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GR 7" SU manifold & hitting the firewall
https://www.ausmini.com/forums/viewtopic.php?f=5&t=52497		 Page 1 of 3
Author:  drmini in aust [ Fri Apr 24, 2009 12:51 pm ]
Post subject:  GR 7" SU manifold & hitting the firewall
Here's pics of this manifold with an HS6 on it, the flange is machined at 12.5° at the moment (no stud holes yet) and the jet tube is just touching the firewall.
If I knock 3° off this angle, it will fit without body mods. :D

There is no way an HIF44 will fit at this angle without touching, as the back of the float bowl is 100mm behind the manifold flange.
Increasing the flange angle to 17.5° means it nearly fits without mods.
But note this is a late (1977) shell (no speedo hole) and these have more room there under the carby. Judicious use of a VBFH above the crossmember would let the HIF fit.

Early cars will need some surgery like Doogie's for an HIF. Whether an HS6 fits those without mods is a lottery. Graham says some do, some don't.

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Author:  poeee [ Fri Apr 24, 2009 2:23 pm ]
Post subject: 
Does the bonnet fit, Doc?
Author:  drmini in aust [ Fri Apr 24, 2009 2:27 pm ]
Post subject: 
poeee wrote:
Does the bonnet fit, Doc?

Yep the HS6 clears it now, will clear even more once I reduce the flange angle to 9.5°.

An HIF44 is shorter in height, even with the increased flange angle of 17.5° it will clear OK.

OK... back to the mill to complete this one... :P
Author:  doogie [ Fri Apr 24, 2009 4:30 pm ]
Post subject: 
I wish mine fit that easily, im not too keen on BFH on my firewall :cry:

Doogie
Author:  simon k [ Fri Apr 24, 2009 9:41 pm ]
Post subject: 
I've split this topic off... other people will want to see it too

Kev, try this picture, I was curious about whether you can pull the carb away from the firewall by machining the head flange at an angle, then the carb flange to tip it back down again, then cleaning up the ports a bit

please excuse the crappiness of my photoshopping

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Author:  Morris 1100 [ Fri Apr 24, 2009 9:48 pm ]
Post subject: 
I think you will get a vacuum leak unless you use another set of vice grips on the other corner. :wink:
Author:  gafmo [ Fri Apr 24, 2009 9:53 pm ]
Post subject: 
not forgetting before you get to fare that you could trial fit it on Morris if you wish :wink:
Author:  1310/71 [ Fri Apr 24, 2009 10:06 pm ]
Post subject: 
simon k wrote:
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Now the bonnet won't close Simon, can you photoshop a bulge in the bonnet?
Author:  drmini in aust [ Fri Apr 24, 2009 10:14 pm ]
Post subject: 
Haha yeah. I've already kicked it up a degree or 2 when I did the port flanges.
I could also make these flanges thinner, they are 10mm now for strength (8mm bend too easy).

No worries with this HS6 though, it'll clear everything there at a 9.5° flange angle. It's the the pudgy HIF44 that is the problem child.
KB has one, I'll trial fit it when manifold is milled at 17.5° and take more pics.
Author:  greyghost [ Fri Apr 24, 2009 10:33 pm ]
Post subject: 
1310/71 wrote:
simon k wrote:
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Now the bonnet won't close Simon, can you photoshop a bulge in the bonnet?


just shorten the top of the carb. "a-la mini sprint with HS4's"
Author:  DTrain [ Sat Apr 25, 2009 1:14 am ]
Post subject: 
simon k wrote:
I've split this topic off... other people will want to see it too

Kev, try this picture, I was curious about whether you can pull the carb away from the firewall by machining the head flange at an angle, then the carb flange to tip it back down again, then cleaning up the ports a bit

please excuse the crappiness of my photoshopping

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You wouldnt want the flange to be at an angle otherwise the nuts and washers wont make a proper seal (top will be loose).
Author:  drmini in aust [ Sat Apr 25, 2009 8:21 am ]
Post subject: 
Simon isn't suggesting that, just that I could mill it to that angle when I started. The flanges of the bare casting are about 13mm thick.
Author:  drmini in aust [ Sat Apr 25, 2009 4:21 pm ]
Post subject: 
More pics, now the top flange has been machined to 17.5°.
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The HIF would need the firewall thumped a bit. Note the carby flange, it's sitting high against the manifold.
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Yeah I know- it's a 38 not a 44 but body is the same size. :P


The HS6 is just touching. Firewall would need a smaller thump, but I'm reducing this angle to 10° for the HS6 manifold (going on our 1412 stroker).
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Author:  EST-071 [ Sat Apr 25, 2009 7:17 pm ]
Post subject: 
Is that setup on a small bore motor?
If it is there will be more clearance on a 1275, would there not?
Cheers Pete
Author:  drmini in aust [ Sat Apr 25, 2009 7:44 pm ]
Post subject: 
This is a on 1275 bare block and head, yes it is 10mm taller than a smallbore.

You will have more probs with those, pristic's HS6 was so close to the crossmember that he drilled a hole in it to clear the jet.
But being aware of that I kicked this manifold up a couple of degrees at the headface, to get a bit more height at the carby.
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