Drilled screws for butterflies

[LincsCerb]

Hi all

Can anyone point me in the right direction, I'm trying to source some drilled screws so I can balanced the inlets. At the moment I've got 3 at 6kg/h and 1 at 4.5kg/h on the even bank so I was thinking of replacing the screws which hold the butterflies with drilled ones but can't find any.

I know the difference once the throttles are open will be minimal but I thought it might help at idle if there all flowing the same.

Thanks

[Adambul]

Have you checked for air leaks on the inlet manifold and valve clearances first? I,m intending on doing what you are proposing as mine are also uneven, I,m going to check everything else possible before i resort to drilled screws. Will be interesting to see if someone knows of a supplier though.

[LincsCerb]

Hi just done the valve clearances and timing.
Heat barriers and o-rings are new so I shouldn't have any air leaks but I will double check tomorrow.

[Tanguero]

Given no leaks anywhere else, I would be checking for both throttle shaft wear and freeplay and the butterfly alignment on the shaft before mucking about with drilled screws.

[Mr Cerbera]

LincsCerb said:

Hi all

Can anyone point me in the right direction, I'm trying to source some drilled screws so I can balanced the inlets. At the moment I've got 3 at 6kg/h and 1 at 4.5kg/h on the even bank so I was thinking of replacing the screws which hold the butterflies with drilled ones but can't find any.

I know the difference once the throttles are open will be minimal but I thought it might help at idle if there all flowing the same.

Thanks

Joo supplied me with mine. Don't know if he sells them on the side though.

[LincsCerb]

Tanguero said:

Given no leaks anywhere else, I would be checking for both throttle shaft wear and freeplay and the butterfly alignment on the shaft before mucking about with drilled screws.

There doesn't appear to be any play on the shaft and the alignment looks the same as the others, everything is nice and tight. It is the inlet on cylinder 6 that is the problem, so if there was air leaking around the shaft then cylinders 8 and 4 would be affected as well or am I completely wrong.
Two of the inlets on the odd bank have drilled screws so it looks like someone has used them to even things up before.

[LincsCerb]

Mr Cerbera said:

Joo supplied me with mine. Don't know if he sells them on the side though.

Thanks, I'll try him next week.
For now I've used an average across the four inlets and balanced the banks. It is running ok but would still like to even them all up to improve it at idle.

[Tanguero]

LincsCerb said:

Tanguero said:

Given no leaks anywhere else, I would be checking for both throttle shaft wear and freeplay and the butterfly alignment on the shaft before mucking about with drilled screws.

There doesn't appear to be any play on the shaft and the alignment looks the same as the others, everything is nice and tight. It is the inlet on cylinder 6 that is the problem, so if there was air leaking around the shaft then cylinders 8 and 4 would be affected as well or am I completely wrong.
Two of the inlets on the odd bank have drilled screws so it looks like someone has used them to even things up before.

It is probably worth checking the gaps round the butterflies with a feeler gauge if you haven't already done so. After that it's Joo for drilled screws.