304 Overhaul - How far to go?

[chopperkarl]

Hello,
I pulled the 304 out of my 73 Scout to replace freeze plugs and motor mounts. Although my original goal was fixing the mounts and stopping leaks (both oil and antifreeze), with the motor out, it seems like I ought to take advantage of it being out and inspect/replace anything else needing help. I've never pulled a motor before, definitely a novice. Any recommendations on what areas are worth digging into? How to inspect certain parts for replacement (bearings, rings, valves,....)?

I did a compression test 4 years ago. The results then for each cylinder in order 1-8 were: 142lbs, 140lbs, 130lbs, 140lbs, 159lbs, 160lbs, 150lbs, 147lbs. Engine runs ok, but seems like there is room for improvement...idle does not seem affected when pulling #2 or #8 sparkplugs and the engine does tend to lug/surge at low rpm. Also, on start-up, it makes a decent exhaust cloud....not so bad once its been running.

Thanks for the advice!
-karl

 

[Robert Kenney]

That's really a tough question to answer with no other testing having been done.
Sounds like it is missing at idle by your description of pulling 2 and 8 wires not changing idle quality. The compression numbers you posted are good enough to allow it to run correctly.
There are other systemic problems if this is the case. Could be air leaks, fouled plugs, etc.

Once you are game to dig into the engine past the heads it is short work to check the rest of the critical parts. You don't seen very familiar with the working in side an engine. I May have miss understood you saying that this is the first engine pull for you..

If this were me and I had the engine out and on a stand,
1) I would at least pull the intake manifold and heads so I could inspect the bores for wear. A bad wear ridge at the top means re-bore. Not so bad you can re-ring the engine
2) pull the pan and inspect the bearings, both rod and main. They can be inspected and put back if they are good but I would replace them while I was at it, if the crank looked ok.
3) remove the lifters one by one. Inspect the lifter face for cupping and or a flat or badly worn cam then replace in to it's original hole. Don't mix them up if you expect to run the cam again.
4) these engines have a tendency to experience cam bearing delamination and failure even with low mileage. I would plan on having a shop replace them. Along with a new stock cam.

If this is just with in your comfort zone ( I fully understand) carry on with your original plan to reseal and freeze plug, and paint it. Then work on getting the other systems up to snuff so it runs as well as possible.