Looking at going back to a carb!!

[mike harter]

I have a holley 750 d/p on my 427w ford racing crate motor never a problem and dynoed at 545 hp

[joyridin']

I would love to ditch the carb on my engine and put an EFI set-up. With EFI, you can make it run however you want throughout the whole powerband.

I have nothing against a carb, but from a performance and driveability standpoint, fix the EFI.

[*13*]

600 is not too small, if you don't plan spinning higher RPMs. In fact, a 600 cfm carb will have a snappier response.
RPM range is really the key. If you are trying to pull large amounts of air through the carb(higher rpm) you will need larger cfm. If you have a larger cfm, lower volumes of air have a more difficult time pulling fuel out of the Venturis(poor response).
So, the carburetor needs to be selected for its use, not max RPM

[Mother]

I use Holley HP 4150 / 650 double pumper with no choke. It looks like a small Dominator. The engine produces 740 HP, with 680 Torque. Mind, the 460 ford engine is highly modified. The only concern I have is that the carb might "lean out" above 5 grand. But with the amount of torque in a car weighing in at 2150 #'s I don't need to use the motor much over 5 grand. Besides, I desire an old school look. And, I use a mechanicl fuel pump with no return to fuel cell. The fuel line is 1/2 inch ID. The engine was modified by "New Generation Engine" of Fonthill Ontario CA.

[terry mason]

Both 13 and mother are right. If you are not racing the car the bigger carb is of no advantage. A 600cfm carb that is tuned right is all you need and will give you better street preformance and a more fun car to drive

[Gaz64]

The gas smell comes from long duration cams using a carburettor.

The bigger the cam, the worse the smell is.

Sequential EFI will eliminate the smell.

If your system is sequential, get hold of a decent tuner to sort it.

Having said that, my mates 355 makes more outright power with a Quick Fuel 750 DP than it did with a dyno tuned group fired EFI system, 4 barrel throttle body etc.

[RallySnake]

I have used a bunch of carburetors on my car and none of them have been perfect. I am always changing this or that to try to improve them. the Edlebrock (or Carter) type stalls when you corner too hard. The Holley's stall the engine when you brake really hard. I am currently running a Holley Avenger 670 and after a year of tuning with a wide band A/F gauge I am getting pretty close with it. I have changed jets, squirter, cam, springs and needle assemblies to keep the mixture between 12.5 to 17 to 1 in each phase of operation.

EFI is the reason that modern car engines go for 200,000 miles without a rebuild. Carburetors never mix the fuel with the air perfectly so you always get some raw fuel washing the oil off the cylinder walls and that causes more wear. Most carbed engines will have to be rebuilt before the 100,000 mark come up. That is the primary reason that I am seriously thinking about spending $2,000 bucks on EFI. The Projection 3 system is nice because the ECU is built into the throttle body. Holley, FAST, MSD, Edlebrock and Accel make "self learning" EFI systems that should be easy to program. However, as you have seen, there are so many components that can fail. EFI systems need a steady voltage supply. You need a 100 amp alternator and a voltage stabilization device like the MSD capacitor. That may have something to do with your problem. They also will not work correctly if you have a camshaft that's too radical. Too much cam overlap drives the sensor crazy.

Since I run long distance rallies in my car, I will probably stick with the carb. I have fixed it on the side of the road many times. Try that with EFI.

However, there are companies that reprogram the stock Ford or GM ECU's so you can run with EFI systems tested for millions of miles. That may be the most reliable way to do it and that is the direction I will continue to investigate. Good luck with yours.

[lippy]

Originally Posted by olddog

Not hard to drop a grand on intake, carb, distributor, fuel pump, etc.

That's an understatement. I'm using a carb (Holley HP Ultra 950). The cost of the carb + intake + fuel pump + fuel lines + fittings + filters + regulator is almost $3k. This is good stuff (Aeroquip, Aeromotive, etc.) but I was shocked how quickly it added up. And you will need to replace most of it.

I agree with the folks who said fix what you have.

[vector1]

Originally Posted by lippy

That's an understatement. I'm using a carb (Holley HP Ultra 950). The cost of the carb + intake + fuel pump + fuel lines + fittings + filters + regulator is almost $3k. This is good stuff (Aeroquip, Aeromotive, etc.) but I was shocked how quickly it added up. And you will need to replace most of it.

I agree with the folks who said fix what you have.

Lippy, if you haven't used the 950 yet you might want to trade it for a 850, the 950 is reported to not pull as good a booster signal which could make it tougher to tune and the 850 flows around the 950. I think blykins had trouble tuning a 950 on the dyno and switched it for something else.

[AL427SBF]

Originally Posted by *13*

600 is not too small, if you don't plan spinning higher RPMs. In fact, a 600 cfm carb will have a snappier response.
RPM range is really the key. If you are trying to pull large amounts of air through the carb(higher rpm) you will need larger cfm. If you have a larger cfm, lower volumes of air have a more difficult time pulling fuel out of the Venturis(poor response).
So, the carburetor needs to be selected for its use, not max RPM

Good advice, it's the throttle response vs. peak HP trade and what RPM band you will do most of your driving. Seems the cam also plays a role, I know my builder got with comp cams to discuss and agreed that a 650 willy's was the ticket for my 427w.

[Frank Messina]

Whether you decide to stay with the EFI or go carb it sounds like you'll need some help tuning. A 750 on a 427 is definitely not too big but a 600 0r 650 is for sure going to be smaller than what the engine wants. Don't think you're going to take it out of the box, plop it on there and live happily ever after. People like to say that but reality is they all need some tuning to get them exactly right. I have a Holley HP 750 on my 351 and give up nothing anywhere. No stink, idles well, pulls strong, no stumbles or hesitation and gets decent gas mileage. The point is you have to tune for what the engine wants. If you've been tuning your EFI yourself you can most certainly learn to tune a carb. It is not hard.

Frank

[*13*]

Frank is correct. Out of the box will almost always need adjustments. Especially if you put a vacuum secondary unit on there. A smaller carb will likely be too quick on the secondaries & a bigger carb slower. Fine tuning is half the fun!

[Cobraqcca]

You guys are terrific - thanks to all who took the time to respond!!

I'm leaning towards going to a carb. Like someone said, I'll sell off the PJ3 to someone who knows/wants to mess with that degree of tune-ability. When I bought it I wanted the latest technology but I'm also a firm believer in the KISS principal. 20 years ago I did a off frame restoration of a '68 Olds 442 400cid. Put in a mild cam with an Edelbrock RPM Performer intake and a 650cfm Edelbrock carb. Was able to set her up sweet - ran strong and smooth. No gas stink. Ran @ 400hp and 375 ftlbs torque.

So I should be able to do the same with the 427W right? I just need to get the right size (cfm) and tune it like I did the Edelbrock. Besides, this car will NEVER see 100,000 miles so the advantage of EFI is somewhat negated. BTW I have an Edelbrock Air Gap on it right now. Ford racing recommended a Victor Jr and an Edlebrock Thunder AVS 800cfm carb, but that was more for a racing application. I wanted something a little more sedate and what I figure less temperamental.

Consensus seems to be in the 700-800 cfm - I don't want to under carb it, but I don't want to over carb it to the point of having drivability issues at low speeds either. I like to cruise (highway & city) as much as I like to have the acceleration that a motor like the 427W should be able to deliver.

I have it coupled to a T-56 Magnum with a 3.50 rear end. That's the starting point. It runs @ 1500 at 110-120 KPH (65-70 MPH). It's a WCC kit so she weighs in at 2600-2800 lbs (est).

I've looked at all kinds of carbs - Holley, Quick Time, Edelbrock and Summit (which is apparently a remake of the Holley 4010 but improved).

What IYHO is the easiest to set up out of the box and maintain (holds its tune)!

Thanks Again for all your input.

Gary

[vector1]

You have information from the pj3 that helps. I would call someone like blp or one of the other custom carb makers and give them the info you have, there is a lot that goes into making a good carb other than putting it into a box.

[Cobraqcca]

Hi Vector -

Due to the fact she never ran right from the beginning, the data files on the PJ3 would be bogus don't you think? It's only been run maybe for a hour at most. Am I missing something?

Gary

[vector1]

would think vacuum at idle would be helpful, cruise vacuum, don't know what else they could use if this. I've messed with the pj3 and wasn't satisfied, in my investigation of carb stuff I've learned there can be much to learn, or much missed. Just depends what a person is satisfied with.

[Cobraqcca]

Originally Posted by AL427SBF

Good advice, it's the throttle response vs. peak HP trade and what RPM band you will do most of your driving. Seems the cam also plays a role, I know my builder got with comp cams to discuss and agreed that a 650 willy's was the ticket for my 427w.

Excuse my ignorance but what is a "650 willy's" Sorry I Googled Willy's and now know!!
I wonder why they recommended a 650cfm when most people are saying a 750cfm here?!
Hmmmmm!!!!

[Cobraqcca]

Originally Posted by vector1

would think vacuum at idle would be helpful, cruise vacuum, don't know what else they could use if this. I've messed with the pj3 and wasn't satisfied, in my investigation of carb stuff I've learned there can be much to learn, or much missed. Just depends what a person is satisfied with.

I'm beginning to wonder if the PJ3 will ever run right with my 427W! On the PJ3 forum, there was another fellow who couldn't get it right with a 427W motor such as mine and he gave up and put on a Quick Flow 750(?) and has had peace since. That thread is no longer there and unfortunately I found out about it long after I bought my PJ3.

How radical do you think the cam is that came with my motor at 242/248?

[vector1]

interesting cam, i am running something with similar .050 numbers on a 408, and pulling 11-12" vacuum at around 1100-1200rpm. i would consider a 650 willys a small carb for a 427.

willys is just who makes it, it is a holley carb.

[Cobraqcca]

Originally Posted by vector1

interesting cam, i am running something with similar .050 numbers on a 408, and pulling 11-12" vacuum at around 1100-1200rpm. i would consider a 650 willys a small carb for a 427.

willys is just who makes it, it is a holley carb.

Yeah I found that out after I googled Willy's!

If our cams are close (those are my .050 #'s) and CID, what are you running for a carb??