I still can't wait to see your finished product. This will undoubtedly be the most blueprinted, and well built 4.3 on the planet when you're done. Lol GM probably didn't put this much effort into developing the engine in the first place.

For aftermarket injection, have you considered the marine intake set up that's been used on some of the 4.3 turbo builds? I would love to do that upgrade with a rear mount turbo one day, but will probably never happen. That doesn't really help you with the ECU part of it, but should remove the TBI issues from the equation. . . . Although I just remembered how strict you said it is over there though, so I assume that wouldn't be allowed in Switzerland.

Anyway I hope you are able to make some more progress with the build soon.

 

Sandman,

Thanks, and great info. I'm in contact with the guy at ExtraEfi. Should be some 900$ including a harness for an MS3X.

KnightBlazer,

Thanks as well and still a veeery long way to go. The marine intake is actually an option as I have found one close to my place. This is Plan B should the sequential fuel injection not work out as expected. If the Megasquirt works out I'll go that way if not the MS will be swapped to the Alfa Romeo and I'l build the 4.3 with a marine intake and TBI.

 

This motor will probably have twice the milage potential as a factory motor , if the factory built motors in this fashion they could easily last past 400, ooo miles .
Great to see someone who takes pride in their work too !!!
Please keep the updates coming , as well as photos too !!!

 

Slow progress last week and this week. Put a couple hours in and put all the rods and pistons without rings into the block.
The valvetrain geometry is kind of an iteration process. First I have to test assemble the whole block with the new camshaft.
Then put the head on and measure for valve to piston clearance. With that out of the way disassemble everything and mill the block.

As I have hydraulic lifters but need solid lifters to check the valvetrain I have fabricated a first fixed lifter couple months ago using one of the old hydraulic ones. To be more efficient I just made a second one.
The hydraulic lifters have a piston riding on a spring inside the lifters body which compensates for the slack of the valvetrain when the engine is running. But to measure you cannot use those as the spring messes up everything. So onto the lathe and turn a small insert which makes it a solid lifter.

Turns out I have a lot of leeway on the valve-to-piston clearance. Actually could use up to 1.70 or even 1.75 ration rocker-arms.
So no headaches there. As I had all assembled I could also check the geometry of the rocker arm on the valve. Turns out that the rocker arms are sitting way too high. The witness mark left on the machinists-blue color is from the center of the valve stem to the outboard side (exhaust side). We will have to cut the bosses by quite a bit (guess is 1/8 of an inch) to get the rocker arm to touch slightly inboard of the center of the stem and wander just past the center to the outboard side when lifting the valve.

Pictures following.
adding promised pictures


Making a solid lifter from an old hydraulic lifter. Left is the new lifter assembly with the coarsely turned insert, right the OEM piston which rides on the hydraulic cushion of engine oil.




the screw in studs. bosses are still high. once geometry is checked we will cut them down.

camshaft retainer plate

chain drive, nothing fancy

the fixed lifter

CompCams bumpstick

the drive for the balance shaft

#1 at TDC

clay method to check valve to piston clearance

valves with check springs

checking lifter bores

0,05mm (0,0018") clearance, should just work out fine.

 

Sounds like you're well on your way to blueprint
that engine . It's quite refreshing to see how detailed your work is 😎 All this work will pay off in longevity of the motor & possible horsepower gains too with a careful consideration of the parts selected 😎 You definitely seem to have a great desire to do this work with a strong passion 😎

 

Thanks, and yes, definitvely.

I've been building engines since 16 years old but only as an aid or with help from specialists. This is the first engine where I had to do all the decision making and where i have actually done the building myself. I like to work with my hands and see stuff come together. It's complex, at times it's frustrating but also fun.

The last two days were my off-days. So test assembled the engine. Rods, pistons without rings, the crank was still in the block from last time. Then I assembled the heads with test springs at each corner to check for piston-to-valve clearance. Turns out nothing to worry. LOL - and I thought it could already get tight...
...not the case I have about 6 mm minimum clearance into the valve pocket. That will slightly be reduced once decked and the heads cut. So I could go with rocker arms up to 1.75:1 ratio before they would touch.

At the same time used the valvetrain components (studs/rocker arms/valves) that will go on the engine and used adjustable pushrods to get the valvetrain geometry. Machinists blue on the stem and it turns out that the swept area is way outboard of the stem tip. So will need to calculate that geometry and then cut the bosses down until it fits.

Yesterday night just did the passenger side deck. Now the block is square to the main bearings, decked as I expected, just 0.11 mm (0.004") were enough to get it where I want it and a clean nice finish. So the pistons should be 0.3 mm (0.011") below deck when finished, which is about the rocking of the pistons in the bore when they turn at the top (or bottom). So they will rock-and-roll within the bore. With a 0.027" MLS gasket I should get to nearly exactly 0.040" squish area.

Now working on the geometry of the rocker arms. The bosses are still too high. The block is nearly finished. The next step in machining is to hone the bores to spec for the JE forged pistons. After that it is cleaning and then final assembly of the bottom end. Then I can work from the short block.

Once I have the block finished, the heads will sit precisely at the correct altitude over the crankshaft/camshaft and then I can determine the correct height of the stud bosses for the rocker arms. Once we have cut them I can finally measure the pushrod length and order them.

Now that I can see the end I will have to order the injection and a couple of things still missing such as camshaft bearings. Turns out we had an incorrect set at the shop which will not fit my engine.


One lifter in place

The stock pushrods turned out to be too short. Finally I had to use a check-pushrod.

Clay says - plenty of room at 0,500" valve lift. So it will even work with 1,62:1 rocker arms in case i needed more lift.

CompCams Magnum rocker arm with the witness mark.

And the rocker arm witness mark on valve stem. Incorrect geometry they are too far outboard.

Squaring the block on the mill.

First cut to get the deck square 0,03mm (0,001 inch)

This is after the first cut. We can see that the block was higher on the right side (passenger, aft). The first cut just scratched the surface at the right front (#2 cylinder). Then we cut it down to get a clean deck with the least amount. The left side (cylinders 1,3,5) was then cut to the exact same height so I have a block which is square to the main crank bore.

Chamfering the lifter bores from below - pure cosmetics.

The cam bearings are out, all cam bearing bores chamfered, cylinder bases chamfered, ready to be honed. Because the cylinders had nearly no wear at all and are cylindrical, we have decided against boring. With the new forged pistons which are 0,002 inches over we save on machining and retain maximum wall thickness for nitrous or such experiments.

 

As promised the pictures uploaded to the "finally finishing the block".

Next will be to order couple of things from Summit to be ready for the blocks final assembly. Then I have a short block from where to work upwards onto the heads.

 

Fun to watch your progress. Will you put this on a dyno when done?

 

Yes, that's the plan. I will need some dyno time also for the new tune.

Just came by the shop. They are busy at the moment with other stuff but the block is in the hone machine.

 

Honing the block. Putting it onto the SUNNEN hone. Torque plates ready.

Pics coming as we progress.

setting up

chasing the threads. bit of dirt and corrosion at the bottom. the threads are open to the water jacket.

used MLS


first strokes on the worst cylinder 0,08 mm inequality (0,003 inches)

and the torque plate

now its hone time... ...will take couple hours.