Fuel Injection for Judge - Pontiac GTO Forum
User Tag List

 1Likes
Reply
 
LinkBack Thread Tools Display Modes
post #1 of 17 (permalink) Old 03-22-2017, 10:30 AM Thread Starter
 
Join Date: Feb 2017
Posts: 29
Mentioned: 0 Post(s)
Tagged: 0 Thread(s)
Quoted: 5 Post(s)
Fuel Injection for Judge

I searched on here but haven't heard of many fuel injection their 400's. The 69 Judge I just got has a Holly drag racing carb and a big cam. I will have to get the exact carb from the build sheet and give you guys specifics for more recomendations. With the new fuel injection set ups (FAST, Holly, etc) is it worth it or should I just get a more streetable carb? I like to drive my car in all year around.

Right now we have it pretty dialed in. A friend of mine who knows how to tune carbs had it pretty dialed in but it is very cold natured. It does not have a choke. Once warmed up it fires right up and runs good, however, it has some hesitation under low rpm cruising and likes the rpms to be up to be "happy". It loves me hammering on it but the low rpm cruise it just acts like it wants to "go faster"...if that makes any sense.

Thanks.
nautoncall is offline  
Sponsored Links
Advertisement
 
post #2 of 17 (permalink) Old 03-22-2017, 11:33 AM Thread Starter
 
Join Date: Feb 2017
Posts: 29
Mentioned: 0 Post(s)
Tagged: 0 Thread(s)
Quoted: 5 Post(s)
I got more information. Its a Holly 4150 HP series. 72 fronts and 74 rears. Not sure CFM but at least 750.
nautoncall is offline  
post #3 of 17 (permalink) Old 03-22-2017, 05:32 PM
 
PontiacJim's Avatar
 
Join Date: Dec 2012
Location: Gastonia, NC - Born & raised in Connecticut - 31 years
Posts: 3,652
Mentioned: 1 Post(s)
Tagged: 1 Thread(s)
Quoted: 390 Post(s)
Garage
Well, I am not a Holley guy, nor an expert, so I had to web check your carb. It seems the 4150 has mechanical secondaries which is not always the best for a street car unless you have some 3.90 - 4.33 gearing, high stall converter if automatic, or a desired close ratio 4-speed. Vacuum secondaries are much better for the street and offer a smoother transition when the secondaries do open as the engine demands more air/fuel. Mechanical secondaries just pop open immediately when you mash the gas and if the engine isn't pulling enough rev's/air flow through the intake, they open too quick and the engine can bog down or even back fire through the carb before it picks up again. This is why the need for the gearing or higher stall converter to help get the engine to rev faster more quickly.

Next issue could be the large cam - too big. Big cams are typically aimed at upper mid-to-high RPM's which sounds like what you have by your explanation. The cam profiles dictates your torque and RPM range where the power really turns on. For a street engine, you would be better off to select a cam for lower end-to-upper mid range RPM's. Not knowing any more about the engine or what is inside it, it would be hard to advise what to do.

The best carb/intake selection is exactly what the factory put on the engine, Quadrajet and matching intake. 750 CFM's, small primaries to cruise on, big vacuum secondaries to kick the power on. The small primaries can provide better gas mileage while pulling higher velocities of air/fuel creating a good transition for the vacuum secondaries to kick in.

So it may be you have the wrong carb for you application, the wrong cam for your application, or both. The first thing I would do is go with a vacuum secondary carb whether you stick with a Holley or go with a Q-jet/intake swap. The vacuum secondaries may help if the cam is a little too big.

Take my advice with a grain of salt and hopefully others will chime in, but that's my opinion on what may be going on with what you have. Fuel injection? No experience using any of the new systems.
PontiacJim is offline  
 
post #4 of 17 (permalink) Old 03-22-2017, 06:22 PM Thread Starter
 
Join Date: Feb 2017
Posts: 29
Mentioned: 0 Post(s)
Tagged: 0 Thread(s)
Quoted: 5 Post(s)
Pontiac Jim, just the thing I was wanting. I think I just need to change the carb first. That may be the simplest.
nautoncall is offline  
post #5 of 17 (permalink) Old 03-22-2017, 09:19 PM Thread Starter
 
Join Date: Feb 2017
Posts: 29
Mentioned: 0 Post(s)
Tagged: 0 Thread(s)
Quoted: 5 Post(s)
This is what was running before the went back to carb.

Click image for larger version

Name:	ImageUploadedByAutoGuide1490235578.696488.jpg
Views:	102
Size:	104.1 KB
ID:	88633
nautoncall is offline  
post #6 of 17 (permalink) Old 03-31-2017, 06:29 AM
 
goat1964-2004's Avatar
 
Join Date: Nov 2005
Location: Clifton Springs, NY
Posts: 26
Mentioned: 0 Post(s)
Tagged: 0 Thread(s)
Quoted: 1 Post(s)
Agree on the carb and cam. A big cam isn't the greatest for a daily driver.

1964 GTO Tripower / 4 speed
1969 GTO Ram Air IV / 4 speed
1970 Judge
2015 Hellcat Challenger
2017 GTS Viper
1957 Plymouth (Christine clone)
goat1964-2004 is offline  
post #7 of 17 (permalink) Old 04-01-2017, 08:33 AM
Super Moderator
 
BearGFR's Avatar
 
Join Date: Aug 2008
Location: Springtown, TX
Posts: 5,742
Mentioned: 0 Post(s)
Tagged: 0 Thread(s)
Quoted: 122 Post(s)
Garage
I agree. If the root problem is "too much" cam, changing to EFI isn't going to solve that problem. However, if the problem is all carb then it could help a lot. The ability to properly tune a carburetor is a dying art. It can be done, but you have to know what you're doing and understand the principles involved. I'm one of the weirdo's who happen to enjoy that sort of thing, but not everyone does or wants to. For them, EFI is a good alternative. I have a friend in my Pontiac club who recently converted his T/A to EFI, and he loves it. Is there any way you could provide the details on the cam? Also.... which transmission, what's your rear gear ratio, etc...

Bear

BearGFR
Springtown, TEXAS
BearGFR is offline  
post #8 of 17 (permalink) Old 04-02-2017, 09:02 AM Thread Starter
 
Join Date: Feb 2017
Posts: 29
Mentioned: 0 Post(s)
Tagged: 0 Thread(s)
Quoted: 5 Post(s)
Bear, I know an old "hot rodder". He's built my Cobra. He drove the car and said it's 100% the carb. He said this carb is perfect for my car and he took it apart and said vanes were wrong, wrong jets (a friend of mine who supposedly knew carbs rebuilt it). He said it was way to lean and all the problems were carb related. He's going to rebuild it and install MSD also.

I should've just take it to him to start with.

I'll keep you guys updated. Going to start a new thread on air conditioning because I want to add and it was not factory.
nautoncall is offline  
post #9 of 17 (permalink) Old 04-02-2017, 11:25 AM
Super Moderator
 
BearGFR's Avatar
 
Join Date: Aug 2008
Location: Springtown, TX
Posts: 5,742
Mentioned: 0 Post(s)
Tagged: 0 Thread(s)
Quoted: 122 Post(s)
Garage
Quote:
Originally Posted by nautoncall View Post
..... (a friend of mine who supposedly knew carbs rebuilt it).....
Man, if I had a dollar for every time I've heard that. The most common problem cause with Quadrajets (or any carb) is usually the last "expert" who touched it.

Bear

BearGFR
Springtown, TEXAS
BearGFR is offline  
post #10 of 17 (permalink) Old 04-02-2017, 03:16 PM
64-67 Expert
 
geeteeohguy's Avatar
 
Join Date: Feb 2008
Location: Fresno, California
Posts: 8,541
Mentioned: 0 Post(s)
Tagged: 0 Thread(s)
Quoted: 117 Post(s)
A LOT of guys over on the Corvette forum have tried out the various aftermarket fuel injection systems with very little success. Poor support, electrical gremlins, and very expensive. A properly tuned/calibrated Quadrajet will run as well as a fuel injected car without the problems. My '67 GTO has its original carb, and is as turn-key as any modern car. Very often, 'upgrades' made by non-experts lead many to believe that Quadrajets are a poor choice.....a bad mistake.
geeteeohguy is offline  
Sponsored Links
Advertisement
 
Reply

  Pontiac GTO Forum > The 1964-1974 Pontiac Tempest, Lemans & GTO > 1964-1974 Tempest, Lemans & GTO General Discussion

Quick Reply
Message:
Options

Register Now



In order to be able to post messages on the Pontiac GTO Forum forums, you must first register.
Please enter your desired user name, your email address and other required details in the form below.

User Name:
Password
Please enter a password for your user account. Note that passwords are case-sensitive.

Password:


Confirm Password:
Email Address
Please enter a valid email address for yourself.

Email Address:
OR

Log-in











Currently Active Users Viewing This Thread: 1 (0 members and 1 guests)
 
Thread Tools
Show Printable Version Show Printable Version
Email this Page Email this Page
Display Modes
Linear Mode Linear Mode



Similar Threads
Thread Thread Starter Forum Replies Last Post
Fitech fuel injection setup/ issues? lil65gto 1964-1974 Tempest, LeMans & GTO Engine Tuning and High Performance 17 03-27-2019 06:16 PM
Fuel Line Routing along Frame Rail, 69 Vert/Judge GTORAD 1964-1974 Tempest, Lemans & GTO Undercarriage, Frame, Transmission and Differential Discussions. 3 06-25-2015 11:44 PM
Fuel Injection Conversion...has anyone done it? Cletus 1964-1974 Tempest, LeMans & GTO Technical and Electrical Wiring 9 05-02-2015 10:35 AM
fuel injection? busaben 1964-1974 Tempest, LeMans & GTO Technical and Electrical Wiring 2 11-22-2008 03:42 PM
Alcohol Injection RamAir69 2004-2006 GTO General Discussion 11 08-04-2005 07:04 PM

Posting Rules  
You may post new threads
You may 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
Trackbacks are On
Pingbacks are On
Refbacks are On

 
For the best viewing experience please update your browser to Google Chrome