ausmini :: View topic - second hand pistons

I bought a supposedly rebuilt 1310 short motor (which turned out to be 1293 anyway) and it was smokey. I put new bearings and a new cam in and a few other goodies but didn't put new pistons and rings in as they looked OK as did the bores (s/h hepolites with new rings). The engine came up a treat but is still smokey so I look like having to do it all again. Apparently Hepolites were reknowned for wearing an oval shape.

It is false economy not to put new pistons in (which usually means going up a bore size) while you've got the motor apart - I learnt the hard way. So it is good you've decided to go for new ones as well.
KB

Author:	mini-dunger [ Thu May 17, 2007 9:57 pm ]
Post subject:	second hand pistons
providing they are in good nick would it be ok to re use some oversize 1100 pistons?. I was going to just take one into a machine shop and get them to bore my new block to suit? CHeers guys

Author:	drmini in aust [ Thu May 17, 2007 10:21 pm ]
Post subject:
Yes you can, but... they won't last like new ones, the ring grooves will already have some wear. Even if they are OK you will need new rings. A ringset may cost nearly as much as pistons with rings. I got new +.040" Hypatecs for a 1098 for $159/set, from Minisport..

Author:	mini-dunger [ Fri May 18, 2007 7:48 am ]
Post subject:	SOLD
sold to minisport for $159

Author:	1310/71 [ Fri May 18, 2007 7:57 am ]
Post subject:
I bought a supposedly rebuilt 1310 short motor (which turned out to be 1293 anyway) and it was smokey. I put new bearings and a new cam in and a few other goodies but didn't put new pistons and rings in as they looked OK as did the bores (s/h hepolites with new rings). The engine came up a treat but is still smokey so I look like having to do it all again. Apparently Hepolites were reknowned for wearing an oval shape. It is false economy not to put new pistons in (which usually means going up a bore size) while you've got the motor apart - I learnt the hard way. So it is good you've decided to go for new ones as well. KB

Author:	mini-dunger [ Sat May 19, 2007 1:07 am ]
Post subject:	new pistons
I pulled all my pistons out and they are all melty around the gugeon pin. I know that the main bearing caps have to be in the correct position and are not interchangable, does the same apply to the con rods? Thanks guys

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second hand pistons https://ausmini.com/forums/viewtopic.php?f=5&t=31861	Page 1 of 1

Author:	richarde [ Sat May 19, 2007 1:26 am ]
Post subject:
Yes, keep the rods and caps in the same order that they came out and put the caps on the end of the rod in the right orientation. Mark them with a centre punch if necessary (1 dimples on rod 1 and 1 on the cap adjacent, 2 dimples on rod 2 and 1 on the cap adjacent, etc. is how I usually do it) Hijack: What type of pistons are those? I pulled similar ones out of my 1100 and I was thinking of just honing the cylinders if I could get away with it and putting them back in, but they have broken rings and I decided to not be cheap. In Vizards book he comments on a similar piston which also has a ring below the gudgeon pin and says that the crown can separate from that type of piston if you give it a hard time. I assume this one would be the same because of the large oil drain holes?

Author:	drmini in aust [ Sat May 19, 2007 7:46 am ]
Post subject:
1310/71 wrote: I bought a supposedly rebuilt 1310 short motor (which turned out to be 1293 anyway) and it was smokey. I put new bearings and a new cam in and a few other goodies but didn't put new pistons and rings in as they looked OK as did the bores (s/h hepolites with new rings). The engine came up a treat but is still smokey so I look like having to do it all again. Apparently Hepolites were reknowned for wearing an oval shape. It is false economy not to put new pistons in (which usually means going up a bore size) while you've got the motor apart - I learnt the hard way. So it is good you've decided to go for new ones as well. KB I bought Anton's 1098 motor which he rebuilt- he had it rebored, using low mileage +.020" pistons from another block. It used oil from day 1, even after reassembly with a NOS ringset it was no better. So I now have a nice new set of +.040" Hypatecs for it...

Author:	Anto [ Sat May 19, 2007 11:33 am ]
Post subject:
Yeah I just reringed a 1098 + 60 and it uses oil. Not sure if it is the rings or the head though. It was only a cheapo rebuild so I'm not concerned. I've pulled a few engines down with pistons that look like that. The wear almost looks like the bores aren't round I pulled one out of an engine that was like that all the way up to the top and has siezed the rings in. That engine did run, but boy was it smokey!!

Author:	drmini in aust [ Sat May 19, 2007 1:45 pm ]
Post subject:
With time, the bores not only wear oval, but tapered too. The best reason to rebore it, and fit new oversize pistons to suit. Fitting new rings alone to an A series is false economy.

Author:	mini-dunger [ Sat May 19, 2007 2:13 pm ]
Post subject:	balancing and polishing
Once I get it bored out and put new pistons in Would it be ok to polish and get all the rods weighing the same myself? and an obvious question what do I use to polish them? a wire wheel be ok?

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