The 1947 - Present Chevrolet & GMC Truck Message Board Network







Register or Log In To remove these advertisements.

Go Back   The 1947 - Present Chevrolet & GMC Truck Message Board Network > General Truck Forums > Engine & Drivetrain

Web 67-72chevytrucks.com


Reply
 
Thread Tools Display Modes
Old 02-01-2020, 09:04 AM   #1
ChevyGearHeads
Registered User
 
Join Date: Jul 2010
Location: Anne Arundel County, MD
Posts: 104
Torque Converter question?

I have a stock LM1 with double hump heads, .500/.500 Cam
and a Hurricane intake with a 600 CFM Edelbrock carb.

With the Hurricanes 3,000-8,000 RPM Power Range, I was wondering what the best stall option is for a TH350 with a current 1,700-2,100 Stall?
__________________
Paul
'68 C10 327/TH350
LWB
ChevyGearHeads is offline   Reply With Quote
Old 02-01-2020, 04:53 PM   #2
garyd1961
Registered User
 
Join Date: May 2016
Location: Henderson NC
Posts: 850
Re: Torque Converter question?

I'm not an expert on stall converters but since no one else has answered I will give it a shot. To start with you need to match the converter to you cam not the Intake. My best guess is with a 500 lift cam you will need about a 2200-2400 stall.
The weight of the vehicle and gear ratio in the rear has a lot to do with it also. A heavy vehicle can make a 2400 stall operate more like a 3000 stall. The more stall you have th he bigger gear you need in the rear. I can tell you from experience a 3600 stall will not work with a 308 gear in these trucks.
So here is my thoughts on this, the bigger the cam the more stall you need. The more stall you have the bigger the gear you need in the rear. Not having anymore info than you provided and with my limited knowledge on the subject I wouldn't suggest you go more than 2400 stall.
garyd1961 is offline   Reply With Quote
Old 02-01-2020, 05:10 PM   #3
Tom
driving is in my blood
 
Tom's Avatar
 
Join Date: Dec 1999
Location: Mesa AZ
Posts: 5,236
Re: Torque Converter question?

He's on the money. We need duration specs @.050 more then anything.
__________________
-78 c10 short/step: 388cid, M20, 5/5 drop, lots more. Playtoy and first vehicle.
-98 c1500 x-cab: 5.7L, 17" rims, 5/6 drop, flowmaster, helper bags,NBS rear disk brakes.
-02 Suburban 4x4: leveled front
-CBR600F4i, CBR600RR, CBR1000RR, and standup skis
DISCLAIMER: I cant spell for the life of me.
Tom is offline   Reply With Quote
Old 02-01-2020, 05:23 PM   #4
mongocanfly
Post Whore
 
mongocanfly's Avatar
 
Join Date: May 2015
Location: Alabama
Posts: 12,000
Re: Torque Converter question?

Or call the converter manufacturer, give them the info they need , they'll tell you what you need...
But also agree with all above...you need your full cam specs...along with alot more info on the truck..

I used to run a vega convertor ( approx 2200 stall) behind a flat top 350 with 500/300 cam...worked good with 5.13 gears and t350
__________________
Mongo...aka Greg

1981 C30 LQ9 NV4500..http://67-72chevytrucks.com/vboard/s...d.php?t=753598
Mongos AD- LS3 TR6060...http://67-72chevytrucks.com/vboard/s...34#post8522334
Columbus..the 1957 IH 4x4...http://67-72chevytrucks.com/vboard/s...63#post8082563
2013 GMC Z71..daily driver

Last edited by mongocanfly; 02-01-2020 at 05:28 PM.
mongocanfly is online now   Reply With Quote
Old 02-01-2020, 09:42 PM   #5
Ziegelsteinfaust
Registered User
 
Join Date: Dec 2012
Location: Temple City
Posts: 2,351
Re: Torque Converter question?

You'll want atleast a 2500 rpm stall to allow the engine to idle better.

We need gear ratio, and desired tire height too. These can crutch a engine with low torque, and move relatively ideal around the map. Also the cam duration is a big deal. More over lap the lower the torque, and bigger need for a high stall converter. Judging by the rpm band your in the neighborhood of 250 duration at 50 thousandths. Or roughly a duntov 3030 cam.

A deep gear ratio like 5.13's are less stall sensitive then lets say 2.73's.

2.73's will get more cowbell from a loose converter the. 5.13's.

Converters are fuzzy logic, and simple changes can have big effects.
Ziegelsteinfaust is offline   Reply With Quote
Old 02-01-2020, 10:13 PM   #6
garyd1961
Registered User
 
Join Date: May 2016
Location: Henderson NC
Posts: 850
Re: Torque Converter question?

Quote:
Originally Posted by Ziegelsteinfaust View Post
You'll want atleast a 2500 rpm stall to allow the engine to idle better.

We need gear ratio, and desired tire height too. These can crutch a engine with low torque, and move relatively ideal around the map. Also the cam duration is a big deal. More over lap the lower the torque, and bigger need for a high stall converter. Judging by the rpm band your in the neighborhood of 250 duration at 50 thousandths. Or roughly a duntov 3030 cam.

A deep gear ratio like 5.13's are less stall sensitive then lets say 2.73's.

2.73's will get more cowbell from a loose converter the. 5.13's.

Converters are fuzzy logic, and simple changes can have big effects.
The power range he quoted was for the intake not the cam.
garyd1961 is offline   Reply With Quote
Old 02-02-2020, 09:14 AM   #7
ChevyGearHeads
Registered User
 
Join Date: Jul 2010
Location: Anne Arundel County, MD
Posts: 104
Re: Torque Converter question?

Thank you guys! The Cam RPM range is 3,400-7,000 and I'm currently running 235/70R15 which will be replaced with something bigger eventually.
It should have the stock 3.73 rear.
__________________
Paul
'68 C10 327/TH350
LWB
ChevyGearHeads is offline   Reply With Quote
Old 02-02-2020, 01:34 PM   #8
garyd1961
Registered User
 
Join Date: May 2016
Location: Henderson NC
Posts: 850
Re: Torque Converter question?

Quote:
Originally Posted by ChevyGearHeads View Post
Thank you guys! The Cam RPM range is 3,400-7,000 and I'm currently running 235/70R15 which will be replaced with something bigger eventually.
It should have the stock 3.73 rear.
Did the truck come from the factory with an automatic or manual transmission?
garyd1961 is offline   Reply With Quote
Old 02-02-2020, 02:09 PM   #9
Ziegelsteinfaust
Registered User
 
Join Date: Dec 2012
Location: Temple City
Posts: 2,351
Re: Torque Converter question?

That cam is a bit extreme for 3.73's as the torque won't be there to move off the line nicely.

Let's figure your going to run 28" tires which will be roughly a 275-60-15 of a 7-8 inch rim. Since the tire size you listed would change to match the trucks whole concept now. I would seriously consider going big to 4.56 gears to allow the engine to be in its power band at 70mph, but also allow mechanical advantage for lack of torque off the line.

Your current combo of tire, and 3.73's puts you at 3100 rpm at 70 roughly which is below the cams stated power curve. Personally I would prefer to be right at the bottom edge of the power curve for better mpg or manners at speed. Factor in the manifold you have you need to keep air speed up for the carb, and engine to be happy. My friend ran a Duntov 3030 with 4.11's, and at 70 it would slow down going up hills due to lack of torque. Where as my torquey 350 didn't care about hills since I had tons of torque by comparison. Yes large hills like the cajon pass needed more throttle, but small ones didnt seem to make a difference to my 70 mph only cruise control system.

Lastly I would seriously go for a 3000-3500 rpm stall with the 4.56 gears to bring your combo into a happier zone. Plus invest in foam ear plugs, and then enjoy
Ziegelsteinfaust is offline   Reply With Quote
Old 02-11-2020, 09:18 AM   #10
68c10owner
Senior Member
 
68c10owner's Avatar
 
Join Date: Oct 2003
Location: Carmichael, California
Posts: 2,997
Re: Torque Converter question?

Quote:
Originally Posted by ChevyGearHeads View Post
Thank you guys! The Cam RPM range is 3,400-7,000 and I'm currently running 235/70R15 which will be replaced with something bigger eventually.
It should have the stock 3.73 rear.
Can you post the entire cam specs so we dont have guys guessing at what cam you got? Lift and RPM range isnt all we need. Take a pic of the cam card and post it.
__________________
Anthony
68c10owner is offline   Reply With Quote
Reply

Bookmarks

Tags
th350, torque, torque converter, trans, transmission

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

BB 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 10:39 PM.


Powered by vBulletin® Version 3.8.11
Copyright ©2000 - 2020, vBulletin Solutions Inc.
Copyright 1997-2020 67-72chevytrucks.com