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General Tech SU HS4 Carb Question

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Herald63nut

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I have two SU HS4 carbs installed on my 1500 cc Spit engine that is in my Herald. I am at a loss to determine what size bolts fit the holes where the air cleaners would be attached. Any help much appreciated.
 
charleyf

charleyf

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I do not have any HS 4 carbs---BUT I am wondering what part of the bolt size you are asking about? All of the other SU's take a 5/16" bolt so I am thinking that you are asking about the length. Most of the other SU's need a bolt that is just long enough to go through the air cleaner + carb body and into a nut on the back side. To long a bolt will not work as it often interferes with some mechanism behind it.
Charley
 
TomMull

TomMull

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Andrew Mace said:
Canley Classics shows the bolt for the 1300 engine (SU HS2) as being HB0867: bolt, 5/16" x 2 1/8" UNC. I suspect the one for the 1500 would be similar if not the same.
Click to expand...
That is consistent with the tin SUs on my Herald although I think mine are HS4s. (I can't get to them until I move the car out of storage) but they do have 5/16 NC 18 bolts. Mine are shorter because the bolts only hold the bases of the air cleaners to the carb bodies. The bolts that hold the bases on screw into threads on the carb bodies.The covers and elements come off with the bases still bolted on.
Here's a picture from the backside.
su cleaner bolt.jpg


Tom
 
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Herald63nut

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Gents,
Thanks for the info. Most appreciated. My challenge appears to be that the air cleaners I purchased have a metric screw thread in the plates that then get attached to the carbs. The carbs do appear to take the 5/16th UNC bolt as you all have suggested. Now to figure out a solution to the differing screw threads between the air cleaner plates and the carbs. Ah the joy and challenge of getting this Herald once again road worthy.
 
TomMull

TomMull

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Herald63nut said:
Gents,
Thanks for the info. Most appreciated. My challenge appears to be that the air cleaners I purchased have a metric screw thread in the plates that then get attached to the carbs. The carbs do appear to take the 5/16th UNC bolt as you all have suggested. Now to figure out a solution to the differing screw threads between the air cleaner plates and the carbs. Ah the joy and challenge of getting this Herald once again road worthy.
Click to expand...
If the plates have screws/bolts attached, then they must be designes to be intended to have nuts rather than to thread into the carb bodies. Can you get the attached screws out and replace with 5.16 18? If not you could drill out the carbs; not a good idea and not much room for nuts there anyway. How attached to those air cleaners are you?
Tom
 
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