1970 F engine rebuild (1 Viewer)

[3mountaineers]

Well finally got my 1970 Fj back to Va at Iron Pig Off Road. Lance did a leak down test and I think his words went something like this, ‘that was one of the worst I have seen….”

Not a good way to start out the day and the first time that I was able to see the vehicle. Even with the bad news on tHe leak down test, I am excited to get the ball rolling on getting this vehicle back on the road. Being that I really want to keep this vehicle as original as I possibly can, we are planning to pull the engine, take it to a machine shop and see what we need to rebuild it. He was very honest with me and let me know that will be a very tall task to get parts. Being the eternal optimist, I wanted to post on the forum to see if anyone could help me locate parts for an original F engine. Keep smiling……

 

[Skreddy]

Well finally got my 1970 Fj back to Va at Iron Pig Off Road. Lance did a leak down test and I think his words went something like this, ‘that was one of the worst I have seen….”

Not a good way to start out the day and the first time that I was able to see the vehicle. Even with the bad news on tHe leak down test, I am excited to get the ball rolling on getting this vehicle back on the road. Being that I really want to keep this vehicle as original as I possibly can, we are planning to pull the engine, take it to a machine shop and see what we need to rebuild it. He was very honest with me and let me know that will be a very tall task to get parts. Being the eternal optimist, I wanted to post on the forum to see if anyone could help me locate parts for an original F engine. Keep smiling……View attachment 3164617

What parts do you need?

 

[Grayscale]

The valve clearances were checked for wiggle, when closed, on a failed cylinder?

Think about it, you can't get horrible leak-down results without other signs of catastrophe, or long-term wear. Does the PCV valve / hose connected to intake manifold look like La Brea Tar Pits?

 

[MDH33]

Yeah, what was faulty in the leak down test specifically? Low compression isn't really a big deal in an old F engine if it's consistent.

 

[miller]

I have a rebuilt head from a 1970 with zero miles if interested Send a pm.

 

[BloodyMGT]

Well finally got my 1970 Fj back to Va at Iron Pig Off Road. Lance did a leak down test and I think his words went something like this, ‘that was one of the worst I have seen….”

Not a good way to start out the day and the first time that I was able to see the vehicle. Even with the bad news on tHe leak down test, I am excited to get the ball rolling on getting this vehicle back on the road. Being that I really want to keep this vehicle as original as I possibly can, we are planning to pull the engine, take it to a machine shop and see what we need to rebuild it. He was very honest with me and let me know that will be a very tall task to get parts. Being the eternal optimist, I wanted to post on the forum to see if anyone could help me locate parts for an original F engine. Keep smiling……View attachment 3164617

I might have a line on some +0.020" pistons.
I just did a minimum rebuild on mine.
New rings, bearings and seals.
Intake/exhaust flatness and gasket seals were my biggest challenge.
I'm replacing all the seals and gaskets in the 3 speed and transfer case now.
I have all the PTO parts except for the winch reel and gear.
Any ides?

 

[Grayscale]

Newby question here? Can't new rings be installed in old pistons? I'd recreate a honing pattern (for better surface oiling) in the cylinder wall, and just call it good? Don't replace parts that aren't broken kind-of-approach on antique or non-resotored vehicles. Unless the bores have enough out-of-center or major out-of-round wear, I'd not want to jump to larger pistons; I'd imagine that most engine rebuilders would call me "loco."

 

[BloodyMGT]

Newby question here? Can't new rings be installed in old pistons? I'd recreate a honing pattern (for better surface oiling) in the cylinder wall, and just call it good? Don't replace parts that aren't broken kind-of-approach on antique or non-resotored vehicles. Unless the bores have enough out-of-center or major out-of-round wear, I'd not want to jump to larger pistons; I'd imagine that most engine rebuilders would call me "loco."

Yes, new rings can be installed on old pistons, once properly cleaned and inspected.
That is what I did on mine. I had 120 p.s.i. on four cylinders and 90, 100 on the others.
I cleaned, inspected and measure piston grooves per the manual.
I installed the old top ring in the cylinder and got 0.044" end gap.
New top (Std) ring in cylinder was 0.020" end gap.
Factory spec is 0.008" to 0.016".
I reamed the ridge out of each cylinder then honed them.

 

[middlecalf]

Newby question here? Can't new rings be installed in old pistons? I'd recreate a honing pattern (for better surface oiling) in the cylinder wall, and just call it good? Don't replace parts that aren't broken kind-of-approach on antique or non-resotored vehicles. Unless the bores have enough out-of-center or major out-of-round wear, I'd not want to jump to larger pistons; I'd imagine that most engine rebuilders would call me "loco."

I did this, similar to what @BloodyMGT describes above. My replacement STD ring end gaps are a little more than his, but way less than what was there, plus none of the rings are broken now , several were before. The bore diameters were 0.010-0.012 which is right at the limit that one piston ring maker says is the max for just re-ringing. The bores were at most 0.001 unconcentric. No more smoke or oil burning, we‘ll see!