Carbureted LSX Forum Carburetors | Carbed Intakes | Carb Tuning Tips for LSX Enthusiasts

Confused As All Hell

Thread Tools
 
Search this Thread
 
Old Oct 2, 2017 | 07:15 AM
  #1  
Kurk78's Avatar
Thread Starter
Teching In
 
Joined: Aug 2017
Posts: 5
Likes: 0
Question Confused As All Hell

so this past swap meet, i picked myself up a Proform 650 CFM carb with manual choke and mechanical secondaries. This is to replace my terrible 1406 Edelbrock carb that was vacuum secondaries and it gave too much hesitation when punching it.

so me and my dad got this carb thinking it would work out great. we started the car and it's getting way too much fuel and i have to hold the throttle down to get it to turn over. in the process, we ran out of fuel in a total of 20 minutes trying to tune it.

im asking for techniques in tuning these carbs because me and my father are scrating our heads and throwing fits trying to tune this stupid thing. anyone out there able to help?
Reply
Old Oct 2, 2017 | 08:29 AM
  #2  
blackbyrd's Avatar
TECH Veteran
20 Year Member
Liked
Loved
Community Favorite
iTrader: (14)
 
Joined: Jun 2005
Posts: 4,641
Likes: 392
From: cookeville, TN
Default

broken jet tip?
Reply
Old Oct 2, 2017 | 09:04 AM
  #3  
Deguila's Avatar
On The Tree
 
Joined: Apr 2015
Posts: 115
Likes: 1
From: Ohio
Default

Hello, If I remember correctly these carbs are based on 4150 Holley platform. Have you checked float level in the bowls? If it backfired at any time in its life the power valve is probably blown. Been awhile since I messed with a carb, but used to run into this with 4150 a lot. Proform does have a tuning guide on line. Hope this helps.
Reply
Old Oct 2, 2017 | 03:57 PM
  #4  
Doug G's Avatar
10 Second Club
15 Year Member
Liked
Loved
Community Favorite
 
Joined: Aug 2010
Posts: 4,468
Likes: 195
From: Harford Co. Maryland
Default

I would tear it down and find out whats in it so you have a starting point of where you are.

Float level
PV
Bad gasket

All could cause the issues you're having.
Reply
Old Oct 3, 2017 | 12:43 PM
  #5  
jimmyp3353's Avatar
Launching!
iTrader: (3)
 
Joined: Aug 2009
Posts: 262
Likes: 1
Default

Too much fuel where? Idle? Part throttle? WOT? Do you have a wideband? What's your FPR set to?
Reply
Old Oct 11, 2017 | 12:19 PM
  #6  
pantera_efi's Avatar
FormerVendor
iTrader: (1)
 
Joined: Nov 2008
Posts: 2,155
Likes: 18
From: Santa Ana, CA. USA
Default Metering Block Gaskets

Hi Kurk, yes do the items check from the above "tech".

MY guess is that you will find the Metering Block Gaskets are damaged.

BUY JUST that gasket set (two of MB/Bowl gaskets) for much lower cost that a carb kit.

Test the Power Valve Diaphragm, I apply a "kiss" to this item after being cleaned.

Set the floats on the engine when in operation, I ALWAYS set the front bowl LOWER than the rear.

Lance
Reply




All times are GMT -5. The time now is 09:58 PM.

story-0
Topdon ONE vs. Artidiag 800 BT2: Which is the Diagnostic Tablet For You?

Slideshow: We take a close look at the ONE and Artidiag 800BT2 diagnostic tools from Topdon and the reasons to buy one over the other.

By Pouria Savadkouei | 2026-05-28 11:05:11


VIEW MORE
story-1
Gas Monkey Built a 6-Wheel Ferrari Testarossa With a Corvette LT4 Engine

Slideshow: The controversial Ferrari F6 swaps its original flat-12 for a Corvette Z06-derived LT4 V8 and sends power to four rear wheels through a custom-built drivetrain.

By Verdad Gallardo | 2026-05-26 18:23:54


VIEW MORE
story-2
7 Most Reliable High-Performance Engines GM Has Ever Built

Slideshow:These GM engines didn't just make huge power, they survived abuse, boost, track days, and six-digit mileage with a reputation for refusing to quit.

By Verdad Gallardo | 2026-05-21 16:45:27


VIEW MORE
story-3
Amazing '71 Camaro Restomod Is Modern Muscle Car Under the Skin

Slideshow: This heavily modified 1971 Camaro mixes classic muscle car styling with a fifth-generation Camaro interior and modern LS3 power.

By Verdad Gallardo | 2026-05-12 18:06:42


VIEW MORE
story-4
6 Common C5 Corvette Failures and What's Involved In Repairing Them

Slideshow: From wobbling harmonic balancers to failed EBCMs, these are the issues that define long-term C5 ownership and what repairs typically involve.

By Pouria Savadkouei | 2026-05-07 18:44:57


VIEW MORE
story-5
Retro Modern Bandit Pontiac Trans AM Comes With Burt Reynolds' Autograph

Slideshow: A modern Camaro transformed into a retro icon, this limited-run "Bandit" build blends nostalgia with brute force in a way few revivals manage.

By Verdad Gallardo | 2026-04-21 13:57:02


VIEW MORE
story-6
Top 10 Greatest Cadillac V Series Performance Models Ever, Ranked

Slideshow: Cadillac didn't just crash the high-performance luxury vehicle party, it showed up loud, supercharged, and occasionally a little unhinged...

By Pouria Savadkouei | 2026-04-16 10:05:15


VIEW MORE
story-7
Top 10 Most Powerful Chevy Trucks Ever Made!

Slideshow: Top ten most powerful Chevy trucks ever made

By | 2026-03-25 09:22:26


VIEW MORE
story-8
Hennessey's New Supercharged Silverado ZR2 Has 700 HP

Slideshow: Hennessey has turned the Silverado ZR2 into a 700-hp off-road monster with supercharged V8 power and a limited production run.

By Verdad Gallardo | 2026-03-24 18:57:52


VIEW MORE
story-9
Coachbuilt N2A Anteros Is an LS2-Powered C6 Corvette In Italian Clothes

Slideshow: A one-off sports car that looks like a vintage Italian exotic-but hides a C6 Corvette underneath-just sold for the price of a new mid-engine Corvette.

By Verdad Gallardo | 2026-03-23 18:53:41


VIEW MORE