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#896031 11/21/22 12:20 pm
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Having now got the ZB32 head restored to a usable condition I've been considering what I need to fit the head and barrel to my B32 bottom half. I have a NOS 8.5:1 piston, gaskets I can easily get but the problem I now have is the short cylinder head bolts.

Looking through the parts lists; 66-134 is for the 350 and 65-1413 for the 500. I can't think why they should be different but there must have been some reason. Whatever, I can't get either of them anyway.

What is available is 65-1822 for the CB/DB/DBD series engines both 350 and 500. Does any one know if these can be used on the ZB, with or without modification?

Last edited by Derek996; 11/21/22 12:21 pm.

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Well, i made a picture for you from 2 different types 500cc “short” headbolts i have , you can do the math yourself, although both are 500, i don’t have 350 examples..

[Linked Image from asset.myonlinestore.eu]

The long thick one is from a 1949 ZB34 GS, the short one from a DB/DBD 34GS, both genuine BSA

Last edited by Motolab; 11/21/22 12:50 pm. Reason: Grammar

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Thanks for that. It looks like the DB/DB one is not only shorter but has a thinner diameter and thread so not a hope in hell of fitting. frown


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It seems that I may may be able to get them on back order from Draganfly. They list 65-1413 which the 1950 parts list says fits the alloy B31/B32 but lists 66-134 for the B32/B34 so I have no idea which I need or if both will fit!
[Linked Image from draganfly.co.uk]


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I do not have a ZB32 head to look at but there are two diameters for the short bolts used over the years, 3/8" and 7/16".

My BB32 uses the 3/8" short bolts and strangely my CB34 Scrambles head use the 3/8" for the short bolts and 7/16" for the long bolts. The ZB34 and BB34 heads I have use the large bolts for all eight bolts.

What size are the holes in your head for the four short bolts?

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Hi Derek
It might be worth messaging seller "dfegold" on eBay, he has head bolts for sale every so often
I know he makes them himself so he maybe able to make them to suit your ZB32 ??

John

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Originally Posted by Derek996
It seems that I may may be able to get them on back order from Draganfly.

MCA is the company where they get them from presumably , MCA has no stock now (as we get them also from them normally ;-) )

And MCA is not very quick… beware..

We have 1 x 66-134 left on stock….

Originally Posted by Derek996
They list 65-1413 which the 1950 parts list says fits the alloy B31/B32 but lists 66-134 for the B32/B34 so I have no idea which I need or if both will fit!

They both fit! Difference is the use of the collar/thick shim, like on my image above..

[Linked Image from asset.myonlinestore.eu]

As BSA reintroduced thet collar/spacer later on, i strongly advice you to use some shim, as you will damage the alloy on the cilinder otherwise…


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Derek, (or anyone else who knows) what is the thread on those 65-1413's you need? I have some extras of those short bolts in both threads and only one more DB engine to build. I may have enough leftovers to move you along to the next problem.

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Originally Posted by Motolab
Originally Posted by Derek996
It seems that I may may be able to get them on back order from Draganfly.

MCA is the company where they get them from presumably , MCA has no stock now (as we get them also from them normally ;-) )

And MCA is not very quick… beware..

We have 1 x 66-134 left on stock….

Originally Posted by Derek996
They list 65-1413 which the 1950 parts list says fits the alloy B31/B32 but lists 66-134 for the B32/B34 so I have no idea which I need or if both will fit!

They both fit! Difference is the use of the collar/thick shim, like on my image above..

[Linked Image from asset.myonlinestore.eu]

As BSA reintroduced thet collar/spacer later on, i strongly advice you to use some shim, as you will damage the alloy on the cilinder otherwise…
Thanks for that useful information.


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Originally Posted by Gordo in Comox
I do not have a ZB32 head to look at but there are two diameters for the short bolts used over the years, 3/8" and 7/16".

My BB32 uses the 3/8" short bolts and strangely my CB34 Scrambles head use the 3/8" for the short bolts and 7/16" for the long bolts. The ZB34 and BB34 heads I have use the large bolts for all eight bolts.

What size are the holes in your head for the four short bolts?

Gordo
Originally Posted by Stuart Kirk
Derek, (or anyone else who knows) what is the thread on those 65-1413's you need? I have some extras of those short bolts in both threads and only one more DB engine to build. I may have enough leftovers to move you along to the next problem.
Gordon, Stuart, I will check the sizes when I get a chance, hopefully later today.


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Well all the threaded inserts in the head are the same as the long bolts and appear to be ⅜"

I think I've now sussed that the ZB32 uses the 65-115 long bolts and the 66-134 short bolts, all at ⅜"
and the ZB34 uses 65-1403 long bolts with 65-1413 sort bolts, all at 7/16" although some later engines seem to use a combination of ⅜ " and 7/16".

Last edited by Derek996; 11/22/22 3:54 pm.

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Derek

Simon at Barleycorn will undoubtedly be able to supply SS versions of probably any size which is used. I’ll send you a pm with a photo of all the ones he’s made different. They’re all either 3/8 or 7/16 BSCY 26tpi thread and you’ll easily be able to work out the length of the short ones just by measuring up the barrel where the studs fit plus allowance for thread depth. Almost certainly Simon will be able to tell you the correct length anyway for both. I think it’s just barleycorn.co.uk but you’ll find it easily with a search.

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That's really useful Mal. Surprisingly, I hadn't come across the Barleycorn website before.


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Funnily enough I've just bought some stuff from Barleycorn! Some engine ancilliary nuts and bolts for a DBD spec motor but `i've bought some bits before and decent quality and speedy postage. My ZB34GS head bolts are all 7/16" but stainless made by Phil Pearson when he built the motor.

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Why stainless for headbolts? What's the advantage? Seems there's also negatives with galling and shear strength? And what about stretch?



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Durability and lack of corrosion are main advantages for me. Do you see much galling with ss and the bronze head inserts? I see it with aluminium and mild steel (depending on quality of the thread finish.
Not sure how much stretch there is on these. 8 short fat bolts at not too high torque settings?
Only place I would measure bolt stretch was on my 500 Daytona con-rods bolts.


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