I've had my 64 F100 4x4 for a long time now... almost 14 years and the 292 is original as far as I can tell. I've always considered it to be "tired" and planned at one point on repowering. I'm thinking I remember a compression test 10 or 12 years ago showed the best cylinder as being 126, then something like 119, 118, 117, 109, 103, 99, 97, 96, give or take. The chalk numbers have mostly worn off the exhaust manifolds by now, but I think that's about what I recall. If I go down a long hill under compression and give it gas at the bottom, the car behind me can see some smoke, or it'll also sometimes smoke starting it up in the morning, but it's not noticeable under most driving conditions. I fouled plugs early in my ownership, especially in #1,7 and 8 (mostly the lowest compression cylinders) until I started using hotter plugs. This truck is not my daily driver anymore, but sometimes I'll drive it 4-5 days in a row and sometimes it'll sit for a month (it always starts though). Now I'm not really looking for work and a place to spend $$ right now, but if I were to rebuild the 292 pretty much stock, how much difference would I notice in performance, fuel economy, etc? It seems like a lot of people just opt for a different engine in these trucks. I don't really want to get too wild, it doesn't see the upper RPM range much and would be overkill to go too hi-perf. Some suggested mods would be ok though.

The odometer shows at least 172,000, but I would say it runs pretty well. How prone are 292 cylinder bores to taper? Would it be worth it to do a good valve job with new unleaded (stainless, right?) valves and call that good? or should I continue my "if it ain't broke..." plan a while longer? Either way I think I'm also due for a new carb; It's pretty worn. I guess that should come first.

Sorry for the long-windedness.
-Mark

 

You have several options.
The first thing I would do is make sure the valves are adjusted correctly. This may explain the 30 lb compession difference from weakest to highest. I recomend adjusting with the engine not running because getting the feeler between the valve stem and rocker arm can be a bit tricky and personally I think you get a more accurate reading. I have the adjustant sequence if you need it. If the valves were off , corrected you will see instant improvement in the engine.
Freshen up the heads, either take them off and have them reworked or do them yourself the old fashioned way or maybe I shoud say the old fashioned way when people had no money.
First you need to remove and inspect the heads if you plan to keep the Y. You may have some valves that are burnt or close to getting that way. My 63 had 4 valves burnt so bad they looked like 4 leaf clovers! My engine had 6 burned valves in all but it still ran, very poorly, but it still ran. The heads were damged so bad I found a good used set and installed them on the truck. This also maybe a good option for you.
After cleaning up the heads inspect the vavles and seats for any problems. This is the time you will see if it can be repaired at home or if it needs to go to a shop or in my case, a new set.
If the heads pass inspection you can do the old time lap job at home. You will need some valve lapping compound, lapping tool [basically a stick with suction cups on each end], a good quality flat file, fine grit emory cloth, a power drill and a valve spring compressor.
Remove the rocker assembly and let it soak in kerosene or diesel fuel. It;s a good idea to thoroughly clean the rocker assembly. Make sure that all parts go back where they came. This goes for the valve springs also. Remove the valve springs clean and place them in a row on a flat surface. They all should be the same height. A short spring is weak and should be replaced. With the valve springs removed the valves can now be removed. With 45 years of use the valve stem will have a flat top like a near microscopic nail head. Remove this "head" with emory cloth and the valve should now slide out with out ruining the guide. Keep the valves in order and clean the bare head casting. Use the flat file to go over the gasket sufrace of the head. Keep the file flat and at a 45 degree angle across the head. File across the head from one end then reverse in a cross hatch pattern until the gasket surface of the head is true. The same can be done to the block.
Keeping the valves in order, place it back in it's guide and place lapping compound on the valve's sealing surface. Place the lappingtool's cup on the valve and spin the tool over between your palms, spinning the valve back and fourth against it's seat. You are now machining the valve and seat surface. Lap and check the surfaces. What we are able is a good clean sealing surface all the way around the seat and all the way around the valve lip. Take care not to get grinding compound on the stem. A little bit of oil on the stem would be helpful. A quicker way to lap valves is with a power drill. Insert the valve place the compound and fron the valve cover side of the head chuck the valve stem into your drill. Spin away slightly pulling the valve agaist it's seat. Be careful a lot of material can be reoved quickly so check your progress often.
With the valves all lapped replace the umbrella rubber seals with new ones over the valve stems. Install the springs, retainers, and finally the rocker assembly. You now have an overhauled head.
It is not quite like new but on a high milage engine new heads can be a bad thing. The rebuilt top end can put too much pressure on a wore lower end causing a knock.
Another at home method is the in chassis overhaul where the pistons are pulled and new rings, rod bearings, and main bearings are replaced with out removing the engine.
The Y shouldnt have any worse bore taper than say a 352-390-302 350 ? ? with the same milage. It all dependes on how it was used and if it was taken care of.
Ys are built like a diesel, very robust. With todays gas their lower compression ratio is IMHO just right. They can be made to perform suprisingly well. The Thunderbird Special 292 and the 57 supercharged 300+ horse motor were Y blocks.
It has been said that Ys are luggers not screamers. They may not tach to 9000 RPM but they can lug a bed and trailer full of concrete blocks over a mountain. A y is perfect for a 4wd.
In my experience rebuilding the original engine or replacing an engine with the same type is always easier and in the long run cheaper than an engine swap.

 

Thanks for all the input. I'm on the fence because, like I said, it runs pretty smoothly. I've always wondered how much difference freshening it up would make, or even a full-on rebuild. I don't mind driving it the way it is for a while longer, but I don't want to mess anything up by doing that either.

 

I'm not sure if the later (1960 and newer) y blocks have a crankcase breather vent filter. If they do, take it apart and replace the filter element or clean it in solvent also the oil fill cap should cleaned or replaced. Both items are critical for the crankcase to vent the way they were designed to. Otherwise it will blow by the rings and out the exhaust. I drove a y-block '54 in highschool (1975-78) and my shop teacher was behind me one day leaving the parking lot. He told me the next day about the blowby and I thought I was going to have to do a valve job. I lucked out, the breather element for the crankcase was partially plugged up. Put in new and soaked the cap, cleared up my blow by problem. Good Luck

 

My oil filler cap has a breather (that I've never cleaned), but I'm not aware of any other breather. Where is it on the engines that have them?

 

In the valley pan , behind and below the carb.

 

On my '55 F100 239 Y-block it is located on the drivers side of the block, just above the oil pan, aft of the timing chain cover. It has a metal can turned upside down with a bolt through it and about a 3/4 inch tube coming out the bottom with the opening pointing toward the ground. The filter I refered to earlier is under the upside down cannister. I think mine got plugged up because I switched to a detergent oil. For some reason I think the later engines don't have this crankcase breather vent. Maybe somebody on this forum can shed some more light on this for us.