Some Carb Advice

On 351's I've used both 600cfm and 750cfm. I think you get a little better top end with the 750, but slightly better low end throttle response with the 600. It's a pretty close call between the two. Personally, I prefer the 750.

Your fuel pump is way too big. The A1000 provides far more pressure and volume than you'll ever need. It's designe to feed a

1300hp race motor. It's large size makes it difficult to mount, and it's pretty noisy. I have one on my Cobra project. It's feeding a 427W, with a stack EFI and making somewhere around 550hp. And I think I probably could have used a Tsunami ppump just fine. Oh, well. Live and learn. Seroisly consider the A2000, so you have a built in pressure regulator and don't need two fuel lines - feed and return. The Street/Strip 11203 with an external regulator is also an excellent choice.

"David Eaton" wrote in a message:

What cam are you using? I'm using a Comp Cams Extreme Energy 31-254-4 which is .554/.558 lift and .294/.306 duration, running 10.0 compression, with

351W heads, and the Holley 4150 HP (750 DP) works great for me. The only difference from yours and mine, is I'm using the Torquer II (single plane) intake. The more lift & duration you use, the more carb you will need. It's also easier to setup a slightly bigger carb to run correctly than to try and make a slightly too small of a carb to work. Don't forget, this carb has 4 corner idle adjustment, which is a good thing.

Gary

"David Eaton" wrote in a message:

IMO a 650 DP would be the better overall choice for bottom & mid range torque & drivability and give away little if any to a 750 at higher rpms. More Torque is why an engine is stroked in the first place! FWIW Holley suggest a 650 cfm for a "HOT" 350 ci engine.

"winze" wrote in a message:

The original poster didn't mention which camshaft he installed, but he did state he installed AFR heads (depending on which ones he went with, some flow great without porting) and which cam he installed, a 750 HP might not be enough. My 302 with 10:1 .030 over pistons, stock 351W heads with mild exhaust porting, and a Torquer II intake with a 750 HP series carb works great. The jetting is 72's in the primaries, and 82's in the secondaries. What's the sense of spending all that money to get it to flow better, then hold it back with a too small of a carb? A friend of mine ran a 326 stroker with Brodix heads and a Victor Jr intake with an 1180 Holley. Now he's running an Hilborn manual fuel injection unit (on alcohol), on a 306 that runs in the low 10's. This winter we're putting the 326 back together, and trying the Hilborn unit on it. It should go in the low 9's. This is based on the fact that the car went a little over a full second faster with the 306 when he changed to the Hilborn unit and ran it on alcohol. The 326 ran low

10's, carb'd and on racing gas. In closing, you need to remember, with larger lift and duration cams, the valves are held open longer and require more fuel. The more fuel you can get into the cylinders the more power your going to make.

Gary

I agree it sounds like a combo that would want a 750 or 850. He may want to try one of the hp vacuum secondary ones in the name of a little less worry about low rpm torque loss. give the best of both worlds.

Holley generally quotes low and they can never have the anal "Not really into horse power but more want a 4 barrel for looks kind" wining about low end bog or loss of torque. A 750 vac was "way" faster than 600 on my

318 and still drove and had the same throttle resp> "winze" wrote in a message:

Hi there,

Thanks for your advice.

Here is the Cam: Ford 289-302 Xtreme Energy XE294H Cam

The tunability is what draws me to this carb. As I said, it may sound silly, but my car came with cruise control and I would like to make sure that works! If not, I may have to get a different carb for driving the long trips with. Central California is well know for financing almost everything on speeding tickets along I-5, and I do not want to be a victim.

Respectfully,

David Eaton

Hello,

Well yes the A1000 is a bit of overkill. I am an engineer by trade and well the foudation is everything. That is why there is a roll cage, subframes, tower braces, K-braces etc to strengthen the car. I wanted to rebuild this car to have a foundation that would be set regardless of what I do in the future. There is a chance that I may upgrade the engine to a 428 or even a 460 some time in the future. Basically, I wanted to have a good foundation so that any engine can be dropped in without having to redo anything else. As for mounting the fuel pump, well it is going into a fuel safe fuel cell made specifically for this application.

I need the dual feeds off the regulator for feed the dual bowls of the carb. Sorry if the wording didn't show this properly.

Respectfully,

David Eaton

Dodgem440 > state he installed AFR heads (depending on which ones he went with, some

Well the original poster plans on doing more street driving than wide open 1/4 mile blast's. You can dump fuel in by the gallon jug if you want but it's a waste without the air to mix with it, the speed at which fuel/air fills the cylinders does alot for torque & horsepower and the right size carb will do it better at real world rpm levels.

FWIW nascar 358's turn 9000 rpm & make 750 + HP all with a 750 DP, I doubt the original poster's 347 is even close to one of these engines.

Dodgem440 > state he installed AFR heads (depending on which ones he went with, some

.......and there are some stock class drag cars running 10's with factory autolite 480 cfm 4 barrel carbs!

"winze" wote in a message:

And your basing your opinion on what? What you read in a NASCAR magazine? Do you think for one minute the NASCAR guys are running stock Holley 750's? If you do, wake up and smell the coffee! If you can get one of them to give you the info, I'd be willing to bet those so called stock 750's are flowing over

1000 cfms.

Do you even understand how a carb works? If the optimum carb for a stock 302 is a 600, then why would you want to put the same carb or just a little bit bigger on a heavily modded stroker motor? Do you even understand that with higher flowing heads & intake, if you run too small of a carb, what it does? I'll tell you if you can't comprehend. A motor capable or producing lets say

500 HP, might only make 400 or 450. Why do you think the fuel injected cars get dyno tuned when they do some hefty mods? To get every bit of HP they can out of that motor. And what is one of the things they are setting? The fuel curve, and timing. All I can say is, I'm glad your not my engine builder or tuner!

Gary

"Dodgem440" wrote in a message:

I have to agree with you. If he's worried about the low end grunt, the vacuum secondaries might be better suited for him, especially if he's running an automatic. In my situation, it's a drag car with a modded C4 (full manual, reverse pattern), the cam starts working at 2800, and I'm launching the car at 3000 rpm's. The redline is 7000 rpms, but I have the shift light set to 6800, for a margin of error of 200 rpms. Usually, by the time I see the shift light come on and I shift, it's already at 7000. After doing a couple hard passes, we pulled a couple spark plugs, and they were all a nice grey. If it was over carb'd, they wouldn't be grey.

Gary

"David Eaton" wrote in a message:

Dave: That's the exact same cam I have in my 306. I will warn you ahead of time, regardless of which tranny your running, set the idle to around 1000 rpms, or slightly higher. With the duration of this cam, it will lope pretty bad, below 1000 rpms. As for the cruise control hook up, you might be able to use the pin from your old carb, if its removable. If not, I'm sure your local speed shop can get you the parts you need to hook it up, or if your good at making stuff, make your own. I've seen guys just use a bolt and 2 nuts for the pin. Just find a bolt that will pass through the cruise control cable end, then turn on a nut with a lock washer, then push the bolt through one of the available holes in arm where your throttle cable hooks up, then put another lock washer and nut on, and then tighten the two nuts up when you have the cable lined up properly. That would be one way to hook it up. But if you want it to look more like from the factory, I'd get the proper pin.

Be sure to let me know how it goes when you fire it up the first time, and what you think when you take it up to the redline (7000 rpms) the first time. ;-) It will definitely put a huge smile on your face!

Gary

Thats a pretty wild cam for a 347 and any thoughts of drivability on the street would be secondary concern. The original cruise should hook up to any holley with minimal hassle, but whether it will work properly is another story, the cruise works off vacuum and your engine vacuum will probably be on the low side with that cam.

"winze" wrote in a message:

What's so wild about it? Because it has a lot of duration? I'm running the exact same cam in a 306 with the same compression ratio. As for the vacuum being low, have you ever heard of a vacuum reservoir? If that isn't enough, they also make a belt driven vacuum pump. Besides, the vacuum is only low at an idle, and the cruise control doesn't work at an idle. Actually, it won't engage until you get up to somewhere around 35 MPH, maybe higher, depending on the model.

Gary

"winze" wrote in a message:

First off, lets see what you actually know. What are they referring to when they state the CFM's of a carb? It's definitely not fuel flow! So it has to be air flow, right? So the recommended carb for a stock 302 is a 600 cfm. Now you install bigger and better flowing heads, with a little larger valves, a better flowing intake, lengthen the stroke, and install a cam with more lift and duration, and you think it only needs an extra 50 cfms? Did you ever stop and think that maybe there are future plans for trips to the drag strip? Secondly, do you really know how a carb works? Fuel is not dumped in, it's drawn in by the air moving through the venturi. As for the speed at which air/fuel filling the cylinders doing allot for torque and HP, you forgot quantity. You have to fill those cylinders with the air/fuel charge to make more torque and HP, and a smaller carb is just going to slow the process down, resulting in not getting enough air/fuel in the cylinders. And don't forget, the cam this guy installed will produce a redline of 7000 RPMS, maybe more, depending on the spring pressures on the valves. There's more to determining which carb to use than just the bore & stroke of the motor. Allot of things needs to be taken into consideration, and some trial and error. If he has a few different carbs available to him to try, he may find that the 750 may not be enough.

Gary

If you knew anything, you'd know that the carbs are very controlled by nascar rules,I'd say closer to box stock on airflow.

Man you are just FULL of big numbers! Save it for your next bench racing session! You are "old school" bigger is better,slap on another part if it doesn't run right, wanna be engine tuner/builder blow your on horn wanna be drag racer!

"winze" wrote in a message:

If you beleive that, I have the Golden Gate Bridge for sale! If every NASCAR out on the track was running the same carb, with basically the same internal parts, they would all run the same, and all the cars would finish on the same lap, BUT they don't! Each team makes modifications here and there to wring out every bit of HP they can out of the motor. I guess the next thing your going to tell me they run a stock intake manifold. Guess again! The average person can't even buy one, cause they are specially made for each racing team.

Look who the F&!K is talking! When was the last time you raced, let alone went to the track? I'm at the track just about every week. If not racing my car, I'm there helping one of my friends. Now if you think I'm just a bench racer, go to

Now let's see aphoto of your car at the track, making a run! At least I can prove I dragrace! Oooh, by the way, when you look at the photo of my car, pay closeattention to the front tires. Only the center section of the tire istouching the ground. This was with the motor basically stock, other than theTorquer II intake, 750 Holley, and a built up C4 with a 3000 stall speedconverter, before I installed the new cam and different heads. If I get therest of the work done to the car I want to do, it will be going back to thetrack next month. Then I'll show you a photo with all of the front tires offthe ground. If a photo isn't enough proof for you, I'll try and have someoneshoot some video, and I'll make it available for download. Ooooh, and by theway, the car has always run right! The parts I've changed was to make moreHorse Power, not to make it run right, something YOU won't learn by readingyour NASCAR magazines, and your Motor repair manuals. Gary

YOU DON'T KNOW SHIT! Carb mods are illegal in nascar! every Cup car uses identical Holley carbs except for jets and the tune. Fwiw I live in the heart of nascar, Junior Johnson lives in the same county! & Mooresville is just down the road, not to mention the Petty's and Richard Childress Racing about an hour away And if you have the money it's possible to buy a competitive nascar legal race car. Nothing on them is "one off" everything on the engine can be bought! however they are all set up a little different as each team sees fit(following the rules) but the carbs are off limits to airflow mods! Honk,Honk!

BFD! front tires off the ground! I've seen factory engined 5.0's do it, that don't make it fast either! I guess it's good for bench racing talk or trying to impress the 4 cylinder pinto crowd! LOL