So which Holley 4150 is best ?

[Side-Oilers]

What's great about Holleys is that there is such a variety and you can keep trying different combo until you find the right one. What you like someone else may not.

Mind you, I am coming from a vastly different place compared to most.
I find the "wheel of carbs" to be annoying.  There is a specific reason one works better than another.
I would rather change bleeds and make the fuel curve appropriate for my usage.  The 650 double pumper mentioned, it seems like the right choice.  Only negative is the majority of them have a tiny PVCR and oversized jets as they were meant for racing.  For street car usage you will juggle between having a fat cruise and being underfueled at wide open throttle.  The only solution is to drill PVCR's and jetting down, of course this brings us back to just make the carb work for your setup in which case who cares what you started with?
The only benefit of swapping to another carb would be that it being a generic vs a valuable original, you could molest it sufficiently to work perfectly in all conditions.

I simply like the 715cfm as the venturi to throttle bore size is very favorable in regard to optimal tube.  (optimal tube being 30 degree inlet, 7 degree outlet, vena contracta being a specified fraction of the outlet).
All of this said, there is a very specific reason that Ford used the 1 5/16, 1 3/8 venturi, 1 11/16 bore combo on so many carbs.
C3-B, CU/CV, BC/BD, 3259, etc.  It simply works very well.  Not big enough?  run two of them.

Bob's 715 probably would have run like poop as delivered to me.
Idle feed is massive, carb was hand made into a double pumper, the details of such are very fascinating to be honest.  Someone tossed a newly minted baseplate on it, which aside from hanging the throttle open, it defeated the purpose of the original modifications.
I'll put it back to stock specs and it should run just fine as is.

of course I could be wrong..... 

I had a bad case of vena contracta one time after I went swimming in the Arctic Ocean.

[shelbydoug]

I'm not arguing for one carb vs the other but it seems to me that this is a disagreement on which carb is "better vs favored sentimentally".

The criteria that Shelby American used to put the 715 on the 289, as well as other modifications,  stems from the initial program of making the GT350 a streetable club racer. Not at making it "streetable" in the traditional sense. As such the 65 GT350 was "certified in it's class" to go to Lemans and be competitive vs a 289 Mustang GT. The 66 and 67 GT350 are just carryovers and there is documentation offered in recent discussions here of how even the 600cfm Holley was an issue on some automatic trans equipped cars.

That isn't me, that's the uncovered moments of the meeting in dealing with issues of induction.



IF this is a scientific disagreement and not a sentimental one, I see dyno testing as likely the only way to show how and where the 3259 is "better" then say a specific 1850 which also has it's origins in original Ford applications.

Then it wouldn't be anyones personal preferences that were the data points, it would be what the dyno showed.


There has been scientific data in existence from Holly since before the 3259 was ever applied to the GT350's that clearly show that a 715 on a 289 is WAY too big. Don't argue with me about that, I'm only the messenger. Since some here would like to lean on Holley's data and Ford's engineering, prove that chart is wrong.

Even Edelbrock uses that data to this day as well.



I often have misconceptions that can only be corrected and clarified by scientific data. Sometimes that isn't easy to arrive at as an individual.

I just keep thinking of the review of the "ice and snow tires being the 'best I ever had' by the guy from Miami, FL, in July' ". Exactly what some people perceive as the best and what actually is are not necessarily the same thing.


Show me the data. Not a '63 Ford F150 as a dyno.

[trotrof1]

You can always have the heads professionally ported, flowed, bigger valves, and then the 715 will work as intended.

[csxsfm]

My street GT350 sampled a 600-1850, 650-4777 and 715-3259.  It liked the 600 best.  Best throttle response.  No strip work.  Just around town and stop light.  Seat of the pants, unscientific I admit.

[oldcanuck]

Guys,

I have to apologize.... it appears that the DP on my GT350 presently is a 600 cfm Holley...... List #4776-2

I was going by what the PO said, but something told me to pull the air cleaner and double check..... its not a 650.

Also if it matters, I run 91 octane pure gasoline and occasionally add a few gallons of 110 Sunoco Race to treat it to a little dose of lead.

I certainly appreciate all the comments and information regarding this, and I can assure you I have no sentimental connection one way or another, as I have stated I just want to to what's best for the engine and keep it happy & healthy.

BG

[shelbydoug]

I agree with Drew on the power valve restrictions and the jetting on a stock 4776.

They tend to idle very heavy, which according to Holley is because it is intended to be a 'race carb' with headers and the heavy idle helps the header scavenging.

I THINK what makes it crispy is that the primaries are smaller giving greater signal and you don't need to wait for the vacuum secondaries because of the mechanical secondaries.



I was running a 4779 on a 351c and couldn't get the idle to where the exhausts wouldn't smart your eyes at idle. Of course I didn't know of Drew at that point and probably should not have been using a 5 pound lumping hammer to tune it?

I never asked Drew if he could fix that on the double pumpers? Hey Drew?

[Drew Pojedinec]

I can.... but shipping a carb to me for 5 minutes of work is expensive.

Enlarge IAB to .070, reduce ifr to .031
If cam over 245@.050 .067/.033 works better.

Be sure the burning eyes is not a lean misfire, lots of folks head the wrong direction.

[gt350hr]

 Drew ,
    I am still AMAZED at how little people REALLY know about carburetors! The FIRST thing they do not understand is the "principal" of how they WORK. MANY talk about "flooding" an engine with a 715-750-850 etc. In truth , a given engine will only flow what the cubic inches , intake and exhaust efficiency and RPM allow. Bolting on a 600 may be an easy way out for some , but I'll take an expertly optimized carburetor any day.

[Dan Case]

Drew ,
    I am still AMAZED at how little people REALLY know about carburetors! The FIRST thing they do not understand is the "principal" of how they WORK. MANY talk about "flooding" an engine with a 715-750-850 etc. In truth , a given engine will only flow what the cubic inches , intake and exhaust efficiency and RPM allow. Bolting on a 600 may be an easy way out for some , but I'll take an expertly optimized carburetor any day.

+1

[trotrof1]

 The original formula with the 715 and R model spec heads works perfectly.   You can detune with a lesser carb or increase the volume of air.  After I had my heads redone it was like turning on a light switch.  Not a cheap fix but with these cars values escalating who cares.

[Drew Pojedinec]

Drew ,
    I am still AMAZED at how little people REALLY know about carburetors! The FIRST thing they do not understand is the "principal" of how they WORK. MANY talk about "flooding" an engine with a 715-750-850 etc. In truth , a given engine will only flow what the cubic inches , intake and exhaust efficiency and RPM allow. Bolting on a 600 may be an easy way out for some , but I'll take an expertly optimized carburetor any day.

To this day, one of my most thrilled customers argued with me about what he needed for months.  350 Chevy with a 600 double pumper, ran like poop everywhere, got horrible economy, etc etc.  He finally relented and I sent him a 780cfm carb that I custom tweeked.  Better economy, ran better everywhere.  He went from ready to sell the car, to wanting to sell his daily driver so he could drive his corvette more.  Lol.  I mean, the guy was fanatical, sent me all sortsa gifts, etc....  kinda funny actually, tho I pondered a restraining order for a little bit.

Agreed with the flooding comment.  You are much more likely to have overly rich issues with a 390cfm carb than you are an 800.  I'm not sure how people do not understand what I consider to be common sense, but I also ignore a lot of people.  I have one of the greatest books ever written about carburetion, by Walter Larew.  I gave a copy to a competitor.  With some of the best info in his hands, he misread it and came to mostly wrong conclusions. The same is present here in this thread.

Ohh, Randy, I sent you an email regarding the carb from the Original Poster.... it is super cool, check it out and save the photos for your records.

Drew

[shelbydoug]

I can.... but shipping a carb to me for 5 minutes of work is expensive.

Enlarge IAB to .070, reduce ifr to .031
If cam over 245@.050 .067/.033 works better.

Be sure the burning eyes is not a lean misfire, lots of folks head the wrong direction.

Shouldn't the PVR's be enlarged to a street carb size as well?


When the plugs and the tail pipes are black, it tends to confirm the rich prognosis on the double pumpers. You can also pretty much rig up a generic oxygen sensor and read what is coming out of the pipes.

[oldcanuck]

Got my 715 LM back from Drew a day or so ago..... looks very good. Thanks again Drew......

Now more head scratching. Do I leave the Holley 600 DP on there, or put the 715 LM back on...... ?

I am attaching on old Offenhauser guide from back in the day.

I am leaning on leaving it alone..... I think.

[shelbydoug]

Got my 715 LM back from Drew a day or so ago..... looks very good. Thanks again Drew......

Now more head scratching. Do I leave the Holley 600 DP on there, or put the 715 LM back on...... ?

I am attaching on old Offenhauser guide from back in the day.

I am leaning on leaving it alone..... I think.

I personally think that the 600 dp is more responsive throughout the rpm range BUT the 715 WILL have more top end.

The saving grace is the vacuum secondary. Drew is gonna' jump on me for saying this but others of knowledge have looked at the 715 on a 289 before and determined that as "delivered" new with original design specs, the secondaries never fully open.

The Boss 302 carb is the same way. A 780 on a five liter, generally is too big.

Look, you paid for the 715 to have gone through. Bolt it on and see how it runs. Maybe you'll like it?


The only way you could REDUCE the criticism, not eliminate it, would be to do a "shootout" on your car with the two carbs. A dragstrip would be the most scientific but it isn't necessarily going to give you "everyday" driving advantages and disadvantages.

The double pumpers are way to heavy at idle for day to day street driving but will definitely give a nice showing on a race car.

[Drew Pojedinec]

I won't jump on you. Don't particularly care what you think.


As I said Bob, toss it on and see. Ran normally for me, and I'm fond of the size, but the true test is always on the street.