2 Barrel Carb (Holly/MC-2100) Conversion Question.

[Rollbar]

I have searched and didn't find much in the finished dept of the Holly 350cfm carb and was wondering if anyone has either used it, and if so the jetting etc.

I also have a few carbs here (MC-2100) that are two barrel and I think they are 270-300 cfm.

Just wondering if the 2bbl would be to much for the 084 with the original intake but modified for the carb to sit on top.


http://street2mud.com/webfiles/MC-21... for a 258.pdf

Thanks,
Jim

[Doozit20]

Very interesting

[Rollbar]

I'm thinking, why not. Ford Carb and used for many years. Cheap to rebuild.

[Doozit20]

Try it ya never know. You might be able to get it done with the proper jetting.

[Corky]

There's a little more to it than just bolting on a 2bbl and "seeing how it goes"...The potential to damage the engine is pretty high with a mismatched air/fuel ratio way out of spec...
I'm very well versed in holley carbs and saw the thread on someone wanting to use the holley 2bbl carb on the 084...
My first thoughts are with the calibration of the carb in general...First up would be the carb's venturi/throat opening...Too small and the engine won't have it's full throttle airflow requirement met...Too large and the carb won't have enough of a vacuum signal at the lower RPMs to draw the fuel properly or atomize the incoming charge of air/fuel...

Next up would be the air bleeds in a holley carb that regulate how the mixture is atomized for a given airflow...

And lastely, even if all would be in the working range of the 084, the jets would be changed out for optimum performance lying somewhere between too rich with washing down the cylinders/rings and too lean making for a hot running engine and possibly burning up the pistons...

At the very least you'd need a wide band air/fuel meter to check where you're at...

I'm putting an O2 sensor bung in my exhaust for my wide band O2 meter so I can see where the factory intended the stock carb's air/fuel ratio to be then work from there on the improvements...Other than this route it's purely guessing at what is going on with the 084 and the mods you're doing...Just because you've picked up a few RPMs with a different carb does'nt mean it was a step in the right/good direction...
I was thinking about checking into a variation of the holley 2300 series 2bbl carb much like the center carb on my 70 cuda's six pack set-up from the factory....It's not as bulky as the 2100 series...

[Rollbar]

Thank you, I'll read up on it.

I was also sent this link- http://www.4secondsflat.com/Carb_CFM_Calculator.html

[Papee]

I mirror what Corky wrote. The biggest thing is the intake vacuum, as Corky wrote there just isn't enough to pull the gas in and get it mixed with the air. 34 mm is about the biggest you can go without figuring a way to get more air to it.

[Rollbar]

There's a little more to it than just bolting on a 2bbl and "seeing how it goes"...The potential to damage the engine is pretty high with a mismatched air/fuel ratio way out of spec...
I'm very well versed in holley carbs and saw the thread on someone wanting to use the holley 2bbl carb on the 084...
My first thoughts are with the calibration of the carb in general...First up would be the carb's venturi/throat opening...Too small and the engine won't have it's full throttle airflow requirement met...Too large and the carb won't have enough of a vacuum signal at the lower RPMs to draw the fuel properly or atomize the incoming charge of air/fuel...

Next up would be the air bleeds in a holley carb that regulate how the mixture is atomized for a given airflow...

And lastely, even if all would be in the working range of the 084, the jets would be changed out for optimum performance lying somewhere between too rich with washing down the cylinders/rings and too lean making for a hot running engine and possibly burning up the pistons...

At the very least you'd need a wide band air/fuel meter to check where you're at...

I'm putting an O2 sensor bung in my exhaust for my wide band O2 meter so I can see where the factory intended the stock carb's air/fuel ratio to be then work from there on the improvements...Other than this route it's purely guessing at what is going on with the 084 and the mods you're doing...Just because you've picked up a few RPMs with a different carb does'nt mean it was a step in the right/good direction...
I was thinking about checking into a variation of the holley 2300 series 2bbl carb much like the center carb on my 70 cuda's six pack set-up from the factory....It's not as bulky as the 2100 series...

OK understood. I'll look at that calculator link I posted to run some numbers etc.

The carb your talking about in the trip setup looks good to. Hopefully you can work something out with that, but in the mean time I guess I'll run the stock carb until I can at least find a Solex 34.

Thanks for the help.

[Rollbar]

CFM Suggestions: http://www.summitracing.com/popup/ca...cfm-calculator

[Rollbar]

What is the CFM of this carb? I looked but didn't find it. Empi 34 Pict-3

VW Solex Carb Info:Setting the 34PICT/3 Carburetor

http://www.vw-resource.com/34pict3.html#carb

http://www.aircooled.net/vw-carburet...-selection-101

[Rollbar]

http://www.summitracing.com/popup/ca...cfm-calculator

[Rollbar]

Someone sent me some more calculators and most likely much better than Summit's.

Good info.

http://wallaceracing.com/Calculators.htm

Carb TBI/CFM Calculator:
http://wallaceracing.com/intakecfm.php

CFM of Head Calculator:
http://wallaceracing.com/calc-cfm-head.php

[Papee]

To figure out cfm.

Engine cubic in x rpm divided by 3456= cfm

[Papee]

I missed the solex question. A pict3 is about 125 cfm stock. I'd have to measure the stock 084 carb to see what it is.

[Rollbar]

Here is a screen shot w/the max rpm (3100) of my new blades and CFM I should run with this set up.

[Corky]

125 cfm is'nt too far off the mark...It's better to miss it with more cfm than to miss it with less in our application where the upper RPM band is where we'll be most of the time...Most 2bbl carbs are just too big for these engines that's the trouble I had when I originally started looking at alternatives to the stock Zenith carb...I was even looking at a replacement carb from the same manufacturer but the Zenith website does'nt really give enough info to make an educated decision on just which carb COULD be suitable...

[Rollbar]

What I'm really worried about is running to lean etc. I know car motors pretty good/work on my own vehicles etc and I know nothing about AC/GP motors.
Would be nice to get an answer as to either a 30 solex/34 solex and the jets for the best tune/run.
Since the wheel has been invented, why reinvent if some are using said setup or is it really that different per boat/per size etc.
I thought it was about rpm/best fuel burn etc and not running these motors lean.
Hence, the CFM calculator and just running some numbers.
A Klein carb off a HD or motorcycle are very good carbs as well BUT if everyone has the VW one dialed in, then it would save me time/money and heartache which I'm limited on.
Thanks so far for the help, been wonderful to get the info and I have really search, just can't find everything so I ask if I can't find it.

[Papee]

You're not going to get an exact answer unfortunately. There is too many variables, where you live compared to someone who has a certain setup. Along with location you have engine tune, header type, intake, exhaust tuning, and prop. I've tried the mukini racing carb and went back to the stock carb before deciding to modify the stock intake. In my opinion the stock intake in its original form is the weak link in the setup. The carb is not ideal because it has no accelerator pump and was designed to run a constant 3600 rpm.

[Rollbar]

You're not going to get an exact answer unfortunately. There is too many variables, where you live compared to someone who has a certain setup. Along with location you have engine tune, header type, intake, exhaust tuning, and prop. I've tried the mukini racing carb and went back to the stock carb before deciding to modify the stock intake. In my opinion the stock intake in its original form is the weak link in the setup. The carb is not ideal because it has no accelerator pump and was designed to run a constant 3600 rpm.

Well, I've asked before about exhaust diameter/length and the response was, "search, it has been stated before". I searched and never could find it/those specs. Those who run the 084 with a solex or other carb and a modified exhaust, I would like to know some of these things. I also heard Chuck retired/AirBoat Pros or I would contact him about purchasing a exhaust header as many have done. I get the fact the jets might be different due to the altitude etc but the carb is still the same. The different props will cause different tuning but we all work from a base line. Being someone who does not know anything about air boating, and have spent many hours trying to go through every post needed until my eye felt like sandpaper I think a few questions being answered might help on the journey. Remember, some were where I am at right now and have learned from others. Just a thought and thanks for those who help others.

[Papee]

We're all here to help. Corky is doing a good job at documenting his build step. I've discussed it with him in the early stages and his build thread will be cleaned up once his build is completed so things are easy to find. I am running a stock Empi pict-3 on mine which is the same as a Solex. I'm using mine as it came right out of the box. Aerokirk has the reduction drive and is running a modified Solex. Same basic carb as mine with bigger jets. I think this is right he can correct me if I'm wrong. He is farther north than me.

The header discussion starts on page 9 of Corky's build if you have page settings set to 50. If 25 I guess it would be page 18. If you're looking for something specific here's a pointer. To find that for you I opened up Corky's thread then clicked on "search thread" on the top menu bar above where the threads start. I then typed in "headers" and searched. If you can't find this I'll do a screen cap for you.