grp a carb size does anyone no

[lawjon84]

New poster! (less than 10 posts)

hi guys does anyone no what size ktec bore the venturi out to make it a grp a

[Scoff]

27.5mm, or 27mm possibly, both equally as horrible to jet.

[raj]

i dont know much about modded carbs but what difference will having a larger venturi have? is it worth it? why is it horrible?

ive just found an enlarged venturi in my box of carb bits.

[Sy5GTT]

It's something to do with more of a pressure drop increasing the off boost performance... As quoted from the GT Tuning cat. :confused:

[Sy5GTT]

27.5mm, or 27mm possibly, both equally as horrible to jet.


Oh I don't know Chris. GT Tuning did a good job with mine. Large venturi,130 main jet and 120 a/c....... I Killed my engine....:mad:

Older and wiser now.

[Scoff]

:D and there a thousand more stories just like that ;)

raj, the bigger you make the ID of that venturi the less of a venturi it becomes, so it works less efficiently. you have to over-compensate with atleast a larger main jet. sensitivity decreases and it becomes hard (near impossible) to reach something I'd consider satisfactory fueling across every load point. they invariably end up being very rich, everywhere. if there was a notable performance gain then you might be prepared to tolerate the draw backs, but there isn't :crap:

[michael tierney]

if u calculate the effective area of the venturi at 27.5 and the eff.area of the throttle with shaft,screws ect then the throttle starts to become the restriction so fueling becomes harder!!

[Rob1980]

:D and there a thousand more stories just like that ;)

raj, the bigger you make the ID of that venturi the less of a venturi it becomes, so it works less efficiently. you have to over-compensate with atleast a larger main jet. sensitivity decreases and it becomes hard (near impossible) to reach something I'd consider satisfactory fueling across every load point. they invariably end up being very rich, everywhere. if there was a notable performance gain then you might be prepared to tolerate the draw backs, but there isn't :crap:

:agree: I have a ktec group A carb and it does indeed run very rich! If ever I take it out of storage and drive it again I will be getting rid of it!

[Guybrush]

Its a pity we don't have some of the old threads about the "group a" carb....

General consensus is that its a waste of time/money.

I had one done, but it didn't have a venturi anywhere near as big as 27.5

[Mart]

:crap:

[BriC]

That's all Mart has to say :D

[Mart]

When talking about tuner 'Grp A' carbs, that is all that has to be said.

[BriC]

Yep :)

[UNICRONICUS]

We need the old, awesome http://img2.mysmiley.net/imgs/smile/sad/sad0013.gif (http://www.mysmiley.net/free-sad-smileys.php) smiley? :(