Changing piston, cylinders and cylinder heads

[Hugues]

Ok, so i've got all 4 pistons, cylinders, heads attached, no sealant yet, just testing,
air intakes and exhaust are installed,
all bolts tight but not torqued yet,
I can turn the engine by hand, nice and smooth.
I will receive the Hylomar Advanced Formulation High Viscosity sealant monday.
How much sealant should I apply ?
Do I need to spread it with my finger or just a bead ?
Should I apply it on the cylinder base and also on crankshaft ?
The joint between head and cylinder is metal to metal I understand, not good to put any sealant in there, just a thin film of engine oil ?

IMG_20240823_145225.jpg (1.89 MiB) Viewed 11734 times

[rmel]

The joint between head and cylinder is metal to metal I understand, not good to put any sealant in there, just a thin film of engine oil ?

Correct -- NO SEALANT or Oil head to cylinder assemble DRY.

With respect to the cylinder to block. First do not install the head bolts until AFTER the sealant is applied.
Apply sealant on the block side on the matting top surface and the top 12mm to 15mm of the top inner
wall. use Nitrile gloves and spread it with your fingers ensuring coverage on these surfaces. You don't need
a lot of sealant but make sure all metal surfaces are covered. On the head side apply a bead on the bottom
inner grove ans again spread it with your fingers so that the bottom side wall and the flange (opposite mating
surface) is well covered. You do not have to worry about a set time it stays plastic forever, it is zero gap so
after torque materiel will flow. You must retorque after 20 to 30 minuets as it does flow SLOWLY.

I put a dab of sealant on the threads of the cylinder bolts, and remember flat goes into the block.

Leave the pistons in the cylinder and install as a unit placing the wrist pin in place. Make sure your rings
are clocked properly or may have blowby issues. And make damn sure you have clean rags around your
connecting rods to prevent ANYTHING from falling into the block, like a circlip that wants to take flight.
You will hate yourself if that happens

[Hugues]

.... On the head side apply a bead on the bottom
inner grove ans again spread it with your fingers so that the bottom side wall and the flange (opposite mating
surface) is well covered. You do not have to worry about a set time it stays plastic forever, it is zero gap so
after torque materiel will flow. You must retorque after 20 to 30 minuets as it does flow SLOWLY.

I put a dab of sealant on the threads of the cylinder bolts, and remember flat goes into the block.

Leave the pistons in the cylinder and install as a unit placing the wrist pin in place. Make sure your rings
are clocked properly or may have blowby issues. And make damn sure you have clean rags around your
connecting rods to prevent ANYTHING from falling into the block, like a circlip that wants to take flight.
You will hate yourself if that happens

Ok, on the block side, I got it clear,
Above you wrote, "on the head side", I guess you meant cylinder.
I show a picture below of my old cylinder, so i apply sealant on the red and green areas ?

cylinder.jpg (475.24 KiB) Viewed 11707 times

I must admit that I did not manage to remove the 4 retaining long bolts. They are seriously stuck and i have nightmares about bolts like this snapping into the block.
If it had been 1 or 2, i would have give it more try, but 16 of them is too much for a newbie like me.
Besides, as pictured below, these bolts stand outside the mating surface between the cylinder and the block.

retaining bolts.jpg (1.12 MiB) Viewed 11707 times

and I did drop a rubber seal into the block LOL, but i could get it back when i removed the pan.

[rmel]

Yes that was a typo....and yes along the red area you noted.
And about 15mm up the side wall should do.

With respect to the cylinder bolts, heat is your friend. You
could try a little heat from a propane torch. The Aluminum
will expand more than the hardened steel bolt. They can
be a real pain to remove. You could keep them in place but
make sure there is absolutely no residual old sealant laying
around, the lower two bolts are a potential area to leak.

[Hugues]

As my Hylomar AF HV is delivered only monday, I took the opportunity to have a look at the clutch:

The splines and flywheel appear to be OK

spline tranny.jpg (489.04 KiB) Viewed 11666 times

flywheel bottom.jpg (668.05 KiB) Viewed 11666 times

spline clutch.jpg (786.59 KiB) Viewed 11666 times

and these are my measurements, it looks like the wear surfaces are still working.
max. 0.5 mm wear of 1.5 mm permitted.

disc engine side.jpg (1.54 MiB) Viewed 11666 times

disc tranny side.jpg (566.82 KiB) Viewed 11666 times

clutch.jpg (1.58 MiB) Viewed 11666 times

[Hugues]

my measures vs Pinz manual

measurements.jpg (221.25 KiB) Viewed 11664 times

[Hugues]

Do I need to put any grease on the spline when putting the tranny back ?
Pinz manual does not say anything.
Flywheel gear seems to be running dry, no grease either ?

[Hugues]

All 4 cylinders installed and sealed with Hylomar AF HV
Air intakes and exhaust pipes installed
Heads torqued to 35 N-m

I performed a leak-down test with my gauge, just out of curiosity, pistons at TDC, valves closed (no rockers). I get:
#1 45%
#2 75%
#3 75%
#4 45%

For all of them i can hear the air leak through the oil filler pipe, so coming from the rings. No noise in air intake or exhaust.
But why such differences between 1-4 and 2-3 ?
I will also do a compression test later on.

IMG_20240827_155012.jpg (1.84 MiB) Viewed 11521 times

[rmel]

Did you clock the rings properly ?

Valves need grinding and to be seated. You don't just stick the valves in the head W/O seating them.

Your also have a "virgin" build, nothing is broken in and seated from a running engine.

So could be an issue here or just need 1,000 KM to break it in.

[Hugues]

Did you clock the rings properly ?

Valves need grinding and to be seated. You don't just stick the valves in the head W/O seating them.

Your also have a "virgin" build, nothing is broken in and seated from a running engine.

So could be an issue here or just need 1,000 KM to break it in.

yes, rings spread 120deg, checked twice
heads were prepared by the shop and seated. I checked them for leaks, nothing. And i don't hear the air leak from the intake or exhaust, only oil intake, so mostly coming from piston side.

As you say, it's a cold engine test and i guess rings will seat better after a while.

For memory, my former engine gave me these measures on the leak test, warm:
#1 42%
#2 25%
#4 32%
#3 82%

[Hugues]

Engine assembled
gores back in the Pinz tomorrow
saturday i can test it, slowly, slowly

IMG_20240829_172410.jpg (764.93 KiB) Viewed 11406 times

[Hugues]

Engine is back in the Pinz !

I ran the engine on the starter while measuring the compression on each cylinder (and waiting for oil top come into the heads). I see:
135 psi on each cylinder,
that's pretty good, considering the engine is cold and the rings are new.
My previous engine was showing 120 maximum.

Then I could see oil coming to the oil filter (just unscrew it a couple of turns).
Then oil started to flow from each push rods on each head, so I closed the valve covers.


Tomorrow saturday:
i will install the exhaust, gear shifter, carbs, air filter, fuel pump, ignition, spark plugs,...
And start the engine with fuel and let it run a few seconds at a time and check temperature, recheck valve gaps, torque heads,
recheck compression and leak down test when engine warm

Sunday:
if everything is ok saturday, will run with the Pinz in the village for a short ride, no big load,
monitor combustion, check for oil leaks,...

IMG_20240830_105857.jpg (983.41 KiB) Viewed 11275 times

[Hugues]

First fire !

Did a few short idle runs today,
a little smokey at first but then it went away,
had to adjust my carbs significantly, idle was too fast and too rich,
maybe because I have more vacuum? runs fine now,

Only problem, engine won't stop when I switch off the key,
it keeps running, initially I closed the main switch behind the drivers seat,
but on the last run that didn't even stop the engine, I had to hold my hands over the carbs,

what could possibly have caused this? I checked to see if my solenoids click when I remove the key and also removed their little plug one by one to hear the click.

I took the temp with my infrared gun, nothing unusually hot, exhaust temp is the same in all 4 cylinders,
with engine warm,
Compression is 120 psi in all 4 cylinders,
Leak down test shows:
Cyl. #1 45%
Cyl. #2 40%
Cyl. #4 30%
Cyl. #3 32%
I will check my valve clearances again tomorrow

[Hugues]

...

Only problem, engine won't stop when I switch off the key,
it keeps running, initially I closed the main switch behind the drivers seat,
but on the last run that didn't even stop the engine, I had to hold my hands over the carbs,
...

Sometimes the problem is located between the steering wheel and the driver seat

I had forgotten to connect back my starter cable to the carburettors, and the starter lever on each carburettor was in the pulled position.
That explains why I had to tune the carburettor, the idle speed was too fast (1400 rpm) and the mixture too rich (10).
That probably also explains when the engine did not want to stop after switching the key off, there must have been residual gas with this rich mixture.

Anyway, this morning everything is back to normal, idle speed around 750, AFR around 14.7, and engine stops right away when turning the key.

[pcolette]

Bravo! Nice job, thank you for the write up.