110 rod piston

[AL BARKER]

Is there a piston that works with a 110X58 crank, 66.0 cast barrel, that doesn't require a 3mm base packer? I know you can get pistons with different crown heights.... cheers

[hullygully]

30Ht & 38Ht are usually the Lambretta norm with 107 & 118 rods bud

[Adam_Winstone]

30 / 116, 39 / 107 are the norms for later Italian S2 and S3

[Adam_Winstone]

However, I'm interested to know why you might want to find a piston that allows you to lose the packer? Especially when the packer is cheaper and easier to source that another piston.

Many tuners today would suggest that having the increase of crankcase volume that the packer gives will actually aid performance, depending on other factors (e.g. exhaust).

Adam

[AL BARKER]

I already have 58x110 jap rod crank and cast iron barrel but no piston so just investigating if a piston is available that does away with packer.... not using a packer will make it easier to fit exhaust other than the bgm type with slotted holes ie my original Ancillotti without stressing it. It's not about the money..... according to some dealers I definitely need to use a packer as it will alter the port timing even if a piston was available......... don't quite understand why, if it does it must be a tiny amount... SO ill fit a packer and use my bgm exhaust.......

[Adam_Winstone]

Depending on which piston it was intended to use and what's been done to the barrel it may or may not need a packing plate. Also, it may assemble to need a different thickness packer to give the intended port timings. Do you know what piston it was using previously, know the barrel length accurately (full length or perhaps fractionally topped or tailed ?), are we talking smallblock or bigblock, bore size, measurement of port heights from head gasket face?

If your cast cylinder was previously run on this rod, then there is a very good chance that it was run with a non-Lambretta piston conversion, in which case the suggestion of a 3mm packer could well be wrong, i.e if intended to be run with a 34mm (for example) compression height then you would need to machine 5mm off the barrel (39mm Lambretta S3 compression height, other than 30mm TV175... so for this example 39-34 = 5mm). However, with a 110mm rod (3mm longer than the standard 107mm rod) you would only need to machine the barrel by 2mm (-5mm piston, +3mm rod = 2mm difference). Change the piston spec and everything changes accordingly as does varying the machining of cylinder from head or base to alter port timings.

^... the above is posted only to illustrate how it would be impossible for us to give any reasonably accurate advice without knowing a lot more detail about the top end you're intending to fit. If the top end is not the one previously fitted to that engine then we need to know exactly what the new top end spec is.

PS - I'm not trying to throw spanners in the work... just trying to avoid giving you bad advice based on me making assumption to fill-in the blanks of current unkown factors.

Adam

[AL BARKER]

The barrel is an unmodified cast stage 4 200. I'm thinking of a quality piston, with the packer etc... the barrel has never been on this casing. The casing has been matched and flowed to the kit I'm taking off so I suppose the new packer will give me a 3mm thickness to blend in as much as possible... I built a taffspeed ts1 many years ago with a 3mm packer and jap rod (and it's still fast with only 1 rebuild) and I know the longer rods tends to be smoother ride... and Ian at the time said more volume under the piston helps as primary volume was unchanged from small block. Then oddly he treasured a stuffer he showed me to increase primary compression....... I really appreciate the comments given. As they say every day is a school day, never too old to listen to opinions... engine will be through a modified airbox, 22mm Dellorto etc so not high tech at all.... 4.8 final drive and probably the MB/ BGM clubman.... Italian early GP 200 1969..

[Adam_Winstone]

^... good additional info.

In which case, the SIL Factory IV, which I assume is what you're fitting, will simply need a 3mm base packer to put everything back to normal with a standard 39mm compression height piston.

There are plenty of piston choices and someone will always have a horror story about each/any brand that might be mentioned so I'll leave that up to you to evaluate any suggestions that people / dealers might give you.

A pal of mine ran a Taffspeed Jap TS1 200 with HPC padded crank, which was very reliable and very fast. I wonder whether the crankcase stuffer he showed you was one of the old Wildcat cast stuffers that were available at one time? I took the opportunity to buy a couple myself, just to satisfy my own collector/home tuner curiosity... and they're still sitting in my drawer(lol).

All the best. Sounds like you're building a very viable motor.

Adam

[AL BARKER]

Yes Adam, was a wildcat stuffer .. weird shape thing.. obviously was a long time ago..

[Fast n Furious]

There's a couple of piston options available which have a 36mm compression height, but you would need to use a reed valve manifold with these. Ring peg positions would need checking also.