[Zio]

Hey guys I went to the track today trying to get a new best and failed again. I feel that I have a few more tenghts in it, but want to see what you think.

I made three passes before the rain started. Here are the break downs.

BTW my best ET is 11.53 with the stick and auto. Best ET with the stick was 118.75 and with the auto 116.80.

1st run: launching off idle at 1400 rpm shifting at 6200
60ft-1.6259
1/8et-7.3739
1/8mph-92.81
1000'-9.6609
1/4et-11.5988
1/4mph-116.39

2nd run: foot brake to 2000rpm and shifting at 6200. lower timing from 38* to 36*

60ft-1.5999
1/8et-7.3710
1/8mph-92.40
1000'-9.6650
1/4et-11.6088
1/4mph-116.01

3rd run: same launch and shift point as 2nd run. Lower jets from 85/93 to 83/91

60ft-1.5919
1/8et-7.3560
1/8mph-92.35
1000'-9.6501
1/4et-11.5901
1/4mph-116.23

I planned on putting the timing back to 38*, but it started to rain.


I think that the engine itself is tuned pretty well and just needs a little more fine tunning. There are a couple other things I am wondering if they will give me a few more tenghts. I am currently running a 26" et street drag radial and I am crossing the line at 6800-7000 RPM which I think is way too high and I feel I might be loosing sometime this way. what do you guys thinks? I will be switching to a 28" tire either way. Second is I am using a 25 year old converter that I got from my uncle that flashes to 3500rpm. It does not seem to hit very hard. It was recommend to me by another member here to go with a 4000 stall. Also my engine builder recommended a 3800 stall if I ever went with an auto which I did. (originally had a four speed behind this engine). Is there a significant gain to be had with a quality stall that is in the 3800-4000 range for my engine? BTW this engine is in a 3800 lbs 56 bel air. I am open to any suggestions about the above or anything else you guys can think of.

thanks
Tom

 

[Dave427]

Your ET to your 60 ft. and MPH all match pretty good. My car runs 11.70's @ 115 with low 1.6 60 fts. I cross the line @ 6400 rpm's. A taller tire will sure help, its still alot of rpm for a 468 with a hydraulic roller stick. I would take a bit of gear out of it too.

Dave

 

[Zio]

Are you saying to take some gear out so I will cross the line at a lower RPM? I am thinking that the 28" might get me into the RPM range I need to be, but not sure. Man I was really hoping there was more in this combo.

thanks
Tom

 

[trmnatr]

Try shifting at 5,500rpm with that set up, times will most likely improve with the TH-400

It wont cost nothing either to try - If your shifting at 6,200rpm by the shift light your not shifting until 6,400-6,600rpm so you need to set your shift light to 5,500rpm

 

[Dave427]

There is probably more in your combo, converters have come along way in the past 25 years. Your builder is accurate by putting a 3800+ converter will help. A hydraulic roller they like 6000-6500 tops in rpms. The taller tire might get you closer, that 25 year old converter may be slipping well over 10% making your rpms that high at the big end.

Dave

 

[Camaro_fever68]

Running your numbers, I came up with 10.6% slip if crossing at 6800 rpm and 14% if crossing at 7K. A better converter will help the most IMO. I'd go 4000-4200 stall because your 60ft could use some improvement.

 

[Zio]

thanks. I am going to start calling around to a few places and see what they recommend for a converter.

Tom

 

[Harold Sutton]

Hey guys I went to the track today trying to get a new best and failed again. I feel that I have a few more tenghts in it, but want to see what you think.

I made three passes before the rain started. Here are the break downs.

BTW my best ET is 11.53 with the stick and auto. Best ET with the stick was 118.75 and with the auto 116.80.

1st run: launching off idle at 1400 rpm shifting at 6200
60ft-1.6259
1/8et-7.3739
1/8mph-92.81
1000'-9.6609
1/4et-11.5988
1/4mph-116.39

2nd run: foot brake to 2000rpm and shifting at 6200. lower timing from 38* to 36*

60ft-1.5999
1/8et-7.3710
1/8mph-92.40
1000'-9.6650
1/4et-11.6088
1/4mph-116.01

3rd run: same launch and shift point as 2nd run. Lower jets from 85/93 to 83/91

60ft-1.5919
1/8et-7.3560
1/8mph-92.35
1000'-9.6501
1/4et-11.5901
1/4mph-116.23

I planned on putting the timing back to 38*, but it started to rain.


I think that the engine itself is tuned pretty well and just needs a little more fine tunning. There are a couple other things I am wondering if they will give me a few more tenghts. I am currently running a 26" et street drag radial and I am crossing the line at 6800-7000 RPM which I think is way too high and I feel I might be loosing sometime this way. what do you guys thinks? I will be switching to a 28" tire either way. Second is I am using a 25 year old converter that I got from my uncle that flashes to 3500rpm. It does not seem to hit very hard. It was recommend to me by another member here to go with a 4000 stall. Also my engine builder recommended a 3800 stall if I ever went with an auto which I did. (originally had a four speed behind this engine). Is there a significant gain to be had with a quality stall that is in the 3800-4000 range for my engine? BTW this engine is in a 3800 lbs 56 bel air. I am open to any suggestions about the above or anything else you guys can think of.

thanks
Tom

A smaller diameter good converter will definately pull better and stall better too. What diameter is this older converter? If you put in a tight 8" from a good company like ATI i'd be surprised if it didn't pick up 2 tenths. The side benefit is if you get the stall right it will also mph higher too. These aren't cheap but they will help. The 28" tire is a real good idea if your running a engine that is out of power at 6300 and are having to turn it too tight to get down the 1/4 mile. A larger diameter tire will have more sidewall to absorb some of the initial shock that the engine and torque converter deliver to the tires. P.S..... That hyd. roller is probably all done making power at 6200 rpm so it will like the taller tires too. I wouldn't change the gear though because it's been my experience that 4.10 are about perfect for a heavy car. Your car is kind of a box so it probably catches more air than a later model Chevelle. Get the best one they have in the stall you need and you won't have to buy more than one. The ATI eight inch can be had with about 3800-4000 stall speed that works well in mid 3000 lb. cars.

 

[Harold Sutton]

Running your numbers, I came up with 10.6% slip if crossing at 6800 rpm and 14% if crossing at 7K. A better converter will help the most IMO. I'd go 4000-4200 stall because your 60ft could use some improvement.

Where are you getting the percentages? Dead locked up this car would cross at 6200 rpm at 117 mph. That is 600 rpm of slippage which really isn't that bad. A car that is showing 116.3 on the time slip is actually traveling 116.9 at the 1320' mark. At that speed, and with no tire growth, i get 8.8% slippage. The bigger diameter tire should drop the trap rpm to about 6300 rpm and that should be perfect.

 

[66 Buick Special]

Can you fit 30" tires under your car?

One of our members "FourEightyNine" is running 30" tires with 4.11's and an 8" ATI converter that flashes to 5000.

I pulled the info below from his signature.... he's a little lighter than your 3800I think, but at 1mph faster he's a bit quicker and still trying to dial it in.

I know all things aren't equal but I thought I'd pass along the even taller tire suggestion.

71 Malibu
489ci, TheDoc iron ovals, pump gas
Th400 transbrake, 8" ATI
4.11s, 35 spline detroit locker
[email protected], still tuning
1.48 60ft
http://i201.photobucket.com/albums/aa50/468Brian/th_SD530727.jpg
Good Luck!

 

[Harold Sutton]

Can you fit 30" tires under your car?

One of our members "FourEightyNine" is running 30" tires with 4.11's and an 8" ATI converter that flashes to 5000.

I pulled the info below from his signature.... he's a little lighter than your 3800I think, but at 1mph faster he's a bit quicker and still trying to dial it in.

I know all things aren't equal but I thought I'd pass along the even taller tire suggestion.

71 Malibu
489ci, TheDoc iron ovals, pump gas
Th400 transbrake, 8" ATI
4.11s, 35 spline detroit locker
[email protected], still tuning
1.48 60ft
http://i201.photobucket.com/albums/aa50/468Brian/th_SD530727.jpg
Good Luck!

The 55-57 Chevies have very small wheelwells and probably won't be able to fit any tire of over 28" in diameter. I'd guess 10 x 28" to be all that is comfortable if centered correctly.

 

[Zio]

I am currently running a 275/60/15 street tire and a 275/50/15 drag radial and I can not really go any wider. A 30" tire would hit the front of my quarter panel. As harold said a 28" is all I am going to fit unless I tub it. Thanks for the help guys. Any more suggestions/advice is welcome.

thanks
Tom