Throttle butterflies out of balance

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skiddusmarkus

Active Member
I'm in the process of swapping my inlet manifold(for an internally
polished one)and I've noticed that the butterflies do not open an
equal amount when the throttle is wide open.The 2 on the right as you
look down on them open approx5-10 degrees less than the 2 on the left.
Surely this could lead to inefficient running?Is this normal,or can I
adjust them?



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Anonymous

Guest
I seem to remember that u can adjust them as they have 2 seperate arms that adjust they have little rose joints theres one on the accelrator cable on the left (looking into the engine bay) and one in the centre of the 2 throttle bodies
 
zia

zia

Active Member
the thing is if they haven,t been moved from the factory
or the rod haven,t been replaced should you be adjusting them without nowing what the correct angel is?

zia

lord of the "R"
 
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AJ4

Guest
Yep, normally the butterfly position is irrelevant, as long as they flow the same amount of air.

In this case though it sounds like a mis-adjustment as it is two adjacent butterflies that are different from the other pair and not a single one on its own. I'd set them up so that are all WOT at the same time, can't go wrong [;)]

'average length member' ? Hmm..thats what my missus says...
 
K

Keira

New Member
There is a pdf file on gtiroz that tells you how to adjust the throttle bodies, theres a link on here from the first page when you enter the forum before u login, the walk right in bit..



It's a big black fly swat
 
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Sirnixalot

Guest
ross i do not agree. i feel that throttle plate position is very important. They should be working in unison. I understand what you mean by your flow statment BUT having one pair @180* and the other pair @ 160* will result in the 160* cylinders run at partial throttle, because they will be restricting air. Am i wrong for thinking that?

Shift_Gears
 
K

Keira

New Member
F*ck knows...

What i can do is photocopy it at work tomrrow and send it you.

Been building up a folder of stuff to bore the missus with.

It's a big black fly swat
 
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AJ4

Guest
Sirnix - I guess we are both right / wrong...

I still stand that its the amount of flow you are balancing, not the physical position of the butterflies.

After thinking about it, there should be a gradual difference from the intake on the left to the one on the right. The intake furthest away from the plenum entrance should be set up fully open, as this one see's the least air as some of the pressure is robbed by the intakes closer to the entrance. The one closest to the plenum intake should be closed slightly, and the other two in the middle somewhere in between. Admittedly the difference in between them is miniscule, so like you said they should all probably be set up at WOT together.

Its like balancing a central heating system in your home, the furthest radiator from the boiler should be set on max temperature and the one closest on a much cooler temperature to get an even temperature on each radiator.

Sorry, not a very good explanation, but I always set my throttles up on flow and not position anyway, having cut my teeth on 40 Webbers with rubber tubes in my ear [:D]

'average length member' ? Hmm..thats what my missus says...
 
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AJ4

Guest
Like Sirnix said, I'd probably set them all up on WOT at the same time, won't do much harm.

I remember on older carb engines it was pretty important to get it right as the furthest intake from the carb could run lean as not enough petrol / air got to it, don't suppose it makes any difference on ours with injectors etc.

'average length member' ? Hmm..thats what my missus says...
 
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