Slant Six Forum
https://slantsix.org/forum/

whats a good basic shift point?
https://slantsix.org/forum/viewtopic.php?t=44730		 Page 1 of 2
Author:  USAJon [ Mon Apr 25, 2011 9:23 pm ]
Post subject:  whats a good basic shift point?
I have this question under wanted tach..
http://www.slantsix.org/forum/viewtopic.php?t=44725
we have a stock 1968 dodge Dart 225, auto column shift. stock rear larger dia rear tires. mufflers 1 barrel carb all stock. I am wondering what is the best manual shift point RPMs for 1/4 mile racing? thanks!
Author:  Joshie225 [ Mon Apr 25, 2011 9:35 pm ]
Post subject: 
Stock 225s are usually done by 4500 RPM. You'll want to try different shift points to see what's quickest. If you are willing to fiddle with the valve body and governor you can get the trans to shift by itself at the optimum RPM gaining consistency and probably bettering the ET.
Author:  USAJon [ Mon Apr 25, 2011 9:47 pm ]
Post subject: 
Ok
how do I fiddle
a link possibally..?

did not know there was a governor..
Author:  Joshie225 [ Mon Apr 25, 2011 10:15 pm ]
Post subject: 
Sounds like you're going to need help. Start reading through the transmission section of your factory service manual to get familiar with the transmission operation. Once you've done that you should have a better idea of how to make changes to optimize transmission function for racing.
Author:  Dart270 [ Tue Apr 26, 2011 5:46 am ]
Post subject: 
Best shift at 4000-4500 on a stocker. I always shift manually and am very consistent (0.02-0.04 run-run) if car behaves off the line.

Adjust kickdown linkage so it is fully rearward at WOT.

Lou
Author:  USAJon [ Tue Apr 26, 2011 8:05 am ]
Post subject: 
WOT ?
Author:  THOR [ Tue Apr 26, 2011 8:10 am ]
Post subject: 
Wide Open Throttle

:mrgreen:

~RDE~
Author:  USAJon [ Thu Apr 28, 2011 6:59 am ]
Post subject: 
OK
with the paperclip conected throttle cable carb linkage I only had 3/4 throttle..
I remember the seller saying how he went to a junkyard to buy a carb as the one on it was shot. well It was never propertly installed.made some test reconnections on the carb and the car launches/bangs 2nd pretty hard..I had put lighter oil 5-30 wt. but I gona re-oil back to 20-50, as on start up the oil light stays lit too long, and after a few 1/4 mile standing/rolling test runs, the motor is talking to me...181K...I would rather cruze then try and find $$$$ for a rebuild...still plan to go to 75-80 and run...them big worn tires did spin on the one side (non-sure grip)....no chirpin so the rear is light..and @ 40-50 mph /still in 2nd the ft. end was kinda floting..strange? I'm not gona shift as it rolls good now in dive.
PS.
the kick down linkage et al was all dirty/surface rust. put some never seeze ALL over....what fun.
Author:  Greg Ondayko [ Thu Apr 28, 2011 5:36 pm ]
Post subject: 
Quote:
Stock 225s are usually done by 4500 RPM. You'll want to try different shift points to see what's quickest. If you are willing to fiddle with the valve body and governor you can get the trans to shift by itself at the optimum RPM gaining consistency and probably bettering the ET.
Okay, So I understand how to adjust Line pressure and The Lickdown etc.


How Does the Governor Figure into all this? I would like to learn.

Do you have to remove the tailshaft to tune the Governor i.e. Putting weights or shims in the Governor itself or is it done in the valve body somewhere?


Thanks!


Greg
Author:  Ross [ Thu Apr 28, 2011 6:17 pm ]
Post subject: 
Not to thread jack but what is redline on a bone stock 225? i have my tach set at 4k as redline.
Author:  Shaker223 [ Fri Apr 29, 2011 4:51 am ]
Post subject: 
Quote:
Not to thread jack but what is redline on a bone stock 225? i have my tach set at 4k as redline.
When the valves float!
Author:  Doc [ Fri Apr 29, 2011 9:13 am ]
Post subject: 
Errr... for me, the stock 1 bbl carb runs-out of CFM before the valves float. :roll: :lol: :wink:
DD
Author:  Greg Ondayko [ Fri Apr 29, 2011 10:33 am ]
Post subject: 
Quote:
Errr... for me, the stock 1 bbl carb runs-out of CFM before the valves float. :roll: :lol: :wink:
DD
Yep, I have the same problem... It's the restriction in the system.

Greg
Author:  Joshie225 [ Fri Apr 29, 2011 12:41 pm ]
Post subject: 
Quote:

How Does the Governor Figure into all this? I would like to learn.
The valve body is an analog hydraulic computer. This is why shift kits are sometimes called reprogramming kits. For the transmission to shift a shift valve has to move. Governor pressure acts on one end of the shift valve while there is a spring and throttle pressure on the other end of the valve. Governor pressure has to overcome the shift valve spring pressure and throttle pressure to move the shift valve. Raising the throttle pressure or lowering the governor pressure will raise both the 1-2 and 2-3 shift points. If one shift point is off then you need to play with the spring on the appropriate shift valve.
Quote:
Do you have to remove the tailshaft to tune the Governor i.e. Putting weights or shims in the Governor itself or is it done in the valve body somewhere?
There are different weights available for the governor. Yes, the tail shaft has to be removed to service the governor.
Quote:
Thanks!
Greg
You're welcome. I hope this makes sense!
Author:  Ross [ Fri Apr 29, 2011 10:15 pm ]
Post subject: 
haha well that doesnt help me much. lol i see 4000-4500 above. so would 4500 be redline? i have a manual tranny and low gears, when i get to 4k its screamin pretty good. Never gone past 4k but if i can go to 4500, would you think itd make a difference in 0-60 time?
Page 1 of 2 All times are UTC-08:00
Powered by phpBB® Forum Software © phpBB Limited
https://www.phpbb.com/