1600 Lancia twincam HELP

[lancia fiesta]

Hi i have a 1600 Lancia twin cam engine in the back of my mk1 fiesta. the tappets need adjusting or shiming, how do i do this?, does the cam or head top have to come off?

Any help much appreciated

Brian

[lancia fiesta]

I can see on the camshaft lobe there is approx 12mm of lift but only about 4/5mm is acting on the bucket due to excessice clearances. I'm guessing the shim's are under the buckets?

Brian

[Guy Croft]

With such a high lift cam Brian, it is possible that top-hat shims have been used under the tappets. I do not know if you running OE bucket tappets or ones with solid top.

OE tappets can be adjusted without removing the head using an OE shim tool of which I have some stock, email on that if you want one. OE 33mm dia tappets must be fall in the 3.25-4.95mm range only and FWIW are available readily from me (if you want) in steps of 0.05mm (2thou"). You can of course buy them from Fiat dealers but that could be a bit laborious, never bought OE, but I think it's done by part number. You can use OE shims and top hats together.

It is perhaps possible that you have a top hat shim fallen out - so my advice might be, since you say there is a huge clearance from cam base circle to bucket tappet, to turn the engine to TDC, cut the cam belt (junk it, you must not re-use belts) and unbolt the offending cambox and see what the situation is. That problem can be caused by top hat fracture, bent valve (from useless valve springs/massive over-rev, piston-valve clearances way too tight).

Ordinarily I would expect the tappet clearance measured with a feeler gauge to be in the order of 12-14 thou inlet (ex maybe 16-18) with a high lift cam of that type.

I must emphasise that with the TC unit, because it has inclined valves, that it is vital not to turn the cams without their being correctly dialled in and with the belt off, unless the head is upside down on the bench and you can see the position of the valves relative to each other.

If you did not build up that head/engine and want to know what is involved in doing it you can read a detailed article on cam timing etc with photos at:
http://guy-croft.com/viewtopic.php?t=213

GC