So which Holley 4150 is best ?

[shelbydoug]

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

I'm relieved. Thanks. 

[gt350hr]

   The 3259 is a derivative of (IIRC) the 2668 designed for a low riser 427. Dan and I have both seen these carbs in prototype form where the original list number was XXXXXXd out and 3259 was hand etched onto them. The major change was the float bowls ( obviously) The -1 revision was a change to the primary metering block.
      Use whatever you want or like best. I do. I just don't "push" what "I" do  onto others.

[Dan Case]

   The 3259 is a derivative of (IIRC) the 2919 ( Dan will correct me) designed for a low riser 427. Dan and I have both seen these carbs in prototype form where the original list number was XXXXXXd out and 3259 was hand etched onto them. The major change was the float bowls ( obviously) The -1 revision was a change to the primary metering block.
      Use whatever you want or like best. I do. I just don't "push" what "I" do  onto others.

The base design was the R-2668A  (Ford C3AE-9510-B) 427 4V carburetor in its 1964 configuration. Delete the square shaped fuel bowl assemblies, create a new version of the "center inlet" bowl assemblies used in the R-2919A 427 4V by changing to 0.110 inch inlet valve seats and DuPont® Viton® rubber resin tipped inlet needles, change the left side fittings to install a transfer tube, and add the transfer tube and presto a R-3259 prototype.

The drawings released December 2, 1964 detailed all the parts including all calibrated orifices for the production R-3259A. The R-3259A was only made in two runs in December 1964. In January the R-3259AAS model went into production; Ford C5AZ-9510-A or Shelby S1MS-9510-A.  During the 1966 model year the R-3259-1A  (Ford and Shelby S2MS-9510-A) was released and before June 1966 the final production version R-3259-1AAS was put into production.

Holley indicates that R-3259 and R-3259A models were rated at 700 c.f.m.. All the others were described as either 713 c.f.m. or 715 c.f.m. depending on who published what when.

Each new suffix denoted a change in functionality. Most changes R-3259 to R-3259-1AAS were made to improve the air fuel mixture curves and make wide open throttle acceleration of the car quicker. The biggest single functional change was the R-3259-1A that introduced a new calibration for when secondaries started opening and how quickly they opened once opening started.  The last change came during the R-3259-1AAS period when a new heavy duty main body went into production circa January 1967.

After all these decades of time many of the family of carburetors have had parts and features mixed around, especially by commercial rebuilders or people making up carburetors by finding one part at a time.  It might take an hour to make a list of the common things people have done / failed to do which  make their performance decline and or create driving problems. 

This family of carburetors had a long development history, years.  As designed they work very well puttering along at low rpm through a neighborhood in fourth gear or screaming down a straight at 8,000 or more rpm over and over.  Some people make unwise changes that make for miserable driving.  Other than float settings, the only changes I have ever found worth the time, and I tried all kinds of going the wrong way "improvements",  was changing main fuel jets and or power valve calibration to suit a specific engine build and or altitude.  With no racing in mind I leave the power valve channels alone for high altitude as being rich during a wide open throttle sprint at 5,400 feet is better than being any lean at 1,000 feet and less. 

The last Ford 'assembly line' variant that I am aware of was the R-3259-1AAS model with some customization of fittings and throttle lever for the GT40 MKIII application. 

[Drew Pojedinec]

Three variants I have seen from 3259 to -1 have massively different idle circuits.

[oldcanuck]

OK.... I have made my decision with the help of another SAAC member and multiple car owner.

Instead of pulling the Holley 600 double pumper and installing Drew's freshly rebuilt 715 Le Mans for comparison testing, I thought maybe putting someone with Shelby and Hi-Perf Ford knowledge in the passenger seat as a good litmus. I figured since this member has owned several Shelbys in the past, and currently has a 1967 GT-350 with the original 715, a 1969 Boss 302 and a Ford GT..... I figured his extensive seat time could tell me if I should leave it alone, or put my 715 back on it.

After a brisk drive including a couple of bursts at almost full throttle to 5,000 rpm...... he simply said..... 'I'd leave it alone...."

Case closed.

[67 GT350]

Good choice Bob, now I can have the 300 cash for the 715 over to you in 5 minutes! LOL!

After you left, I thought I would go out for a short 5 mile spin, my 715 ran great, but then on the way home, I had to pass a truck full of sod, (Knowing that is was going to the house next to mine!!) So on my pass, it was no problem, then as I was coasting back down to the normal speed, I felt that dreaded wanting to stall, I thought, no way am I going to let the guy I just passed see me Found On Road Dead, I put the pedal to the metal and opened it back up again, and the car ran like it never happened, so I got home and I let it run and it showed no sign of any problem....my carb was restored, but by who? Maybe a rebuild is in store for my car, or a nice new 600DP?

[Drew Pojedinec]

Bob, what works works!

67gt350, sounds like a lil trash got flushed out the seat.
Fun story.... so I daily drive a 76 F100 with a 390FE and a holley.
Well, driving to the airport to go to work at 2am. Dark South Georgia road, middle of the swamp. Real dark.
Anyway, cruising at 60mph and I feel the engine wanting to die. I realized a bowl had a stuck float.
Well, if the float drops it normally flushes out the trash, so no cars for miles, I floor it.
100mph and my crappy truck shakes bad.
I hit the railroad tracks at 112mph.
Anyway, no more issues. Rest of the trip was smooth.


Also of note on old Ford downleg carbs. There is no killbleed. The siphon break is in the emulsion tune feed. So can have an issue if blocked.

[oldcanuck]

Fran,

Glad to hear that maybe you have it flushed out...... its telling you, I want to be driven more !

Thanks again for your help yesterday....... I'm still amazed that the Police Officer didn't read us the riot act !

If you do think your 715 needs a going through, Drew is certainly your guy. I have his contacts if required.

[JamesWill]

For your GT350, it sounds like the 650 double pumper is doing a great job, especially if you're enjoying those spirited drives. The 650DP is known for its performance and responsiveness, which can really enhance your driving experience on twisty roads. However, if you're looking to bring back a bit of that original vibe, the Holley 715 might be worth revisiting once Drew has it all sorted. It's always interesting to see how different setups can change the driving feel.

On a side note, I recently added a horn from bosshorn.com to my car, and it's been a game-changer. It's super loud and reliable—perfect for making sure I'm heard during those spirited drives! If you're ever looking to enhance your ride in other ways, their stuff is definitely worth checking out.

[Bill]

For your GT350, it sounds like the 650 double pumper is doing a great job, especially if you're enjoying those spirited drives. The 650DP is known for its performance and responsiveness, which can really enhance your driving experience on twisty roads. However, if you're looking to bring back a bit of that original vibe, the Holley 715 might be worth revisiting once Drew has it all sorted. It's always interesting to see how different setups can change the driving feel.

Another 3 year old thread resurrected, imagine that 

[shelbydoug]

For your GT350, it sounds like the 650 double pumper is doing a great job, especially if you're enjoying those spirited drives. The 650DP is known for its performance and responsiveness, which can really enhance your driving experience on twisty roads. However, if you're looking to bring back a bit of that original vibe, the Holley 715 might be worth revisiting once Drew has it all sorted. It's always interesting to see how different setups can change the driving feel.

Another 3 year old thread resurrected, imagine that 

People do come and search for information. In fact, SOMETIMES the search function actually works?

[Bill]

For your GT350, it sounds like the 650 double pumper is doing a great job, especially if you're enjoying those spirited drives. The 650DP is known for its performance and responsiveness, which can really enhance your driving experience on twisty roads. However, if you're looking to bring back a bit of that original vibe, the Holley 715 might be worth revisiting once Drew has it all sorted. It's always interesting to see how different setups can change the driving feel.

Another 3 year old thread resurrected, imagine that 

People do come and search for information. In fact, SOMETIMES the search function actually works?

True, but to offer information on a subject that has clearly already been determined (think about it, 3 years later), and a questionable post at that, and it makes you wonder if we are being trolled.

[shelbydoug]

It doesn't appear to be trolling to me. Just someone late to the party, but nothing in either that reply or the post is outdated at all. It is still relevant.

The OP asked for opinions based on personal experience. Not necessarily a right or wrong application.

In that sense, it is a successful thread. Why couldn't you add to it now?

[oldcanuck]

Being the OP, I am certainly grateful for all the responses on this topic.....and I hope it is helpful for anyone else.

[FL SAAC]

Had not seen this post previously

Great information

Thank you !