This will take you to the main site where there is history, technical information and other information on these cars.
This takes you back to the main page of the forums.
This is the control panel to change your password, information and preferences on this message board.
Click here if your lost your password or need to register on this message board. You must be a registered user to post. Registration is free.
Search this board for information you need.
Click here to buy cool Squarebirds mechandise.
Click here to support Squarebirds.org. For $20 annually receive 20mBytes webspace, a Squarebirds e-mail address and member's icon on the message board.
  #41  
Old 10-18-2015, 07:41 AM
simplyconnected's Avatar
simplyconnected simplyconnected is offline
Slow Typist
 
Join Date: May 26 2009
Posts: 7,130
simplyconnected is on a distinguished road
Default

Now wait a minute...
If you buy a cam with a "Basic Operating RPM Range of 2,200-5,800" (these numbers are right off the page), why on earth would you run OUTSIDE these numbers??? Isn't that why you bought this cam in the first place?

So now here we are changing stock parts to accommodate the new service. Yes, 'service'. This engine is intended for a specific service and it ain't 'getting groceries'. It is a street racing cam that needs at least 9.1 compression ratio, headers and a stall converter to match the cam.

This cam will NEVER render good gas mileage by any stretch. It creates NO power below 2,200 rpm then it unleashes all your engine has above that. A 2,500 rpm stall converter is a MINIMUM for this cam. I would look for something a little higher. Yes, 'slip' creates heat but you obviously need the converter to slip.

What rear end gear are you running? - Dave
__________________
My latest project:
CLICK HERE to see my custom hydraulic roller 390 FE build.

"We've got to pause and ask ourselves: How much clean air do we need?"
--Lee Iacocca
Reply With Quote
  #42  
Old 10-19-2015, 12:00 AM
scumdog's Avatar
scumdog scumdog is offline
Super-Experienced
 
Join Date: May 12 2006
Posts: 1,351
scumdog is on a distinguished road
Default

Quote:
Originally Posted by simplyconnected View Post
Right Tom, I agree. It's not the loping but undulations tend to make idle speeds impossible for anyone not very familiar with the car.

A 3.77 rear end would give you loads more torque at the rear wheels and a 2,500 rpm stall converter would be perfect.

Have you got an idea of what your 'all in' ignition advance is?
Initial timing + distributer centrifugal weight + vacuum advance = All In Timing. - Dave
Dave, as mentioned my Mallory is an old race-type one without any vacuum advance, I have a Pertronix unit inside it and run an equally old Voltmaster coil. From memory I have 12 on the crank and 24 on the dizzy. (The motor doesn't like low grade gas!)
The reason for the 12 degrees initial is to TRY to compensate for the lack of vacuum advance when cruising. When racing I used to knock it back to 9 degrees or so to spare the motor getting hammered to death.

Fave,
__________________
A Thunderbirder from the Land of the Long White Cloud.
Reply With Quote
  #43  
Old 10-19-2015, 10:22 AM
HighwayThunder's Avatar
HighwayThunder HighwayThunder is offline
Apprentice
 
Join Date: Nov 19 2013
Posts: 90
HighwayThunder is on a distinguished road
Default How it works?

OK, so I'm trying to visualize how this works...

Stock cam stall speed is 1800-2000. Fast idle is 1500, warm idle is 500. Even at fast idle the car should remain motionless. Give it a little gas, rpms increase past 1800, the converter "catches", and the car starts to move.

With the aftermarket cam and a 2400 converter, the rpms have to increase past 2400 for the converter to "catch".

Is it correct that at 2400 the acceleration curve of the tire rotation will be steeper than it would be at 1800, resulting in tires "breaking traction"?

BTW, rear end is stock 3.00:1.
__________________
Richard
1966 Thunderbird Hardtop,
390 with Edelbrock heads. Visit my restoration blog at hwythunder.com .
Reply With Quote
  #44  
Old 10-19-2015, 02:37 PM
simplyconnected's Avatar
simplyconnected simplyconnected is offline
Slow Typist
 
Join Date: May 26 2009
Posts: 7,130
simplyconnected is on a distinguished road
Default

Close, but not exactly. Even at idle speeds your car still pulls forward, doesn't it??? You let your foot off the brake at a light and the car rolls forward. The converter is slipping as it should because a torque converter takes the place of a clutch. When the light turns green you raise rpms and slowly let out the clutch. The whole time your foot depresses the pedal the clutch is slipping. Let your foot off and the clutch stalls, or locks up. If your engine speed is too low, the car will buck. The same happens with an automatic.

Quote:
Originally Posted by simplyconnected View Post
...All OEM converters lock up at relatively low rpms. At idle speeds your stock engine still pulls hard but the converter lets the transmission slip until it gets to a high rpm to ensure you're in the power portion of the torque band. Stall converters come in different 'lock up' rpm ranges. The higher the converter is allowed to slip, the more costly they become. They also add heat from all that slip...
Quote:
Originally Posted by HighwayThunder View Post
...Even at fast idle the car should remain motionless. Give it a little gas, rpms increase past 1800, the converter "catches", and the car starts to move...
There is a drastic difference between 'slipping' and 'locking up'. At fast idle (1,500 rpm), your car is pulling HARD. If the converter was locked up your engine would labor and buck.

Torque converters still pull at low rpms, otherwise your car wouldn't move, but they slip, like 'feathering' the clutch for a smooth start. Once they get to 'stall speed' they lock up.

Quote:
Originally Posted by HighwayThunder View Post
...With the aftermarket cam and a 2400 converter, the rpms have to increase past 2400 for the converter to "catch"...
No, the converter still pulls while it is slipping. At 2400, the new converter locks up.

Do you know why we use rear end gears like 3.90:1 on a street or strip machine? 3.0:1 is more for highway driving or the Bonneville Salt Flats, where we have all day to reach top end speed.
Quote:
Originally Posted by HighwayThunder View Post
.. Is it correct that at 2400 the acceleration curve of the tire rotation will be steeper than it would be at 1800, resulting in tires "breaking traction"?..
I have no clue as to what 'the acceleration curve of the tire rotation' means.
__________________
My latest project:
CLICK HERE to see my custom hydraulic roller 390 FE build.

"We've got to pause and ask ourselves: How much clean air do we need?"
--Lee Iacocca
Reply With Quote
Reply


Thread Tools
Display Modes

Posting Rules
You may not post new threads
You may not post replies
You may not post attachments
You may not edit your posts

vB code is On
Smilies are On
[IMG] code is On
HTML code is Off
Forum Jump


All times are GMT -4. The time now is 09:59 PM.

Driving, racing or working on cars can be hazardous. The procedures and advice on this website including the message board are opinion only. Squarebirds.org and its webmasters and contributors do not guarantee the correctness of the advice and procedures. The Squarebirds.org and its webmasters assume no liability for any damage, fines, punishment, injury or death resulting from following these procedures or advice. If you do not have the skills or tools to repair your car, please consult a professional. By using this site you agree to hold harmless the Squarebirds.org, its authors and its webmasters from any resulting claim and costs that may occur from using the information found on this site.

Powered by vBulletin® Version 3.6.8
Copyright ©2000 - 2017, Jelsoft Enterprises Ltd.
Any submissions to this site and any post on this site becomes property of Squarebirds.org . The webmasters reserve the right to edit and modify any submissions to this site. All material on this is site is copyrighted by the Squarebirds.org. Reproduction by any means other than for personal use is strictly prohibited. Permission to use material on this site can be obtained by contacting the webmasters. Copyright 2002-2016 by Squarebirds.org.