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Help: Rings for a +.030" Specialloid Piston wanted

miked

Active Website User
VOC Member
Hello,
I wondered does anyone know a source of replacement piston rings for a + .030" Specialloid piston?

My Comet barrel is on size and only .002" out of round, but I may have to have a rebore if I can't find any replacement rings (1 broke while removing it).

Many thanks in advance,

Mike
 

Bill Thomas

Well Known and Active Website User
VOC Member
Hello Mike, I think you might have to have the ring grooves made deeper and wider, And fit car rings, I hope I am wrong !! We will see if anybody comes up with something, I used rings from an old Leyland van, Brian Chapman told me of the trick, John From USA said he used old chevy Rings ? Good Luck, Bill.
 

Howard

Well Known and Active Website User
VOC Member
Not sure what the problem is. If finding Specialoid piston rings is the problem, I can't help. If it's the +30 which seems a strange size (to me at least) can you get +40 rings and gap them to the bore?

H
 

miked

Active Website User
VOC Member
Thanks for the replies chaps!
As Bill mentions, the spares company rings are deeper than the originals, which are only available in STD, +.020" & +.040" sizes.
It did cross my mind to machine the piston to accept the +.040" rings (as I had already purchased a set) and then gap them to suit. I was unsure that machining the groove wouldn't weaken the piston & if there was a risk of the modified ring being under too much (sprung) tension.
It would also be on the limit of my modest skills, so I would be "putting a job out", which always invloves its fair share of hassle / disappointment.

I'm no expert Howard, but I think +.030" was a standard oversize from the factory, but yes I suppose today it is not a common one - hence my predicament...

Cheers,

Mike
 

miked

Active Website User
VOC Member
Thanks David,

They have a UK agent not too far away from me, so I will call them when I have some exact measurements to hand and see if they can help.

Thanks again,

Mike
 

vibrac

Well Known and Active Website User
VOC Member
Just cant get the right sized cast iorn drain pipes anymore -damm plastic :)
 

Nomadnigs

Website User
VOC Member
Reactivating an old thread as it seems I am facing the same problem as Mike. I have a '49 Rapide which is having the engine serviced and rebuilt by Ben Kingham at BSK. He says the bore is fine with minimal wear but would benefit from a set of new piston rings. The engine currently has Specialoid pistons at +30thou bore (yes this was a standard oversize apparently). The older type of Specialoid pistons had narrower rings than those available through VOCS today. We have sent a message to Hastings piston rings (link above) but no joy. I would definitely like to avoid an unnecessary rebore out to +0.40 all because we can't find a set of replacement rings. If anyone knows of a secret source or has a spare set sat in their shed, I would be very grateful to hear from you.

All the best

Nigel
 

Bill Thomas

Well Known and Active Website User
VOC Member
Someone has told us, " British Motorcycles Bikes & Spares ", May be able to help ?.
John Harding 01989 750731, He has an advert in Vintage Club.
Let us know how you get on, I may have the same trouble soon. Cheers Bill.
 

Howard

Well Known and Active Website User
VOC Member
Try F W Thornton. They sorted some rings for me. They work on dimensions if they haven't got a set specifically for your piston, so get your vernier out and give them a ring. :)


Cheers
Howard
 

Bill Cannon

Well Known and Active Website User
VOC Member
Take a look at Total Seal rings. I successfully fitted these to specialloids after having the ring grooves machined to size.
 

mercurycrest

Well Known and Active Website User
VOC Member
Nigel,
Deves used to list Vincent rings, try them 1st. I used to take Chevrolet LUV 84mm rings and fit them (order +.030), but you have to machine the ring grooves to fit and it's pretty tight. It might be simpler to leave your old 2nd rings in.
 

peter holmes

Well Known and Active Website User
VOC Member
Thanks for the replies chaps!
As Bill mentions, the spares company rings are deeper than the originals, which are only available in STD, +.020" & +.040" sizes.
It did cross my mind to machine the piston to accept the +.040" rings (as I had already purchased a set) and then gap them to suit. I was unsure that machining the groove wouldn't weaken the piston & if there was a risk of the modified ring being under too much (sprung) tension.
It would also be on the limit of my modest skills, so I would be "putting a job out", which always invloves its fair share of hassle / disappointment.

I'm no expert Howard, but I think +.030" was a standard oversize from the factory, but yes I suppose today it is not a common one - hence my predicament...

Cheers,

Mike
I am not an engineer so please don't laugh, well not out loud anyway, rather than modify the piston grooves would it be possible to very carefully reduce the thickness of the available rings on a slipstone, that is if we are only talking a few thou. Sometimes the most dreadful bodges work, in the sixties, with very little knowledge or money, I took a swiss file to an oversize half time pinion, got it to there or there abouts, and it worked for a good few miles, I don't think Tony Maughan was overly impressed when he rebuilt my engine at a later date though.
 

van drenth

Well Known and Active Website User
VOC Member
I can help somebody out with Wellworty pistonrings
Seize 84 + 010 x 1/16 x .118
84 + 010 x 1/8 x 126
In total I have 11 rings for Two pistons,
Those comes from Argentina as new ols stock.
So how can use them, for only the cost of sending them ?
Regards,
van Drenth JC
 

Flylow

Well Known and Active Website User
VOC Member
Hello,
I wondered does anyone know a source of replacement piston rings for a + .030" Specialloid piston?

My Comet barrel is on size and only .002" out of round, but I may have to have a rebore if I can't find any replacement rings (1 broke while removing it).

Many thanks in advance,

Mike
Hi Mike,
You can get rings that fit Specialloid's here:
www.deves.com

Best -Kurt
 

Cyborg

Well Known and Active Website User
VOC Member
I bought some for my Comet project from Deves, He made them up for me and if I recall correctly it was approximately $50 USD.
The oil ring he supplied is 4 pieces and a bit awkward to deal with unless you have a proper ring compressor. I “may” have some 30 over rings, but they have beveled ends on them ( looks like a scarf joint) so they are a PITA to gap properly. I’ll check.
 

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