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TwinSU on RB car

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mgtacar Avatar
mgtacar Gold Member Steve Kaufman
Delta, BC, Canada   CAN
Can anyone please tell me if the valve cover needs any modifying, when converting from
a single Zenith to Twin SU's. Does the emission pipe coming off the valve cover need to be left
open, or, closed off. Thanks

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lewisrn Avatar
lewisrn Gold Member Bob L
Danville, IN, USA   USA
1980 MG MGB "The "B"
No modification. And leave the hose from the rear of the cover to the charcoal canister.

warekl Avatar
warekl Silver Member Keith Ware
White Bear Lake Mn, USA   USA
1973 MG MGB GT
1979 MG MGB
No modification needed, leave it open and hooked up to the charcoal canister.



USMC ... Semper Fi
79 RB Lowered, HS4s by Dave Braun & "Schlemmerized" 25D Dizzy, 9.5:1 CR, Mild Performance Cam, 18V with OD Tranny.

73 GT in Black Tulip

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Fogliner Avatar
Fogliner Mark Vanherd
Port Clements, BC, Canada   CAN
1974 MG MGB
The hose off the valve cover should go to the carbon canister.

The front rocker cover vent tube gets hooked via a Y fitting to both carbs, onto the brass 5/16ths tubes on each carb.

Shouldn't need to do anything to the valve cover.
regards

mark

fast-MG.com Avatar
fast-MG.com Gold Member Dave Headley
Cortez, 4 corners, Colorado, USA   USA
Depending on which SUs. Some do not have any venting provisions.


Member Services:
Dave Headley, dba FAB-TEK offers full service race car parts and preparation for MGB & MGA race cars, SCCA and Vintage. Dave is a mechanical engineer and has raced MGBs since 1963.
barry s Avatar
barry s Silver Member Barry Stoll
Alexandria, VA, USA   USA
1972 MG MGB GT
1974 MG MGB
1976 Triumph TR6
1980 MG MGB
Hopefully you know the manifold(s) combination needed for your particulars SUs to replace OE RBB Stromberg and combo manifold.

mgtacar Avatar
mgtacar Gold Member Steve Kaufman
Delta, BC, Canada   CAN
Dave, I'm using HIF4 carbs.

fast-MG.com Avatar
fast-MG.com Gold Member Dave Headley
Cortez, 4 corners, Colorado, USA   USA
Should have vent tubes.


Member Services:
Dave Headley, dba FAB-TEK offers full service race car parts and preparation for MGB & MGA race cars, SCCA and Vintage. Dave is a mechanical engineer and has raced MGBs since 1963.
danthefitman Avatar
danthefitman Dan H
Portland, OR, USA   USA
1979 MG MGB MkIII "Simply, A Great B!"
Said bye bye to my emissions canister years ago. Just one breather, out the back of my valve cover, with a hose attached that is tucked down through the bay, down the tunnel.



1st Place Winner ABFM Portland Oregon 2008, 2010, 2011, 2012, 2013, 2014, 2015 & 2016!
Email me for questions or needs, I'll respond promptly! dan@allpointsorganized.com
Life. Positively in order.


Attachments:
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20180919_175038.jpg

riley1489 Avatar
riley1489 Gold Member Bruce H
Great White North, QC, Canada   CAN
1953 Jaguar XK120
1959 Riley 1.5 "King George"
1973 MG MGB
.



Check your ego Amigo!


Attachments:
BH_18V vents.JPG    71.3 KB
BH_18V vents.JPG

lewk Avatar
lewk Silver Member Keith Lewis
Cambridge, ON, Canada   CAN
Plumb as Bruce shows.

mgtacar Avatar
mgtacar Gold Member Steve Kaufman
Delta, BC, Canada   CAN
Many thanks everybody. Much appreciated. Steve

Donthuis Avatar
Donthuis Don van Riet
Rijswijk, ZH, Netherlands   NLD
X2, HIF's do have them though

In reply to # 3889384 by fast-MG.com Depending on which SUs. Some do not have any venting provisions.

BFC Avatar
BFC Ben Clark
Allegan, MI, USA   USA
1980 MG MGB "Kilr B"
1980 MG MGB MkIV
If you're using HIF4's, make sure that your distributor and your intake manifold are set up for vacuum advance correctly.

(I put HIF4's on my 80B and the manifold that came with it didn't have the vacuum advance fitting. Still trying to find the right thread/hose size fitting.)

In reply to # 3889427 by mgtacar Dave, I'm using HIF4 carbs.



I don't know. It's always smoked like that/made that sound/done that.

Al Ben Al Benvenuti
Dundas, ON, Canada   CAN
1968 MG MGB MkII "Super Bee"
1975 MG MGB MkIII
The other concern is the interference of air filter canisters to the brake booster . Also, the studs that hold the rear HIF to the manifold may have to be shortened to install and remove the carb .

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