Injection is way over priced and doesn't really add much, if anything, and can add a lot more hard to trouble shoot headaches. They are worthwhile for playing with a lot of boost, and a few other rather niche applications, in my view and experience. They are also trying to combine injection with carbs, and if simple and cheap, and dependable enough, then there might be something there, but only time will tell.

 

Oh, I'd like to see this efi/carb combo. Sounds interesting.

 

Yeppers it does. Of course what else I would like is a simple injection system CPU box, that was reliable and cheap, and not a lot of input sensors required, like the original OEM TBIs used. But only China could provide such a thing, since they follow different economic models, to make their profits.

A carb is real hard to beat at this point, and certainly when you factor in price and reliability of something like the 750 Street Demons.

 

Mine is in the header collector before the gasket bolting it to the exhaust. Before removing the headers from the car, check fitment and location of the O2 bung in the collector. Slight angle up gets it close to the floorboard. Also check parking brake cable location before installing the bung.

 

Well crud. I'm not sure I can get my header out. I'll have a look when work lets up a bit. Thanks w8i.

 

You may be able to weld it into the collector with header in place. If not, and you can drop the exhaust right after the header, I would put the O2 right after the header.

 

I really don't know what your level of education is on this topic but it doesn't seem to be on par. Maybe you shouldn't post on these things.
And anyone want to guess why this guy used both carb and EFI on this?
Thanks.

 

Always trying to make yourself look bigger than you are aren't you, as well as trying make the up sell to the big ticket items with more bells and whistles. The Street Demon is pure poison to you and your game. Big tire burning power and huge mileage, and no computer or special wiring harness needed, and even the beginners can understand and tune LOL

From Hot Rod dyno testing a series of carbs and the little 625

We now have an option previously unavailable that sounds like a good fit for these types of builds—the new Street Demon. A 625 cfm version was tested here, but we were assured that a 750 version will be released shortly as well. We ordered ours with the polymer main body, so we could also test the claims of cooler fuel temperature advertised with them. We have to admit, we were pleasantly surprised when everything they advertise about a product proved to be true. We installed the Demon with its supplied plate, which is designed to help shear fuel as it leaves the slot on the idle circuit in the baseplate. Once we primed the fuel, the engine started easily, and the mixture at idle was nearly perfect at 14.0. In factory trim, we had the best idle and part throttle tuning, and our top end horsepower was on par with the best we had gotten with other carburetors after they had been tuned. Our cruise mixture was 13.8, and the top end was 13.2.We ordered the tuning kit with our Street Demon, so we would be able to dial it in as close to perfect as possible. With our low vacuum at idle, as soon as the throttle was cracked open, the metering jets would open, requiring a change to a lighter spring. The primary side of the Street Demon uses a metering rod/jet combination, while the secondary side uses standard Holley type main jets. Since our A/F was slightly lean for best power, we tuned the primary side for a nice cruise power mixture of 13.5, and as the Demon’s manual stated, we tuned the secondary jets for a good top-end A/F mixture. It took quite a jump in jet size to make much of a difference in the overall mixture. On a typical Holley, we would normally make jet changes in two stop increments. But the Holley-type jets in our kit were 86 and 90. With the factory installed jets being 80, we ended up moving up to the kit’s 86 jets, which proved to make a very small change in the mixture, so we moved up to the largest jets (90) to bring us up to a perfect A/F mixture for our engine of 12.5. We now had even better performance throughout our testing.While testing the modular Holley carburetors, we checked temperatures of the fuel bowl area after making our dyno pulls. The fuel bowl temps were always within 10 degrees of the intake manifold. With a water temperature of 180 degrees, the intake below the carburetor averaged 144 degrees. The fuel bowl was, on average, 134 degrees. The Street Demon kept the main body cooler, which is where the fuel resides, averaging 95 degrees. That much of a drop in fuel temperature should really help on a hot summer day when idling in traffic causes extreme under hood conditions to boil fuel.It is refreshing to see a company devote the research and tooling into making a nice improvement in carburetors for those of us that don’t want to make the switch to fuel injection. With the response and tuning ability of the Street Demon, it would be hard to beat for a nice, street-driven hot rod

https://www.hotrod.com/articles/carb...owing-results/

 

Quite the contrary, I have no problem with carbs. 90% of the builds I do are carbureted. I try to give the facts from first hand experience, consequently my opinions are based off my experience. It seems sometimes you’re a bit out of your element that’s all. Sorry.

 

Please tell up your first hand experiences with the Street Demons you have sold to people and tuned??

 

I wasn’t talking about those. I was questioning your statements about EFI, both early and later versions.
And my god have you ever known any of these magazines to ever print anything negative about a product from one of their advertisers? Really?

 

Overall the reviews for the Street Demon has been positive like the Quickfuel carbs. Obviously Quickfuel and others has improved on the old Holley design which was miserable anywhere near freezing and always seemed to have driveability issues. I know Holley did a bunch of improvements on the old Thermoquad with the new Street Demon like a 3 barrel design to fit square and spreadbore intakes, no O rings that always failed between the bowl and body, better choke, easier adjustment on the secondary air door and Aerospace main body instead of the old Bakelitel. Add one like a TPS also make electronic OD trans simpler to run. I actually ran a 800 cfm Thermoquad, some things good, some bad. The choke was a joke and the O rings failed. Changing metering rods was easy and fuel economy was good. I plan on trying a Street Demon 750 on the 424 SBO and will buy a wideband to tune it right. Cmon guys this isn't ROP.

 

The real secret to the AFBs or the street demons might lie with the metering springs. As you know the therrmoquad had a manual rod that pushed up the metering rods hanger, and not just springs working off vacuum. Some of the old AFB guys said there use to be a 10 inch rated black spring as well. Just a thought, and the ball point pen springs inside the regular springs, but stretched to the desired tension should work, if needed. I replaced the tiny e clips, with larger hair pin clips. Harder to loose, and you can disconnect with your fingers, or reinstall them that way as well.

 

I've been meaning to do this. I can barely see those e-clips.

 

There is no way I was going to try and deal with those tiny monsters, after I saw them mentioned in an article and then took a close look at mine, and I learned many decades back the hair clips worked fine, to replace them. In fact, I did that before I even took it apart, which made taking it apart and putting it back together a whole lot easier.

 

https://www.ebay.com/sch/i.html?_fro...ion=1500&rt=nc

all different sizes for all occasions, and with many then losing one is no big deal.

 

You don't happen to know which size you're using on the Demon, do you? I'm going to buy a kit but want to make sure the smallest is small enough. This will come in handy for the riding mower and other things around the house, as well. Are you in the U.S.? The link shows overseas items for me.

 

They are very handy, for anything that needs to just be held in place, and a lot of things are like that. In mm the wire diameter is about 1,38mm and about 24.6mm long, or about .057" on the wire diameter and .966" on how long.

That was a US Ebay link and yes I am in the US and I was born in East Texas.

 

You might find kits at a TSC, Farmfleet or auto parts store.

 

Weird. The first listings I see from the link are from the UK, Australia, and China. Sorry, I just assumed. Thanks for the measurements. I might just run by Farm & Fleet. I need house-winterizing stuff anyway. It's already 32* here this morning.