Difference between 67-1549 & 67-1571 Cyl Hd's

[bsa-bill]

counterbored to take a sleeved nut, which I assume requires shorter studs in the inlet end of the rocker box,

only have one alloy head but the rocker studs are long (all four), do you have the correct sleeve nuts, there are/is different sleeve nut/s used elsewhere on the bike.
Also requires special washer to sit between sleeve nut and head, and as I recall it takes a bit of fiddling about to get the sleeve nut up into the counterbored bit and started.

[sprint]

counterbored to take a sleeved nut, which I assume requires shorter studs in the inlet end of the rocker box,

only have one alloy head but the rocker studs are long (all four), do you have the correct sleeve nuts, there are/is different sleeve nut/s used elsewhere on the bike.
Also requires special washer to sit between sleeve nut and head, and as I recall it takes a bit of fiddling about to get the sleeve nut up into the counterbored bit and started.

Hi Bill

I don't have any sleeve nuts for the rocker box studs just plain washers and nuts.

You say that all of your rocker box studs are long? What length are they?

I can only estimate mine as they are on the bike, but the front one look to be about 1 3/4" - 2" and the rear ones about 2 1/2" - 2 3/4" long. If the front ones were any longer I would not  be able to get the nuts on between the gap in the fins at the front.

From the photo you can see that the rear studs are long and have to be screwed in after the rocker box has been lifted over the push rods. There is also insufficient thread to take a sleeved nut. As previously indicated a friend has a 57 RR and 60 SR with the same arrangement with long rear studs and no sleeve nuts?

How long is the sleeve on the nuts which I assume go some way up the counterbore? Can you remember if the ends of the studs are hidden inside the counterbore?

[bsa-bill]

Hi Sprint
Not sure if I have a spare stud, I'll have a look tho
this page [urlhttp://www.draganfly.co.uk/index.php/bsa/bsa/a710--b3133--c101112--m202133/category/867-pre-unit-a-group][/url]
will show the numbers for the studs ( No 11 ) in the list ( note front and rear are different for rigid and plunger could this be a factor)
Think maybe the front are correct and the rear ones are wrong as mine goes on with the studs in the rocker box

Also here http://www.draganfly.co.uk/index.php/accessories-a-misc/product/13923-
picture of the rear extended nut, you might get an idea of the size from the pic (don't think I have a spare to measure but I'll look

[bsa-bill]

update
just been down the shed, took the extended nut off the r/box (it was only finger tight - phew)

total length including hex on end is 25mm special washer is 2mm thick and width just covers the nut head
Estimate of the stud length I judge to be 35mm from the base of the rocker box ( you can just feel the end of the stud with end of your pinkie - does not protrude through the head)
a word of warning I bought a set of long studs from Draganfly that turned out to be wrong (unusual for them I've always been happy with there stuff)
The threads were wrong, the whitworth bit that screws into the box was too long (result cracked box) so double check before fitting them.

[sprint]

Thanks for the replies Bill and checking the length of your sleeved nut, looks like it was just as well that you have had a look your nuts!

It does seem strange as to why mine and my friends RR and SR, all with alloy heads, have been fitted with longer studs to the rear with std washers and nuts? Must have been a std BSA build at some stage as I can't imagine that all three could have just have been randomly converted by owners as it makes it impossible to remove and re-fit the rocker box with the engine in the frame without first removing them.

I guess one of those many mysteries, the answer to which is now long gone?

[dynodave]

All these aluminum heads I have are bored for the sleeve nuts... 5-1549, 3-1126,  1-1122, 2-1106dual port, 1-1102dual port.
Again, no knowledge of 1571 heads.
plus 3 late big fin iron heads, I should never have sold the early small fin head.

The end of the rear studs are inside the bore of the head and do not stick out.

[trevinoz]

Sprint,
                I would be inclined to make it right and use the correct studs and nuts.
Years ago I put an alloy head on my Flash and not having the correct fasteners I removed the rear studs and used Allen screws.
I don't believe that BSA would have used sleeve nuts on the majority of alloy heads and not on a few.

Trev.

[trevinoz]

Just a note on the washers for the sleeve nuts.
They are 7/16" x 11/32" x 0.175". A bit more than 2mm thick, Bill!

Trev.

[bsa-bill]

yep - picked up a head bolt washer I reckon, there in the same bag
the washer I bought with the extended nuts is 3mm - probably depends on supplier

[sprint]

Just a note on the washers for the sleeve nuts.
They are 7/16" x 11/32" x 0.175". A bit more than 2mm thick, Bill!

Trev.

Correct parts now including 3mm thick small O/D washer.

[Briz]

Just a thought; when you're opening up the inlet ports, one place you have to be real careful is around those sleeve-nut holes. Easy to break thru there. Sleeving those holes would make sense if the head has been ported.
Can you detect any sign of something having been pressed in there? or indeed if port work has been done?