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Drag race preparation
https://slantsix.org/forum/viewtopic.php?t=30682		 Page 1 of 2
Author:  Aggressive Ted [ Fri Aug 22, 2008 11:39 am ]
Post subject:  Drag race preparation
Quote:
We have a Carter BBS on Twiggy at the moment. We will see if we can run some 17 sec ETs with the 1 bbl Carter carb.

Please start a new thread with your drag strip preparation question. I can post some tips but I don't want to do it in this engine build thread.
DD
Doc,

Since you are running a one barrel for racing, which one are you using and what did you do to it so you could race with it?

The reason I am asking is that I would like to take my car to the strip and get a slip or two before I switch over to a four barrel. However, with a leaned out 1920 #56 jet, I am running about 19 seconds using my sons G-Tech. Should I put a #64 jet in the 1920 with some race gas and clean out the trunk? I am right at 3600 lbs with the tank full and my son. Any thoughts would be appreciated. :D

Thanks,
Author:  CARS [ Fri Aug 22, 2008 1:30 pm ]
Post subject: 
Why not go to the track as it is and make a few passes, THEN if you want, change the jetting and make a few more passes? If it likes what you did keep going up slow until it doesn't like it anymore.
If you can jet a carb in your garage, you can do it at the track. If fact, it may be easier because if you need something odds are someone can help you right there.
Author:  slantzilla [ Sat Aug 23, 2008 1:37 am ]
Post subject: 
I agree, get some baseline passes before you start changing things. Also, stay away from race gas. If your engine doesn't have the compression to use it, it will slow you down. It will make your exhaust smell good though. :lol:
Author:  Aggressive Ted [ Sat Aug 23, 2008 9:13 am ]
Post subject: 
Is 9.5 to one too low of compression for race gas?
You can see my setup and build in the signature block.
The engine is very spunky until the float bowl goes down too low.
Author:  Shaker223 [ Sat Aug 23, 2008 10:50 am ]
Post subject: 
93 octane is quite fine for 9.5:1 cr. Sunoco has 94 around these parts. Slantzilla is right on both counts. It will slow you down if it is not needed but sure smells purdy.

As a kid, I put some in my mini bike expecting miracles. The bike would not even start (because the burn was to slow) until I put regular back in.

If you still think you need it...put 5 gals in a container and spike your tank at the track.
Author:  slantzilla [ Sat Aug 23, 2008 5:19 pm ]
Post subject: 
Mine is just shy of 11-1. It will slow down on 100 octane on motor only. :shock:

I have sprayed it on 114. On 114 motor only it is really a pig. :lol:

It smells real good though. :D
Author:  sandy in BC [ Sat Aug 23, 2008 5:34 pm ]
Post subject: 
I run my 9.5 build on 87.

Race gas is for race cars.
Author:  Aggressive Ted [ Sun Aug 24, 2008 10:33 am ]
Post subject: 
Sandy,

What does it run at the track on 87?

I am looking for a race tune, not general driving. My 9.5 build runs fine on 87 as well. In fact it gets pretty fair mileage for a heavy car and my lead foot.
Author:  Shaker223 [ Sun Aug 24, 2008 1:10 pm ]
Post subject: 
Quote:
My 9.5 build runs fine on 87 as well..
If it does not spark knock, it needs nothing more
Author:  Doc [ Mon Aug 25, 2008 10:14 am ]
Post subject: 
Well... we got a bunch of 17.30s out of Twiggy with a bone stock and well-used Carter BBS 1 bbl and factory exhaust manifold into a 2 1/4 pipe... that's a good starting point and baseline to work from.

As others have already said, the first time to the dragstrip is more about getting familure with the track and to get a "baseline" to work from.

Here are a few things I do to my street cars before going to the dragstrip:
- Check to be sure the carb opens all the way when the gas peddle is "floored". This sounds silly but have found many cars that do not fully open the carb when I do this check.

- Test the car to be sure it will "take" a WOT "hit", then hold it floored in drive, to see if the shift points are OK. If the engine bogs when floored, fix that before going to the track.

- I put an exhaust "dump-out" with block-off cap, into the exhaust so I can uncap the exhaust at the track. I do this so I can hear the engine better... especially when you are racing next to another open exhaust car.

- Check the How to Drag Race article for more tips and things to check before going to the track.
DD
Author:  Aggressive Ted [ Mon Aug 25, 2008 11:16 am ]
Post subject: 
Doc,

Thanks however, I was looking for info on what jet your running in the carb and the weight of car and fuel your running, tire size, rear end ratio, mods to the 904, what torque converter, etc. Got the other areas covered.

Good point on checking the throttle blades. I will do that...

Is the BBS better for racing over a Holley 1920? If so, I will look for one.
Author:  Dart270 [ Mon Aug 25, 2008 11:21 am ]
Post subject: 
Yes, put in 64 jet and clean out the car. Might not even hurt your mileage.

Lou
Author:  Doc [ Mon Aug 25, 2008 11:42 am ]
Post subject: 
Carter carbs run a "floor jet" with a step-up rod that drops into the floor jet to reduce fuel flow at light loads... there is no useful correlation between the Holley and the Carter jet sizes so you just need to 'find your way' with your Holley carb and set-up.

One thing is not to get to rich on the jetting, that tends to actually slow the car down. My "gut feel" is that a 64 jet may be a little on the rich side but it's a starting point. What is the track's elevation?
What I do is to pick a somewhat rich starting point, then try leaner jets to see if the car "picks-up" on the time clock, once it starts to slow, I go back a step richer.

As for SL6 1 bbl carbs I feel that a Holley 1920 can be tuned to be a little faster then a Carter BBS but the Carter is way more "foregiving" as far as not being "spot-on" with the tune and still running pretty good.

As for the rest of the Dacuda combo, the trans & converter are stock with the converter flashing at 1800 RPM.
The rear gearing is a compromise, seeing that we are driving long distances to get to the race track... usually the "drive to the track" cars get a 3.23, 3.07 or the 2.94 gear. Once we get to the track, we swap-on some real short rear tires to help off-set some of the tall gear ratio.
DD
Author:  Aggressive Ted [ Mon Aug 25, 2008 12:36 pm ]
Post subject: 
Doc,

Good info. I am getting closer.

A few more questions.

How much does your car weigh?

The cam is a Erson 280 correct?

What diameter of tires?

I am at 25.1" diameter P235 60's with a 2.76 posi.

Thanks,
Author:  Doc [ Mon Aug 25, 2008 1:08 pm ]
Post subject: 
I need to re-weigh the car... It 'feels' like its 3000, may-be a little less.
The cam is one of the special Erson RDP grinds, 266 (RV15) on the intake and the Mopar 244 lobe pattern on the exhaust.

The tires we swap-on are 225-50... on a 15 inch rim, about 23.5 inches diameter.
DD
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