331 Carb choice, the Carb guyz say 750.???

[iskwezm]

Were speaking the same language just using different words.

it had some magic worked on it and yes, it is now a 830.

mine too

 

[D.Hearne]

Think outside the box----- On my 331, I've got a Mustangs Unlimited repro 3x2 setup with three Holley 250 cfm 2 bbls. Performance is awesome. Excellant throttle response from idle to 6500+rpm's. This engine has Canfield heads, a Ford Z303 roller with 1.7 rockers, 10.4 to 1 compression. Idles at 600 rpms. In my 3800 lb Ranger with a Toploader 4 speed and 3.73 gears, 28" tires it runs mid 13's in the 1/4 and tops in at over 135 mph. Tame enough that I can drive it anywhere, even a 55 mile round trip commute. And if you think or heard that 3 carbs are hard to deal with , that's BS. This setup has been on the 331 for over a year now, and I've not touched them once, since the initial tune and jetting.

 

[12sec67]

i dyno my mustang with a 306 with customer cam and edelbrock heads 2.02/1.60 and 750dp and dyno 313rwhp/ 331rwtq went to the track and ran my best times (see sig). Then tried again later in the year with the 650dp - the 60' was better but the 1/8 mile and 1/4 time was slower and with less MPH.

gas miliage was better with the 650 but i never got close to betting the times that i had with the 750.

 

[69Rcode_Mach1]

I went with a 750 with mechanical secondaries on my car, cause it does give you more power if you tune it properly. Plus with my combo it will give me room to grow when I throw in a huge cam and Vic Jr. Intake so I won't get a bottleneck effect up top. Unfortunately I don't know squat about tuning a double pumper. Which is why I keep fouling the plugs.

 

[12sec67]

hey 69RCODE- If the plugs are black when you pull them out its means your running rich


10SECGOAL keeps telling to buy this book he purchased about carbs from summit racing because he wanted to know everything about everything- like he usually does...

NOW HE IS A PRO!

you could be too...

 

[06cobra]

10SECGOAL keeps telling to buy this book he purchased about carbs from summit racing because he wanted to know everything about everything- like he usually does...

you could be too...

Refresh our memory please, which book?

 

[SoCalCruising]

I called the Carb Shop (Ontario, CA) and gave tham all my specs on my 331 with intention that it would be driven 90% street. They suggested their Stage II 750 dp. That's what I got, but haven't run it yet. Motor is pretty much done, but I still have a lot to do to the car before I fire it up.

 

[12sec67]

Refresh our memory please, which book?

i'll have 10secgoal get the name for you

 

[rbohm]

i will put my vote for either a good 750 vacuum seconday carb, the 3310 from holley is good, and edelbrock also has a 750 carb. but then D.hearn suggested the 3x2bbl settup, which is a good settup also. so those are my votes.

 

[10secgoal]

06COBRA I think it's called "How to tune tune and modify your Holley" It's written by Dave Emanual. I would still look at the Quickfuel/Profrom. But don't buy the whole carb. It's like buying an HP series Holley. Expensive, but worth it on a racecar. the part I am talking about is just a main body. It can convert your 600,750, and I think the 800 to a 750. You get rid of your choke horn, then you have a smooth flow in a main body, and adjustable air bleeds. You can make a 750 get the same or better gas mileage. It's all in the book. So for 89 bucks at summit, you can change your holley into a more tunable Holley. Either way your go, stick to a DP for performance, and vac. secondaries for more street oriented motors. If there is a change of boost in your future, that is the carb for sure.

 

[06cobra]

Thanks for chiming in.

Boost is definitely a dream of mine., how to hide the snail from the misses will be the biggest task LOL

 

[D.Hearne]

I went with a 750 with mechanical secondaries on my car, cause it does give you more power if you tune it properly. Plus with my combo it will give me room to grow when I throw in a huge cam and Vic Jr. Intake so I won't get a bottleneck effect up top. Unfortunately I don't know squat about tuning a double pumper. Which is why I keep fouling the plugs.

Try putting in the jet size that Holley recommends for the primarys, then make a few full power strip runs, pull the plugs and then decide what size jets are needed to bring it to a proper mixture and jet up or down on the secondaries.

 

[jcode68]

Opinions are like...

Just adding my 2 cents
I got a 347 from CHP with AFR 185's, RPM Air Gap and ~9.5:1 compression. CHP suggested the Holley Street Avenger 670 carb with vaccum secondaries as hitting right in the sweet spot given the car will be mostly street driven. I haven't purchased the carb yet, but will be soon, that is unless this thread changes my mind. Damn opinions

 

[D.Hearne]

Just adding my 2 cents
I got a 347 from CHP with AFR 185's, RPM Air Gap and ~9.5:1 compression. CHP suggested the Holley Street Avenger 670 carb with vaccum secondaries as hitting right in the sweet spot given the car will be mostly street driven. I haven't purchased the carb yet, but will be soon, that is unless this thread changes my mind. Damn opinions

A 670 would be an excellant street only carb, it would just throttle that 347 some on the top end. Might be better with a 770 in that regard, the primaries would only be slightly larger and that's where you stay mostly on the street ( provided you've got control over your right foot) On the other hand, three-two's would be perfect

 

[Max Power]

Both will work. I would go with the 750 vacuum, as vacuum secondaries are the perfect variable venturi carb. The 750 has more upside, and it can be tuned with annular discharge boosters and other tricks if you feel it is soft down low.

Keep in mind that different carbs are tested differenty. Edelbrock is tested dry flow, vs. Holley wet, so a Holley 650 will actually flow more air than an Edelbrock 650. The cfm is just a guideline anyway, as it is measured at 1.5 inches of mercury. We don't drive in a lab.

BTW, I work for the publisher of that Holley book. We are trying to do a DVD to match it.

The only problem I have with Hearne's setup is price. That and they don't make those intakes for 351 based motors yet.

 

[69Rcode_Mach1]

Try putting in the jet size that Holley recommends for the primarys, then make a few full power strip runs, pull the plugs and then decide what size jets are needed to bring it to a proper mixture and jet up or down on the secondaries.

My valves were adjusted pretty badly which was a contributing factor. I also leaned out the idle and now have 10-11in hg of vacuum. I also can rev it smoothly, so I just need to a little more tweaking. Atleast there is no more black smoke anymore.