78 620, L20B foreign matter in combustion chamber.

[Atikin9000]

Also some pics of said truck.

 

https://imgur.com/a/eIU8J

[datzenmike]

[flatcat19]

Is it in fact the seat?

[G-Duax]

Could be a guy with really fat fingers lost his gold wedding band....:)

[flatcat19]

Looks to me like the carb sucked something up in to the head.

 

 

But you showed a pic prior of something in he spark plug hole...so you have 2 foreign objects?

[datzenmike]

The seat has dropped but caught on the larger valve width.

 

 

 

L head spark plug location points directly between both valves so seats are easily seen....

 

[flatcat19]

Damn.

 

That's what I get for not clicking external links from Ratsun.

[datzenmike]

I fucking hate links. (I hate PB too)

 

I know. Today I learned that Canadian football is actually American football even though we play on a longer wider field, have 3 downs and an extra player to make the game faster and more enjoyable. Canadian football (AKA American football) is closer to European football (AKA Soccer) Go figure...

[hang_510]

Today I learned that Canadian football is actually American football even though we play on a longer wider field.

Damn metric system.

[distributorguy]

I see a bevel cut on that valve seat - not ok.  I also have to assume that's why the press fit was no good.  Whoever installed it deserves a kick in the nuts.  

[datzenmike]

 

 

 

 

I know. Today I learned that Canadian football is actually American football even though we play on a longer wider field, have 3 downs and an extra player to make the game faster and more enjoyable. Canadian football (AKA American football) is closer to European football (AKA Soccer) Go figure...

Damn socialist system.

 

[Atikin9000]

Little update, sorry for the imgur link again.

 

https://imgur.com/a/Oj0A4

[datzenmike]

 

If you are precisely set at TDC without backing the crank counter clockwise, then this is good

.

[Atikin9000]

Yea but I bumped the bottom end on accident so there goes that out the window.

 

I went 10 and 2 on the compression stroke on #1.

[Atikin9000]

https://imgur.com/a/BOcDc

 

The timing mark on the block was way off.

 

It’s gonna have to get timed again I guess, because it’s looking like this head might not be repairable.

[Atikin9000]

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

[datzenmike]

 

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.

.

[Atikin9000]

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

 

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

[Atikin9000]

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

[G-Duax]

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

[flatcat19]

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.

[distributorguy]

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.  

[Atikin9000]

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.

[flatcat19]

Meh. Not really.

[distributorguy]

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.