I need some engine advice

You may have looked here http://www.earlycj5.com/xf_cj5/index.php?threads/determine-your-own-entertainment.117203/

I have come to the part where I want to reassemble this POS. There is visible wear in the cylinders. The pistons are mismatched. The one piston where the majority of the damage occurred connecting rod is flat on one side across big end/small end and not so flat on the other when laying on a straight table. I could not remove the jammed piston rings from the damaged piston and need a new set. Gotta buy the whole set, not just one pistons.

The engine ran fine for what I want it to do, but its not remotely right. I don't have a bunch of money to throw at this thing. I had 18lbs of vacuum.

So, do i just buy a ring set and trow it back together or wait until I can bore and buy new oversize pistons/rings. I tried to ask my crank grinder who to take the heads and block to and he could not recommend anyone at all.

A ring set is under 40 bucks. it will get me driving when the rest of it is put back together.

Or should i just push it into the corner and rebuild something else ?

 

How about a 'quick and dirty' on this one, drive it 'til it dies, and
meanwhile that would buy you time to do a good build on another one.
Swap them later.

 

Treat it like a challenge. See how little you can do to get it running, then see how long you can get it to run like that.






It works for me.

 

JMO - if you are going to buy new pistons, you may as well go oversize and straighten the bores. Check with your local shop about the cost of machining. IIRC it's not nuch compared to the cost of new pistons.

 

I am leaning in that direction. This engine has new rings, new timing chain, bearings, cam, lifters etc.. Had a crank guy polish the mains and journals, still std. I just didn't bore it when I put it back together because there was little to no ridge. Good thing too, I would have wasted my money. didn't do a valve job either, just lapped them. intake valve guides leak a bit of oil. I may just order a full ring set from rock auto just to re ring this one piston. I got 2 good exhaust valves out of 6 from that junk engine that I actually bought. intake and exhaust valves seized, rusted seats and the thing had valve covers on an the heads were bolted tight.

I happen to have 2 new pistons in my possession

I will lap those valves again, instal new piston on rod and new rings on piston, hone and slap it back together. I might re ring one of the correct facing rod/piston assembly from the junk engine. 2 of the assemblies from that engine are serviceable.. barely.

I have so many junk engines here that it would be a real shame to not try and use the parts and save money to rebuild a real one later.

What I did see is that the valves from 1965 are the same and stamped GM just like the ones from 1970 or so even though they are supposedly not GM.

Conn rods are slightly different casting though.

 

If I was doing a real rebuild I would take the block and heads to the machinist, deck it, bore it and then buy whatever oversize was appropriate.

 

27 bucks for the head gasket kit with a pan gasket from rock auto and a ring set from summit for 44 bucks. 71 bucks with the shipping is as cheap as I can make this repair. Gaskets are here and rings are ordered.

I will reuse the bearings because they only have 1100 miles on them.

 

Do what you feel is needed. I have done L134s, Buick V6s, Corvettes and Volvos and a Harley. A machine shop is your friend or at least know somebody that has the proper instruments to check out taper and such things. The Harley was bored a whopping .003 oversize and I had to file the new compression rings to have them fit right on them huge pistins. It is still mostly an 80 CI motor that will outrun anything up to a 104 CI Harley. The cam and carb and head work helps a bit as well.
About ten years ago I decided to put the V6 back together in the 3B that had been apart for around ten years. An ex Corvette mechanic showed up for a beer. He did the passenger side and I did the drivers side. What else to do on a Thursday afternoon?
That engine probably should have had new rings fitted. but even at 185,000 miles, it will still run over 80 MPH. It does burn a bit of oil.
Every every motor I went through the full meal deal. The b18 Volvo read like it was in specs but it got bored and the crank ground. 327 Corvette motor, I made the mistake of putting Chrome Molly rings on. It took a few years for them to seat in properly

 

I am going to drive it everywhere i can when i get i back together. i know this guy in Idaho........

 

so much junk

 

At least you can see the floor in yours. and, yes, I have piles of sheet goods piled up aginst a wall and some oak boards hanging around but I don't have as many stationary powertools.. A couple friends have a garage that you could eat off of the floor. Don't they have anything better to do?

 

I put all my hand tools away ASAP because if i don't, I lose stuff that is right in front of me. That makes me insaner. All the tools aside from the extra large ones are on wheels. planer, 5 wheel oliver sharpening station, shaper, etc.

Really, the junk is all that engine garbage spread out on my out feed table. I will put it back together and it will run, but I want to do better.

Already thinking about the real engine rebuild. Where to get the new guides and seats cut in, where to get the block bored and decked and if I want to press on my new oversize pistons or trust a shop to do it without damaging the pistons or overheating the conn rods.

I have been taken for rides before with machine shops. not going to do this for a bit, but the idea is there. vroom vrrom mother eeffer!

 

All 3 of the passenger side pistons are bad. One has a hairline crack from top of piston to the top compression ring, one has smashed the piston enough to crimp all the rings including oil rings together and the third is just dented enough for me to think the ring will have a hot spot and blow up maybe.

As i said I only have 2 new pistons, but I do have a pretty much unlimited supply of STD pistons that are used and well worn, but probably won't explode. I would just swap in a used doner piston /con rod assembly but the ones I have are visibly heavier and will probably seriously imbalance the rotating assembly. I may never know it, but I decided to see if i could press off the piston without destroying it.

Those of you who have worked on these engines understand that the wrist pins are pressed in the connecting rod and do not float on the conn rod, but the piston itself.. T slot pistons in the 134 have a bolt if I remember correctly. Chevy stuff has a cir clip and thats where my experience ends. Anyway, if you just take a press and press out the wrist pin, even if you support it, chances are you will destroy the piston.

I have no torch, but I do have a cheap mapp gas/oxygen set up. I heated the small end to brown color, supported the piston with a socket just oversize of the wrist pin and pushed that pin out. I was successful. The wrist pin slides in and out of the piston and when cleaned up will go back in on the factory set of buick conn rods.

Reassembly means heating the small end as hot as i can get it uniformly, freezing the wrist pin and really quickly pushing the pin in through the piston and through the conn rod making sure it is centered. you only have about 3 seconds or less to do this before the conn rod and wrist pin return to their interference fit. Unless your hands are made of asbestos you need to wear heavy gloves. I have successfully done this a couple times on this engine and ran it with no issue.

Disclaimer! I have no training in engine rebuilding, do not have a scale to measure conn rods and pistons, yet, and do not have a rod heater.

 

You sound a bit like the friend that helped put my V6 back together. He would get done with a wrench and go put it on a table next to my garage door. I would be looking for the 9/16 box end wrench and it wasn't where I left it. He had put it on the table, "Why did you do that, You know we aren't done with it"? Afterall, thats what fenders and the radiator support is for.

 

man, I make a giant mess of things so bad that i literally have piles of tools that i trip over. I used to go nuts trying to find a tool right in front of me. Now, I just put away everything either at the end of work or the beginning or sometimes a couple times in between if I am frantic enough. Small work spaces make you do that.