The Triumph Dolomite Club - Discussion Forum

The Number One Club for owners of Triumph's range of small saloons from the 1960s and 1970s.
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 Post subject: HS8 Bonnet Clearance
PostPosted: Thu Jun 30, 2022 8:28 pm 
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Joined: Tue Oct 03, 2006 5:48 pm
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Location: Winscombe, North Somerset, England
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?

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Sprintless for the first time in 35+ years. :boggle2: ... Still Sprintless.

Engines, Gearboxes, Overdrives etc. rebuilt. PM me.


1997 TVR Chimaera 450


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 Post subject: Re: HS8 Bonnet Clearance
PostPosted: Thu Jun 30, 2022 8:57 pm 
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Location: Harrow Middlesex
When i had my HS 8 carbs they hit the bonnet strengthener,

had to cut the strengthener

Dave


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 Post subject: Re: HS8 Bonnet Clearance
PostPosted: Fri Jul 01, 2022 12:52 am 
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Joined: Fri Oct 06, 2006 9:57 am
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Location: Auckland, New Zealand
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


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 Post subject: Re: HS8 Bonnet Clearance
PostPosted: Fri Jul 01, 2022 8:56 am 
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Joined: Mon Apr 18, 2022 10:33 am
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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


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 Post subject: Re: HS8 Bonnet Clearance
PostPosted: Fri Jul 01, 2022 9:39 am 
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Location: Winscombe, North Somerset, England
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.

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Sprintless for the first time in 35+ years. :boggle2: ... Still Sprintless.

Engines, Gearboxes, Overdrives etc. rebuilt. PM me.


1997 TVR Chimaera 450


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 Post subject: Re: HS8 Bonnet Clearance
PostPosted: Fri Jul 01, 2022 10:49 am 
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Joined: Wed Oct 04, 2006 9:49 pm
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Location: Sutton,Surrey.
Would a tapered alloy carb Mount help.
I.E thicker at the top but thinner at the bottom.
Technically bringing the height down.

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2009 Mini Clubman Cooper S Daily Driver.
1980 Dolomite Sprint with a touch of BLTS
Balanced Lightened and Tweaked 13B Rotary and SuperCharged.
Back in my possession 22 September 2019.
Rebuilding the Sprint time taken so far, 111Hrs@15/12/2020
212Hrs @31/12/2021
352 @ 28/11/2022
455Hrs @ 20/10/2023
480Hrs @ 14/03/2024
This is time taken at the Sprint not necessary time worked.

Working on a ratio of just 7Hrs a day not including driving to the Sprint.
That equals to 68 days that doesn’t include weekends.
Member TDC no 0471

Project 13B Sprint now back on.


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 Post subject: Re: HS8 Bonnet Clearance
PostPosted: Fri Jul 01, 2022 5:03 pm 
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Location: Harrow Middlesex
I did think about getting the carbs tops machined down a bit to help clear the bonnet structure

Dave


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 Post subject: Re: HS8 Bonnet Clearance
PostPosted: Sat Jul 02, 2022 1:35 pm 
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Joined: Tue Jan 10, 2012 12:39 am
Posts: 516
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.


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Russ Cooper
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 Post subject: Re: HS8 Bonnet Clearance
PostPosted: Mon Jul 04, 2022 2:51 pm 
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Joined: Thu Jan 22, 2009 5:53 pm
Posts: 37
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


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