I have just fitted a modified carb with the usual improvements including mechanical linkage rather than vacuum. Based on1/4 times I calculate the increase in power is 20-25hp.

The secondaries come in around 3,000 which gives my good cruising fuel performance, about 26-28mpg.

There is the usual hesitation as the secondaries first open. I have read that one solution is to connect the primary and secondaries so that they open together. It was claimed, modified this way a Nikki can give the same performance as a Webber IDA48. does anyone have evidence or comment on this.

 

So the carb works alright? Did you have it re-jetted to suit your engine? I assume this is my carb you're talking about.

I haven't heard of opening the primaries and secondaries together but I don't see how it would have much of an effect on performance. Obviously at wide open throttle it wouldn't make any difference. Plus, it would take a bit of mucking around with the linkage for it to work properly.

 

Revhead yes it is your old carby rejetted slightly to get the mixture right. Thanks I was just about to let you know everything fitted and I have just used it on a 2500km round trip over the weekend. Performance was good and surprisingly minimum change in fuel consumption. I put the choke back on due to minus 6 conditions. Not certain why but a cold start requires a few foot taps before it fires.

The question about the primary-secondary linkage was after reading it on the Forum from a Melbourne tuer who apparently claimed it performed equal to a 48 carb.

 

I'm glad it's working well.

Cold starting was the same when I had it. A couple of pumps of the accelerator and it would fire right up.

Did you have any trouble with the missing linkage?

 

No, I used the linkages from the original carb. I used your manifold inspite of comments on this forum that modifying the ports was a backward step. I have not noticed a problem as the total package is quite an improvement especially in the 100-120 kph range.

Quite important when you are overtaking a 60m long road train!

On another subject, do you know of a firm called Mazdafix in Brisbane?

 

I think you probably mean Mazfix. Yeah, I've been to their workshop/showroom a few times. Very nice setup. Though I think they're a little on the expensive side. They've got to find some way to finance their race car afterall.

 

REVHED purely by chance on my recent thread on hp of 12a and 13bt there was a post from Melbourne [Albys Virtual Garage] which gives a link to BA Performance who produce such a carb mod called StuBer.

 

Are you sure they're not just talking about the regular mechanical secondary mod like on my carb?

 

Oi its Adsy's virtual garage not albys :P

The StuBer carby opens all 4 butterflies together not staged.... the normal flatspot when converting to mecanical secondaries is overcome by doing this mod.

Ive only driven the car once (without an exhaust) scince have the carb done, and im already wrapped
with it, the throttle response is great!

It will be a few weeks before my exhaust is done as ive just had a operation on my wrist, but as soon as i can i will be getting the car on the dyno to see how good power wise the Stuber acttualy is.