So which Holley 4150 is best ?

[oldcanuck]

This will fire up some discussions.....!

The original owner of my GT350 replaced the Holley 715 Lemans in early 1975. According to the second owner, and the OO's best friend, someone at the local go fast speed shop in FL told him that the new Holley 650 double pumper was the hot set up for a K code 289.

Car is running just fine with the 650DP, and as of right now Drew is going through the 715 LM to make it fresh and right again.

With all things being equal since I drive my car more than most, which really is the best set up for spirited 3-4 times a month, twisty roads, weather permitting, driving enjoyment ?

Thanks in advance,
Bob

[jerry merrill]

I used to have a 66 289hp car that I put a 600 DP carb and it felt like  50 hp increase, of course it wasnt that much but felt great, a lot may depend on your engine but even though on a dyno you may show an increase with a large carb, for driving around I have found 600 or so carb on a stock type engine feels better especially a double pumper. gas mileage is a different story.

[Kent]

I had several 289 and 302 with the 600 double pumper carbs and what always was a big + that they were really crisp on the throttle with good adjustments they were running like efi. But the original 715 carb is also a great runner with some modifications on the dyno I had better results at real high rpm´s with those but then it was not a stock engine anymore. On a pretty much stock engine I would take the 600.

[68gtcoupe]

This might be apples to oranges, but many years ago I owned a 1974 Mustang II that the PO had installed a 351W into. I tried many different carburetors on it back then, being a teenager working at a local speed shop in the DC area. Finally happened upon a Holley 600 DP that a local fellow had been using on a small block Vega that he drag raced. The choke had been removed, including the air horn, it was painted orange and just looked ratty.  That carburetor was just RIGHT. I bolted it on, set the idle speed and never fiddled with it again.   

[shelbydoug]

On a 289 I'd go with a 4176, a 600cfm double pumper. It will feel crisper.

[csxsfm]

+1 on a stock hipo.

[Drew Pojedinec]

You should try the 715 when I'm done before making any other decisions.

[Dan Case]

You should try the 715 when I'm done before making any other decisions.

+1

[GT350DAVE]

+2. I have run 3-4 different carburetors through the years and got the best quarter mile times with the 715.

[roddster]

  After the rebuild from Pony carbs some 15+ years ago, it runs great with a 715.  With old carbs one often overlooked issue is that the throttle plate bores wear.  They start sucking in a little more air plus the idle speed is not consistant.

[shelbydoug]

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.

[68gtcoupe]

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.

+1. Well said.

[Drew Pojedinec]

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..... 

[oldcanuck]

You should try the 715 when I'm done before making any other decisions.

Drew, I posted here to get a general consensus from owners/drivers, to see what they had experienced between the two.  However, you were still going to get the last say...... I probably should have noted on this thread that when the engine was rebuilt, it was rebuilt to stock specs per the second owner.

BG

[Dan Case]

Performance preferences are subjective. I do not desire the ultimate power today in one location with just today's fuel. One can tune to chase conditions but I like smooth seamless performance from idle up under a wide range of ambient conditions. A GT350 Holley fills the requirements for me in GT350s and Cobras. Most of the ones I have serviced since the 1970s have been inadequately serviced or modified intentionally or not to work not so well. Last fall I serviced a carburetor for an early 1966 GT350 with really strange jetting and deactivated secondary on purpose. I repaired it to work as designed.


I have used R-3259 and R-3259-1 models on pure stock to seriously modified HP289s. Barring carburetor part failure or ill advised modifications engines do very well cruising slowly in the neighborhood or running 8,000 to 8,500 rpm playing or going down a race tack's main straight. Performance being smooth and seamless from that slow crawl to 160+mph.

The only modifications I found useful were power valve and or jetting changes depending on camshaft, altitude, and or fuel type. No surprise, no stock carburetor covers 0 to 5,000 feet plus or wild camshaft, and or ethanol in fuel without adjustment for conditions.