Oversize pistons

[HFStuart]

With apologies for the cross post from BetaBoyz

I know these are scarce but does anyone know a source for oversize (0.4 or 0.6) 84mm bore pistons ? Or does anyone have a set for sale ?

I'm trying to keep my original engine but UK sourced forged pistons are a touch expensive.

Thanks,

Stuart

[radioal]

Bayless shows both 8.9 and 9.8 CR 84.4s in stock at $290 and $325 respectively. I'm sure if they have them then most of the other US Fiat vendors probably do as well.

Al

[Hamish]

Stuart,
You might consider looking for any of the 8 valve Fiat/Lancia derivatives and seeing what's available. IE: Thema/Delta/Chroma/Strada twincam pistons. Yes, I do know that some of these engines run the "other way" but in 8 valve format it's not a problem. For instance, I know a guy had his Beta twincam fitted with oversize Thema/Integrale 8 valve Turbo pistons so it's possible.
You still might be cheaper sourcing them from the 'States however ;) Especially if a nice American based Lancista sent them over in such a way as to avoid customs charges :o

[Will]

I think that would depend on the CR you wanted- oversize high CR pistons are readily available here, standard CR are in lesser demand so not as coomon- try the usual suspects Vicks, IAP. Bayless- and if you need a middleman for international shipping, let me know and I'll be glad to help out. I'm in NY and can ship US post, UPS Int'l or Fedex as you need.

I think you'll find anything from a turbo application is likely to have LOWER than stock compression (stock is typically 8.5, turbo is typically 7.5 on the earlytype motors) so make sure you are getting the CR you want- personally I'd go with 8.9's for stock cams and 9.8's for warm cams. 9.8's on stock cams can require a fairly severe ignition retard to control ping, depending on orther factors. This is why the 8.9's are offered.

[HFStuart]

Thanks for the response -

Hamish, I have considered something like a Croma / Thema piston and I will go this route as a last resort. I'm told that the gudgeon pin is off centre so the piston needs to be turned around and the valve cutouts checked but that wouldn't be too difficult. I agree that turbo pistons would be far too low CR (unless I facied machining the block or fitting a supercharger).

With the $/£ rate as it is though a US source could be a winner though even with UK Sales Tax+Duty especially as I bring a lot of stuff accross for work and I could (ahem) loose the tax payments somewhere. So thanks Al I didn't know of Bayless, I'll call them tomorrow.

Stuart

[radioal]

You might want to try an e-mail first. Apparently its now pretty much a one man show now and they don't really answer their phone most of the time. Don't be alarmed by this, though. They are very much still in business and ship internet orders very promptly. I just got a set of brake pads and radiator hoses for the Beta from them last week.

As Will suggested, any of the usual suspects will probably have them. I've had good luck with Vicks on other items and I've heard good things about IAP as well. Also Bruce's is worth a try.

Al

[HFStuart]

OK Pistons sourced - thanks for the help.

I have a choice of 8.9 or 9.8 CR. 8.9 is OE spec oin the in the UK. The engine is otherwise standard apart from an Ansa 4 branch manifold. I intend to get the ignition and carb set up on a rolling road once it's all back together.
Do you think I'll run into any problems running 9.8 CR on UK 97 octane fuel ?

Also why did Lancia make it so low compression in the first place ? Was it to run on dodgy 70's fuel ?

Thanks
Stuart

[radioal]

My guess would be to run on dodgy American unleaded fuel. The Beta was the first (and sadly only) attempt by Lancia to reenter the US market after the Fiat buyout and it occurred at a very bad time for cars over here as it was the first year ('75) of the stringent emissions regulations that forced most manufacturers (Fiat being a notable exception) to use catalytic convertors. Although the Beta was a sales disaster due to overpricing and a lousy dealer network, they were and still are one of the best of a poor vintage. And unlike most cars of the day, they still run great on 93 unleaded.

Are British octane numbers rated on the same scale as American? If so, I would think the 9.8s would be fine on 97. Back in the days of US 98 leaded, I had 9.8s in a 1608 twin-cam 124 and all was well. It really took some trial and error ignition timing to use 93 unleaded after the leaded gas ban, though.

Al

[HFStuart]

US and UK octane numbers are not directly comparable. Your 93 octane would be rated higher here. The problem is I don't know how much higher !

[FiatFactory]

The trouble is ... what is a "9.8:1" piston ... this is a bit like "how long is a piece of string?"

Different Compression heights , different dome heights, and completely different pistons for the "reverse" flow motors ...

Most of the vendors in the US have probably never built a Fiat TC ... they sell parts for them.

If your building a 2litre engine, it's pretty obvious your requirement for dome height to acheive 9.8:1 is vastly different than if you were building a 1600 ... and I've been through this all many times at mirafiori.com ... do a search over there and you'll find the info you need.

I think my post over there was something like "will the real 9.8 piston please stand up"

SteveC

[HFStuart]

Steve,

Thanks for that.

To be fair to Bayless they've been around since at least the early 70's and I wouldn't want to bet against them never having built a TC. They also had the sense to quote me a range of pistons giving their CR for the 1.8 and 2.0 motors.

Perhaps it would be better to call them '9.8 Nominal CR' ?

Anyway I decided it was too expensive to buy the '9.8' pistons and risk them giving an actual 10.5 or higher so I'll buy the 8.9 CR pistons, them calculate the actual CR after measuring the combustion chamber volumes etc. The if I want to up the compression I can face the block or head to suit.

Thanks for everyone’s help.

Stuart