Manifold allen bolts

Status
Not open for further replies.
In addition to the thread being BSW, you may not have noted the UNC allens require a larger allen hex size then the correct BSW.
Therefore if you're out on the road, and need help from a norton owner such as borrowing the special cut down allen wrench... you will be out of luck, since the correct tool won't work on unc.
Regardless, the large UNC allen wrench is a bigger PAIN to do the same job as the smaller BSW allen key.....which is bad enough.
I refuse to buy and use the UNC for this reason alone... I have notified suppliers of this and have returned incorrect parts.
 
These take a 7/32" allen wrench. I thought I read someone else had bolts that used 1/4 " wrench. Haven't made it to town yet to get a new UNC tap.......Spent yesterday getting power back in the scoot while I decide what to do about the mounts.

MIKE
 
pbmw said:
I would likely also tap it with a UNC. Same pitch, Major and minor dia's. Just the thread angle is different. And you're on the good side as the material comes out, it'll work nicely.
I check bolts with my optical comparator down in QC. Tells the tale pretty quickly.
I've seen a lot of British threads that were pretty sad. Seems the machinist was told to use the cutter long past the time to freshen it...
The pitch has generally been fine but the thread form has not always been the best.
Click to expand...

this is NOT a professional way to fix anything. it is not that expensive to get the right stuff to do a proper fix. another member has a barrel for sale I also WOULD NOT consider to purchase as it was BUTCHERED to a metric thread. JMHO
 
I have no idea what this thread is about.

Are you talking about the 4 bolts that hold the manifold on? For a post-71 bike?

I just got some SS socket heads and was done. Heck, I was even trying to give away the extras that I had to get but no one wanted them. :roll:

Manifold allen bolts

combat-proddy-build-t4186-105.html#p58765
 
swooshdave said:
I have no idea what this thread is about.

Are you talking about the 4 bolts that hold the manifold on? For a post-71 bike?

I just got some SS socket heads and was done. Heck, I was even trying to give away the extras that I had to get but no one wanted them. :roll:

Manifold allen bolts

combat-proddy-build-t4186-105.html#p58765
Click to expand...


Dave this thread is about threads OK................ :roll: :D
 
That's them. In my case, in this case they were extremely hard to unscrew, and one hole seems to have the threads messed up a bit. I didn't want to screw things up worse, so I'm attempting to get the thread size right...Whitworth or UNC. The allen bolts are OK, though there a bit of metal transfer to them when removed from the head.
 
bill said:
here is one place to get the stuff to do a PROPER fix so the next owner or professional repair shop don't give you the DPO label.
Click to expand...

If you run a UNC tap thru these holes the threads will probably be back to pretty usable condition and bolts will be very easy to source. This leaves one further attempt for later repair methods should they ever be needed. And there is enough space between the inner bolts to mark "UNC" there just to be sure.


Tim
 
Tintin said:
bill said:
here is one place to get the stuff to do a PROPER fix so the next owner or professional repair shop don't give you the DPO label.
Click to expand...

If you run a UNC tap thru these holes the threads will probably be back to pretty usable condition and bolts will be very easy to source. This leaves one further attempt for later repair methods should they ever be needed. And there is enough space between the inner bolts to mark "UNC" there just to be sure.


Tim
Click to expand...

I don't know if I even used a tap to fit those. Seemed to just work. Of course I wouldn't ever rely on just my memory, hence the reason I post so much. Documentation. :mrgreen:
 
dynodave said:
In addition to the thread being BSW, you may not have noted the UNC allens require a larger allen hex size then the correct BSW.
Therefore if you're out on the road, and need help from a norton owner such as borrowing the special cut down allen wrench... you will be out of luck, since the correct tool won't work on unc.
Regardless, the large UNC allen wrench is a bigger PAIN to do the same job as the smaller BSW allen key.....which is bad enough.
I refuse to buy and use the UNC for this reason alone... I have notified suppliers of this and have returned incorrect parts.
Click to expand...

I made the trip into town, bought a UNC tap. then swung by the hardware store to check on new UNC allen bolts......they are bigger and clunkier. So I just ordered a BSW tap from British Fasteners, thanks Bill, almost 20 bucks delivered. What the heck, another tool.
 
openroad said:
I made the trip into town, bought a UNC tap. then swung by the hardware store to check on new UNC allen bolts......they are bigger and clunkier. So I just ordered a BSW tap from British Fasteners, thanks Bill, almost 20 bucks delivered. What the heck, another tool.
Click to expand...

glad to see you do it right . a man can NEVER have too many tool's :mrgreen:
 
Interesting discussion. It makes me wonder what I have on my bikes. Now I know not to go out and buy some shiny new SS UNC bolts from the fastener store (although if a DPO ran a UNC tap through them, I suppose that is what would be needed).

Debby
 
openroad said:
dynodave said:
In addition to the thread being BSW, you may not have noted the UNC allens require a larger allen hex size then the correct BSW.
Therefore if you're out on the road, and need help from a norton owner such as borrowing the special cut down allen wrench... you will be out of luck, since the correct tool won't work on unc.
Regardless, the large UNC allen wrench is a bigger PAIN to do the same job as the smaller BSW allen key.....which is bad enough.
I refuse to buy and use the UNC for this reason alone... I have notified suppliers of this and have returned incorrect parts.
Click to expand...

I made the trip into town, bought a UNC tap. then swung by the hardware store to check on new UNC allen bolts......they are bigger and clunkier. So I just ordered a BSW tap from British Fasteners, thanks Bill, almost 20 bucks delivered. What the heck, another tool.
Click to expand...


The problem is, now that you 've had a UNC bolt in there, you've deformed the BSW threads. You can't cut material that isn't there any more...
Your nice new BSW hardware is going to be pretty loose.
 
I never ran the UNC tap through the hole, I did buy one, but couldn't pull the trigger. The UNC allen bolts at the hardware store take a 1/4 wrench, mine takes a 7/32 , so do my engine head steady bolts.
 
I was just looking at my original manifold and head steady bolts. One of the manifold bolts is 1" long, the rest look to be 3/4". I have a UNC 5/16x18 SS bolt and nut. All 4 BSW bolts thread into the UNC nut just fine, if a bit tighter fit than the UNC bolt. I personally cannot see the difference in the thread angles, but I don't have a microscope.

I wonder why one of them is longer than the rest? I always remember they were like that. The old Allen head bolts also take the 7/32 Allen wrench. Why did they use black bolts for these two items?

Dave
69S
 
I'm pretty sure on my MKIII I went down to the local bolt joint and bought some SS ones off the shelf in UNC and they threaded in just fine. I recall I had to wait for the proper length to come in and all they sell there is UNC.

Use loctite since you don't want those two inner bolts loosening up and getting sucked into the motor. That could ruin just about anyone's day.
 
Coco said:
I'm pretty sure on my MKIII I went down to the local bolt joint and bought some SS ones off the shelf in UNC and they threaded in just fine. I recall I had to wait for the proper length to come in and all they sell there is UNC.

Use loctite since you don't want those two inner bolts loosening up and getting sucked into the motor. That could ruin just about anyone's day.
Click to expand...

I think you are a little confused all these bolts are external its only with a single carb conversion that the manifold commonly has 2 internal bolts and you are spot on about not wanting those to come loose so must be fitted with Loctite for peace of mind :D :D
 
DogT said:
I was just looking at my original manifold and head steady bolts. One of the manifold bolts is 1" long, the rest look to be 3/4".

I wonder why one of them is longer than the rest? I always remember they were like that.
Click to expand...

I believe the longer manifold screw goes at the far right, because I think it also retained a rigid rocker feed pipe support clip?

The longer screw was introduced at Eng. 131257 (check '69 parts supplement) as the factory appeared to have decided that a longer (1") screw (part 21248) was required.

When the flexible rocker feed pipe replaced the rigid pipe, a standard (7/8") length screw was used again as there was no support clip in that position.
 
And you definitely DON'T want to Loctite those puppies. Accessing the 2 inner bolts is a major chore as it is. The threads need to be clean and the bolts need serrated heads so you can turn them with the tips of your fingers. I'm sure most everyone here knows exactly what I'm talking about.
 
Status
Not open for further replies.

Similar threads

Anvill
Mikuni single manifold inner bolts
Replies
4
Views
466
Larry S
Larry S
S
  • Locked
How to stop the carb manifold Allen screws from backing off?
2
Replies
26
Views
2,853
joe czech
joe czech
nortriubuell
  • Locked
Commando 850 Cylinder Allen bolts install question
Replies
7
Views
1,573
robs ss
robs ss
DogT
  • Locked
Head Steady Allen bolts
2
Replies
22
Views
1,555
DogT
DogT
tomspro
  • Locked
Carb manifold bolts (2014)
2
Replies
24
Views
3,003
L.A.B.
L.A.B.
Back
Top