blue head mac 67

[Tofastformellow]

Hi ,

ive got a blue head mac 67 .

the id of the bore on this carb is 12 mm , (11.985mm )

cmdi website these carbs were supposed to be 14 mm is that the carb bore or bellmouth?

if it came out with a 12 mm carb on the 67 then ill settle at that ,

will i or wont i will have to redrill the spray bar larger to suit a 67 engine .. ? even retaining the 12 mm bore ,

can these 12 mm carbs be bored to 14 mm ??and not loose all drivability ?

i measured the carb bore ID with my digital vernier

i have no way of measuring the spray bar ID other than an old eyeball.. and a jump up in ID would involve me buying the right precision drill and running it thru..

Many Thanks

Jason

 

[Brian Schymik]

There are 2 carbs that fit that motor from CMDi

.510 inch and .550 inch

This is the carb barrel size...not the the top of the venturi, but the narrowest part that is hard to measure deep inside.

both are good on a 67 as is, although I did get a spraybar punched out on one of mine

Brian

 

[Don Ferrette]

Jason what Brian told you is correct. As for which is better?? Depends on application but all my scale boats run the MAC67 with the .510 throttle bore. FYI- the carb body is the same, only the barrel bore size changes. The stock late model blue head spraybar will work just fine. B)

 

[Russell Bear]

I have a .510 carb if interested.....

 

[Tofastformellow]

There are 2 carbs that fit that motor from CMDi

.510 inch and .550 inch

This is the carb barrel size...not the the top of the venturi, but the narrowest part that is hard to measure deep inside.

both are good on a 67 as is, although I did get a spraybar punched out on one of mine

Brian

Thanks Guys!! , anyone got a .550 barrel lying around ?? to slip in this carb ? can i try cmdi ? or can someone p.m. me

Thankyou very muchly

Jason

 

[Russell Bear]

CMD has them. Believe they are $84 US

 

[Tofastformellow]

CMD has them. Believe they are $84 US

Holy schinit ! 84 us for a barrel or the entire carb ??

Thanks Jason

 

[steve wood]

Jason what Brian told you is correct. As for which is better?? Depends on application but all my scale boats run the MAC67 with the .510 throttle bore. FYI- the carb body is the same, only the barrel bore size changes. The stock late model blue head spraybar will work just fine. B)

the old carbs were different. new carbs use the same body, just use different barrel. sucks. using the small barrel in the big body and there is a step where the body meats the barrel. guess it's a way to save a few bucks

 

[Tofastformellow]

Jason what Brian told you is correct. As for which is better?? Depends on application but all my scale boats run the MAC67 with the .510 throttle bore. FYI- the carb body is the same, only the barrel bore size changes. The stock late model blue head spraybar will work just fine. B)

the old carbs were different. new carbs use the same body, just use different barrel. sucks. using the small barrel in the big body and there is a step where the body meats the barrel. guess it's a way to save a few bucks

i think i have an old carb , the bore at .510 matches the case pretty close ,

throwing a .550 barrel in there will just choke the carb ,

i think another carb will be the order if i wish to try this bigger dia . bummer

still $84=ship for the complete carb isnt so bad ..

does anyone know if andy has a .550 carb complete at cmdi ?? in stock

thanks so much for the help guys..

Jason

 

[Craig Knight]

Jason

PM sent

Cheers

Craig

 

[Tofastformellow]

Craig , You ARE the man B)

Thankyou very very very much !!!

Jason

pm sent back

 

[Don Ferrette]

i think i have an old carb , the bore at .510 matches the case pretty close...

Jason, how long is the carb velocity stack (venturi)?? If it is the old style with the 3/4" long velocity stack I'd be interested in it.

 

[Tofastformellow]

i think i have an old carb , the bore at .510 matches the case pretty close...

Jason, how long is the carb velocity stack (venturi)?? If it is the old style with the 3/4" long velocity stack I'd be interested in it.

did you get that money for that prop DON ??

ill look into it. Don, the carb is very long when removed

but at this stage im waiting for this big carb to turn up..

Jase

 

[Don Ferrette]

i think i have an old carb , the bore at .510 matches the case pretty close...

Jason, how long is the carb velocity stack (venturi)?? If it is the old style with the 3/4" long velocity stack I'd be interested in it.

did you get that money for that prop DON ??

ill look into it. Don, the carb is very long when removed

but at this stage im waiting for this big carb to turn up..

Jase

Yes prop goes out tomorrow. Sounds like you have the old style with the long venturi, new style is about 3/8" from carb body to opening, much shorter. B)