Zoom 21 Carbs

[tnrcboatracer]

charles.
i havn't ran one yet but i no on my own boat the banjo fitting won't clear the cowl.. is there a way to move it closer to the center of the motor?

i know a minor thing.. just don't want to make another cowl mold.

chris

Jon Thibodeau bought some for me - the seller would only ship within USA - named AF2 Alum 90 Deg Pressure Fitting 10/32. Only half the hight compared to the banjo fitting.

I belive they came from late Ron Paris.

The Zoom carb's banjo fitting isn't much larger than those 90 fittings; and yes, they came from the late Mr. Paris' shop. When I purchased the ones for Kim, they still have about 800 pcs left.

 

[Kim J]

On my Zoom 45 the banjo fitting is 9,7 mm high. The AF2 Alum 90 Deg Pressure Fitting 10/32 is 5,7 mm.

Not exactly half - but close.

 

[DON MAHER]

On my Zoom 45 the banjo fitting is 9,7 mm high. The AF2 Alum 90 Deg Pressure Fitting 10/32 is 5,7 mm.Not exactly half - but close.

Is the AF2 fitting adjustable, like the banjo?

Don

 

[Charles Perdue]

The design of the Zoom carb does not allow the spray bar or side plate to be rotated once it is calibrated. That is why I went to the Banjo type fitting so that the fuel inlet could be rotated for ease of installation.

Attaching the spray bar securely in the side plate and having enough room to thread the other side for the fuel fitting leaves a minimum thickness that you can not physically go under.

If the carb clearance is too close for the Banjo fitting to clear you will have performance issues caused by disturbing the airflow into the carb with the Zoom and ANY other carb. I am not saying that it won't work, I am saying that it won't work as well as a carb with adaquate clearance.

.

Charles

 

[DON MAHER]

The design of the Zoom carb does not allow the spray bar or side plate to be rotated once it is calibrated. That is why I went to the Banjo type fitting so that the fuel inlet could be rotated for ease of installation.

Charlie,

This is why I asked if the AF2 fitting is adjustable. :unsure:

Don

.

 

[Kim J]

Simply rotate the AF2 fitting to your liking, and secure with epoxy or locktite.

Kim J

 

[Charles Perdue]

OK guys, after most of you that purchased the Zoom carbs have had some play time on the water, I have received some questions about the tuning of the engine with the Zoom carb.

One of the most common questions is, why doesn't my engine run any better with the Zoom carb and the other common question is when I lean the engine down until it doesn't 4-cycle, it doesn't surge or give any other warning, it just dies.

Both questions have the same answer. Due to the unique design of the Zoom carb, it atomizes the fuel much better than conventional designs. The smaller size of the fuel droplet burns quicker and more completely without detonation. This requires a different approach to tuning the engine. Some guys have tried a slightly smaller head volume and a shorter pipe tuned length with some success, however the best approach that we have found is when the carb is installed, run the engine slightly richer and increase the load on the engine with a little more pitch or slightly larger props until the engine stops the 4-cycle sound until the very end of the sraightaway. At this point the engine is producing more power, more speed AND more RPM. You will also find at this time that it is burning more fuel. More power requires more fuel, you have to feed the horses well to make them run.

If you have any more questions just let me know.

Thanks, Charles

 

[carlnoki]

Charles;

just one question,,,,,,,,,,, when are yo ugoing to make them for the red head valvola?

carl

 

[Charles Perdue]

Charles;just one question,,,,,,,,,,, when are yo ugoing to make them for the red head valvola?

carl

Hello Carl. Probably the next "Cool Season".

Charles

 

[carlnoki]

GREAT!!!!!!

carl

 

[LarryConrad]

OK guys, now that the water has softened up and most should have had a chance to run their Zoom carbs, I would like to hear what you think about the carbs and their performance.I would like to hear the GOOD, the BAD or the UGLY. :huh:

After this is done I will post some of the things that we have found.

Thanks, Charles

I have run my zoom on a SS Novarossi in a Speedmaster mono. The motor starts easy and runs very well on the water with good throttle response. Is there any difference between the large venturi zoom 21 and the small venturi zoom 21 other than the size of the bell?

 

[Charles Perdue]

OK guys, now that the water has softened up and most should have had a chance to run their Zoom carbs, I would like to hear what you think about the carbs and their performance.I would like to hear the GOOD, the BAD or the UGLY. :huh:

After this is done I will post some of the things that we have found.

Thanks, Charles

I have run my zoom on a SS Novarossi in a Speedmaster mono. The motor starts easy and runs very well on the water with good throttle response. Is there any difference between the large venturi zoom 21 and the small venturi zoom 21 other than the size of the bell?

Hello Larry, thanks for the response and the question. The smaller bell ( .850 instead of 1.00 ), was just to help the carb clear the start belt and to have better clearance around the bell where space is limited. The smaller bell has a slightly different profile to compensate for the size, and there is no performance difference at all.

All of the future carbs will have the smaller bell. If any of you guys that purchased one of the earlier carbs with the larger bell would like the bell size reduced to the smaller size just send it back to me and I will resize it for you, NO CHARGE.

Thanks, Charles

 

[Richard Dahlheimer]

OK guys, now that the water has softened up and most should have had a chance to run their Zoom carbs, I would like to hear what you think about the carbs and their performance.I would like to hear the GOOD, the BAD or the UGLY. :huh:

After this is done I will post some of the things that we have found.

Thanks, Charles

I have run my zoom on a SS Novarossi in a Speedmaster mono. The motor starts easy and runs very well on the water with good throttle response. Is there any difference between the large venturi zoom 21 and the small venturi zoom 21 other than the size of the bell?

Hello Larry, thanks for the response and the question. The smaller bell ( .850 instead of 1.00 ), was just to help the carb clear the start belt and to have better clearance around the bell where space is limited. The smaller bell has a slightly different profile to compensate for the size, and there is no performance difference at all.

All of the future carbs will have the smaller bell. If any of you guys that purchased one of the earlier carbs with the larger bell would like the bell size reduced to the smaller size just send it back to me and I will resize it for you, NO CHARGE.

Thanks, Charles

Hello Charles, did some more testing with the ZOOM carb, and the results are all positive. What a great carb. I am running my ZOOM on a CMB early release red head 06 Valvola, CMDI fat pipe @ 7 and 5/8ths. I am running a stock turbo plug insert from Dave Marles with either a Novarossi #6 or a OD097T plug. Motor starts great, and is very easy to keep running on the beach. launches great, and response is super. I have not touched the needle since i first tried my ZOOM last October. Thanks Charles for a great carb! ZOOM ZOOM ZOOM Richard D

 

[bolton19]

Charles, do you have any 21's for a CMB?

 

[Charles Perdue]

Hello bolton19, the current Zoom 21 carb will work on the older CMB 21 Valvola engines, as for the newer CMB 21 engines with the bolt on carb, those will be produced this coming winter.

Thanks for the interest,

Charles

 

[bolton19]

Understood, I have the older CMB style,do you have any for sale?

Thanks

Neil

 

[Alan terry]

Charls do you curretly have a zoom carb for the 91HR cmb motors?

Alan Terry

 

[Charles Perdue]

Understood, I have the older CMB style,do you have any for sale?Thanks

Neil

Hello Neil, I am all sold out on every carb that I have built EXCEPT for the MAC 45/CMB 45 HR combo of which I have 2 left. The demand for the carbs were way beyond my expectations.

Thanks, Charles

 

[bolton19]

Thanks for the info.....

 

[BDM Racing]

Understood, I have the older CMB style,do you have any for sale?Thanks

Neil

Hello Neil, I am all sold out on every carb that I have built EXCEPT for the MAC 45/CMB 45 HR combo of which I have 2 left. The demand for the carbs were way beyond my expectations.

Thanks, Charles

Charles,

I have a CMB 45 cam motor, Gold & a purple head motor.

Will your carb fit and work on these older motors. I read the thread, i may have missed where it mentioned they do fit.

Thanks, Bob M.