My 82 Silverado

[VileZambonie]

What is Lornes method you mentioned a few times?

Stall speed is easily measured if your tires don't break loose. Baiscally stand on the brakes as hard as you can and accelerate to WOT. Your highest RPM is your stall speed. Don't keep repeating this test but do it for your own knowledge. When you reach your stall speed the fluid in the converter is essentially impeding on itself and that in it's own can cause a poor launch. Try seeing what it is if your brakes can hold it. If your tires spin the test is invalid. Have you considered a trans brake?

[HAULIN IT]

Vile, I have never found a converter that wouldn't "flash" to a higher stall than it would go to up against the brakes. I bring The RPM's up just enough to know it will take off cleanly. A little playing to see where that is, but I spend many a minutes working the carbs. My 3900lb. truck is happy to leave on the last Yellow from 1200-1300 &  flash on take-off. Some vehicles do take a little more. I've pretty much used this method in any auto tranny vehicles. The carb/engine has to be able to take instant RPM, any hesitation here & you need to work on the carb/ignition.This also limits the possiblity of "pushing through the brakes" once your staged. Just my two cents, Lorne 

[team39763]

I've considered a trans brake, but in the end, I didn't feel it was worth it.  I'm not a serious racer and I heard that the TB was a little harder on driveline parts.  + I see plenty of other trucks/cars just fly off the line without the T-brake.  I'll try that stall speed test this afternoon.  Yeah, Lorne told me about his method a while back(described above).
 I'm gonna mess with the carb today and see what I come up with.  The carb worked flawless when we first put it on a few months ago...no bog or hesitation.  Nothing has been changed on the setup, so I don't know why it's doing that.  But like I said, it's only off idle. 

[Captkaos]

Its a Holley, and the temperature changed that is why it runs different. 

I would experiment with different launch rpms.  Once you get it stalled, hammer it, that is the point of the stall to get to where it makes power...
This is a video of my brothers 2000 RCSB 5.3L with an STS.  This was one of its fastest times at 12.26@109.95mph in the quarter..  SRT10 Ext cab on the far lane was Sure he was going to blow him away at the beginning with his 500hp truck...

http://www.gracemotorsports.biz/video/JCfreakvsSRT10Extd.mov

[HAULIN IT]

Chris, I'm assuming your kidding about the weather changing based on the wink? Holley carbs can be a little fickle when getting them dialed in, but really not that hard. The turbo idea adds a whole new dimension to the launch (getting the boost up). I love watching the turbo vehicles run, however allot of  them seem to be a handful on the starting line. Lorne

[Captkaos]

Not really, but I hate Carbs, Holley being at the top of the list.  They are finicky and weather changes do effect them.

His truck is injected so dialing it in is simple as changing the variables in HP tuners, WAY more simple than dialing in a Carb..

[team39763]

Goodness, I wish I had a launch like that.  Yeah, I've heard that Holleys need to be adjusted for the weather.  Maybe just richen the idle screws a bit?...that fixed the off idle stumble I had with my 750(only at part throttle though).  I think I may go to that crappy track and give that guy a run on Sunday.  I'll see if we can get some video of it for you guys. 

[HAULIN IT]

Team, It sounds to me that you need to work on the accelerator pump cams/squirters. The idle screws are not going to fix the problem. The engine is going lean when you whack the throttle open, there is not enough fuel to cover it up. Does it ever shut off clean when you go straight to the floor? If your going to play, just spend the bucks now for the Holley master kit # 36-182 & the cam assortment. From there you should be able to get the bog out. You need to work on the initial "flat to the floor" problem until the engine revs straight up from near idle, once you have this, your 60 ft's will drop. I don't feel there is much need to run a full trottle pass every time until you have the bog worked out, no sense in working over the engine until your on top of your game. Good Luck, Lorne     

[team39763]

You're right Lorne.  I think my trip to the track will be strictly for tuning and dialing it the combo.  It looks like I'm rolling solo on this trip, so I probably won't be able to film any of it....maybe from inside the truck.  I know the truck has 50cc pumps front and back, the squirters are pretty small if I remember, but I have some 35's and 37's somewhere around here.  No, it never shuts off clean, it recovers and goes.  I have a few pump cams laying around, I'll see what's on there and what I have.

[HAULIN IT]

The 50cc pumps can't hurt. Your thinking you have less than 35's in there? I would not be supprised if you needed some in the low to mid 40's, you gotta cover 475cfm per. I just went & checked, the other kit I have is Holley pt # 36-184, it has squirters up to 50 & the cams

[HAULIN IT]

Team, What I was thinking & what my fingers typed last night wasn't really the same. The idea that you will need conciderably more pump shot is correct. Forget the part about CFM. What I meant was that a 600 cfm carb may work well with a 32 or so squirter, the 950 having bigger bores/throttle valves needs more fuel the cover the bigger opening holes, understand?

[team39763]

Yep, I understand that.  That makes sense too.  It's funny, the "gearheads" down here think you can put smaller jets to make a carb smaller.  I never believed that(especially after I learned how carbs worked). What you said earlier made sense too.  Thanks.

[team39763]

Would anybody happen to have any videos of their trucks doing a launch on the street?  How much faster do you guys' trucks take off compared to mine?  Am I asking too much from my combo?  Tomarrow is raceday, so I'm gonna work on my launches and see what I come up with.  I won't worry about E/T's because this track is crappy and they get the times/speed wrong all the time.

[team39763]

Well, Dude didn't bring his truck to the track, so I didn't get a chance to race him.  Instead, I ended up racing a Shelby Cobra and beat him by 2-3 cars.  Then I raced a Z28.  Here's the video of it.  I was taking it easy off the line because this track is very slick.  Then I backed off before the finish line because the track has huge bumps and I ended up scraping the lower control arms on the ground.

[eventhorizon66]

Bumps at the end of the track bad enough to scrape the control arms!!!  I wouldn't race there either, sounds like a death trap for really fast cars (and trucks).  But then again I gather from the video, this isn't an NHRA-sanctioned track, LOL.  Any idea what your trap speed was?