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This may be sacrilege, but I'm rebuilding a numbers matching 70 ls6 454, and I want to drive it without issue after its been sitting for a few months. Also, my wife doesn't want the smell in the garage. Since it costs a lot more for a divorce, I'm putting in the Holly Sniper kit. When I get ready to sell it. The old carb will go back on.
 

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I agree with pretty much what everyone has said in this thread and I would do it again. Its not for everyone and saving money big picture wise isn't likely so I always try to convince people that that alone isn't a good reason to do EFI.

I don't think I had my handheld controller hooked up more than one time last year and I know its had not yet been plugged in this year and I really like that fact. Its just been working. Actually its been working so well that a lot of other issues with the car have started to really bug me. Just about every time I accelerate I think how nice and smooth it is except for the vibration in the tires and the rattle and the squeak int he dash and the non working speaker and the non working heat or ac and the ........


1975 was a year that Cadillac had a 6 jet Quadrajet. Would that make it a hexajet? I don't know if any other makes used it and I think it was just part of 75 that Cadillac used it. I had a 73 and a 75 almost identical cars except for that carb. That 75 got dang near 20 mpg mixed driving while the other ones would be lucky to get into the low teens.

One of the extra jets was for altitude and I think that was an option on other cars but you only got it as the high altitude option, not on all models like this one year Cad. The metering rod for the jet was hooked to and controlled by what they called an aneroid which was basically a metal balloon.

The other extra jet and variable metering rod I think they called a part throttle compensator that must have had some different vacuum signal than the primary metering rods.

I have heard that they were very difficult carbs to get tuned and running right and very easy to abuse and screw up. Mine was a low mile original car that I don't think had been apart before I took it apart. I was very careful and apparently got it back together correctly.
 
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Gotta tell you, I have a $4k Holley EFI/fuel sys on the Chevelle, and it runs stupendous. BUT, that Holley 950HP carb was just as responsive for $300.00 used lol!!!! It would be hard to give up all that datalogging, rev limiters, ignition control, safety systems, etc.

But then again, if you drive the car ~1000 miles a year, why complicate things more than they need to be? Carbs do work pretty darn good....
Hit the nail on the had with this.
That is how I feel myself LOL

Also I sent you a PM, I am curious about your windstar fans.
 

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I've put the cheap 400 hp fitech unit on stock '72 c10 with a 350 that previously had a quadrajet. It was a pretty sizeable improvement, though I can't speak about the mileage as it's not my truck. That said, I took a well tuned 850 dp off the 468 in my chevelle and put a street demon 750 on it. I have not compared mileage yet, as I don't have it fully dialed in. By watching my gas gauge, it seems to be better than the 850, while not giving up a noticeable amount of power. The reason I mention the street demon as it has really good manners and cost me $355 or so. It's not as good as efi, but (assuming you already have a carbureted engine) it's a fraction of the price. I could make a case for either efi or carbs, I'm quite comfortable with both. If you get good quality stuff, you won't go wrong with either.
 

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I don't regret going from carb to the Holley Sniper system. My reasoning was that I was going to have to buy a new carb anyways when I dropped in the small block 400 going from a fairly stock 350, so why not?

Of course, just the "master kit" wasn't enough to get the EFI going. And also I decided to pick up the dual sync distributor to be able to control timing. I spent probably 4-5 times as much as i would have just buying a nice holley carb and being done with it. But I love a challenge and learning new things. As a car guy, isn't wasting money a hedonistic pleasure of ours?

I do regret wasting quite a bit of time chasing down what I believed to be a tuning issue for the better part of last summer, which ended up being fuel starvation on acceleration. My car would only behave if i had 3/4 tank of gas or more.

Do yourself a massive favour and just buy an EFI tank if you decide to make the switch to EFI. You will thank me in the long run. I now am running a holley hydramat on a RobbMC 1/2" pickup. The pickup, hydramat, and submersible tube probably cost me just as much as an EFI tank would have. Still considering going to an EFI tank as FiTech has some very affordable options.

https://imgur.com/t1JYALn
 

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I like EFI because you can drive at elevations ranging from sea level (CA) to 12,000' (CO) and the EFI will adjust. No way to tune a carb to run well across that range! I've heard that Cadillac used an altitude compensating Q-Jet carb on some of their engines. If you drive somewhere flat, a carb can be tuned to run well. Factory EFI is a big reason I went LS.
You get it! There is no way to tune a carb to run well across that range.
 

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Do yourself a massive favour and just buy an EFI tank if you decide to make the switch to EFI. You will thank me in the long run. I now am running a holley hydramat on a RobbMC 1/2" pickup. The pickup, hydramat, and submersible tube probably cost me just as much as an EFI tank would have. Still considering going to an EFI tank as FiTech has some very affordable options.https://imgur.com/t1JYALn
Edelbrock makes an EFI sump kit (https://www.edelbrock.com/adjustable-universal-efi-sump-fuel-kit-67gph-35-90-psi-36031.html) that might help when using an OEM carb tank. But I agree that an EFI tank with an in-tank pump is the way to go. I used a VaporWorx controller (https://www.vaporworx.com/documentation/vaporworx-pwm-fuel-controllers/) to increase pump life and eliminate the return fuel line.
 
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For me it was 30+ years of Holley carbs tuned for WOT, which means driving around town for a night out I'd stink up my clothes with rich fuel smells. After the switch, I'm EFI tuned for all RPM ranges and couldn't be happier. I don't think I gained horsepower vs carb but I did gain consistency in power range. I also have noticeable low end torque that I wasn't able to achieve with my carb setup for WOT. And my long distance travels where I'm out for 200 mile run, my gas mileage has improved from 11mpg to around 14mpg. There ain't no way I'm going back to a carb, even if the carb was free, no way.
 

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No Regrets at all....Holley Sniper

I actually originally did it because I couldn't us my AC with my 670 Avenger, it would just die when the compressor kicked on and there were no good idle up solutions. Also, cold starts in the spring and fall were a pain as I had to wait for it to warm up before I could drive it reliably...

All that is solved and gone. I had some glitches with EMI early on and learning to get the IAC set up for my car as well the timing control set up, but once I learned all that it has been a great thing...turn the key and it starts and drives! No reliability issues at all.

Anyone want to buy a 670 Avenger with electric choke and all sorts of spare parts?! Boxed up and ready to go!
 

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For me it was 30+ years of Holley carbs tuned for WOT, which means driving around town for a night out I'd stink up my clothes with rich fuel smells.
This was a big EFI benefit for me as well. The garage would stink for hours after cranking it up. My professionally prepped blow thru carb was awesome at the track but dead rich at cruise/idle.

Last night I finally made it to the track with the Super Sniper and it did awesome. I put a very conservative tune in it since it was my first time to the track with it and it is all done in seconds on the PC. No loosening the distributor on a scalding hot engine to adjust timing. No draining bowls to change jets. Not to mention air bleed tuning.

I know it is not for everyone, and it is definitely expensive but I am very happy with the Sniper so far.
 

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Without a doubt the best thing I've done!!!

What made me make the switch was when I forgot to turn the fuel pump on and ran the $700 Quick fuel carb out of gas, and when I turned it back on the back float stuck and filled the motor with raw fuel and hydro locked my $13k 540.

After taking the carb apart and drying the motor out and changing the plugs I swore to myself i'll never use a carb again.
I've got about $1600 in the sniper including tank, lines, pump and filter and had about $950 in the Quick fuel carb (without a choke) and electric pump so not that big of a difference if i would have gone Inj. from the get go.
I did sell the carb and pump so all was not lost!!
Do it you won't regret it!!
 
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