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Discussion Starter #21
Funny, the last Car I had that was carbed was my old CR 427. Since then, I've been involved with Megasquirt from the first group buy, I've only used EFI. I am just starting to build a MK-IV roadster and I have yet to ship the Engine to Thailand. In a few months it will be here with the car and all my tools, then I can get the harness built and connected to the MS3-pro ECU. It will be running ITB's from Pro comp setup for flex fuel, since E85 is plentiful here in Thailand.
I have one car on megasquirt. LS platform with a turbo. Runs quite well for being tuned by me. I've considered swapping out my A9L to Ms since I'm familiar.
 

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This looks interesting, but I suspect it might be one of those ideas that works better on paper than it does it real world. They claim you just tap into the existing fuel line but I don't see how it will generate the pressure necessary to atomize thru the injector. Will be interesting to hear some reviews.
I hadn't thought of that but that is an important point. Most carb systems recommend a fuel pressure regulator to keep the pressures around 6-8 psi but any fuel injection system is going to need a lot more than that. I guess you could tee off the fuel line prior to the regulator and connect the injector directly to the fuel pump.
 

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I ran my car for a few years with a Holley 650 DP (engine is a Ford Racing X302 crate engine). Generally ran ok, but there was a lot of fussing around. I often figured I had the jets, cams, choke, etc, perfectly tuned, and it would start and run like a top for a few days or maybe even weeks. But then some weather system or something would blow in, and it would run rough again. Starts and consistent idling were usually the problem areas. Always tinkering with it, looking for the perfect balance.

Admittedly, I live at 4,000 ft, and there are often significant changes in air pressure, as well as temperature. I mostly drive between 3,500 and 5,500 ft, and between 30F and 90F. I found it difficult to tune the carb to handle all of those conditions without hiccuping. I hated the feeling that it may not want to start again after a restaurant break, when far from home.

So I decided to give the Holley Sniper EFI a try (I’ve got it setup to handle the ignition too). Kinda looks like a carb, and the computer is inside the body, so it’s clean. It took a while to install it properly, but once that was done, wow, what a difference! Now it always starts on the first try, hot or cold, idles perfectly, never stalls, and is able to handle any changes in pressure and temperature. As well, the engine temperature is far more stable, even when I’m stuck in lengthy standstill traffic with the air-con running, whereas it used to start climbing pretty high with the carb. Of course, the fuel control is a lot more precise, so the fuel smell is far less pronounced now, and my gas mileage has improved quite a bit, especially when I’m “on it” for a while. The only slight drawback is that the carb seemed to pull a tiny bit harder at WOT at high RPM, but the EFI seems to improve torque a bit at low-to-mid RPM. Barely perceptible, but since I don’t tend to drive around at WOT all the time (anymore... too many demerits... :frown2:), so I’m not too concerned about that.

I initially tried to save some money by using my existing MSD disti, but after much f’ing around, I finally bit the bullet and got the Sniper distributor. Instant improvement! From experience, I would highly recommend anyone to just get the recommended disti to match your EFI right away, so as to not waste your time. It’ll save you a lot of frustration. Also, be very aware of any EMI in your engine compartment; I shielded all my cabling.

Guess I just proved to myself why all the actual car manufacturers, performance or not, went to EFI years ago. Might be different if I was at the track all the time, but since my driving is all street-driving, in a wide variety of conditions, this is working better for me at the moment.
 

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Yep.

Originally had the stock speed density EFI setup, then moved up to MAF with 42lb injectors, pro M, hi flow pump with a Vortech blower. In the end, wanted a period correct look. Haven’t had any issues with the carb drivability.



I'm running a 289 Hi-Po with an original dual quad Carter set up. They run just great and I love the look.



John O
 

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Carb!

I'm old school with a 600 Holley DP and a dual point Distributor.
 

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On my first FFR roadster, it was a lot of used mustang parts including a really screwed up efi system. It took quite a while to sort through the sensors, which ones to block and which ones can be cut out. Eventually the computer crapped out but not before sending me and others on wild goose chases (is it the injectors?). Sold it and was not sad about it. Built a 23 T-Bucket next and all carb. What a pleasure but what a nightmare to drive anywhere (large rears and small fronts).
Now I am back with FFR and with my Mk IV, it is all carb as well. Might change it out one day but not yet. It's just so right!
 

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I made the switch from carb to the Holley sniper. Had a few bugs at first I had to work out but overall happy with the switch. Big difference in throttle response and perfect starts every time
 

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Just my $.02 -- A carb is only tuned right once in a while. Old Ford 302 EFI is OK if left stock. The 4BBL EFI are better. Add timing control, even better. Port EFI w/ timing control is great if you can't afford the stack EFI or a factory crate motor. I'm the guy with too much compression, too much camshaft duration, and too big heads. I have 535HP, 30 MPG, runs perfectly at sea level, perfect at 14,000 feet, starts every time, sounds angry, never dies, never floods, never needs a tune-up, annual oil changes, throttle response that will scare you, and you can let it sit all winter, reach in and turn the key and it will start and idle w/o touching a pedal. Sure, it's a little more work to set up, but your wife can drive it w/o knowing all your carb secrets. I had an early Edelbrock Pro-Flow. It was hard to tune because of my radical engine configuration. Once it was tuned, it was as easy to drive as a new Corvette and as dependable as a Lexus. I ran it the last 20 years on the same spark plugs. The new EFIs are all MUCH better. The difference between port injection and EFI carbs is wet vs. dry flow in the intake, injection timing, more balanced air distribution, maybe a tad more power, and better able to tune engines with questionable parts selection. If you price a new intake, carb, and distributor, Port EFI is not much more. One more thing. Stack - Webber style - EFI looks authentic and runs even better, but make sure your EFI controller (and tuner) has a tune for stack EFI. They carry much less vacuum at idle so "standard" tunes are way too rich.
 

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I have to run a carb due to the SCCA rules. But I have to say I just really love my set up. I guess I’m just an old school guy also, because I just really like the the idea of it, the way it looks, sounds, etc. Probably because this is how my cars were put together when I was a kid and I just really like it and it makes me feel good. I know this sounds kind of silly but it is what it is. I’m running a Holley 850 Ultra Double Pumper and it works absolutely fantastic. No hesitation, no bog. Great throttle response. Love it.
 

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This looks interesting, but I suspect it might be one of those ideas that works better on paper than it does it real world. They claim you just tap into the existing fuel line but I don't see how it will generate the pressure necessary to atomize thru the injector. Will be interesting to hear some reviews.
It's more like a supplement to the carb so it's only adding fuel when it goes lean. It can't cut fuel from the carb. As far as the injector, the carb is atomizing fuel under a vacuum really. Designing a low pressure injector to atomize at 5-8 psi shouldn't be that hard.
 

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Discussion Starter #32
Just my $.02 -- A carb is only tuned right once in a while. Old Ford 302 EFI is OK if left stock. The 4BBL EFI are better. Add timing control, even better. Port EFI w/ timing control is great if you can't afford the stack EFI or a factory crate motor. I'm the guy with too much compression, too much camshaft duration, and too big heads. I have 535HP, 30 MPG, runs perfectly at sea level, perfect at 14,000 feet, starts every time, sounds angry, never dies, never floods, never needs a tune-up, annual oil changes, throttle response that will scare you, and you can let it sit all winter, reach in and turn the key and it will start and idle w/o touching a pedal. Sure, it's a little more work to set up, but your wife can drive it w/o knowing all your carb secrets. I had an early Edelbrock Pro-Flow. It was hard to tune because of my radical engine configuration. Once it was tuned, it was as easy to drive as a new Corvette and as dependable as a Lexus. I ran it the last 20 years on the same spark plugs. The new EFIs are all MUCH better. The difference between port injection and EFI carbs is wet vs. dry flow in the intake, injection timing, more balanced air distribution, maybe a tad more power, and better able to tune engines with questionable parts selection. If you price a new intake, carb, and distributor, Port EFI is not much more. One more thing. Stack - Webber style - EFI looks authentic and runs even better, but make sure your EFI controller (and tuner) has a tune for stack EFI. They carry much less vacuum at idle so "standard" tunes are way too rich.
What efi are you using?
 

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I wanted my car to be old school like a Cobra. That includes, warm up, snotty when cold, have to pedal it now and then. I even push out of the garage so I don't rattle my wife's dishes. The kitchen is over the garage. That is all part of the fun to me, the experience, so I went carb. Tuning the carb was also part of the fun. Yes, I have better brakes and tires, so I'm a hypocrite to some extent.
 

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Back in college I wrestled with a Holley carb on my 69 Chevelle and for the most part it ran pretty well as long as I spent time under the hood. As a newbie for the cobra build I figured I would go with the reliability of EFI. I have a Holley Sniper EFI on my DART 347 and so far in the go cart stage it is much easier than I remember the carburetor being, however, certainly not hassle free. I have had to reprogram it several times because of stalling. I'm hoping that as I get it out on longer runs on the open road it will "learn" more and perform more smoothly.
 

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As you are finding out, both carbs and EFI need tuning. If you have to keep tweaking a carb, something is wrong with it. I haven’t touched mine for several years on a high strung engine. Road, autocross and track.
 

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I'm with Derald, old school.

I've been bitchin' at, cussing out and banging on carbs for almost 50 years now, way too late to change.

I've had four different Holleys on the current motor, 670, 770, 780 & 940 and keep eyeing the 750/850 Ultra XP but that's only because I want something new/different. The current 780 runs well, and starts with 2 pumps, warms up in a few minutes w/o a choke, cruises at 2,200 rpm and pulls to 7k.

Every now and then I run the numbers on an EFI system that I'd like, $4k is a beginning. Probably not going to happen.

Change is good but it makes you crazy and I'm a long ways down that road.

Jim
 
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