HOME FORUM RULES SPONSORS CONTACT
     
   
   
Go Back   CLASS RACER FORUM > Class Racer Forums > .90 Heads Up Class Racing Tech


Reply
 
Thread Tools Display Modes
Old 06-06-2021, 07:59 PM   #1
EVIL CLOWN
Junior Member
 
Join Date: Jan 2009
Posts: 34
Likes: 0
Liked 1 Time in 1 Post
Default Throttle stop carb adjustment

Just looking for some advice running a 540 on a number 1 stop carb is set up for power been banging bearings due to destination I donít have 02 or egtís just wondering if anyone has advice on tuning it for stop was told that when you put a stop under it gets very lean itís a 1250 carb I know everyone tells me itís to big not the best combo any help will be appreciated thanks
EVIL CLOWN is offline   Reply With Quote
Old 06-06-2021, 10:41 PM   #2
Jeff Stout
VIP Member
 
Join Date: Dec 2001
Location: phoenix
Posts: 1,196
Likes: 30
Liked 458 Times in 177 Posts
Default Re: Throttle stop carb adjustment

Lack of proper quality fuel can promote hammering bearings to death.
Jeff Stout is online now   Reply With Quote
Old 06-07-2021, 11:55 AM   #3
Tom Goldman
VIP Member
 
Tom Goldman's Avatar
 
Join Date: Jan 2003
Location: Allentown,PA
Posts: 2,307
Likes: 410
Liked 359 Times in 112 Posts
Default Re: Throttle stop carb adjustment

Fuel and timing would be the first place to look . especially if you use a grid and pull timing out on the stop . cylinder pressure skyrockets up and can kill bearings [and cranks]. and yes that knowledge is from personal experience.
That said , the carb is way too big for a 540. again ,I speak from experience .
I've had 1050's 1150's 1250's on 1000hp 565's and found the 1050 to be the best all around for the Stinnett under carb stop I run.
All of the above carbs were from name shops and all ran lean when on the stop.
I recently put on a 1050 carb from ATM Innovations . It is the first carb to not go dead lean on the stop, pulls great off the stop with no lag in rpm gain and has a great fuel curve for the entire run. and I lost no MPH over the 1150.
Plus they were great people to deal with .
__________________
Tom Goldman 1500 SG , 1506 STK
Tom Goldman is offline   Reply With Quote
Old 06-07-2021, 08:44 PM   #4
EVIL CLOWN
Junior Member
 
Join Date: Jan 2009
Posts: 34
Likes: 0
Liked 1 Time in 1 Post
Default Re: Throttle stop carb adjustment

The carbs that I run are done by CFm and book very good carbs to big for stop racing irk very well off stop I know these guys donít do stop carbs just looking to adjust what I have I run vp c 14 fuel trying to see if anyone knows when they go lean on the stop is what Iím thinking but what do I know need to put a 1050 on it in the future timing is 37 degrees and we donít pull any timing out on the run motor runs 8.40s in 3080 lb car makes 1004 on dyno
EVIL CLOWN is offline   Reply With Quote
Old 06-08-2021, 09:40 AM   #5
Tom Goldman
VIP Member
 
Tom Goldman's Avatar
 
Join Date: Jan 2003
Location: Allentown,PA
Posts: 2,307
Likes: 410
Liked 359 Times in 112 Posts
Default Re: Throttle stop carb adjustment

Quote:
Originally Posted by EVIL CLOWN View Post
The carbs that I run are done by CFm and book very good carbs to big for stop racing irk very well off stop I know these guys donít do stop carbs just looking to adjust what I have I run vp c 14 fuel trying to see if anyone knows when they go lean on the stop is what Iím thinking but what do I know need to put a 1050 on it in the future timing is 37 degrees and we donít pull any timing out on the run motor runs 8.40s in 3080 lb car makes 1004 on dyno
Without fuel data ,it's difficult to focus the cause ,or the time of detonation, If that is what is causing the bearing issue.
Are the spark plugs also showing signs of detonation? they should if the detonation is bad enough to cause bearing damage.
several carbs I've run have gone as lean as 15.3 AFR while on the stop ,running the same timing and fuel with 16 to 1 compression and conventional heads , not that any two engines want the same timing ,especially with your car weighing 700#'s more than mine.
__________________
Tom Goldman 1500 SG , 1506 STK
Tom Goldman is offline   Reply With Quote
Old 06-08-2021, 07:30 PM   #6
EVIL CLOWN
Junior Member
 
Join Date: Jan 2009
Posts: 34
Likes: 0
Liked 1 Time in 1 Post
Default Re: Throttle stop carb adjustment

The plugs are showing signs thanks fo your help probably going to run no stop until I get some o2 s going to call some carb guys this week that do carbs for stop racing donít know if I will get anywhere then send me your carb or I can sell you one Iíd like to put a stunner 1050 on it but not buying one now
EVIL CLOWN is offline   Reply With Quote
Liked
Old 06-08-2021, 08:49 PM   #7
Tom Goldman
VIP Member
 
Tom Goldman's Avatar
 
Join Date: Jan 2003
Location: Allentown,PA
Posts: 2,307
Likes: 410
Liked 359 Times in 112 Posts
Default Re: Throttle stop carb adjustment

Quote:
Originally Posted by EVIL CLOWN View Post
The plugs are showing signs thanks fo your help probably going to run no stop until I get some o2 s going to call some carb guys this week that do carbs for stop racing donít know if I will get anywhere then send me your carb or I can sell you one Iíd like to put a stunner 1050 on it but not buying one now
Talk to the people at ATM. I'm sending them one of my QuickFuel 1150's to them to do.
Very good people to talk to, and they really do know throttle stop carbs.
__________________
Tom Goldman 1500 SG , 1506 STK
Tom Goldman is offline   Reply With Quote
Old 06-10-2021, 07:11 AM   #8
Charlie Yannetti
Member
 
Join Date: Jan 2005
Location: Alpine, NJ
Posts: 449
Likes: 40
Liked 50 Times in 22 Posts
Default Re: Throttle stop carb adjustment

I'm running a 1250 by DC Carbs on my 565, but I have a bit more HP than you, and my car is almost 1000 lbs lighter than yours.. I just don't have Tom's compression at 14.5 to 1.. on the stop my O2's get to about 13.9 to 14.1 or so.. I also changed from VP C-14+ to VP X-14 with positive results... no tuning changes, and picked up 1 MPH..

I have also been told by many that 1250 is un-necessary on my combination, and that a 1050 or 1150 would probably work better.. next test and tune, I'm going to back to back my 1250 with the renovated 1150 from my 522 motor.. bigger isn't always better, but some carb builders go by HP numbers.. at 1004 HP, I would say that 1250 is not for you, especially at 3000 lbs..

Running lean while on the stop is kinda the norm, but if you're banging bearings, and possibly hurting the crank, I'm not thinking that running lean for 2 to 3 seconds is your problem.. but that's just me..
Charlie Yannetti is offline   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

BB code is On
Smilies are On
[IMG] code is On
HTML code is Off

Forum Jump


All times are GMT -5. The time now is 02:14 PM.


Powered by vBulletin® Version 3.8.11
Copyright ©2000 - 2021, vBulletin Solutions Inc.
Copyright © Class Racer.com. All Rights Reserved. Designated trademarks and brands are the property of their respective owners.