Fresh stock 2 liter, best deck height

[Timas]

I had to log back in so forgive me if this post is submitted twice.

Short on time right now so I'll just get to my question.

New factory 2.0 in a late bat that needs to pass smog

What should my deck height be?

I think back in '77 compression was 7.7:1.
I was thinking to shoot for 8.2:1.
Better fuel quality and such.

[Piledriver]

No head gaskets
no cylinder base shims
If should be ~zero deck.
(1.7/1.8 should be ~.020" down the hole)

Pick up some .030-.035" cylinder base shims to set compression.(EMW)
If you have had block decked or have heads with a step cut...etc adapt as needed.
.030-.035" deck That's fine on a stock motor that won't willingly rev over ~5K.

I suggest fine wire indium plugs, something with an extended nose to put the spark closer to middle of the chamber.
They also will probably last 100K miles, use milk of magnesia on the threads as Jake suggests, it works well.
I have had the same bottle for 15 years, the plugs don't care how it tastes, but I use the sugar free mint.

[Timas]

Hey there Piledriver.
I will ask about the milk of magnesia in a sec.

I have a 2 liter, and I picked up some .04 shims already and new AMC heads.
Off the top of my "head" ( he he.)

Initial measurements showed I was already above .03 at zero deck.
I know there is a formula, but math is not my strong suit.

I thought I would be shooting for around .2-.3 deck height? I thought that would put me around 7.9 - 8.2 : 1. ?

All of you know better than me,
I just want to be running and enjoying my ride.

Now about the milk of magnesia, I think mint would also be preferred by my motor

Does it act like a conductor?

[Piledriver]

It's very, very good high temp anti-seize that is also very thermally conductive.
High $$$ FAA blessed versions of it are used on spark plugs in jet engines/turboprops and even piston engines in general aviation.
Jake was a helo mechanic in the Marines.,

A deck of 0.040-045 is still great, just try to keep it down tight.

Check your block/deck with a straightedge if still apart, not unusual to need a shave, tends to droop in the middle.
I ran .028" deck for ages on a 1700 T4 that ran great, only took it down at 300++K as the cam thrust bearing disappeared and it started sounding funny. due to that.

At a larger bore I'd probably aim closer to .035"-.045".

[Timas]

Understood.

Milk of magnesia....who knew
Fingers crossed, I will be able to begin rechecking things again this weekend.

Thanks Piledriver.

[Piledriver]

You may find you can get the deck closer to even by swapping rods around.
Assuming they have been rebuilt a time or two they are seldom exactly the same length.

[Timas]

Interesting.
I didn't realize rods can stretch ( or that's what I pictured)

Got up this morning at 6 and headed straight to the garage.

Cylinder 1/2 side sit flush at 0 deck.
Cylinder 3/4 side was wonky.

Added .03 to cylinder 3 and .05 to cylinder 4. To get them not to rock.

I can't afford to deck the case.

Cylinder 1 ( 0 deck = .054)
Cylinder 2 ( 0 deck = .042)
Cylinder 3 ( 0 deck = .06)
Cylinder 4 ( 0 deck = .058)

New deck height #'s
* Added .04 shims to 1/2 just to get them closer to other side

1= .058
2= .046
3= .09
4= .108

I know compression is all over the place, do I just shoot for a relatively close figure and call it?

[Piledriver]

Rods length doesn't usually stretch, they usually shrink due to how they are rebuilt.
The big ends stretch in long use, so the cap and rod get a shave where they join, and the hole for the rod bearing gets remachined round. This makes the rod just a bit shorter.
There is also manufacturing variation to start with.

Invest in a bit of case machining, and measure (or have an auto machine shop) see if your rods are in spec...
Also, T4 heads have a hard enough time sealing.
If the jugs are rocking someting is badly wrong.
They really need to be bolted down with a bar across, and the deck & jugs need to be clean/flat/burr free to get true readings

[Timas]

I will investigate further to see what is actually going on
I broke some of the fins off of a jug and bought a used one. I have a feeling that the jug is the problem and not the case itself.
At least I am hopeful that was the case.

Can I cut fins off of one jug and weld them to the other?

Or is that too much backwoods engineering?

Thank you for your insight

[Piledriver]

I have seen it done well once with what I think was TIG brazing but it sounds like you really need a new set of P&L.

[Timas]

I had read on Samba that you can still potentially use the cylinder, it would have to be used for #1 cylinder definitely NOT #3.
I'm hoping to at least understand where the rock is coming from without getting yelled at for not helping around the house ( equally as Important
IMHO

Have a great day.

[Piledriver]

if you are reusing random used cylinders I strongly suggest turning them into cupholders.
Seriously, it won't end well.
Sometimes you need to buy new, or a complete set of good used can sometimes turn up.
(engine had wiped cam or such)

[Timas]

Apologies, I should have indicated that my last post was in reference to using the cylinder that I broke the fins on
The pistons and cylinders I am using only had ~1000 miles in them before I dropped a valve on a used head. Except for the cylinder that I bought to replace the cylinder that I broke the fins on.
I never know how much detail to give without it sounding like I am rambling

[Piledriver]

Lets look at the broken fin... if you are not building a hipo engine you can get away with a bit.
You might also find a good welder who would take it as a challenge for pizza and beer.
(Welders and machinists love pizza and beer that turns up...)

Simlpy getting the jugs turned to the same length might be an option, but a fresh set of jugs (only) might be cheaper.

[Piledriver]

Also note you need to bolt EACH jug down to check that things are flat and true, easiest bit of angle iron across EACH top and bottom.
(old bed rails are awesome stuff, very hard and springy steel, will dull a bimetal bandsaw blade in a flash if you go too fast)
The most you want between a pair of cylinders is .005" (measured under a straightedge), the heads are not very flexible like that, although a bit too flexible on other ways...