Twink Ignition

[hemibum]

Any advice please? To convert our Twink to electronic ignition, Aldon or Lumenition? Megajolt seems too complicated and a bit scary for DIY set up. Thanks people.

[ELAN+2]

try these guys:

http://www.h-h-ignitionsolutions.co.uk/

they reconditioned my distributor nd fitted electronic ignition inside the dizzy, no extra boxes.

I have run a Twink on lumenition and can highly recommend either set up, however you my get rev counter issues, this is easily cured by fitting the guts from a smiths RVC type rev counter in the lotus housing.... speedograph do the upgrade if you prefer.

[hemibum]

Thanks Mark. I did see the adverts for H&H. Sent them an e. mail they replied saying they could do the conversion to suit the engine spec. Trouble is, it was advertised as being a "big valve" head, but I don't see anything on the head or valve covers to confirm this. Not sure if there would be any ignition advance issues given the slightly larger valve sizing if that's what we have.

[ELAN+2]

according to Miles Wilkins book on the twink( THE BIBLE!!) the big valves have next to no effect, its the cams,compression ratio and the porting that make the difference. The 'Big Valve' was a marketing exercise really, the big valves are only 1mm larger in diameter!! Mile's book tells of a super S/E engine on strombergs producing 125bhp and better driving characteristics and economy than any webber/dellorto engines. It had Sprint spec cams,compression and a port job,,,,, but standard valves!!.
the advance curves are all a bit hit n miss with the twink, various different ones were used over the years. do you know what cams you have? they are identified by 'grooves' under the cam gears, non is for the std engine (105bhp), one is for the S/E spec (STD on plus 2s with 118BHP) and two for the 'big valve' or sprint /S130 +2 engine(126BHP), I'd go by the cam type when speccing the distributor.

mark

[hemibum]

Mark, thanks for that. Will now order the book! Stupid question but, can I see the marks if I remove the cam cover? Thanks again.

Barry

[Sam_68]

I wouldn't worry too much about whether you have a big valve head or not... the increased valve size does make some difference (with a poppet valve, it's 'curtain area' - perimeter x lift - that's important, so you need to multiply that 1mm increase in diameter by pi, then multiply it again by the valve lift to get a true picture).

Certainly, it's easy to get up to about 125bhp with a Stromberg engine, but you can't get much more than that. A Weber/Dellorto 'Big Valve' can make an easy, tractable 145bhp with little more than accurately timed QED cams, re-jetting and a bit of a clean-up of the head, however. The variable chokes on the Strombergs do make for slightly better low- and mid- range torque, however, as Elan+2 says.

In terms of ignition curve requirements, compression and cam profile are far more important, though.

Unfortunately, it's difficult to establish whether either compression or cam profile is standard without taking things to bits and measuring them accurately because cams have often been re-ground or heads skimmed over the years.

As Elan+2 says, you can identify standard cams (ie. assuming they've not been re-ground) by counting the 'grooves' at the front and yes, you need to remove the cam cover to check.

The Miles Wilkins 'Bible' includes a chapter on ignition and shows the advance profiles for the various distributors used. It's even more hit and miss these days, though - not only can the engine specs have changed over the years, but the petrol we have available isn't as good as the Twin Cam would like and they can be quite prone to pinking... it seems to vary, though, with some engines being more prone to pinking than others.

So as Elan+2 said, it's all a bit hit-and-miss! YOu can get mapped ignition systems from QED and others, that make a huge difference to the engine's manners (especially if combined with fuel injection), but they're expensive and most people prefer the originality of carbs and dizzy.

Edited by Sam_68 on Tuesday 12th February 08:11

[hemibum]

Thanks everyone. After much searching webwise for a copy of Miles Wilkins book, I suddenly remembered a rather old fashioned source of information; Local Library!

Got it out on a 4 week loan, renewable anytime. Result.

I now at least know that we seem to have a bitsa. Early sand cast head with no I.d. in front of no.1 plug. 1600 block with spacer plate. C type cams. Home made fuglin' ugly manifold. Botched up accelerator cable fitting under the Webers. Broken Thackery washers. Missing Seloc washers.

Funny thing is, it runs spectacularly well. No smoke, good oil pressure, consistent temp.

So I guess we'll stick in the Lumenition system more as a maintenance upgrade than anything, and just run it with a sympathetic ear. Oh, and 97 octane with a booster/additive

thanks again for the help.

Edited by hemibum on Thursday 14th February 22:27

[anonymous-user]

Try a 123 ignition, nice bit of kit and has 16 differant curves you can select. Plus all the bits are in the dizzy. Cost 200 quid. I have one in my twink, dumped the luminition for it and it works a treat.

http://www.123ignition.nl/

Got mine off a shop on ebay.

http://stores.ebay.co.uk/Bestek-Ignition-Systems

Cheers

Doug

[hemibum]

FB said:

Try a 123 ignition, nice bit of kit and has 16 differant curves you can select. Plus all the bits are in the dizzy. Cost 200 quid. I have one in my twink, dumped the luminition for it and it works a treat.

http://www.123ignition.nl/

Got mine off a shop on ebay.

http://stores.ebay.co.uk/Bestek-Ignition-Systems

Cheers

Doug

Where were you earlier? Just ordered a Lumenition kit from Burtons and received it this morning! Story of my life! Thanks anyway.

[anonymous-user]

Sorry, not been on for ages, usually surfin elan net... Luminition is good kit, I went for the 123 because I can change the curves to suit engine development.

Doug