HS8 Bonnet Clearance

[Mad Mart]

The Tolly Sprint project has HS8s fitted. The dashpot of the front carb looked very close to the bonnet and, after placing the bonnet, it actually coincides with a bonnet stiffener. I'm not sure if it is actually touching but it is very close. To those of you that have fitted these carbs, have you modified the stiffener or did yours clear ok?

[new to this]

When i had my HS 8 carbs they hit the bonnet strengthener,

had to cut the strengthener

Dave

[gmsclassics]

I ran my Mimosa Sprint with HS8s for a couple of years (2011-3) before going back to standard carbs to improve drivability of what was essentially a road car. I was never aware of carbs hitting the bonnet but there was evidence that they did as the paint was worn away, along with a slight indenting on the bonnet strengthener. I suspect this was at the extremes of engine movement such as going through a pothole in the road, rather than in normal use.

New engine mounts rather than ones that have well 'settled in' would probably make the situation worse. Alloy carb mounts rather than original rubber ones may also exacerbate the problem. When I rebuilt the engine in the white car last year I noticed it appeared to sit higher at the front of the engine than with the other cars, but has since settled down a bit. Standard carbs though.

I've had the HS8s and manifold sitting on the shelf since Dec 2013!

Geoff

[Philip Larmour]

I used HS8s on my Ex BTCC Broadspeed Sprint at one time to comply with FIA Group A rules. To make them fit I cut away the bonnet stiffer and had the inlet manifold milled to remove approx 3mm from the lower edge of the manifold tapering to nothing removed from the top. This alloyed the carb tops to drop down and fixed the contact and gave some clearance for engine movement.
Philip

[Mad Mart]

Thanks for your replies guys, I think I may have to cut the stiffener then as I think with all the vibrations it will clash.

[SprintV8]

Would a tapered alloy carb Mount help.
I.E thicker at the top but thinner at the bottom.
Technically bringing the height down.

[new to this]

I did think about getting the carbs tops machined down a bit to help clear the bonnet structure

Dave

[dursley92]

The Special Tuning HS8 carbs (FZX1050) had the tops machined. See the comparison with a normal HS8. I also measured the modified height for interest.

[10yearsafter]

No real road experience as yet but at the moment there does not appear to be an issue with mine but they are on solid mounts. No bonnet seal fitted. engine steady and mounts replaced. The car has only been driven around the block but no signs or sounds so far!
Bob