Fiat 128 engine timing belt

rotorhead

Help needed ? Anyone have a fiat 128 manual ,I need to find out if timing is set on 1st or 4th cylinder to replace timing belt .Engine is 1300 cc (soch)was fitted to 128,128 3p and maybe some x19

245

It's 20 years since I changed the belt on my 128 but I don't remember it being unusual - on any engine that I've come across its a case of aligning the pulley marks with the engine at TDC on cylinder 1. If it was me, I'd set it like that and turn the engine over by hand several times to make sure that there's no interference. Once you're sure that there's no interference you can try starting it.

rotorhead

Thanks for your reply. I am still wary of setting on cylinder 1. I have a uno manual for 1300 cc engine which states cylinder 4 see below. I know this is later type engine but I dont want a head full of bent valves.


28 Timing belt - renewal 3
1 Set No. 4 piston at TDC. Do this by turning
the crankshaft pulley nut or by jacking up a
front roadwheel, engaging a gear and turning
the wheel until the mark on the flywheel is
opposite to the TDC mark on the flywheel
bellhousing aperture. Remove No. 4 spark
plug, place a finger over the plug hole and feel
the compression being generated as the
crankshaft is rotated and the piston rises up
the cylinder bore.
2 On some models the TDC marks on the
crankshaft pulley and belt cover may be
visible and can be used instead.
3 Remove the alternator drivebelt (Chapter 2,
Section 8). Unbolt and remove the timing belt
cover.
4 Check that the timing mark on the camshaft
sprocket is aligned with the pointer on the belt
cover backing plate (photo).
5 Slacken the nut in the centre of the
tensioner pulley and push in on the support to
release the tension on the belt, then retighten
the nut. Slide the drivebelt off the pulleys.
6 Check that the crankshaft and camshaft
pulleys have not been moved from their
previously aligned positions.
7 To check that the auxiliary shaft sprocket
has not moved, take off the distributor cap
and check that the contact end of the rotor
arm is aligned with No. 4 HT lead contact in
the cap.
1•24 1116 cc and 1301 cc engine
28.4 Camshaft sprocket alignment marks
27.13A Removing camshaft end cover 27.13B Withdrawing camshaft from carrier 27.18 Tightening a camshaft carrier bolt

carchaeologist

The autobooks manual for the 128 says "Check that no1 piston is at TDC and crankshaft pulley mark 7 is inline with fixed timing mark 5..."
Here is a scan of that page of the manual..hope you can read it!!

Blue850

The photo om bottom right is from the Haynes manual for the 128

245

I take it that there's no belt on the engine at the moment?

rotorhead

Hi guys
Thanks for your help. A bit more info . The engine is fitted to a uno race car belongs to my son . Gear linkage lost a bolt in last outing hence no 3rd gear or reverse. hit 1st gear at high revs but still finished race. linkage repaired but did compression test on engine,result very low compression on cyl 1 . timing gears marked and head removed suspected bent valves.New valves fitted and now ready for refitting cyl head and belt. Probable cause of damaged valve is belt jumping a tooth during last race so I want to be certain of timing marks for refit as the marks before removal may be off. Also cam wheel is not original and timing cover in image from blue850 is not fitted or available .Next race is Easter sunday mondello .

245

If the worst comes to the worst you could try it fitting it at either TDC on 4 or 1 and turn the engine by hand - you'll be able to feel any interference long before it becomes an issue. Even before that you should also be able to tell visually from the movement of the cam what the engine is up to as the exhaust stroke will hold the valves open for a lot longer than on the compression stroke.

rotorhead

Hi Guys
Thanks for all your help. Up and running again and gone for final tuning.
Maybe should stick one of attached in it !!! none of them valve thingies to worry about

carchaeologist

Lol!Did you set the timing on 1 or 4?

rotorhead

Set on 1 as per advice received, had to move distributor a bit to get it fire up.
Back from rolling road,dyno test today so ready for another blast around mondello on sunday

carchaeologist

rotorhead wrote: »

Set on 1 as per advice received, had to move distributor a bit to get it fire up.
Back from rolling road,dyno test today so ready for another blast around mondello on sunday

Let us know how it gets on,stick up a pic of the car too maybe,unos are getting scarce even on the road these days.