Project 75: Dal pollaio alla pista (parte 5) – Davide Cironi Drive Experience (SUBS)

Project 75: Dal pollaio alla pista (parte 5) – Davide Cironi Drive Experience (SUBS)


Ezio Campoli: “The 2.0 was another evolution of Alfa’s twin cam engine. It started with a displacement of 1.3, then 1.6 and 1750: the distance between the cylinders axis is the same on all these engines. With the 2.0 though the Bialbero was modified: the 1st and the 4th cylinder are “offset”, nearer to the front and the back of the block. So the interaxle spacing is no longer the same and the crankshaft was redesigned as well and as you can see the rods are not perfectly symmetrical here. These two have to be mounted like this, we mechanics say that they have to “look at each other”, in this way they move from the center and was possible to mount the 84mm-bore cylinder liners in an engine block that was already at its peak with the 1750 (80mm bore). The stroke was the same as the 1750cc, they just modified the 1st and the 4th rods as I showed you to make all four fit. Now I’m going to finish the assembly of the pistons so we can put them in the engine. Put oil everywhere: when you start the engine, the oil takes a while to get everywhere and lubricate everything. In this way, we help it. Steel snap rings: it’s very important to mount them correctly, otherwise you can also bend them If it’s bent, it could fly off and the piston pin can move and do damage. Doing so, I’m sure it’s in place. Let’s see if it moves… ok, then you press and we are sure the pin won’t move When you hear the “click”, it means it’s in place I always spin it to check if everything’s fine… Ok, it’s properly placed This is the 3rd piston As I said the rods have to look at each other, see? There has to be some axial play, it has to move freely Lubricate all the rings, spin them Rotate the rings to an angle of 180° between the holes We are now ready to put this one in the liner This is another delicate process; you have to be careful not to get the band stuck to the rings So first you check by rotating it and then you tighten Ok… Oil here as well The compressor clamp has to fit in the liner… Put it in the middle and tap it The crankshaft is at top dead center position, we are ready for the next one Half bearing in… Cleaning is the most important thing because a tiny speck can make a huge difference Oil again Second piston ready to go in I know this way of putting the pistons in may cause some criticisms because on the original Alfa Romeo cylinders, the pistons go in from below. We do it like this because yes, it’s easier for us, but we also made a bit of countersink on top of the liner for two reasons: 1. to eliminate the sharp edge because sharp edges in a combustion chamber are spots were heat concentrates and 2. allows us to put the pistons in from the top after correctly fixing the four liners in place because you have to be careful with wet liners like these. By doing so, they had already been sealed and we are ready to go Now we have to turn it upside down to tighten the other halfs of the big end bearings I use this product made with nanotechnology to lubricate the engine during the first start when there is no oil pressure Let’s lubricate the bearing so we are safe from this potential issue ARP high-resistance bolts Under the bolt we are going to use another low-friction product so that the tightening torque you read is not distorted We are not done yet… We are now ready to tighten the bolts with the torque wrench” Davide: “How many Newtons?” Ezio: “About 55 N You should always tighten the bolts gradually, never tighten one first and the other next. Or at least this is my opinion… I prefer this way, gradually tighten and then pull The amount of play is right… Same story for the other three When the rod moves on the axle, it means everything is ok. The bottom is finished, now we are ready to put the head on These are the original Alfa Romeo washers, the material they used was quite refined: this is a steel curved washer you can find only on Alfas This does the job of a self-locking nut Head gasket with stainless steel rings to bear the compression ratio, now higher with CPS pistons There’s always a bit of oil passing through here, we are going to use this high-temperature grey sealant for motorbikes sumps A bit more here too because unfortunately in this area there are no bolts and to make sure oil doesn’t ooze as it often does in Alfa engines, we have to use a bit of sealant Your finger is essential As you can see the gasket has the reinforced stainless-steel rings These are O-rings that have to be put on the oil canals on the right of the cylinders As you can see the oil canals that carry the oil to the head, camshafts… were modified and made smaller to increase the pressure on the lower part (crankshaft bearings etc) Last check on the head so we are sure it will fit properly Ok… we’re ready to go Here it is, it’s starting to look like a Bialbero Now we are going to tighten the head bolts following Alfa’s path but using different torques because of the higher compression ratio and the different gasket installed This is a trick to avoid water drops coming out of the stud bolts Ok, let’s tighten the bolts following Alfa’s path and the torque established … – 36=110 We are doing some math following the Colombo & Bariani camshaft diagram (36°/76° intake, 76°/36° exhaust) So it’s 36°, 76°, 76°, 36° 36 + 76=112… and then + 180 because the camshaft revs at half the speed of the crankshaft (360°)=292°, which is the valvetrain duration angle 292 / 2 (because again it’s half of the crankshaft speed) – 36° (the angle at which the intake valve opens)=110°, which is the so-called lobe center We are going to synchronize the timing bearing in mind this angle to make it as precise as possible What does it mean? It means that with this camshaft 110° after the TDC, the intake valve lift has to be at the top This for all the cylinders, 110° as I said: it’s not an aggressive valve timing, but we aimed to build a street engine with a good amount of power. The maximum lift is 12 mm so it’s not bad, it doesn’t last long (less than 300°) and this makes the car easy to use in the traffic Here we can read the maximum inlet valve lift and here the maximum exhaust valve lift, so we can check the overlaps We are using this to check the TDC and the maximum lifts and later we’ll check the right angles at which the intake valve opens and closes Same story for the exhaust valves Here there’s the diagram disk on which we read the inlet and exhaust valve angles It seems odd to see all these clocks attached but it’s daily occurrence when you need to adjust the timing on an engine like this Obviously these are numbers that come from math, everyone then adds his secret “spices” When I build an engine, I start from the camshafts and then I tune the engine following them. I do not build the engine and then buy the camshafts and put them on, because I already know what I want when I buy the camshafts Today you saw something not many show you, many secrets regarding lubrication and there are many more that are the result of experience gained over time. These are the remains of dirt roads and chicken coops” Davide: “If I had a longer one, I would spend the day here” Ezio: “Despite this, the car is in good shape underneath This is nice, it’s well-made This is a true trumpet: you don’t put trumpets on to make the engine louder, it has to accelerate the air flow Many ask for the original trumpet made for Alfas back then, those are anything but trumpets, they are made to be loud Many ask for them because of the sound they make, but they actually make carburation and efficiency worse Raise it a bit more… Turn it… Slowly, lower it slowly A bit lower… ok Let’s put it back home” Davide: “Ok, oil in… it’s just to start it up, we’ll later change it” Ezio: “It’s a 20W/60, so it’s fitting This is the coolant, it’s the red one for aluminum engines” Davide: “How long will the break-in take?” Ezio: “Racing engines after two hours on the test bench are ready… This is a street engine, I usually suggest 1000 km Then we’ll put bigger jets, test it on the bench and then you can have fun Wait… Davide: “C’mon” Ezio: “Hold on, Massimo… she’s drunk Try again Listen to it Screwdriver! Turn it off… she’s already pissed Listen to the idle The smoke comes from the exhaust manifolds that are warming up There’s more to do: carburation and stuff… the baby shows promise, don’t you think?” Davide: “I think so too… May I listen to it again? Ezio: “How many degrees?” Massimo: “54, 109, 129, 149” Ezio: “I’m satisfied, and when I’m satisfied I know what will happen…” Davide: “I love the low-end”
Ezio: “Did you hear it? Vroom! and there’s still room for improvement Guys, I have to go. We listened to some music… Francesco: “Where do you have to go, Ezio?” Ezio: “I’ve got something more important to make than engines this evening” Written and directed by Davide Cironi Filmed by Francesco Colantoni Filmed by Stefano Ianni We had to leave with the 128 on Friday, on Thursday we still had the cylinder head there With the support of and the support of What can I tell you, Ezio already said everything! See you at the first start, let’s hope it sings as it should Translated by Elia Pozzani For more contents and photos feel free to check out our website WWW.DRIVEEXPERIENCE.IT