3b push rod lifter?

[dkyuss]

Also, I was gonna ask earlier about how tight the valve springs should be when assembled. Should you be able to twist the outer spring at all? It took mild amount of torque, but all springs could be twisted under the spring keepers. I was expecting them to be tighter, just didn't think much more of it till now

 

[lostmarbles]

..
Cam is likely on its way... Grindable? 2 cams look like this (This is the worst)
..

Certainly showing heavy wear .... but I'm not experienced enough to say whether it's repairable (by grinding)..

But I am also noticing the manual indicates I should have spring seats on the head.

But which FSM are you using? This is from the Aug 1980 FSM that should apply to a 1981 3B and I don't see those seats:

As for the rust colour, probably best to ignore my comments.. Perhaps it is just rust from corrosion that occurred sometime when the engine wasn't in use or something like that (rather than being connected with the head gasket damage).

I think all the experts here on mud will say this engine needs a full strip-down and rebuild .. but if you have budget constraints or whatever that prevent this, then it's all a matter of "judgement" as to what you can get away with now as a short-term fix.



Edit.. As for the twist-test on the springs.... I've never done that. But don't forget there's a second spring to back the outer one up.

So long as you can't easily open a valve by pushing down on the collet-area I wouldn't be worried..

 

[dkyuss]

But which FSM are you using?

Good detail! I see my manual (and all I can seem to find?) is dated 1994 on the first page. This explains a few discrepancies I have noticed.
Where might I find the 1980 version?

 

[dkyuss]

And now that I have the head getting cleaned up, I find 2 hairline cracks. One each between valve seats on cyl 2 and 4. Its definitely never overheated on my watch, but obviously seen some prior abuse/neglect.

I am contemplating my options as I have short term (this summer) plans and long term plans..... I may have a line up on a bottom end that spun a crank bearing. Potentially able to steal the cam shaft and lifters and make my current bottom end 'ready to go' for this summer. This will also provide me with a core to rebuild as $$$ becomes available. Good winter project.


As the head (I assume) is scrap as is? I may bring it in to work and give er a try (it costs me nothing but time, which I do have more than $$$). Take a carbide cutter on a CNC mill to these two cylinder valve seats. Machine out both valve seats (and a little more, say 5 or 10 thousandths of an inch) plus a groove between valves to (hopefully) eliminate the cracks (cracks look small, and I can not see them on the inside past the valve seats).

With both valve seat bores cleaned up and connected by a channel, I would CNC mill a single shouldered valve seat(s) to press fit in. So one piece of metal that would be both intake and exhaust valve seat connected together (to fill the up crack removal groove).

My initial concerns are, selection of the best alloy for this new piece, considering thermal expansion and wear properties. As well as how to ensure a air tight seal between intake and exhaust. Press fit with a shoulder *should* provide this but alloy selection I am not sure of.

I would love your guys thoughts on this, but Im sure at the end of the day (seeing it still all makes sense) there will be only one way to find out.

 

[lostmarbles]

....
Where might I find the 1980 version?

eBay or refer to the various threads on downloadable FSMs.

And now that I have the head getting cleaned up, I find 2 hairline cracks. One each between valve seats on cyl 2 and 4. Its definitely never overheated on my watch, but obviously seen some prior abuse/neglect.
...............
As the head (I assume) is scrap as is? I may bring it in to work and give er a try (it costs me nothing but time, which I do have more than $$$). Take a carbide cutter on a CNC mill to these two cylinder valve seats. Machine out both valve seats (and a little more, say 5 or 10 thousandths of an inch) plus a groove between valves to (hopefully) eliminate the cracks (cracks look small, and I can not see them on the inside past the valve seats).

With both valve seat bores cleaned up and connected by a channel, I would CNC mill a single shouldered valve seat(s) to press fit in. So one piece of metal that would be both intake and exhaust valve seat connected together (to fill the up crack removal groove).

My initial concerns are, selection of the best alloy for this new piece, considering thermal expansion and wear properties. As well as how to ensure a air tight seal between intake and exhaust. Press fit with a shoulder *should* provide this but alloy selection I am not sure of.

I would love your guys thoughts on this, but Im sure at the end of the day (seeing it still all makes sense) there will be only one way to find out.

If you search you'll find cracks between valve seats are quite common in B-series heads and many people continue to run heads with these cracks. I think the consensus is that if the coolant and oil both stay where they should be (and don't choose these cracks as an escape path), then you're OK. But of course any professional doing work on such a head will generally not provide any warranty.

(Cracks in the seats themselves are of course a different story and would require new seats to be fitted. So I'm talking only of cracks in the head casting and these shouldn't go right through to the coolant passageways otherwise you're definitely knackered.)

I don't understand what you're planning with the valve seats but whatever it is, unfortunately it doesn't sound at all feasible to me.

 

[ozcrusier]

I would drop the sump and check the big end bearings before you order any parts.

 

[dkyuss]

I don't understand what you're planning with the valve seats but whatever it is, unfortunately it doesn't sound at all feasible to me.

Half the battle is explaining myself!

Plan to set up the head on a CNC mill.

I would then bore both intake and exhaust valve seats to remove them, creating a deeper valve seat bore (say approx 3/8" deep?). These two bores would have a channel removed between them but only at about half the depth. Metal removal would look something like this.

The Idea is to remove the crack which bridges between valve seats. Cracks in heat cycling cast iron vibrating parts WILL grow with time. If the crack is terminated completely, theoretically the casting is as strong/healthy as it was new.

The insert piece would look something like this.

(not to scale)
This one piece of steel would replace both valve seats and fill the void left by removing the cracks. The bores would be an interference fit and need to press these into the head. The deeper bores would also ensure the intake and exhaust gases stay separate.

So is this clear as mud? lol

Anyone know what grade of steel valve seats are typically?


Just to show off a bit, here is an example of something I did on the CNC last year because I was bored.... Amazing machines if they are not stuck doing production all the time!
Flower of Life in Aluminum

 

[dkyuss]

IF there is enough room (I have not done any measuring yet), a better fix would be to leave the factory valve seat boss in my insert piece. Then just install new valve seats.

 

[ozwallaby]

With your machined "figure 8" insert, I think your in uncharted terrirory..... I think I would be inclined to get it (the crack) welded by a pro... yes $ v time is always a problem...... my thoughts on the figure 8 is it will be relatively thin and therefore quite susceptible to distortion during insertion and the heat cycling of the head..... or leave the crack be if it's not leaking.....

 

[lostmarbles]

Thanks for the explanation. (I imagined that might be what you were planning.)

I don't think it is possible engineering-wise to press in something as fragile as that (with an intereference-fit) without the "bridge" breaking.

And I know modern technology is amazing, but manufacturing that figure-8 looks to be in the "too hard basket" to me.

And while I can see the benefit in "ending a crack to stop it spreading", machining these cracks out involves reducing metal-thickness in crucial areas for strength (and to fill what you've cut with weld in a cast-iron is also known to be problematic).

And ..............

So unfortunately I see it as a tremendous amount of work with little or no chance of success.





PS. I'd choose from the follwing options:

• Run the existing head with the cracks
• Buy a replacement second-hand head
• Get a new Chinese/Taiwanese head from Engine Australia

 

[dkyuss]

Thanks for all your input guys. Still not exactly sure what I will do with the head. Either way Im sure it will work just fine.

Got a replacement bottom end today.
Camshaft and lifters look good. Plus a whole bunch of other better parts than I have. Will probably install all new BEB and cam bearings while im in here. Just leaving the pistons and liners alone cause I dont want to pull the engine from the truck.

In an attempt to contain most of the detail in one place, I will continue with pics and more in my build thread. Maybe see ya there.
Finally Bought my first CRUISER!