Our U20 build up from hell (56k go away)

[josh817]

Of all the engines you can choose from to "adopt" into your shop... There was a reason the last dude couldn't finish it.

 

1 cylinder had to be lined, wrong bearings sent to us, only domed pistons left or forged, 500000 zillion Deves rings to install, contorted and almost $%&@ing demonic engineering.

 

I did however like the little bracket that holds your cam sprocket for you without having the head on the block. Too bad those brackets always break off bounce around in the front cover... Upon inspection of the old parts, the older upper guide have that happen. Enough talking, here you go.

 

Before, dead piston, dead bearings, timing chain tensioner and guides are dead, etc:

 

 

 

 

 

 

[josh817]

Rods. They started out as 912 grams, finished at 840 grams. Had them line bored and new bushing put in.

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

[josh817]

We basically did a mock build, and then built it for real the second time. Why? Because some of the gaskets and hardware go on in a certain order obviously. Being this isn't my own personal motor, I'd rather be cautious than to jump right in.

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

I'll post a video or something when we start it up. It will still be another week or two because I have school too. I still have to detail the engine bay, make it look pretty.

[slownrusty]

Sweet work Josh!

 

Some questions for you:

 

1) Will the rod lightening = a bit more rpms at the top end?

 

2) Which engine gasket set did you buy?

 

3) What caused the stock piston to pit and get so damaged?

 

4) What Compression are the new pistons?

 

5) Any head work?

 

5) Will this U20 run SUs or Side drafts?

 

6) Stock cam?

 

Thanks for sharing

Yasin

[josh817]

1. I guess you could say yes, but I personally wouldn't get this motor spinning up to any crazy RPM's. I did the rods more so to lighten and hopefully relieve the bottom end. Bearings take a beating on these things, so I'm trying to avoid that. The owner will be scooting this thing around a fair bit too.

 

2. We bought a gasket set from Dr. Dean, consequently, its just a set from Nissan.

 

3. Since we adopted the motor, I can't really say. The last time this car ran was more than 5 years ago. The owner had been waiting for it. I would guess it was detonating on that cylinder.

 

4. New pistons should get 10:1 compression.

 

5. No head work. I am not confident enough to port myself for others. With the budget we're working with, there isn't any money to have someone professional do it.

 

6.This U20 will run SU's however the owner it constantly asking what he can add onto the car. This car is his baby. He may want to switch over to DCOE's however I don't know if he can do that without going broke trying to find a manifold. I don't know how popular or rare they are.

 

7. This cam is a little bit bigger than stock. Don't ask me what brand or grind because I don't know. This is serving to be a problem when we are timing the motor... I'm still searching for possible answers but I think its a hopeless cause.

 

For the amount of money the customer spent on this motor, its honestly not very special. A buzzy street motor out of a U20 these days will be financially painful. We were lucky enough to have a new oil pump and water pump on the motor already. Water pump isn't such a big deal but the oil pumps are going for $500. We new this motor had been rebuilt once before and didn't last long. When I clearanced the pump there was barely any wear at all! When we went to go get pistons, Dr. Dean said he was out of flat tops and we had bought the last domed set he had. There are other sources out there, but this stuff is getting ridiculous to find...

[MONGO510]

BEWARE!! If you are running R-16 pistons(that's what they appear to be), You absolutely must check piston to valve clearance. I had to flycut my pistons for clearance. Bent valves are very likely otherwise!

 

Mongo

[josh817]

We checked our valves an nothing was hitting... :/ What sort of cam lift/duration were you running? Ours isn't too radical, at all.

 

One thing to note is that I HATE how the book has us time this cam. It says it wants 38 links between the mark on the cam sprocket to the mark on the jackshaft sprocket. The book also says it wants the bolt holes and dowel on the cam sprocket to be horizontal and perpendicular to the motor axis. Multiple ways you can check this. On the cam towers (bearing cap in this case) they have arrows to tell you which way is the front on the very top of them. The first tower is close enough to the sprocket that it should point, aiming out, into the dowel hole of the sprocket. Second way, the one that makes you cringe, is to get a level and rest it on the valve cover surface. Make sure its level first of all. See if the dowel hole centerline is even with the levels edge. Alternatively you can use the two cam bolt centerlines too. But of course, this is all assuming stock cam.

 

Picture I am talking about:

 

The chains we bought didn't have any discolored links or any marks on them. The only discolored piece we saw was the "connector" end if you could call it that.

 

Also, we shined a light into a spark plug hole and use a contraption of mirrors to look inside the cylinder, without a head gasket, loosely torqued, and turned the motor. The report was "they're not close at all to the piston".

 

I guess we'll find out. If something happens, as usual, we'll fix it before the owner shows up to take it home. Everything we do, besides race motors, are 1 year warranty, at least thats what I hear from Dad. Our race motors, depending on where the event is, we go with the owner and help him test and tune, etc.

 

EDIT:

Also I note, the edge of the piston, was sitting about 2-4 millimeters below the deck with the dome of the piston poking above deck, but only by a smidgen. Kind of hard to eyeball but I'd say maybe 1-2 millimeters. Add that to what looked to be a pretty hardy headgasket. After we break the motor in, we'll wind it up a little to see if we have unfortunate luck. From the looks of things, the oil gauge is mechanical. I hated cranking my Z motor over with my stock gauge. Takes like an hour to register. Haha

 

Not so haha when you're cranking it though. :[