As long as the engine is apart. Must change items?

[Shvegel]

I am about to put my 90,000 mile engine back together after pulling it all apart for a resealing and cosmetic restoration.  Piston to wall,  rod and main bearing specs, timing chain etc are all good so it is going back together untouched( I left the pistons in so as not to disturb the ring sealing).  Other than the timing chain guides what are the must do items while it is apart?

[Tyler S]

I would leave the timing chain guides alone if there in good shape. They are plastic on metal. The new ones currently available are all plastic and have a known issue of getting brittle and breaking off.
I would replace at the very least the chain if not the sprockets unless yours are newer.
Now would be a good time to check/replace the oil pump/tach drive bushings, upper AND Lower.
Replace the small head to water pump housing pipe and banjo bolts as they corrode from the inside out. Their cheap and its good insurance. How are the ball stud adjusters and rockers looking?
Check Ancillaries like water pump, hoses, motor mounts, etc.

[Shvegel]

Original chain is tight and all else is new or rebuilt.  good tip on the chain guides.  Thanks.

[GGR]

I would check the valve guides for play. They usually start letting oil through at around 100.000 miles, with nice puffs of smoke as a result. Replacing seals only will be a temporary fix which won't last very long. 

[Shvegel]

GGR,
Thanks for the response.  I just did the head about 5K before I pulled the motor.  All new guides, ball studs and valves.

[Benz Dr.]

I would pull the pistons and look for wear in the grooves and on the piston skirts. There are enough miles on your engine that you can expect most of these parts to be worn out and you won't be able to tell otherwise without inspection. This is the time to look at everything.

 I would also replace the oil pump. They're good for about 150,000 miles, depending on running conditions, but in most cases they won't maintain volume and pressure through to the next rebuild. I won't warranty a rebuild without a new oil pump.

[Shvegel]

Dan,
i had it apart about 15 thousand miles ago when I first bought it.  At that time it had sat for 25 years and it was stuck solid.  I ended up having to destroy the pistons in order to gt them out.  I didn't have a lot of money at the time and Joe was kind enough to sell me a set of used slugs for $30.  I honed the block(with a good micrometer hone) and Put it back together.  When I pulled the head the other day the cylinder walls were nice with a few small scratches,  the carbon on the piston crowns was nice and even with no wash out at the edges which tells me that the rings are sealing and no oil is washing over the sides of the piston.  When I built it I put Deves iron rings in it and they have obliterated the honing marks but have left almost no ridge.  My gut tells me that the car just won't see enough miles to make it to a full rebuild any time soon so together it goes.

[Benz Dr.]

Ah..... the plot thickens. If everything is as you say it is, you're probably OK. Are you confident that the oil pump is good?

[ja17]

The crankshaft chain sprocket takes the most abuse, change it and the spacer ring. The cam sprocket is inexpensive, change it also. The timing gear bushing (thrust piece)  should be checked. I also like the old style aluminum/rubber chain rails. I have never heard of one of these breaking off and destroying an engine. The rubber does get a little hard with age.

[Shvegel]

Dan,
I pulled it apart and checked end clearances.  It is actually pretty clean.  There is a little drive end wear but it should make it to 150k.

I did have a fair amount of wear at the bushing that acts as a thrust bearing for the upper shaft of the oil pump drive.  After looking at it I don't see how it ever gets oil.  It is splash lubricated but on the side of the engine that doesn't see much upward splash.  I decided to try and turn my own bushing out of some better material some research on Bronze alloys and ordered a chunk of C937 which is a lead, tin, copper alloy that is supposed to be good for wear and lubricity.   I had thought about just putting a roller thrust bearing in there but the thought of having it break and drop the needles down between the oil pump drive gears scared me off.

[RonDwyer]

Crankshaft sprocket, if the teeth are sharp points, or the top flat is almost gone, it is a good replacement candidate.