kdouville

Hi Yota-techies, have been reading for a while, first time poster. Look forward to following up with this for others and contributing to the community with answers as my skills improve. Looking to keep my 84 alive and well for many years setting myself up for future success and modifications.

I’m trying to diagnose my motor before tearing into a rebuild. I would like to replace what it needs, but not anxious to pour cash into things that are fine.

Jan. 1984 4WD pickup, solid axle, 22R, MT, PS, stock carb, 292K miles on what I assume is the original motor. EGR system blocked at the manifold, rest of the emissions hooked up but probably in a state of disrepair and will eventually be removed. May do a Weber 32/36 swap someday, but it runs allright with 17-19 mpg so would like to hold off for now. Seems a bit tired and not a lot of pep. Puff of blue smoke from exhaust on startup.

Leaks a fair amount of oil from all over. Broken drivers timing guide, single row chain eating the cover, but not through yet. I am going to put in a engnbldr kit w/ front cover, and FIPG the raised ridge oil pan as well (unless I can come up with the grooved oil pan first). Pretty familiar with that job, I have had heads resurfaced and put gaskets in on other yotas as well, but this time I want to do the valve work instead of the machine shop if it needs it. For the learning experience, you know?

Dry/Wet compression tests 1 to 4 are: 162/181, 162/164, 175/179, 163/167. Plugs look fairly carbon fouled after ~ 20 K.

Questions:
Would any other tests be valuable before I tear into this? Is it worth my time to go buy a leakdown tester?

How can I tell if it’s time for new valves? Relap or replace?

New cam a good idea? Do I need to do the rocker arms if I put a new one in?

Any suggestions on how to decide if its time for a lower rebuild? Is it unreasonable to just replace rings and rehone? How do I assess the lower bearings and the cylinders?

I would like to do it right, but am learning that replacing everything for piece of mind seems to be a bit overkill on these tough trucks. Don’t want to be “cheap”, but looking to get this motor purring intelligently, with the most bang for my buck,

Thanks for the advice, then and now. All will be considered. Great resource here. Point me at existing threads I might have missed if that’s more appropriate.

millball

Lapping valves by hand is an old-school rite of passage, but the practice is more suited to lawnmower repair than to good engine rebuilding practices.

When an automotive valve job is properly done, what is known as a three angle grind is done. This must be done with precision power equipment.

This procedure moves the area where the valve contacts the seat to the correct area of the seat, and insures that the contact surface area between the valves and seats is neither too wide, or too narrow.

This is not something that can be addressed by simple hand lapping.

At near 300,000 miles, a half-ass rebuild is likely to bite you.

Don't cut corners, the cheap ends up expensive.

Take your head, block and crank to the machine shop and let them examine them and refurbish them correctly according to what they find.

Make friends with the machinist, bring the shop a box of donuts or something, don't rush them.

The condition of the block and crank can only be assessed with precision measuring tools that are handled by someone who has experience using them.

Nothing wrong with doing all the assembly and detail work yourself, but leave the precision work to professionals.

That being said, I have a good selection of machinist tools, and quite a bit of experience, so I do measure my own stuff to determine any wear, and when my blocks, cranks and heads come back from the shop, I measure the piston to cylinder clearances and the rod and main clearances again myself.

It's the only way to know what you've really got, ultimately.

It is possible to make a fair assessment of the rod and main bearing clearances with plasti-gauge if everything is tweekishly clean and dry.

kdouville

Thanks for the reply millball!
I can appreciate that cutting corners starts to catch up with a mechanic quick. I reckon a head gasket is in order at that mileage (as well as a good idea if the front cover comes off) and might as well have the head and block and crank checked while I am in there.
I will continue to research how to plasti-gauge check bearing clearances.
The last time I had a head decked and valves done (on my 86) I realized I may have been better off just buying a new one complete, I ended up a little bit lower than I liked and I will probably be following that job up with a adjustable cam gear to offset it. Plus it didn't really save me much money and the head is still warped a bit across the top, luckily without cam binding (yet). Thus my desire to assess as much as I can to have at least a rough idea how bad things are before I waste money.
Ultimately, I agree the internal machining and valve grinding is better left to a shop. The extent of my machining tools is a quality straightedge, feeler gauges, and basic calipers.
I will keep updating this as I move along, but it may be intermittent as I am in no rush. Just finally have a shop and am enjoying the learning experience out of the rain for a change.
Anyone suggest a good machinist in western Washington?

kdouville

Well, I got the head off and found extensive electrolysis of the water jackets. Picked up 2 early 22 heads for cheap, but both have issues, one can maybe be fixed with damage from a foreign object, another was found to be shaved too thin to be usable. Rebuilt early 22R heads are generally scarce. I do have a good 20r head laying around so going that route for the hassle (LOL) and neato factor. I have the intake etc and being later it has the power steering bosses so that is going for me. The block was found out of taper (in #1 especially at .009 out) so boring .020 over and skimming a minimum for seat on the deck with the cover. Crank and bearings looking good, just a polish and new stock bearings there. Switching (maybe not upgrading) to dual row chain. Possibly going Weber 32/36 or else a 22R carb adapter to 20R head.

I planned going slightly oversized valves and using a good set of cast iron rocker arms with it. I also have a 260-270 split duration NW Offroad cam with unknown (yet) lift. I want to have the right oversize valves put in and plan to follow with a DIY port/polish/blend of the head, then a final valve seat from the machine shop. The new question is: What valves in the 20R head? I am unsure if I should go with a set of 22R valves, at least the intake, but maybe I should go with an oversize 20R valve instead? Any thoughts out there on the proper valve HEIGHT/LENGTH to maintain proper geometry? I am reading myself in circles and would appreciate any thoughts on how to pick the right valves to make it run well? I will follow any job with a clay test to check clearance. Thanks for any and all advice!