Urraco Engine Rebuild starts again

I’ve now discovered that the gap between the pistons and the liners was between 7 and 10 thousanths of an inch.  This is much too large and probably explains the compression issue on cylinder 6.  I dont know if the others are the same but I have decided to replace all the pistons and liners.  They come from Lamborghini with the rings and new gudgeon pins all in place and matched to  the liners.  The gudgeon pins will have to have no bearings made for them as these are no longer available from the factory.   I will also be taking the crank out  and having it inspected.  I think the big ends and the main bearings are fine but its worth checking at this stage.  If the crank needs regrinding there are over size shells available from Lamborghini or they can be made.  I am also coinciding having my local engine rebuilders put at least the bottom end of the engine back together and maybe the pistons and heads assembled by them.  This work needs doing in very clean conditions to make sure no wear and tear is caused by a stray piece of rubbish or dust.  I will keep the blog up to date and if anyone wants specific pictures just ask by replying to this  blog or by contacting me on the Lamborghini-talk website.

17 responses to “Urraco Engine Rebuild starts again”

  1. Chris Holl says:

    Nice site. I’m rebuilding my Urraco too. What are you using for valve clearnace? I’ve seen .40mm and .45mm. Thanks.

    • admin says:

      I think I remember them being 0.45. The hardest thing to find was the shims which arent made any more. However they can be made. I actually think my engineering company used Ford Escort Diesel engine shims which are the same size (37mm rings a bell) and easily found.

    • admin says:

      Chris I have a mass of rebuild photos and knowledge. Additionally if your in the UK your welcome to visit to look at the car.

  2. admin says:


  3. admin says:

    Today I have taken the stripped down engine to Modus engineering in Langton Green near Tunbridge Wells in Kent. These boys really know their stuff. The plan is for them to take out the crankshaft measure the big ends and main bearings and check everything. If all is well we will probably leave the crank as it is. However if we find damage particularly to the main bearings I will get them to grind the crank down for new oversized end shells and bearings which are available. Modus will then hopefully rebuild the engine for me with the new Pistons and Liners. I’m also going to see how much it would be to get them to acid clean the whole thing. I’m not sure if I will get them to rebuild the top end as I think I can handle that myself but we will see how much that will cost. They will also make the new small end bearings which are no longer available.

  4. Greetings from Urraco 15812 in Norway. My owner is unable to find the “AA” ignition timing mark shown in the owner’s manual Fig. 21. Can you help?

    • admin says:

      Very happy to try and help out. The crankshaft and fly wheel are at my local engineers at the moment. However from memory the two sets of marks on the flywheel are about 7 or 8 cm’s apart. Can you find the other set of marks on the fly wheel. The fly wheel is one of the few parts that was manufactured by Lamborghini themselves so its not possible to have an after market part without the marks. Can you see any marks on the flywheel?

      • I have found only one slot on the flywheel at what I take to be the 18 degree advance position. I can email a photo if you wish.

        • admin says:

          There isn’t a slot it should be stamped on the rim with AA at the advance point. The flywheel is at the engineers currently but I will try and find an old pick.

        • admin says:

          Caleb I have taken some pictures of the flywheel for you. I will up load them later today. There should be two marks on which says PHS or PMS by it which should be centre of the window when number one cylinder is at TDC. The other is the advance mark with AA next to it. Its possible I suppose that it has faded. I could measure the exact distance for you. But it shouldnt matter becuase with the key for the flywheel to the crank it cannot be in any other position when no 1 is at TDC. Its the AA mark if memory serves that you set the timing from. Hope this helps.

          • Caleb Bradley says:

            When the flywheel is at the AA mark, both cylinders #1 and #7 should be close to TDC but only one should have both valves closed for compression. I suspect my timing belt is wrongly engaged because at the AA setting I can blow freely into BOTH #1 and #7 sparkplug holes. Unfortunately with the engine in the car it is impossible to see the alignment marks on the sides of the camshaft pulleys, and difficult to see much of the forward pulley. On the rear pulley I see the slot that should align with the pointer at #1 exhaust TDC = #7 ignition TDC. Can you tell me whether the forward pulley has a similar slot and whether it should align at the same time?

          • admin says:

            Caleb, I’m in and out of the country at the moment and worse my engine is in the middle of a rebuild and is not here for me to look at. I will admit from memory I thought it was cylinders 1 and 6 that are at TDC together but I may be wrong. You should however be able to see the cam timing marks very easily even with the engine in the car. Do you have the indicator arrows on top of the cam covers. Look at engine pictures page on my site 4th row down second from left. Do you have these metal pointers? Some cars have lost them. Without them you will find it very hard to see the exact location. The wheels have little slots which I put white paint on in my car. However on the back of the cam wheels there are another set of marks. See the same pictures page row 7 second and third from the left. However you will have real trouble seeing these with the engine in place. Particularly if you have the cam belt covers on. I think you can take the covers off with the engine in place but its tricky. The valves on this engine push down into the space left by the piston so if you have the timing very wrong you shouldnt be able to turn the engine over because the valves will hit the pistons. Let me know how you get on and if you have any other questions.

          • admin says:

            Caleb you may find it useful to join the Lamborghini-talk.com group or the classic lamborghini group on Yahoo.

          • admin says:

            Caleb one last thing I thought of over night. Your blowing test may not be right. There is a point where both the valves are open, Overlap I believe they call it. I’m not an expert mechanic or anything I’m just going on my experience. If you try the Lambo talk web site there are folks on there who can really help you out. I think you will find that the cam pully marks can only be in one place. If they are right in line the mechanical valve timing will be right. But again I think an expert will help. When I rebuilt mine I turned it over by hand several times to make sure nothing was clashing. Good luck

          • admin says:

            Caleb one last thing we may be confusing the numbering. I count from the right looking from the back of the car. front bank right to left 1,3,5,7 rear bank 2,4,6,8 if you’ve counted from right to left 1,2,3,4 then 5,6,7,8 then what I call 6 you are calling 7. That would make some sense so we are talking about the right cylinder. Its the one directly behind the distributor that is the most difficult to access.

  5. Caleb Bradley says:

    I count the rear (of car) bank 4321 and the forward bank 8765. Firing order is 15487263. (Driver’s handbook p.46) Both my cam cover pointers are intact. The engine turns with no cam-piston clash.The breaker gaps, coils and ballasts are ok and make sparks. I reason that a contact breaker must open at the flywheel AA position to generate a spark to #1 or #7, but at AA there is no breaker change within the mechanical adjustment range of the distributor.

    • admin says:

      It was my mistake we are talking about the same cylinder which is no 7. You may have to revert to some of the experts on Lamorghini talk. However thinking out loud and remembering when I did mine (some time ago). Make sure both the marks on the cam wheels are pointing at the cam arrows. Turn the engine over by hand until the flywheel marks are in the window but making sure that cylinder no 1 is on the firing stroke. I cant remember but Its possible that in this position the flywheel marks are no longer pointing at the arrows but are 180 degrees out. Release the belt that turns the distributor and the alternator. Lift the distributor off its cams and turn it so the rotor arm points at the number 1 cylinder HT point in the cap. There are pictures of this position on my site. Replace the distributor belt making sure you dont move the rotor arm. You should now get a spark at the right place.

      I dont think it makes this clear in the manual but the set up of the mechanical timing i.e. the valves and pistons etc is done with the number one cylinder on the exhaust stroke and then turn the engine over and the electronic part is done with the number one at TDC which I dont think has the marks necessarily in the same position. Give that a go.

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