So I need to get my truck back on the road. She's a 1985 f350 with the 300 and its non efi, carb'd. I did a compression test today because of the massive blowby and the second closest cyl to the front of the truck had 35 psi compression and the last one had 50 psi. I dribbled some oil in and it went all the way back to normal, so I know its my rings. I took the valve cover off and its clean as a whistle in there. Just oily like it should be and no broken springs or anything. the truck has 120,000 on it. I dont think anyone has ever opened it up based on the condition of the gasket which was very crumbly and old, looked original like the starter and alternator. So what I plan on doing is measuring the bore and inspecting the cylinders for damage and if all goes well, Ill hone the cylinders and install new pistons and rings which I've never done before, and any tips would be appreciated. I definitely can do it no doubt. the engine makes no weird noises. it just idles rough obviously because of the low compression cyl's I think. the pushrods are straight too.

So
pistons and rings+Im almost sure it just needs honing
bearings
new oil pump
new timing gears. I'd have to assume they are worn too
gaskets
new plugs and wires
already have a brand new carb on it

It seems I can get to everything I need to with the engine in the truck, dont even need to lift it to get the oil pan off. its a huge box truck btw.

 

Here is info on my "In the truck" repair.
https://www.ford-trucks.com/forums/1...l#post18630486

I did not feel the need to swap out the oil pump or timing gears. I only did Rod Bearings.

The only reason I did not use a hone is there is no way to clean out the metal filings (grit dust) out of the engine. Without honing it might take a little longer for the rings to break in.

I used an engine hoist and pulled the Head with both manifolds and the carb all at once.

Good luck, Jim

 

If the holes measure stock size then no need for pistons if all you are going to hone to break the glaze just fit new rings to the holes and install on the right pistons.
You may find the old rings stuck to the pistons and why the blow by.
Just make sure you clean the grooves using an old ring before you put the new rings on.
Dave - - - -

 

I've been wondering about that, too. What's the history of the truck? Was it parked for a long time and now you're resurrecting it? In that case, I wonder if the primary problem is the rings are stuck. That might explain the low compression in two cylinders.

How much have you driven the truck recently? Perhaps it would be worthwhile to add a spoonful of Marvel Mystery oil or ATF through each spark plug hole. Leave the plugs out and rotate the crankshaft a few turns with a breaker bar to distribute the oil. Rotate the engine like that once a day for a week or so. Add a little more oil if needed, but don't overdo it. With any luck, this will help free up the rings.

Before reinstalling the spark plugs, crank the starter a few turns to blow out any excess oil to avoid hydraulic lock. This step can get messy, be forewarned. Then reinstall the plugs and take the truck out for a good, hard workout. You want the heat to help free the rings. After that, repeat the compression test. You might be pleasantly surprised.

 

Im not sure the history of the truck, but it was sitting for a LONG LONG time and belonged to some company before I got it. It actually has rust by the door panels and behind the seats where the water got out from having bad door seals. it literally looks like it just sat for ages and someone bought it and never got to it mechanically. I think the guy I got it from drove it and didn't know **** about carb's and ran it lean for too long. None of the cyl's look worn or anything but I've got a rebuild kit on the way for it. I might as well change all the bearings and everything I have in the kit right even though the engine makes no tapping or scraping noises? It was only 215 bucks for new pistons and rings, oil pump, gaskets and timing gears so I might as well

 

I would say no, don't just go replacing a bunch of parts right off the bat like that, especially on this particular engine.

 

well I need the truck to drive long distances without problems and I know it needs at least new piston rings. I'm surprised how clean the inside of this engine is though. Should I replace the charcoal canister(rectangle thing) up front by the passenger side headlights? I'm not sure how important it is but mine has a huge crack in it and I had to disconnect it. I also have tons of those little brittle vacuum lines Im going to have to sort through. I also need to test my EGR and probably clean the inside of that. I'm also thinking of installing a wideband O2 sensor kit so I can see what the air fuel mixture is like and the exhaust on the truck has a bung for one, but its plugged with I dont even know what but it aint factory. I think this was a computerized truck at one point and someone installed a duraspark ii at some point. I think that gauge even though a tad pricey is good for knowing the health of my fuel mixture and carb.

 

You can deglaze in place , put plenty of insulation tape around big end journals and , use a ball hone , deridge if a little worn ,make sure pistons don't have any fine cracks usually from the oil slot , top ring groove gets the most wear , if worn you can get ring inserts which move the top ring down away from any bore wear , needs to be machined for them , pistons can stay on rods usually end pressure in a lathe is enough for a machinist to center them up and machine groove, the center stalk of ball hone can mark big end if not protected , don't over stroke ! , and give block a good soapy water wash and hose down , spray with wd40 or light rust starts immediately. Gap the rings , ☺

 

If you want to do it right, take it apart and rebuild it. work with a machine shop to see what it needs. Factory pistons and rings are a joke, don't be surprised to find broken piston skirts.

- Factory crank, rods, main bolts, rod bolts are all plenty strong unless you are truly building the engine for serious power and rpm. Mines fairly built with all these stock parts and takes 5000rpm dozens of times a day without a sweat.
- Have it bored and honed. H519p pistons are cheap and work well for rebuilds, they will provide highish compression though. E-229k rings should be pre gapped.
- Its quite easy to rebuild on a table as opposed to an engine stand. Power nation TV said the length of the engine may bow it and offset clearances, who knows of that's true, maybe.
- For a stock to medium build use the factory head bolts.
- Aftermarket timing gears are recommended, stock fiber gears will shear and break eventually. The metal plate between the gear and cam is fragile and shatters easy don't press on it. They are hard to find.
- The French town flyer recommended to another user that if they don't need to hone the mains, don't as it may offset the timing gears. Maybe he'll chime in and offer some tips.
- The inline 6 is very well balanced inherently. For a stock to medium rebuild you should be fine with buying pistons in a set that are already weight matched (my h519p were). You shouldn't have to pay for balancing.
- I'd change the oil pump with a stock replacement. Get a good brand. Why people above are recommending skipping a part like that to save a couple bucks is interesting.
- Fel pro sells an engine gasket kit, use the included head gasket for a stock rebuild. Add fel pro head gasket #1024 for upgraded builds.

 

Never heard of the crank mains being off set ground only the rods.
This would be to get zero deck because of the piston change or a little more stroke.

Now mains done under size I have heard of and to line hone the block mains to true up everything.
Same with resizing the rods, take a little off the cap / beam, bolt back together and hone back to size.
Dave ----