So im buying twr pistons and liners, and on examination the piston only has one ring groove, can someone explain this to me? Does it take a two piece ring?

 

do you have a piston in your hand? are they a compltely finished piston.

i have seen two ring pistons, but never a one ring groove piston, UNLESS they leave it to the engine builder to cut his own groove, where he thinks its best.

how do you know that they are TWR parts??

 

They are actually from TWR the guy im buying my parts from has all yhe old twr parts. They are actually a one ring piston made forthe 88mm stroked crank and a dry sump. I don't know if you can cut anothee groove, ill post the picture. They were assembled and test ran in a twr motor

 

https://mail-attachment.googleuserco...9eJv8&sadssc=1

 

The link does not work.

 

here we go

 

best picture i have

 

Cal, you are a piece of work!!, those are 2 ring pistons, one top compression ring and an lower oil control ring, good for racing as less friction loss.

they do look like they are used not NEW. if say, one was slightly damaged, you could send a good piston out to a manufacture, and they can easy make a good copy, lots of piston makers here in usa.

but if they fit the crank and liners, it would make a nice combo.

you have only started, now comes the big money, lot more than a set of pis.&liners to build a complete engine, i see that you looking for a set of pre heads, and you gotta have some cams that will work, and you gotta have more valve area, to make the big lungs get some air.

at this point GO FOR IT!

 

i ment one compression ring! and they were assembled and test ran, then dissassembled. the damages one is number 13 of the set, with matching liners. 1600$ aint such a bad deal. cams were a must anyways. im going to assemble and break it in with the stock ones. then get new ones when i figure out exactly what i need from how it feels when im driving it. switching to gm ls throttle bodies, and a self tuning efi unit, doubled to act like two six cylinder units. that is the plan as of now, but it always subject to change.

 

those dont look like flathead pistons to me.

 

no they are not. if i chose thoes, im going to need a slightly shorter rod to give me clearence or use HE heads. But i think ive found an e type motor

 

Wondered if you ever did this; You may have found that if you have TWR 7.4 pistons and liners then the liners will not fit the block, not too hard to overcome bore wise but dont make them a press fit as they will crack. Height is a different matter and will require special casting heads to sort this properly. The liners should also be for coopers rings too, start applying for the bank loan now.

 

i dont think this will ever happen!

the engine build never mentioned liner protrusion, or block to sleeve fitting information!

 

Looked at these pistons again and simply dont believe they are 7.4 TWR items. Looks like someone has put the pistons in a lathe and taken the 'eyebrows' off to allow the pistons to move further up the bore. You can see the tell tale machining mark in the centre of the pistons, Give me the etched number underneath and I will tell you what they were originally.