Our '70 Camaro has a destroked 400 (386 CID), .646" solid roller, 11:1 compression, "Box Stock" Dart 230CC Iron Eagles with 2.08"/1.60" valves, and Edelbrock "Super Victor" intake.

Last season we had our 950 Holley off about 10 times trying to get it right. I went the best of a 10.90 with it. Finally after giving up on the 950 I swapped on a 750 Holley...The car ran the same.

Over the winter, I went against just about everybodys advice and ordered a Predator carburetor for it. It was kind of a nightmare getting my fuel lines and linkage to work, but we finally got it done late Friday night.

Without changing anything else on the car, I went a 10.85 the first pass, and a 10.83 the second pass.

After hearing everyone tell me what a piece of junk a Predator is, I ran faster with one the first time out than the Holleys ever went.

I had 3 different people rebuild the 950 Holley last year. Everyone thought they knew a secret. The "secret" was to take it off and throw it away...lol.

BTW, weather conditions were the same yesterday as they were when the car went 10.90 with the Holley.

Frank
http://www.geocities.com/max_wylde/70_Camaro.html

 

That's valuable information. David Vizzard (a guru as far as I am concerned) likes the Predator. To paraphrase what he wrote about it:the Predator makes a few percent less hp than a perfectly tuned conventional carb. But it will essentially do it out of the box, with minimal tuning.

Since most carbs are far from perfectly tuned, I'll bet there are a lot of combos that would go faster with one. I've never used one.

Rich

 

I've only seen them but never worked on one. What's the Predator's cfm rated at?

Trouble with the HP950 is that the numbers are misleading. It's really a 750 body on an 850 baseplate. Picking the right Holley carb isn't easy to do. There are multiple 750's or 850's to choose from. Using the wrong one gets poor results in mileage or performance and everyone tries to blame the carb. I use Holley list 8162 carbs. Everyone is selling 4781's on Ebay. The 8162 is a race carb and the list number has changed up to a new one. The 4781's are metered differently and have a choke. Both are 850's but both work differently.

Not saying your HP950 was a bad carb but maybe it just wasn't what your engine needed. Good luck with the Predator.

 

The Predator meters itself to draw anywhere from 390 - 930 CFM. It works off whatever the engine needs.

The 950 we had was built by a local carburetor guru. It was a converted Double Pumper with the choke housing milled off. We went through numerous jets, and squirter combinations. It is a 4 corner idle carb, with 50 CC pumps. We tried several power valve sizes (5" manifold vacuum), and even a plug in the primary with richer main jets. It was rebuilt once with a BG kit, and another time with an AED kit. We had 2 different sets of float bowls on it, and a few different metering blocks...As well as having the mating surfaces on the main body milled to make sure they were flat. I even tried the old "drill holes in the throttle plate" trick.
The big problem we had was this thing would steady dump fuel off the primary boosters at idle (or atleast where it should idle)...Because of all the extra fuel, it wouldn't ever idle correctly below 1500 RPM's

With the Predator, it starts easier, idles at 1000 RPM, and pulls like a beast right up to the 7600 RPM shift points.

We put waaaaay too much money in the Holley last year. This year we bolted on a $400 Predator and ran faster. We've probably got twice that in the Holley.

Thanks for the encouragement.

BTW, just incase anyone is curious...Yes, it does get alot of strange looks when we pull the hood off. Most people at our local track have never even seen a Predator...LOL

Frank

 

Duh! What's that box on your intake?

One of my carbs decided to keep flooding the engine through the boosters. I found the o-ring on the needle valve had failed and the needle/seat wasn't stopping the fuel from entering the float bowl. A rebuild means changing everything not just the gaskets. I keep a lot of extra parts with me at the track now.

The good thing about the Predator is the constant velocity design. Harley carbs have used that CV design for many years. I just didn't know what the max CFM was of the carb.

 

I tried a new set of Holley needle and seats, as well as the new ones from the BG kit, and the AED kit. I was looking pretty heavily in that area. That's also why I changed the bowls/float. I was thinking my brass floats had developed a hole...eventhough they didn't seem like it. I changed them just to eliminate the possibility.

Frank

 

If I can ask, why did you decide to go with a destroker 400 - for high RPM horsepower? That's an impressive car you have there. Just curious as to why you went with less cubes than say, stroking the 400 out to 420ci or so.

 

The engine was originally destined to go in an untubbed /stock suspension '77 Camaro. I didn't want all the low end torque of a stroker, and it was also supposed to be a street motor, so I didn't want all the RPM of a 377 (350 stroke in a 400 block).
I found a 386 forged rotating assembly from Speed-O-Motive with a 4340 3.56" stroke crank, 6.125" 4340 H-beam rods, and JE Flat-top pistons. I figured it fit what we were trying to do pretty well. The block is a .030" over 400 block (4.155" bore). The cam is a Lunati solid roller with 268-276* @ .050" / .646" lift with our 1.6 rockers.
Low end torque? I can "burp" the throttle and yank the front wheels 6" off the ground.
High RPM? We're shifting at 7600 RPM's.

I'll tell you pretty straight forward that I'm not a fan of stroker motors...Rather they be a 350 block or a 400 block. I've seen many 355 LT1 cars run circles around 383 (or larger) motors. The '70 wouldn't have ran any better if we built a 420+ cube motor.

The car still hasn't seen it's full potential. It needs more gear. We've only got 4.88 in it with 30" tall tires. It needs 5.13s. It also needs an air pan to draw the air into the scoop...and a few other things.
It's cutting 1.52 60 FT. times on 30x10.5" slicks...leaving on the footbrake at 3000 RPM's.

Frank

 

So you don't like 350's then? A 350 is a stroked 327 which is a stroked 302. They all share a 4" bore. They all used 010 castings. What's the difference?

Cubic inches is cubic inches no matter how you get them. Stroke builds torque, bore builds HP. A 302, 327 and 350 all using the same parts would make the same hp but torque would increase with the stroke.

 

An equally preppared 327 and 350 will run pretty close to one another. A 302 likes to be spun a little faster to make the power.

Frank

 

Frank - seems like you really thought out your combo well. I'm looking at a possible new motor for this year, and your combo has given me some ideas. Sure looks like a strong runner!

 

"Low end torque? I can "burp" the throttle and yank the front wheels 6" off the ground."

If you're only cutting 1.52 60' times I wonder why mine won't yank the tires at the track... I leave the line on the nitrous and it's cut a best of 1.51 60' but it's not pulling the tires and I have a drag suspension. This is in a fairly light '70 Nova. Nice combo you've got there, btw.

 

The Predator works well for you because your combination has low velocity. The VV design of the Predator compliments the 230cc intake ports, long rods and 3.56 stroke. The "950" if it had been performing right would have been happy with a 6000 converter and 4.88 - 5.13 gear. Predators are good max effort carburetors for smaller engines and ones with less intake velocity that are expected to run over a broad powerband. The main obstacle to the Predators acceptance really is its unique looks and lower precision fuel metering design. I suspect there will be a small resurgance in Predator use as everything old becomes new again. They had some following in the 80's.

 

Where shall I begin to tell the story? Way back in 1992 I had a Speedomotive 415 short block, bodie 215 cc heads, 246* @ .050 with .575 lift Isky hyd. roller cam, Victor Jr., a 750 Holley DP(sawed off air horn) and tried both Predator carbs (street and race), 1 3/4" Hooker supercomp headers, turbo 400 with a 10" 3500 ATI converter, Ford 9" with 3.70 gears Detroit Locker in a 82 TA that weighed "3750 lbs". with driver. Raced the car in "Drive" off the foot brake (the little man did the shifting in the trans @ 5900) and never saw more than 6200 rpm's at the finish line. Car got 17 mpg at cruise. AND NOW FOR THE REST OF THE STORY When I first tried the Predator; I said Holly$hit with 1/4 of a gas pedal it felt like the 750 at full pedal, but after much tuning both Predators were still a tenth and a half slower than the tweeked 750 at the track. An out of the box new 750 was a half second slower than the tweeked 750. AND NOW THE FINAL ROUNDUP At 3750 lbs. on 93 octane gas and no more than 6100/6200 rpms at the finish line back in 1992 and the car ran within a tenth most of the time can we say: 11.0's at 123 mph. with a best of a 1.47 60 ft. with one wheel 2 inches off the ground (28.5" by 10.5" Firestone's at the time slicks on 15" by 7" wheels). PS: That was the first smallblock that I builted and sold, now I have my first street big block that I builted and installed in the car back in 1995 which is in my sign.