Holley 3255 (BE) vs 3255-1 (BV)

[dcdoug]

What's the difference between the Holley 3255 and 3255-1? From what I read the 3255 (BE) variant was from '65 and the 3255-1 (BV) variant was for '66/67 and was for high riser manifolds and the metering plates were different part numbers, but was there any significant difference between the two?

[elmariachi]

Interesting read on these carbs here:

http://saac.memberlodge.com/resource...209-holley.pdf

[dcdoug]

Originally Posted by elmariachi

Interesting read on these carbs here:

http://saac.memberlodge.com/resource...209-holley.pdf

I read this. It was interesting. Still would love to know if there are real difference between the BE and BV variants though. Is there anything specific to the BV to run better on a high riser?

[Dan Case]

I haven't worked on but a few of the R-3255 series but I have worked on many of the R-3259 series. (In Holley® engineering literature the R- prefix means what you see as the "LIST-" prefix stamped on air horn.)

The -1 suffix in a part number means a functional revision or revision set of some type. It could be just jets and metering blocks or they could include some other subtle design change. In the case of the R-3259 / R-3259-1 assemblies a subtle difference most won’t notice is an additional air passage to modify the vacuum secondary operation timing and rate over the original design.

To thoroughly answer the question of differences the Holley Variable Specification manual and two (unmolested preferred) carburetors for examination would be necessary. The manual is the easy part, got one in my office. Does anybody have one of each R-3255 / R-3255-1? If so check to see if the R-3255 has one vacuum pick up (small hole inside right front bore near venturi towards the back right of the bore) for the secondaries and if the R-3255-1 has two (one like above and a similar hole in the right rear bore) as that detail will not be in the manual.

My 2¢.
Dan

[Dan Case]

Holley® References

Model Assemblies R-3255A and R-3255AAS
Primary Jets = 22R-40-76
Secondary Jets = 22R-40-85
Primary Metering Block = 34R-4137A
Secondary Metering Block = 34R-4241A
Throttle Plate & Shaft Assembly = 12R-3052A


Model Assemblies R-3255-1A and R-3255-1AAS
Primary Jets = 22R-40-73
Secondary Jets = 22R-40-85
Primary Metering Block = 34R-5127A
Secondary Metering Block = 34R-5129A
Throttle Plate & Shaft Assembly = 12R-3537A
Also shown as different from the earlier models were throttle connector parts 46R-409 and 48R-22 but what the R-3255A and R-3255AAS used is not specified.

[dcdoug]

Very informative!

[Dan Case]

I don't know much about the R-3255 series of carburetors but the functional changes in the R-3259 series for 289 engines was aimed at improving all around drivability and performance. I have experimented with both R-3259 and R-3259-1 carburetors on CSX2310, both tuned to the application. In city traffic driving I could not tell a difference. The main functionality change between the R-3259 and R-3259-1 involved delaying the initial opening of the vacuum secondaries, have them open faster once they started to open, and then have the secondaries close quicker in response to backing off throttle.

Disclaimer of sorts, other than the COBRA kit induction system and SHELBY BLUEPRINTED distributor a former owner had his local Shelby/Ford dealer install circa 1968-69 my old car is pretty much stock specification so I doubt that the secondaries have ever opened all the way if they ever opened. A 715 cfm carburetor on a near stock HP289 is just way too much flow capacity, 500 cfm might be stretching the how much is too much limit. I have worked on lots of vacuum secondary carburetors for people with near stock performance cars and most show signs of never having the secondaries move in street use. Race cars is another subject.

Dan

[elmariachi]

I have spent considerable time in the last 30 days farting around with my 3255-1 (BV), which I bought from Carl's supposedly "fully restored and ready to bolt on." Previously I have been running a Mighty Demon 750 annular, so I had a pretty good performance baseline. I fought with the 3255 for two weeks fouling plugs and loading up before sending it to Keith Craft for a baseline tune. Last thing I tried before boxing it up was a 4.5PV and that didn't help. Ironically the only mod he made was a 4.5 PV and said it ran great on the dyno. Maybe my PV was bad. Carb came back from Keith, I installed it out of the box and it rewarded me by dumping the number 5 cylinder full of raw gas. Got that mess cleaned up and it was with considerable effort that I finally got the engine just started and idling. Keith sent it back with 73/85 jets (stock sizes I believe) and the 4.5 PV was to account for my 7-8" idle vacuum. Through trial and error using my 02 sensor and looking at the plugs I have since gone up to 77/85 on the jetting, changed to a more aggressive pump cam and increased the discharge nozzle from 25 to 31. I have confirmed the secondaries are opening but I sure can't feel it; even with the lightest spring its almost unnoticeable. And on a few occasions it has coughed hard at 3500-4000+ rpms while winding up in the top of the upper gears, right where you'd expect to feel the secondaries. I can nail it in first with the Demon and all hell breaks lose. With this carb, its anemic and will hardly spin the tires from a dead start.

Good news is it idles beautifully, even better than the Demon. The cam just lopes nicely at 950 rpms and its really sweet. So I got that goin' for me.

I'd really like to hear from someone who has been able to get this carb to perform. I think I am just about done with it.

[dcdoug]

Since Elmariachi's experience was so positive, I thought I'd do the same thing. Just got my 3255-1 today. Hopefully to be installed this weekend.

Here are a few pics:

[elmariachi]

I've decided to double my pleasure now that I am a Holley expert. The BC/BD carbs for my 2x4 setup are on their way to Texas.

BTW, where's your transfer tube?

[patrickt]

Originally Posted by dcdoug

Just got my 3255-1 today. Hopefully to be installed this weekend.

Very nice. You probably started on it last night. Up and running yet?

[dcdoug]

Originally Posted by elmariachi

I've decided to double my pleasure now that I am a Holley expert. The BC/BD carbs for my 2x4 setup are on their way to Texas.

BTW, where's your transfer tube?

Nice. Hope it goes better this time.

As for the transfer tube on mine, my fuel log feeds both bowls so I don't need the tube.

[dcdoug]

Originally Posted by patrickt

Very nice. You probably started on it last night. Up and running yet?

Didn't start yet. I may get some time on it today, but today I am changing out my oil pan to a RR pan on Scott's lift if this rain stops and will wait for the carb project until that's done.

[elmariachi]

Originally Posted by patrickt

Very nice. You probably started on it last night. Up and running yet?

Ahhh, we know each other so well. Actually the carbs aren't here yet and I still have to gather up a few remaining small pieces before I can dive in. Plus once they arrive I then have to stare at them for at least a week so I can enjoy them before the misery begins.

Originally Posted by dcdoug

As for the transfer tube on mine, my fuel log feeds both bowls so I don't need the tube.

Wise move, otherwise you get this skit everytime you open the hood:

Tourist #2: What the hell is that?

Tourist #1: I don't know what the hell that is!

Tourist #2: What in the hell is that?!

Tourist #1: Hey, you kids! Get away from there!

Tourist #2: I would not mess with that thing..

Tourist #1: Don't put your lips on it!

Tourist #2: [ ever curious ] What the hell is this?

Tourist #1: Well.. get a photo of me with it, anyway!

[mickmate]

and a thermal choke........where are you gonna hook that puppy up to?

[dcdoug]

Originally Posted by mickmate

and a thermal choke........where are you gonna hook that puppy up to?

It's locked open. I won't be hooking it up, but figured I'd just leave it on there.