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Tappet chest cover bolts
Posted: Fri Jul 30, 2021 9:59 pm
by jagnut66
Hi,
What size are the long tappet chest cover bolts?
I've had my spare block rebuilt, as the one in Elsie May is knackered and needs replacing. As part of this process my spare block was completely stripped and cleaned up, wereupon the tappet chest covers on it were found to be toast.
Fortunately I expected this and was planning to change them for a good spare set I have, which I have repainted in readiness........ 
Unfortunately it appears the bolts were slung out along with the unserviceable covers....... 
So I went looking on the ESM site and they don't specifically list them, however there are a few likely suspects, I just need to know the size??
Many thanks,
Mike.
Re: Tappet chest cover bolts
Posted: Fri Jul 30, 2021 10:29 pm
by jagnut66
Re: Tappet chest cover bolts
Posted: Sat Jul 31, 2021 7:52 am
by philthehill
For the convex covers (803cc/948cc) the bolt size is 5/16" UNF x 1.875".
For the concave covers (1098cc) covers the bolt size is 5/16" UNF x 1.25".
Re: Tappet chest cover bolts
Posted: Sat Jul 31, 2021 11:42 am
by jagnut66
For the convex covers (803cc/948cc) the bolt size is 5/16" UNF x 1.875".
For the concave covers (1098cc) covers the bolt size is 5/16" UNF x 1.25".
Thanks phil, I will look out for the 1098 ones but good to know both sizes.
Still on the subject of engine bolts but digressing slightly:
Out of interest the bolt at the back of the engine which the engine steady bar connects onto seems to be a little longer than the other four of the shorter head bolts. is this correct or just an optical illusion?
ESM only show two sizes, the long and the short.
Charles Ware seem to recognise it on their diagram as number '8', with the other short bolts as number '9's.
However, when you schroll down to the actual parts, the bolt is shown as '#8,9' and only one bolts size is then listed for sale.
Best wishes,
Mike.
Re: Tappet chest cover bolts
Posted: Sat Jul 31, 2021 1:10 pm
by Declan_Burns
Mike,
I would also fit the long studs to where the heater pipe is fitted. This means you can remove the pipe without disturbing the head e.g. if you want to change the thermostat.
Regards
Declan
Re: Tappet chest cover bolts
Posted: Sat Jul 31, 2021 2:11 pm
by philthehill
The engine stud that the engine steady bracket fits over is slightly longer to accommodate the thickness of the bracket.
The Pt No: of the engine steady bracket stud is either 51K244 or 51K254. I am unaware of any differences between those two studs.
For completeness - the short head stud is Pt No: 51K256 and the long head stud is Pt No: 51K255.
Re: Tappet chest cover bolts
Posted: Sun Aug 01, 2021 11:56 am
by kevin s
I was wondering why one of my studs is longer !
I've put it at the front but I don't use the steady with a hydraulic clutch so it won't be a problem for me.
Re: Tappet chest cover bolts
Posted: Sun Aug 01, 2021 12:32 pm
by jagnut66
The engine stud that the engine steady bracket fits over is slightly longer to accommodate the thickness of the bracket.
The Pt No: of the engine steady bracket stud is either 51K244 or 51K254. I am unaware of any differences between those two studs.
So the follow on question is: Does anybody know where members could source this slighly longer stud that the engine steady is fixed to.
As above, neither ESM nor Charles Ware seem to supply them....
Best wishes,
Mike.
Re: Tappet chest cover bolts
Posted: Sun Aug 01, 2021 1:25 pm
by philthehill
The extended stud was discontinued and the 51K256 stud used in its place.