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Reassembling gudgeon (wrist) pin, piston and con-rod

Posted: 31 Oct 2016, 17:21
by Mohamster
Hello clubbers!

So I'm halfway to a rebuilt engine (in the sense that I have managed to get two pistons back on the engine and struggling with the other two).

1 and 3 went on somewhat easily with a bit of assistance from a blow torch and freezing of the pins. I'm finding the reassembly of 2 and 4 much more difficult because of the lack of space now that the first two pistons and liners are on.

So, my question:: What methods, if any, exist to align the conrod small end with the piston so that the gudgeon pin goes in without hassle. With the first two it was easy to lift the con-rod up and down and almost 'feel' the gudgeon pin into the hole. But now, I need to align con-rod and piston holes and I need this alignment to hold while I am applying force to get the pin in, yet the alignment is never right and the con-rod keeps dropping.

Thanks: So far while I've been rebuilding my engine I've had a lot of good advice from so many forum members .. just thought I'd note again how thankful I am to everyone who's been sharing their knowledge and experience. Hopefully I'll be in a position to do the same at some point :-)

Re: Reassembling gudgeon (wrist) pin, piston and con-rod

Posted: 31 Oct 2016, 20:12
by itchyfeet
Firstly its easiest I find, to lay the engine on the flywheel to get the pins in, the con rods then stay where you leave them, gravity is not fighting you.

Secondly the gudgeon pins ( 'mericans call them wrist pins) can hit the circlips and cause a burr, this burr makes the pins hard to slide out and back in.

I bought a 24mm spiral hand reamer reamer for 25 quid which takes the burr off and help it slide, you don't want to be whacking it unless everything is supported with wooden packers, remove burrs make your life easy.

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Re: Reassembling gudgeon (wrist) pin, piston and con-rod

Posted: 01 Nov 2016, 16:01
by Mohamster
That's great advice Itchy, as ever! I'm gonna give it a try resting on flywheel!

Will let you know how I get on :-)

Re: Reassembling gudgeon (wrist) pin, piston and con-rod

Posted: 01 Nov 2016, 16:07
by itchyfeet
And I'm going to try this today on an engine I'm resealing, got standard bearing shells.

E D I T, looks far too prone to dropping bits inside so I'm not doing it.
You would need the get the bolt half of the conrod held in place while you fitted the other half and nuts making sure bearing shells don't come out. Holding bolt half would be tricky, very little acess from other side.

Mohamster wrote:
2- Is it possible to replace the big end bearings without taking apart the crankcase? I know you can get the rods off without dissassembly of crankcase, but I'm wondering about actually getting them back on and fastened to the correct torque.

!

Re: Reassembling gudgeon (wrist) pin, piston and con-rod

Posted: 02 Nov 2016, 21:02
by itchyfeet
Did this today, all four in 1 hour sitting on flywheel

more pics end of slideshow
http://s1145.photobucket.com/user/paul_ ... ead%20seal" onclick="window.open(this.href);return false;

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Re: Reassembling gudgeon (wrist) pin, piston and con-rod

Posted: 03 Nov 2016, 10:49
by Mohamster
It worked a treat!!! Thanks ...

Two pistons in within an hour, although that included refitting some broken piston rings ...

The previous two pistons took a whole bloody evening.

Thanks again, one step closer to being back on the road. Hopefully heads back on tonight and ancillaries on engine ready to refit to van on Saturday provided I can find the manpower.

Re: Reassembling gudgeon (wrist) pin, piston and con-rod

Posted: 03 Nov 2016, 11:07
by itchyfeet
don't forget to stretch.pushrod tubes
I use a piece of thin aluminium rolled around the folds to open them up to the specified length
Also dirko on both sides of water jacket gasket and clean with meths first

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Re: Reassembling gudgeon (wrist) pin, piston and con-rod

Posted: 03 Nov 2016, 13:41
by Mohamster
Van came with telescopic pushrod tubes. So gonna stick with those if they're still functioning.

Oh the cleaning of sealing surfaces ....soooo satisfying!

Re: Reassembling gudgeon (wrist) pin, piston and con-rod

Posted: 03 Nov 2016, 14:10
by itchyfeet
Got some engine porn to post up then?

Ground valves?