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78 620, L20B foreign matter in combustion chamber.


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#41 Atikin9000

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Posted 15 October 2017 - 03:43 PM

AS well as a lash pad decided to pop out too.

#42 datzenmike

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Posted 15 October 2017 - 03:47 PM

2rU9oBQ.jpg

 

Pistons are nowhere near TDC. Get a long stick that will fit the spark plug hole but can't fall in. You can watch it move as the piston comes up.

.


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#43 Atikin9000

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Posted 30 October 2017 - 07:47 PM

https://imgur.com/a/1n6xf

Got the head back from the machine shop today thought I’d share some pics.

#44 Atikin9000

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Posted 30 October 2017 - 07:51 PM

The machinist decked the head and had to remove the dowel pin, there’s one in the middle still in the block and this one but I’m not sure where it goes.

https://imgur.com/a/9HhlI

#45 G-Duax

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Posted 31 October 2017 - 03:46 AM

One goes left side, in front of #1. the other goes left side, between #3 and #4.



#46 flatcat19

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Posted 31 October 2017 - 08:19 PM

There are larger holes on the block surface those will slip in to.

Look at the head bolt holes. You will see a couple are larger bore.

You can't hang if your nuts haven't dropped...it's physics


#47 distributorguy

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Posted 01 November 2017 - 06:34 AM

Looks like they made it work, but boy are those valves sunk in the head.  Did they adjust valve lash for you?  I'm sure they either needed thinner pads or they had to "tip" the valves to make it work.  

That's half an engine rebuild right there.  



#48 Atikin9000

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Posted 01 November 2017 - 09:47 AM

Looks like they made it work, but boy are those valves sunk in the head. Did they adjust valve lash for you? I'm sure they either needed thinner pads or they had to "tip" the valves to make it work.
That's half an engine rebuild right there.



Nah the lash needs to be set still, both the machinist and a mechanic I stopped by said the head needs to be back on before they can adjust it.

#49 flatcat19

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Posted 01 November 2017 - 10:14 AM

Meh. Not really.

You can't hang if your nuts haven't dropped...it's physics


#50 distributorguy

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Posted 02 November 2017 - 08:51 AM

Absolutely not.  Its not a pushrod motor.  Everything that needs to be checked and adjusted can be done on the bench, then installed as a full assembly.  Their reply was a cop-out.  In fact, they could have ground the valve tips before assembly so you wouldn't have to buy new shims.  Given the varying valve depths in the photos, they made a real mess for you.  



#51 Atikin9000

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Posted 02 November 2017 - 04:35 PM

Also another fun question, #1 or #2 for cam sprocket position.

#52 wayno

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Posted 02 November 2017 - 05:26 PM

You should never lay an L head on it's face like that, you stand them on the end or on its side, laying like that can bend a valve.

My machine shop always adjusts my L head valves before sending it out the door.

L16 cam hole 1, L20b cam hole 2, don't know about the L18.


 

 


#53 datzenmike

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Posted 02 November 2017 - 06:17 PM

L18... I believe they run the L20B cam so #2. HOWEVER the hole position is less important that the V to etch mark alignment. This governs cam timing.

 

V in back of the cam sprocket should be below and just slightly to the right of the etch mark in the cam thrust plate behind it, regardless of the hole used.

 

iMnwYVD.jpg


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#54 Atikin9000

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Posted 02 November 2017 - 09:09 PM

This will be the first engine I’ve taken apart and put together, first datsun too.

Any suggestions or things to look for besides fluids, timing? I’ve read about the torquing sequence, I plan on draining the coolant and oil prior too aswell.

#55 Atikin9000

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Posted 02 November 2017 - 10:30 PM

p.s. imageshack is the devil. Lol

#56 wayno

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Posted 02 November 2017 - 10:41 PM

No, Photolame is the devil, imageshack is just a pain.


 

 


#57 datzenmike

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Posted 03 November 2017 - 07:29 AM

p.s. imageshack is the devil. Lol


Try imgur .... https://help.imgur.c...3-Upload-Images

 

Not saying it's the best, there are others.


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#58 Stoffregen Motorsports

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Posted 03 November 2017 - 09:20 AM

Two things I noticed.

 

One - the dowels go in the block and align the head gasket. If it was in the head, that just means it got stuck there upon disassembly. Not sure you were aware of that.

 

Second - BOTH the machine shop and the rest of you guys are right. Valves should be adjusted after the head has been torqued, but they should also do it after they assembled it on the bench. If for no other reason than to check the wipe pattern on the rockers.



#59 Atikin9000

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Posted 03 November 2017 - 10:20 AM

Two things I noticed.

One - the dowels go in the block and align the head gasket. If it was in the head, that just means it got stuck there upon disassembly. Not sure you were aware of that.

Second - BOTH the machine shop and the rest of you guys are right. Valves should be adjusted after the head has been torqued, but they should also do it after they assembled it on the bench. If for no other reason than to check the wipe pattern on the rockers.



As I mentioned this was my first time round with this, I didn’t think to mention any of this until I read it here. There was mention of shims as well, I was planing on calling the machine shop today to see if everything is still in spec.

I’ve heard a couple of things regarding valve lash and that I needs to be adjusted both hot and cold.

#60 wayno

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Posted 03 November 2017 - 12:11 PM

L18... I believe they run the L20B cam so #2. HOWEVER the hole position is less important that the V to etch mark alignment. This governs cam timing.

 

V in back of the cam sprocket should be below and just slightly to the right of the etch mark in the cam thrust plate behind it, regardless of the hole used.

 

iMnwYVD.jpg

Are you sure about this photo above, I cannot even get the lobes close to 10am/2pm with the cam timed this way, to get them at 10am/2pm the crank is at 30 something degrees.