Sealing washer under HD8 float needle seat

In process of rebuilding a set of HD8s for my Mk2. When assembling the bowls I noticed that SU does not provide a sealing washer for under the float needle seat. I purchased a major service kit from Burlen so expect all seals would be in the kit. On the HD6s I took off the car they did have seals under the seats, but also noticed the tech drawing shows no seal.

I assembled without seals and did a leak test with air (certainly much more pressure than the 2 psi fuel pressure) and one of them leaked.

Anyone have experience here? Needles are Vinton tipped standard needles.


I always used the seal.


I have very good reason to suggest that there is no sealing washer under the float valve. What you have is a sealing washer to be placed on the float chamber ticker.

As I have mentioned in another thread the flooding is usually because the tangs on the float arm have not been set to prevent the arm dropping too far down. In this condition the arm jambs the float valve as it tries to rise against the acute angle.

IIRC, the HD8 on my 2+2 had fiber washers under them. I know for a fact the Grose jets I have laying around here came with black fiber washers.

Thanks everyone for the feedback. I’m in agreement that there should be a sealing washer so took the sealing washers from my HD6s as they looked to be in good shape. Just so there’s no confusion, the washer I’m talking about is under the seat circled in below diagram. As to why Burlen wouldn’t include this in their kit is a mystery to me, the needle and seat are included as is virtually every other seal/gasket. Both this and the diagram leave it open to interpretation, I guess.


Sorry Guys, back on this old chestnut.
I recently had flooding issues & replaced the Grose Needle & Seats with the pointed tipped Viton Needle & Seats.
The Viton ones came with no fibre washers, so I used the original washers that were under the Grose Needle & Seats.
There is quite a bit of difference in height between each type & consequently I’ve had trouble keeping the designated area of the fork flat as instructed in the manual whilst also trying to maintain the 7/16" diameter spacing. The fork ends up with a hump in the middle to achieve both!
So reading this post I can only assume that the Viton Needle & Seats should have come with their own gasket as well, but perhaps not as thick as the Grose units.
Is there a marked difference in the thickness of gaskets between each type?
Assuming I do need a gasket?