LZ22 head spacer shim?

[toshts]

11 minutes ago, banzai510(hainz) said:

80 is low. but i coulnd hear it on the vid. long as rocker wiggles u know valve is closing. ck valve for crack and seat. Hole in piston or rings are all lined up letting blowby

Head was pressure tested at the machine shop as there was pitting that seemed like cracks, ended up being fine just needed 26 thou taken off. I'm betting the valves bent, piston looks great with a boroscope and was making 180psi in that cylinder before I swapped the head. Tons of crosshatch and with the previous compression I doubt rings are bad

[toshts]

2 minutes ago, ggzilla said:

More common: burnt valve or valve seat

 

Hopefully it is just deposits on the valve seat. I have fixed engines by lapping the valve seat

 

80 psi is very low

I'm thinking 100psi difference is a little too low for them to be burnt, no carbon on the valves they were cleaned at the shop same with the head. Tons of air blew out of the intake port when I stuck the air compressor with a rubber tip in the spark plug hole.

[toshts]

Also when the head was machined I did not get a valve job, he looked over the valves and seats and didn't see any pitting and he didn't think it was worth the extra money. So most likely going to replace that one valve and get all of them done at once. 

[banzai510(hainz)]

should have made the pres cheak at tdc on cyl 3 then see if blows out intake otherwise int valve could have been open

[toshts]

1 minute ago, banzai510(hainz) said:

should have made the pres cheak at tdc on cyl 3 then see if blows out intake otherwise int valve could have been open

Intake cam lobe for cyl 3 was straight up, could wiggle rocker 

[banzai510(hainz)]

also u should have put motor tdc .then put head back on. If u wedged it u got to put excactly back when removed

[toshts]

1 minute ago, banzai510(hainz) said:

also u should have put motor tdc .then put head back on. If u wedged it u got to put excactly back when removed

Haven't pulled head yet, will set TDC and wedge chain when I do. 

[banzai510(hainz)]

h

i have a spare block and turn mtr so pistons are halfway down. Then a bolt the head on w the 2center bolts and i turn the cam and see if the valves move and close and wipe pattern is good

[banzai510(hainz)]

yOu didnt use that head saver gasket that fits with the headgaket?

 

[toshts]

Just now, banzai510(hainz) said:

yOu didnt use that head saver gasket that fits with the headgaket?

 

Nope no head saver, did shim the cam towers though. Don't think valves are hitting during rotation as all the other valves are fine 

[datzenmike]

4 hours ago, toshts said:

Straight out the intake 😕, already had the manifold off when I checked. Valve cover off as well with the cam lobe straight up and the rocker had the proper lash as well. 

 

No no no. Of course air will blow out the intake at full lift of the valve. On a leak down test the piston is at TDC, both valves must be closed and air pumped into the combustion chamber. With 80 PSI compression the air is going somewhere. With valves closed any leak will be obvious. 

[toshts]

10 minutes ago, datzenmike said:

 

No no no. Of course air will blow out the intake at full lift of the valve. On a leak down test the piston is at TDC, both valves must be closed and air pumped into the combustion chamber. With 80 PSI compression the air is going somewhere. With valves closed any leak will be obvious. 

I meant that was with the valve fully closed, just to confirm here's pics of what I did. 

 

 

TDC cyl 3 set with boroscope 

 

 

Shoot air

 

 

With rubber bit that fits spark plug hole

 

 

Air shoot out of intake port here, lots of it and my compressor is pretty low pressure right now.

 

That right?

[banzai510(hainz)]

well thats a good test. since not out the ex you know thats good. has to be intake. get spray bottle squirt soapy water in there and look w that bore scope when u pressurize.

[toshts]

Also with the cam in this position (hopefully 3 and 4 intake valves closed)

 

 

Here's what the intake valves look like through the manifold ports

 

Cyl 4 (good cylinder)

 

 

Cyl 3 (bad cyl)

 

 

Looks like a gap on cyl 3 to me?

[toshts]

2 minutes ago, banzai510(hainz) said:

well thats a good test. since not out the ex you know thats good. has to be intake. get spray bottle squirt soapy water in there and look w that bore scope when u pressurize.

there is the ever slightest amount of air coming from the exhaust, just barely feel it but it goes straight through the intake like I have the compressor blowing directly on my hand. Machine shops open tomorrow, I'll give him a call and figure out a game plan. 

[datzenmike]

Bent intake valve and/or damaged seat. Replace valve and lap it and should be OK.

 

Was this head ever dropped or set down on a counter or table, valve side down???

Was the cam ever turned to line up the cam timing chain marks after head installed??? #3 would be at BDC so unlikely this.

 

This is the easiest way to explain a bent valve.  

[toshts]

1 hour ago, datzenmike said:

Bent intake valve and/or damaged seat. Replace valve and lap it and should be OK.

 

Was this head ever dropped or set down on a counter or table, valve side down???

Was the cam ever turned to line up the cam timing chain marks after head installed??? #3 would be at BDC so unlikely this.

 

This is the easiest way to explain a bent valve.  

Was very careful to never let it sit on the valve side down, when I put the head on I took note of where on the crank piston 1 was at TDC and rotated 90~ degrees so all pistons were in the middle of their track then spun the cam to top then the crank back to top. Only thing I can think of is when setting valve lash that one rocker that was hung up on the lip of the lash pad or that my machine didn't notice the slight bend 

[toshts]

3 hours ago, datzenmike said:

Bent intake valve and/or damaged seat. Replace valve and lap it and should be OK.

 

Was this head ever dropped or set down on a counter or table, valve side down???

Was the cam ever turned to line up the cam timing chain marks after head installed??? #3 would be at BDC so unlikely this.

 

This is the easiest way to explain a bent valve.  

Also do you think I could get away with just lapping a brand new valve and throwing it in? I'm leaning towards a full valve job but it would be tight on the wallet 

[ggzilla]

Hand lapping is the way to go. Unless the valves seat is cracked or burnt or loose

[toshts]

3 minutes ago, ggzilla said:

Hand lapping is the way to go. Unless the valves seat is cracked or burnt or loose

Seats were inspected and claimed good, hand lapping the new valve rather than getting full job? Getting about 190~psi across all the good cylinders so I think I've got a small amount of leakage across all the valves, was getting 180 with my stock z22 but with the increased compression ratio I'd assume it would be a good bit higher or is that not how it works?

[ggzilla]

190 psi is very good and indicate zero leakage

 

I hand lapped valves in several times. On one Datsun with a burnt valve (section burned out), the valve seat was fine and the new valve only need hand lapping. Datsun started using the best valve seats in 1971, a type of stellite. I drove that Datsun daily for the next year before my friend bought and and he continued to drive it

[datzenmike]

 

That's a U67 head??? but has coolant holes drilled out?

 

Either way an open chamber head on a Z22 would have a compression of 9.84. Stock L20B would be 8.4 so yeah the 180-190 compression is reasonable.

[toshts]

1 minute ago, datzenmike said:

 

That's a U67 head??? but has coolant holes drilled out?

 

Either way an open chamber head on a Z22 would have a compression of 9.84. Stock L20B would be 8.4 so yeah the 180-190 compression is reasonable.

Yup u67, coolant passages are there if they were drilled they were done pretty well. You calculated it at close to 10.5 compression ratio with how much the head was milled and found out this wasn't the first time it was milled so unsure of quite how high it really is. Just thinking that if I had 180 before raising the compression 190 seems lower than I'd expect? But if I can get away with just lapping new valves (ordered both intake and exhaust) for cyl 3 that'd save me a good bit of money and time. I guess it would probably be worth doing a quick lap on all the other valves too?

[datzenmike]

Measure between the valve cover and head gasket. A stock uncut head is 4.248". If cut, it will be less. Tell me what you get and I can up the compression 

[toshts]

10 minutes ago, datzenmike said:

Measure between the valve cover and head gasket. A stock uncut head is 4.248". If cut, it will be less. Tell me what you get and I can up the compression 

I think this bottom part is cut flush with the head gasket mating surface? These calipers are cheap and not super accurate

 

 

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