#1  
Old 06-15-2020, 05:53 PM
footjoy's Avatar
footjoy footjoy is offline
Chief Ponti-yacker
 
Join Date: Oct 2009
Location: KC
Posts: 977
Default 6200 rpm in 1st and 2nd but will only do 5600 in 3rd

I have a friend who is playng with a 1/4 mile race car. Its a sbc any way he has a turbo 350 with 4.11 rear end. He does 6200 in the first two gears but can't go over
5600 in 3rd.

could it be in the fuel delivery?


Thanks

Greg

  #2  
Old 06-15-2020, 06:01 PM
Jack Ferris's Avatar
Jack Ferris Jack Ferris is offline
Ultimate Warrior
 
Join Date: Dec 1999
Location: West Jordan UT
Posts: 2,861
Default

Do you mean before he runs out of track?

__________________
Jack Ferris
RestoRacing LLC
www.restoracing.com
Sandy, UT
---------------------------------------------------
  #3  
Old 06-15-2020, 06:05 PM
Scott Stoneburg's Avatar
Scott Stoneburg Scott Stoneburg is offline
Ultimate Warrior
 
Join Date: Sep 2007
Posts: 2,179
Default

So youre saying that it pulls to 5600 in 3rd. Then falls flat or it just hangs there at 5600 for the last few hundred feet?

  #4  
Old 06-15-2020, 06:25 PM
footjoy's Avatar
footjoy footjoy is offline
Chief Ponti-yacker
 
Join Date: Oct 2009
Location: KC
Posts: 977
Default

Quote:
Originally Posted by Scott Stoneburg View Post
So youre saying that it pulls to 5600 in 3rd. Then falls flat or it just hangs there at 5600 for the last few hundred feet?
It just hangs there. Its done

  #5  
Old 06-15-2020, 06:32 PM
GTOGEORGE's Avatar
GTOGEORGE GTOGEORGE is offline
Suspended
 
Join Date: Mar 2003
Location: South Rockwood, MICHIGAN
Posts: 8,884
Default

Sounds like a fuel issue.....check your float level.


GTO George

  #6  
Old 06-15-2020, 06:53 PM
Scott Stoneburg's Avatar
Scott Stoneburg Scott Stoneburg is offline
Ultimate Warrior
 
Join Date: Sep 2007
Posts: 2,179
Default

I have had fuel delivery issues before. Usually happens in 2nd gear for me. But each car/fuel system act differently. Check floats like george mentioned. Then check pressure. Also depending on what type system and car make sure the tank vent isnt clogged.

  #7  
Old 06-15-2020, 07:32 PM
JC455 JC455 is offline
Ultimate Warrior
 
Join Date: Dec 1999
Location: Fresno,Ca USA
Posts: 2,005
Default

I'd guess fuel- My old 455 4 speed T/A would empty he Q-jet's bowl going into 2nd, then it'd fall on its face. Had to put an electric pump on to keep up with demand.

__________________
John
IG: @crawdaddycustoms
YouTube: https://www.youtube.com/channel/UCK9...Nc_lk1Q/videos
  #8  
Old 06-16-2020, 06:09 AM
steve25's Avatar
steve25 steve25 is offline
Ultimate Warrior
 
Join Date: May 2008
Location: Westchester NY
Posts: 14,633
Default

That's a unquestionable classic effect of having a fuel supply issue, either from the pump to the Carb, and or the G force action coming into play and slowing down fuel delivery from the tank pick up to the pump.

What 60 ft times does the car produce on average?

The faact is that if the car had a pump back at the tank then just a 1 G force launch or better ( quite common with slicks) will back down the fuel pressure .3 psi per foot of fuel line going up to the Carb.

If you concider then the fact that the car likely has 15 feet of fuel line between the tank pickup and the Carb, and if the fuel pressure at launch was 6 psi then that 1 G force applied reduces that 6 psi down to 4.5 psi!

__________________
Wernher Von Braun warned before his retirement from NASA back in 1972, that the next world war would be against the ETs!
And he was not talking about 1/8 or 1/4 mile ETs!

1) 1940s 100% silver 4 cup tea server set.

Two dry rotted 14 x 10 Micky Thompson slicks.

1) un-mailed in gift coupon from a 1972 box of corn flakes.
Two pairs of brown leather flip flops, never seen more then 2 mph.

Education is what your left with once you forget things!
  #9  
Old 06-16-2020, 12:29 PM
ta man ta man is offline
Ultimate Warrior
 
Join Date: Apr 2006
Location: Clinton,Ontario,Canada
Posts: 5,348
Default

Maybe it doesn't make the power to pull that high? Need more specifics?

__________________

466 Mike Voycey shortblock, 310cfm SD KRE heads, SD "OF 2.0 cam", torker 2
373 gears 3200 Continental Convertor
best et 10.679/127.5/1.533 60ft
308 gears best et 10.76/125.64/1.5471
The Following 2 Users Say Thank You to ta man For This Useful Post:
  #10  
Old 06-21-2020, 07:24 PM
77 TRASHCAN's Avatar
77 TRASHCAN 77 TRASHCAN is offline
Ultimate Warrior
 
Join Date: Oct 2008
Location: 31May2013 Temporary home to the world's widest (that we know of) tornado. Lord, NO more Please...
Posts: 6,591
Default

AND just because it's turning 6200 in 1st and 2nd, doesn't mean it's got good power numbers there.

The less torque multiplication there is is higher gears, puts a bigger load on the engine, it may not have enough grunt to do much at even, 5600. AND, LOL sounds like it's a maybe a SBC 350???

__________________
1977 Black Trans Am 180 HP Auto, essentially base model T/A.
I'm the original owner, purchased May 7, 1977.

Shut it off
Shut it off
Buddy, I just shut your Prius down...
  #11  
Old 06-22-2020, 08:44 AM
footjoy's Avatar
footjoy footjoy is offline
Chief Ponti-yacker
 
Join Date: Oct 2009
Location: KC
Posts: 977
Default

Quote:
Originally Posted by 77 TRASHCAN View Post
AND just because it's turning 6200 in 1st and 2nd, doesn't mean it's got good power numbers there.

The less torque multiplication there is is higher gears, puts a bigger load on the engine, it may not have enough grunt to do much at even, 5600. AND, LOL sounds like it's a maybe a SBC 350???
You nailed it

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 -4. The time now is 09:51 PM.

 

About Us

The PY Online Forums is the largest online gathering of Pontiac enthusiasts anywhere in the world. Founded in 1991, it was also the first online forum for people to gather and talk about their Pontiacs. Since then, it has become the mecca of Pontiac technical data and knowledge that no other place can surpass.

 




Copyright © 2017