• Welcome to the website of the Vincent H.R.D. Owners Club.

    Should you have any questions relating to the Vincent H.R.D. Owners Club, or Vincent H.R.D. motorcycles in general, please contact Graham Smith, Hon. Editor and Webmaster by calling 07977 001 025 or please CLICK HERE.

    You are unrecognised, and therefore, only have VERY restricted access to the many features of this website.

    If you have previously registered to use this forum, you should log in now. CLICK HERE.

    If you have never registered to use this website before, please CLICK HERE.

E: Engine spark plug 'ole

vibrac

Well Known and Active Website User
VOC Member
As I am retrofitting a 84bore cylinder I need a new second spark plug hole in my cylinder head for my decompressor
Its not something I have done before but I have a mill and an angle plate so...
I have worked out is a 14mm X 1.25 tap and a 12.8 mm tapping drill but does anyone know the angle from the cylinder base of the hole? by eye it looks like 45 degrees.
 

Marcus Bowden

Well Known and Active Website User
VOC Member
Tim my handsome, if "B" Nighted reads this post you might receive in a few days my hand JIG for doing just that, putting in a 2nd plughole, I made it at sea about 35 years ago and you only need use handtools.
bananaman.
 

Cyborg

Well Known and Active Website User
VOC Member
Same as the valves I think IIRC. Do you have a rotary table? Set the mill up using the existing plug hole and then turn the table 180.

Somewhere there is a discussion about the angle, but a search wasn’t successful.

After drill and tapping, I was able to find a old valve seat cutter that I could use to shape the top of the hole, so it looked the same as the original.
 

clevtrev

Well Known and Active Website User
VOC Member
All the holes are at the same angle, If you have a plate with the four stud holes mounted on an angle plate, set at 32 1/2 degrees, clock in a valve hole, lift the head off the plate turn through 90 degrees and you are centered for the plug hole.
 

Robert Watson

Well Known and Active Website User
VOC Member
OK Tim

I just had this feeling that there was something out there. I have one slightly used Omega 3273 piston Bore 90.0 Yours for the asking if it's any use. No rings and no pin and keepers.

Robert
 

Marcus Bowden

Well Known and Active Website User
VOC Member
You area Dorsetboy now Bill, only two hours away from Looe and there is two idling away here, small and a monster. No charge nice to have a little company. Does her in-doors like gardening? Stacks of it here.
 

vibrac

Well Known and Active Website User
VOC Member
Well I have made a second plug hole and what a magic jig it is thanks Bananaman (and Ian) . Now I have the hole it seems a shame to carbon half of it up with a short reach RE decompressor! I know I saw a UK supplied long reach 14mm decompressor a year or so ago I thought it was Venhill but if I look on their site I cant find it can anyone give me a UK supplier?
 

Black Flash

Well Known and Active Website User
VOC Member
@vibrac
Could you please post a picture of the jig assuming you are not violating intellectual rights.
I need to do the same and it sprobaly cheaper to built a jig than paying postage from and to England.

cheers Bernd
 

Marcus Bowden

Well Known and Active Website User
VOC Member
Information should be moved on for everyone. Some folks onboard held info very close to their chest as it was power, me, I would show everyone how to do things all the way, the simple reason was if I trained them to know as much as me then I wouldn't get called out at ungodly hours.
Pass it on my handsome Vibrac. I can't as you have it. Just be prepared to send it onto the next person who asks, for it as it was designed / made nearly forty years ago to be used in a garden shed with just handtools.
bananaman.
 

vibrac

Well Known and Active Website User
VOC Member
Here is the magic jig you could do it all with a power drill
The final stepped drill (5th from the right) I did drill in a pillar drill using the H fixture to hold hole at 90 degrees
the extreme left group of parts/set I did not use.
apart from the facing bit 6th from the right its all done from the inside
I used my own 14mm tap

1605350901072.jpeg
 
Last edited:

Latest Forum Threads

Can't Find What You Need?

Buyer Beware: Fake or Real?

Top