i read somewhere that the original carby on the 4k it has two butterflies and one opens when u push down the accelerator and the other opens at high speed

if thats true is there a way to make that both open at the same time?

would this mean that i would have more power at lower rpm

thanks

What you are referring to is 'Vacuum secondaries', and NO stock 4k carbs don't have it, they're mechanical secondaries.

 

With most vacuum secondary carbs, its only a matter of a strategically placed cable tie or 2 to lock it up and have mechanical secondaries. Very common on Gemini or mazda Nikki carbs.

The stock carbs have a "high speed valve" in front of the secondary butterfly. It is a weighted butterfly, which does give a vacuum secondary type effect.

 

The problem is that the stock carbs don't have transition circuit on the secondaries like webers do. You might find that you end up with a lean flat spot.

 

An easy experiment would be just to tie the high speed valve open and take it for a drive.

Edited May 12, 200818 yr by Felix

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Edited May 24, 200818 yr by Sbox

Give it a go.

 

I actually removed the "vacumm" butterfly on one of my carbies and it had no noticable negative effect. Can't say that it made any difference either.

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Edited May 24, 200818 yr by Sbox

No, coln72 is saying he removed the extra weighted butterfly (high speed valve) that sits above the secondary butterfly.

Just buy a cheap second hand 32/36 weber and be done with it

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Edited May 24, 200818 yr by Sbox

well my car idles a 1500 to 2000 rpm

its doing it because the choke gets stuck open a bit when i push down the accelerator

i have to manual go and close the choke so it idles properly

but i will try keeping one open and see i it has any affect

thanks

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Edited May 24, 200818 yr by Sbox

Is only been doing it lately

my carby started stuffing up before and would stay at 3000rpm and wouldnt go down

my grandfather had to take off the carby and fix it i think one of the butterflys or something was stuck open

lately it just stays at 1500 to 2000

when i look at the carby the choke is closed just a little bit so i open it fully and it idles properly but when i rev the car it goes back up and idles at 1500 to 2000

Check the linkages like Sbox suggested. Sounds like something isn't setup or adjusted right.

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Edited May 24, 200818 yr by Sbox