Advice re piston for ‘55 G3LS
- G3L1946
- Member
- Posts: 542
- Joined: Tue Feb 25, 2020 1:57 pm
- Location: North Yorkshire UK
Advice re piston for ‘55 G3LS
Hi all,
It looks like the Matchless will need a rebore. I’ve spoken to my local, and knowledgeable, engineering company and sorted that end out. But I’m not sure which piston to purchase to replace the old, wire wound, one. Will the JP ringed piston be suitable as on club spares #800313/4 ) The present piston, see attached, is 20 thou oversized so a +40 will probably be required ( I await confirmation from the engineers ). A replacement wire wound, I guess, is not on the cards ( unless there’s one out there in a shed! )
Any advice, help or suggestions much appreciated.
Steve
It looks like the Matchless will need a rebore. I’ve spoken to my local, and knowledgeable, engineering company and sorted that end out. But I’m not sure which piston to purchase to replace the old, wire wound, one. Will the JP ringed piston be suitable as on club spares #800313/4 ) The present piston, see attached, is 20 thou oversized so a +40 will probably be required ( I await confirmation from the engineers ). A replacement wire wound, I guess, is not on the cards ( unless there’s one out there in a shed! )
Any advice, help or suggestions much appreciated.
Steve
You do not have the required permissions to view the files attached to this post.
-
- Member
- Posts: 1586
- Joined: Mon Jan 01, 1990 12:00 am
- Location: WEST SUSSEX UK
Re: Advice re piston for ‘55 G3LS
the 800313/4 will fit 350 WD G3/16M Piston 0.040" 1947 - 1955 , however the clearance you need to run will be for a non - wire wound piston
Id recommend 0.0015" per inch of bore , so 4 - 4.5 thou clearance at biggest diameter on piston shirt
your rebore shop should do this for you when you get the rebore done
Id recommend 0.0015" per inch of bore , so 4 - 4.5 thou clearance at biggest diameter on piston shirt
your rebore shop should do this for you when you get the rebore done
- G3L1946
- Member
- Posts: 542
- Joined: Tue Feb 25, 2020 1:57 pm
- Location: North Yorkshire UK
Re: Advice re piston for ‘55 G3LS
Hi ,
Thanks for your reply. I understand that 800313/4 will fit my ‘55 G3LS. I think what you’re saying is that a ringed piston requires a different clearance than a wired one? I’m putting my hands up to general ignorance on this matter!
I assume the rebore shop will understand all this and factor this in automatically when I turn up with the piston and cylinder? They are engine specialists so I’m assuming so.
Regards,
Steve
Thanks for your reply. I understand that 800313/4 will fit my ‘55 G3LS. I think what you’re saying is that a ringed piston requires a different clearance than a wired one? I’m putting my hands up to general ignorance on this matter!
I assume the rebore shop will understand all this and factor this in automatically when I turn up with the piston and cylinder? They are engine specialists so I’m assuming so.
Regards,
Steve
- Joker_Bones
- Member
- Posts: 545
- Joined: Sat Apr 27, 2013 3:51 pm
- Location: DORSET UK
Re: Advice re piston for ‘55 G3LS
I fitted a JP piston to a '59 G3.
It came with fitting instructions, clearance given.
It came with fitting instructions, clearance given.
You do not have the required permissions to view the files attached to this post.
- Joker_Bones
- Member
- Posts: 545
- Joined: Sat Apr 27, 2013 3:51 pm
- Location: DORSET UK
Re: Advice re piston for ‘55 G3LS
It was heavier than the Hepolite that came out.
I can't remember the numbers but appreciably so... perhaps 20% or 25%.
I machined some material away from the inside to get it closer to the weight of the Hepolite. I'm not saying it was necessary, I just decided to.
I can't remember the numbers but appreciably so... perhaps 20% or 25%.
I machined some material away from the inside to get it closer to the weight of the Hepolite. I'm not saying it was necessary, I just decided to.
- Joker_Bones
- Member
- Posts: 545
- Joined: Sat Apr 27, 2013 3:51 pm
- Location: DORSET UK
Re: Advice re piston for ‘55 G3LS
The wrist pin supplied with the JP was thicker walled than the original and was therefore also heavier.
The little end bush may need reaming to suit.
Also it was 0.875" outside diameter. The original was 0.874".The little end bush may need reaming to suit.
You do not have the required permissions to view the files attached to this post.
Last edited by Joker_Bones on Tue Aug 22, 2023 11:49 pm, edited 2 times in total.
- Joker_Bones
- Member
- Posts: 545
- Joined: Sat Apr 27, 2013 3:51 pm
- Location: DORSET UK
Re: Advice re piston for ‘55 G3LS
You do not have the required permissions to view the files attached to this post.
- Joker_Bones
- Member
- Posts: 545
- Joined: Sat Apr 27, 2013 3:51 pm
- Location: DORSET UK
Re: Advice re piston for ‘55 G3LS
That said... It has been okay since I fitted it.
- Expat
- Member
- Posts: 1037
- Joined: Thu Nov 12, 2015 2:22 pm
- Location: Tennessee, USA
Re: Advice re piston for ‘55 G3LS
Hi Russell, I’m going through the exact same procedure as you at the mo except at +0.020 oversize bore on my 1960 G3. I have the piston and ring kit from club spares too and like you, have found that the gudgeon pin is larger than the original, which slid out easily when the piston was warmed slightly. I was hoping the new one will slide into the small end bush after a spell in the freezer. It’s a slide fit in the new piston obviously.
Did you need to ream the bush after all?
Thanks, Steve
Did you need to ream the bush after all?
Thanks, Steve
Keep shiny side up.
These are my principles, if you don’t like them, I have others. (Groucho Marx)
These are my principles, if you don’t like them, I have others. (Groucho Marx)
- G3L1946
- Member
- Posts: 542
- Joined: Tue Feb 25, 2020 1:57 pm
- Location: North Yorkshire UK
Re: Advice re piston for ‘55 G3LS
Hi Russell,
Thank you for that absolute wealth of information! I’ll digest all of it and discuss it with the guys down at the rebore shop. Likewise, interested to know if you needed to attend to the wrist pin.
Very much appreciated.
Regards,
Steve
Thank you for that absolute wealth of information! I’ll digest all of it and discuss it with the guys down at the rebore shop. Likewise, interested to know if you needed to attend to the wrist pin.
Very much appreciated.
Regards,
Steve