Clearkut

iTrader: (1)

I am looking for any links or arctual experience with putting a IDA 48 on a 12a. It looks pretty straight forward, as I plan to use mixed gas, Any info on these set-ups would be greatly appreciated as this is my first attempt and I just want to make sure it goes smoothly.
thanxs for any help in advance,

cpa7man

iTrader: (2)

search in the first gen and race sections. Lots of old threads and links to useful info.

Good luck!

speedturn

iTrader: (1)

What will be your application? Road race only, street only?
What kind of porting on your 12A?
I have been running an IDA since 1994. In my opinion, a modified Nikki 4 barrel would probably be better for street applications.

cpa7man

iTrader: (2)

No doubt.....a nice Sterling Nikki or a Weber DCOE would be better for street.

Clearkut

iTrader: (1)

My 12a has small primary porting, and large secondary w/bridge added, the builder said that he runs a dcoe, but the IDA is ideal for the size of the porting, I plan to run a few quarter miles just to see what its like , but road race / street use mostly.

jgrewe

iTrader: (1)

The sky is the limit on tuning an IDA. If you don't need any bottom end you can go huge on the chokes. That is why you see IDA's bored out to 51mm so you can still get venturi action with a 46mm choke. (I've never been able to run anything that big so I'm just guessing on the size, it could be 48mm!) Weber never made a 51 IDA. For some kind of drivability or low end 42mm would be about the biggest on a 12a. That's bigger than any rules have ever allowed for me but I'm sure it's possible. You may end up with 36m it will depend on what you want for bottom end.

speedturn

iTrader: (1)

The small primary port / bridged secondary port motor is known as a half-bridge port motor. It is designed for good mid range power. It has more top end power than a street port motor, but not as much top end power as a bridge port motor. It is designed to work best with a 4 barrel carb that keeps the primary and secondary ports feed by different barrels of the carb.

I cannot over emphasize how important it is to feed this kind of motor with a 4 barrel carb. If you try and run it with a 2 barrel carb, then you will feed both the small primary ports and the large bridge ports at the same time thru the same carb barrel. The resulting vacuum signal to the carb will be very weak at low rpm, the flow velocity will be very low at low rpm, and you will loose all the low rpm torque that the half-bridge motor was designed to produce. With a 2 barrel carb, the half bridge motor will never produce the smooth low end power that it was designed to make.

If you want a high rpm motor, then go with an all out bridge or peripheral port motor.

Jgrewe was correct on his comments on chokes