Someone was kicking around the idea of a Predator carb on a 300 not long ago and I just happened to come across one on cl for cheap ($75). If you've ever wondered what the deal is with Predator carbs, and who among us hasn't, here you go.


Side by side with an Autolite 4100

Right off, it's freaking huge. The manual says it works better with a spacer - 1" is good and 2" may be better. I guess it's good I don't have a V8 or the Bronco might need a hood scoop. The throttle lever points to the rear of the engine when it's mounted correctly for a 4x4 and is gonna require some sort of bell crank (which Predator sells but might not work on a 300) or pulley, so that's a pita.

It's supposed to be variable venturi, changing depending on engine need. Pull off the air horn and it's easier to see.



Two spring-loaded air flaps close against the spray bar (what they call it) which has holes drilled along the length on both sides. Dunno if it's just because it needs a rebuild, but the air flaps are a lot harder to open than the secondaries on an Edelbrock. So the air getting drawn through is hugging the spray bar.



The throttle plates trap door together. The "bore" is 3.25" x 3.25".



Inside, it's a little less elegant than the Kendig on which it's based, but maybe less persnickety. Linkages connecting the throttle shafts instead of gears. The air flap shaft on the right passes through into the fuel bowl and controls the fuel metering. How much fuel passes is controlled completely by the air sucked into the engine.



The brass cam in the upper left is attached to the air flap shaft and rides on a ball-topped metering rod. The idle mixture screw next to it raises or lowers the entire metering block and affects mixture from idle to ~3,000 when the cam profile kicks in.

So there you have it. The Predator carburetor.

 

Wow..never seen a carb like that before. I'm running a 600 edelbrock on my 6..what is the advantages to a carb like this?

 

The theory is it works from 390 to 930 cfm. They're set up to run rich - the manual says to expect to lose some mpg - but very consistently which is claimed to help throttle response.

And if you remember back in the day Bigfoot ran Predator carbs before FI conquered the world. They're supposed to handle sloshing around better than Holley or Edelbrocks.

All hearsay and regurgitation of Internet searches for now.

 

Well..ya learn something every day

 

Are you going to put it on and see how it does?
They've always seemed like an intriguing carb. Thanks for going over it.

 

Ja, I definitely plan to give it a go one of these days. If there's one thing I love it's dicking with carburetors. The theory of a variable venturi is nice, how it works in practice is another matter. Most folks tend to dismiss them because "if they worked why does everyone who races have a Holley?"

They supposedly don't idle low either - manual says between 800-1,000 rpm. Eight hundred is tolerable with a manual tranny.

Legend has it the NHRA banned the old Kendig carb at Holley's insistence - they threatened to pull sponsorship, etc. Some old car mag had an article where they took an out-of-the-box Kendig and ran a tenth slower than a fully flogged (their words) Holley race set up.

Anyway, it needs a kit and a couple of other parts that don't come in the kit. The biggest thing I can see is the plate to which the metering cam is attached is worn and slips around on the shaft - so the cam hops around on the metering shaft. That's gotta screw up things. And is probably the reason it got shelved.

Then I'll have to figure out a throttle linkage or get a longer cable and come at it from the passenger side. But I figure a patient man with a wideband O2 sensor can make it work.

 

Took the thing apart to clean it up and got a few more pics. This thing is super simple.



Rubber strips seal the air valve doors and give in case of a backfire through the carb. Six screws on the side and one on the bottom hold the linkage plate to the body.



I ended up taking it all apart for cleaning anyway, but with a little care the whole thing come off intact.



The throttle shafts ride on needle bearings. It's easy to see here how the thing is designed to pull air right down the middle.





That white goop on the metering block is some kind of cement. Somebody broke it at some point. Probably overtightened it trying to lean it out after the cam slipped. No worries, the refurb kit comes with a new metering block. I'll be on the horn with Predator on Monday to see about the parts that don't come in the kit.

 

Fascinating. That's definitely like no other carb I've ever seen.
Rebuilt an Edelbrock a few days ago and at least I could figure out what was comparable to a Holley.

 

Just spoke to Predator and they're sending the extra hard parts I need. I asked him about setting one up for a 300 and he said they've done that before. He said something about taking three 351C heads and brazing them, mentioned the Clifford intake, asked what compression ratio I was running. Maybe 9 or 9.5:1, I says. Oh, he says, well if it's sloppy on the bottom with a 2" spacer don't be surprised if a 4" spacer clears it right up. A four inch spacer under this big ol's thing? That would be a sight.

Makes me wonder what an open spacer below the four-hole spacer under the Edelbrock now might do.

 

Wow, a tall, box carb on top of a tall, box spacer? Gonna look like a smoke stack sticking off of your intake.

 

used to run one down in texas. needed a carb to come out of river bottoms of the brazos river. very steep pulls for short distance up and down hill. once laid my truck over and she kept on idleling. we shut if off and was amazed how well it idled on its side. dispite the fact we almost died in a offroading crash! funny the things you think about when death is upon you. tried to mudrace with but could never get it to tune like a holley that is setup. but for all around beating around the predator was great and simple and easy to work on. mine ended up dieing because of salt water eating up carb and bolts stipped out. ran for about a year. also heard of people drilling out metering plate and jetting the holes smaller for better tune but not sure on this. the upper plated have springs on then and can be tuned also a little. one of the best carbs i ever ran in bouncy stuff in 4wds. they just don't tune as good as a holley.

 

AKA the Texas Trailer Park Tunnel Ram. Maybe I'll go with a 6" spacer, cut a hole in the hood, and stick a bug catcher on top.

They do sell leaner fuel bars and richer ones, so there is some adjustability. I'll see how it runs as is and see. Got a wideband O2 sensor, so with some patience I should get it figured out. I heard they handle off-road stuff well, which is nice on a 4x4.

 

Holy smoke, I can't believe it's been almost two years. Finally got the Predator carb all ready to go. Fabbed up a functional bracket to mount the stock cable and a bellcrank - bolts across the back of carb so it's oriented correctly in the intake. Picked up some of those fancy swivel linkage ends. Bolted the Predator to an extra intake with a spacer and the bracket and bench tested everything with the stock throttle cable to ensure it opens the throttle plates all the way. Success.

Swap out the four hole spacer on the truck for an open 1" spacer. Hang the throttle bracket/bellcrank on the carb studs so I can connect the gas pedal to check the slack and...my cable is about three inches too short.

>That's what she said!

That's what she said, indeed.

 

Glad to see this project is revived! lets see some pics once you got her hooked up. O got a buddy who said I should put this on my 300.

 

JBG sells a new, five-inch-longer cable for $28. I needed a pair of camber adjustment bushings anyway so it's on the way too. Spent almost as much on the dadgum linkage and cable than I paid for the carb in the first place. Hope she runs like a scalded dog.