Niki carby secondary modifications

Adam · Site Admin Joined: 04 Oct 2001 Posts: 682

I did this on my TG years ago, the description may sound sketchy because it was 10 years ago!

The secondaries on a stock carby are mechanically opened and dont fully open until 4500 rpm or upwards... u and i both know a stock motor is gutless at these revs anyway. This will normally leave the driver wanting something like a 32/36 weber or holley... but where are the bucks??

so heres the tip.... port match yourself a stocky manifold, and for even better flow, grind out around the plenum area at the base of the manifold for better flow.

on the carb you will notice the mechanism that opens the secondaries consists of an arm that moves around and actuates the butterfly. this is the area of your simple modifications.

if minor gains are to be met, I just whacked a screw threw the mechanism, forcing the secondaries to open that little bit faster... not happy with this, I actually drilled a hole and solid mounted the actuating mechanism to allow the secondaries to be fully open at 1700 rpm!

I will try to take some pictures, to further explain this, as it doesnt translate well to words, but those of you with a ;little bit of mechanical know how... go and stick your head under the bonnet and take look for yourself... 15 mins work on a stock carby is well worth the money!

lowrideTG · tinkerer Joined: 17 Jul 2002 Posts: 80

this tip is a load of crap, i did this on one of my carbies, it dusnt do a thing!!! if anything it just makes your plugs go black from running too rich on low revs. modifying the secondary to open earlier actually restricts the primary throat! what a load of garbage! i bought a 180 holley on a g180 for $70, there are plenty of webbers in the tradingpost and i would recomend a little bit of money and a bit of half assed effort into installing a webber or holly carb over bunging a screw in your nikki carb.
cheers

Evil_TC · newbie Joined: 03 Jan 2003 Posts: 1

hey, if you have no dollars to spend, this is a great tip. Just a few extra notes though: I put the screw in about half way along the slot. This will give you better fuel economy, 'cause you can open it when ya want it that way. Also, you'll be able to feel abit of tension and then a 'click' through the accelerator pedal as the the secondary opens. The trick is to push it down till you feel this tension, then wait till about 25000-3000 revs build up, before you punch it through. If you dont this, the extra fuel will cause your motor to bog down momentarily, and thats what will cause your plugs to choke with oil/carbon/shit. Now go screw in some free power!

nosboy · newbie Joined: 09 Apr 2003 Posts: 1

why not just use a XE / XF FORD falcon 32/36 webber and hook up a power wire to the idol solonoid from positive side of the coil. and yep it should set u back about $30 all up . and yes u will feel the big difference.

nosboy · newbie Joined: 09 Apr 2003 Posts: 1

why not just use a XE / XF FORD falcon 32/36 webber and hook up a power wire to the idol solonoid from positive side of the coil. and yep it should set u back about $30 all up . and yes u will feel the big difference.

nosboy · newbie Joined: 09 Apr 2003 Posts: 1

why not just use a XE / XF FORD falcon 32/36 webber and hook up a power wire to the idol solonoid from positive side of the coil. and yep it should set u back about $30 all up . and yes u will feel the big difference.

mpg · rice boy Joined: 16 Aug 2002 Posts: 16

Not really. secondaries on a stock carby are vacuum operated, thus the secondary butterfly takes a while to be opened by the vacuum.

Thats the main reason why people go for after markets like Weber/Holley, as they aften have machanically actuated secondaries. When you put your foot down, the butterfly opens up straight away.

Ive tried to set the vacuum link solid on a Nikki, and it made no difference for me. It cane asily make it worse too.(see previous comment) It might make a diffrence if you keep experimenting, but by that time, you'd have been better of going woth a second hand performance carb.

PROJECT_MADGEM · tinkerer Joined: 14 Jul 2003 Posts: 69

read a bit about carbies before you go fiddling with em you dunger! that is not the way to power. there is a free way but until you study you'll never understand it!

Sprocket · Posted: Sun Jun 17, 2007 8:18 pm Post subject:

There is a way to modify these carbs. The one I run is actually bigger than a 32/36 Webber,The primary and secondaries have been borred out and venturies have been machined to suit..Secondaries have been made mechanical (simple mod which will make a difference on its own) looks stock and will flow better than the webber..Sams performance modifies secondaries only and wanted to have a look at mine but the only way he will look is to buy one...trust me a visually stock gem engine punching out over 100 hp not bad...no hairdryers on the side