Converting 90 GT to carb - Ford Mustang Forums : Corral.net Mustang Forum
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post #1 of 18 Old 06-18-2017, 02:09 AM Thread Starter
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Converting 90 GT to carb

I know i'll need an intake, carb, air cleaner and an electric fuel pump . My question is what do I need to do to the electrical system? The entire EFI harness seems to be on my car. Car will be about 80% street and 20 strip. I really don't care about fuel mileage. It will use a 306 CID engine and manual trans....

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post #2 of 18 Old 06-18-2017, 10:07 AM
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The efi just runs so much better, you sure you want to go down this road on an 80% street car? Just leave the EFI on, it is a simple system that adapts well to modifications and there aren't really any combinations left that someone hasn't tried and got to work.

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post #3 of 18 Old 06-18-2017, 11:20 AM
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post #4 of 18 Old 06-18-2017, 01:41 PM Thread Starter
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That link had the exact information I was looking for. My reason for converting is that most of the EFI system is not with the car at all (also has no engine). Over the past 40+ years I've worked with numerous Holley carbs and pumps and whole carbs so this is really a low dollar answer to my situation. The state where the car is (Michigan) has no air quality testing at all......
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post #5 of 18 Old 06-18-2017, 03:29 PM
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I am doing carb now from efi. Just so much easier to tune and change things. Dont have to go to tuner every time something changes. This diagram helped me.
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post #6 of 18 Old 06-18-2017, 10:44 PM
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Stroked my 302 to 331 and I converted to carb. I am happy I did. You will end up deleting most of the EFI wiring like I did or just zip tie things out of the way like my buddy did. I took a lot of pictures did a lot of labeling and then pulled the the stuff I didn't need. The reason I did it that way was in case there was something in any of the harnesses that I needed but overlooked. Take your time think things thru and it's pretty simple.......
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post #7 of 18 Old 06-18-2017, 10:51 PM
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Originally Posted by bwdz View Post
The efi just runs so much better, you sure you want to go down this road on an 80% street car? Just leave the EFI on, it is a simple system that adapts well to modifications and there aren't really any combinations left that someone hasn't tried and got to work.
I completely disagree with this statement. In what way does the efi run so much better?
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post #8 of 18 Old 06-18-2017, 11:27 PM
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EFI is better.

Carburetor is a gasoline toilet.

I grew up with carburetors and would never go back to that #### unless it's some classic car that's too expensive to convert to EFI,lol.
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post #9 of 18 Old 06-19-2017, 12:48 AM
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there is a night and day difference between even the best OOTB holley and a BLP, Braswell, AED, QF, or any of the other custom/semi custom carbs that actually have decent emulsification packages and are suited for a given combo. After horrible luck with holleys when i was young i spent about 15 years thinking the technology of EFI was better. and in some ways in some applications it is, but technology in carburetor circuitry has come a long way. after watching a low power NA car pick up half a second in the 1/8th with an AED that is the same size as a holley HP we tried everything on, and even the holley tech line was out of ideas, i was sold on quality carburetors (for the right application.) not saying its right for every application, but ive run my AED 750 (no choke) in mid 30* weather after i nursed the throttle about 30 seconds with great results.
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post #10 of 18 Old 06-19-2017, 01:40 AM Thread Starter
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I'm doing a carb conversion due to the fact that it would cost too much money to keep the car EFI. Just counting the big missing parts I quit counting stuff I would need when I counted to $750. The conversion won't cost that by far. Not being real wealthy I have to really watch the costs of this whole car as I have an engine to build and may well have a clutch/ pressure plate to get as well as a steel bearing for the input of the T-5.........

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post #11 of 18 Old 06-19-2017, 09:13 PM
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I completely disagree with this statement. In what way does the efi run so much better?
I should just leave that alone but if you must know my reasoning then it basically boils down to the fact that a carburetor is like a toilet, it has a jet that allows some fuel to go down it to mix with air all while sitting on top of the intake and feeding all 8 cylinders while fuel injection actually meters the air, adjusts for temperature, throttle position and even adjusts based on the amount of oxygen in each side of the motor exhaust while injecting highly pressurized mists of fuel into each cylinder. If I have to explain any more than that we will just have to agree to disagree but just ask yourself when was the last time you could buy a car with a carburetor if they do such a great job of accurately delivering the correct fuel mixture that is atomized and burns so well? It is also the reason you don't have to put plugs in your car every 8-10k miles if daily driving, same reason you get great part throttle response, don't have to choke it etc.... I'd love to see you try to get someone to want a car today that needs plugs all the time and the carb adjusted and has to choke it or bleep the gas to get it started, the EFI on these cars with the distributor and all is crude enough but still much better than any carb could ever hope to be. Keep in mind the original poster is going to use this on the street far more than on the strip.
To the original poster. If you are not comfortable with EFI and don't care for a trip to a local u-pull yard then go whichever way will make the car more enjoyable for you. I am in Michigan also, Detroit area but I haven't run a carb on anything since my 1982 Monte Carlo that I got rid of back in the early 90s.
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post #12 of 18 Old 06-19-2017, 10:21 PM
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I'm so glad my carbed cars don't know they're supposed to suck so bad. Took my vert to NM last month on a 1800 mile road trip, from 500ft above sea level to 8000, from 30 degrees to 95. Averaged 20 mpg running the AC and it never stalled. Started everytime, and I never had to rejet or change the plugs. Crazy that obviously every other carbed car runs so bad.... With that said, for $1000 bucks some of these stand alone systems are looking might tempting.

I've spent the time trying to run down the gremlins on a 30yo hacked up EFI system, that sheet I wish on nobody. If it ain't there and working, carb or freestanding can make a lot of sense.
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post #13 of 18 Old 06-19-2017, 10:30 PM
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I should just leave that alone but if you must know my reasoning then it basically boils down to the fact that a carburetor is like a toilet, it has a jet that allows some fuel to go down it to mix with air all while sitting on top of the intake and feeding all 8 cylinders while fuel injection actually meters the air, adjusts for temperature, throttle position and even adjusts based on the amount of oxygen in each side of the motor exhaust while injecting highly pressurized mists of fuel into each cylinder. If I have to explain any more than that we will just have to agree to disagree but just ask yourself when was the last time you could buy a car with a carburetor if they do such a great job of accurately delivering the correct fuel mixture that is atomized and burns so well? It is also the reason you don't have to put plugs in your car every 8-10k miles if daily driving, same reason you get great part throttle response, don't have to choke it etc.... I'd love to see you try to get someone to want a car today that needs plugs all the time and the carb adjusted and has to choke it or bleep the gas to get it started, the EFI on these cars with the distributor and all is crude enough but still much better than any carb could ever hope to be. Keep in mind the original poster is going to use this on the street far more than on the strip.
To the original poster. If you are not comfortable with EFI and don't care for a trip to a local u-pull yard then go whichever way will make the car more enjoyable for you. I am in Michigan also, Detroit area but I haven't run a carb on anything since my 1982 Monte Carlo that I got rid of back in the early 90s.
A carburetor is much more effective than you're giving them credit for.......
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post #14 of 18 Old 06-19-2017, 11:18 PM
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A carburetor is much more effective than you're giving them credit for.......
exactly. its no longer 1985 and its funny how if EFI is so superior in every way why the Butch Kemp's Uratchko built SBF that made over 1200hp NA had a single 4500 on it. weird.

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post #15 of 18 Old 06-20-2017, 07:49 AM
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Carbs are junk! And slow!

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post #16 of 18 Old 06-20-2017, 07:57 AM
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exactly. its no longer 1985 and its funny how if EFI is so superior in every way why the Butch Kemp's Uratchko built SBF that made over 1200hp NA had a single 4500 on it. weird.

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Not that I care about this debate but I didn't see where that guy up there said anything about WOT performance. On a dyno you'll find little to no difference as long as you have a similar AFR, even fuel distribution to each cylinder, and similar flow rates. It's the cold start, hot start, neutral-cruise idle up, baro/map sensing, factory fuel distribution, AC idle up, Fan idle up, LTFT/STFT, self diagnosis, etc. that make efi superior for street cars and OEM's now.

I do agree that our ancient cars have issues with gremlins, hack jobs, etc. due to their age so I can agree with the desire for simplicity. For the price of a carb conversion though I'll go megasquirt every time (and I have twice now). One of my cars I converted from EFI car to Carb in high school, then to standalone efi with a one-off Throttle body injection system here recently.
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post #17 of 18 Old 06-20-2017, 09:39 AM
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Quote:
Originally Posted by cab0154 View Post
exactly. its no longer 1985 and its funny how if EFI is so superior in every way why the Butch Kemp's Uratchko built SBF that made over 1200hp NA had a single 4500 on it. weird.

All Motor All The Time For Butch Kemp And His Mustang
How much did the carb and intake cost for that set up? Don't forget the tuning tweaking and dyno time to get it there. I would also make a bet that it has decent electronics in it to log and monitor a bunch of different parameters.

One thing I do know is that carbs are more forgiving when it comes to tuning.I'm all about keeping a vehicle as it came from the factory.

Cases in point.......
I have an old 57 Chevy that has a carbed 350 sbc, the car has had the same carb on it for 27 years , it has never been rebuilt or even off of the car in that time. The car is as stone solid to drive as any other car in my driveway.

With the stroker set up in my 94GT, I went with a standalone(MSPNP2) set up. I just recently changed injectors and pump and made all the changes in tuner studio in about 2 hours give or take. Car runs and drives great. Tuning a car via tuner studio is not voodooo unless you want it to be. Not tied to a tuner is definite plus. Granted there is only one or two people I would trust to tune my car.

Painless makes new wiring harness to combat hack jobs, and stock parts can be had for cheap through the classifieds here. Heck I just sold a set of low impedance 42lb injectors for 175 shipped. Stock parts go for much cheaper.

Do as you will and have some fun and do some learning.

94 GT
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post #18 of 18 Old 06-21-2017, 05:21 PM
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I have worked with a fair amount of people on cam swaps. I can say, with experience, that tuning was so hit or miss with many of these 'typical' and popular combinations, that just one shop's best tune versus another's often resulted in 20-40 hp differences. Several of the these troublesome cars were switched to carbs because of the problems. The ability to tune and run was easier and the cars that were track cars were rewarded quicker ET's and better launches.
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