uninformed. Great thread!!

Mec

 

Tyson from Performance Auto Fab set the car up...I was in the driver's seat going up and down on the 4 digital scaling system he uses...I think its all about moving the effective weight around the car to get it hit the tires hard...With the Wolf bar he could do that very easily...Most shops call it a suspension tune...Hes a sponsor on LS1tech if you have any questions as to how it all works, I'd pm him for the details...Sounds like you have all the right stuff, it just needs to be tuned...

--Alan

 

Finally got into the 1.5s today. Had the front shocks set at 3, the rears at 7, ET Streets at 17psi and bringing the converter up to around 1500rpm. Best was a 1.5698 back up by a number of 1.59s

 

Did your times improve?

 

Yes, previous best was 11.60 @ 116.95mph with a 1.622 60ft. Today I got a 11.514 @ 118.50mph with a 1.569 60ft and 7.340 @ 92.63mph in the 1/8th

 

Good for you!!!! Nice job.

 

The car ran very well yesterday - congrats on the new bests!!!