The throttle should be held open, all plugs out, when you crank it for compression tests. Is that how you have been doing it?

 

Unfortunately--no. I did not have the throttle open. Maybe with the throttle closed, the cylinders were starved for air and my results were lower then they should have been. Good reminder, Ross. Thanks.

 

I was able to get some new, hopefully correct, compression numbers today. The engine was warm, the throttle open, and the new gauge was the kind that screws into the spark plug hole. The new numbers are as follows: #1 80, #2 88, #3 70, #4 62, #5 62, #6 80.
I was hoping for better results--especially since I recently added the Lucas oil treatment.

Prior to this most recent compression test, I topped off my oil. The oil on the stick was all the way down to the add mark and my oil pressure gauge was reading even lower than usual (maybe about 5lbs to 20lbs). I ended up putting in 2 full Qts of SAE 30 and a Qt of Lucas Oil Treatment to bring it up to the full mark. Can this be right? I think the system only holds 5 Qts. Could my dip stick be wrong? With these additions, my oil consumption is really horrendous-- Eight Qts in only 675 miles. I'm not seeing any big leaks either.

Once the "driving season" ends, I may have to look into having a little engine work done. I just met an old guy with a shop way out in the country. He mostly works on old tractors, but he liked my truck, and said he thought he could hone the cylinders and replace the rings and bearings in my engine for $800. Is this a reasonable offer? This guy has someone else that works on heads for him. Reconditioning the head was not included in the $800.

 

That kind of oil consumption is mind-boggling, if there truly is no big leak. Your compression is terrible. While you have the screw-in compression gauge, can you connect up compressed air to the tube for the gauge? My gauge's tube has a quick-connect in the middle where I can do that. With each cylinder on TDC, put ~30 psi air into the cylinder and listen for where the air leaks out.

What's baffling about your oil consumption is that if it were bad rings, I'd expect a LOT of smoke. If it were valve stem seals, I'd expect fouled plugs or oil dripping out of the exhaust. It sounds like you have neither? It would be real interesting to see the valves thru their ports, but removing the manifolds on your engine is a real pain.

Honing doesn't correct taper in the cylinders. Honing and new rings may help significantly, but if the cylinders are tapered, the rings won't last.

 

My gauge does have the quick-connect fitting, so I will be able to do the compressed air test that you suggest. My engine does smoke some when I race the engine in the driveway, and I do see some smoke on a cold start (maybe that would be consistent with worn valve guides), but I just don't see any smoke in the mirrors when I rapidly accelerate and decelerate out on the highway. I once drove a 68 plymouth 383 with 230,000 miles on it that could produce an amazing cloud when floored at 50 and it kicked down into passing gear.

I guess we can't know if the cylinders are tapered until the pistons are removed.The plugs this time were all dark, but none of them were wet. Is an unacceptable taper something I should expect given my engine's 81,000 miles?

My truck was a government vehicle for almost all of those miles. I would expect it would have been well maintained--probably driven hard, though. I know my Dad thought nothing of blasting down the highway wide open at 108 mph in his 55 Oldsmobile with his family on board. Just imagine how he drove the CG truck back in the day before there was traffic on the roads in the UP.

The tractor mechanic I talked to said he would like to see the valve train with the cover off.
I said I would get a gasket and we would take a look.

 

Can you post a video of your engine running? Even better, find two people to follow you and have the passenger video your exhaust as you accelerate and decelerate.

It sounds like your engine is fairly worn. I agree with Ross, a bore job with new pistons & rings, or a valve job, or both are probably needed. 215 engine hard parts are expensive if you buy them new from Egge. If you think you are going to need to replace bearings and pistons I recommend watching ebay, the Ford Barn classifieds, and the HAMB classifieds for NOS 215 engine parts. One other thing, if you use pistons with the stock ring width they are the same rings as 235 Chevrolet engines.

 

Ross--Do you determine TDC for each cylinder visually through the spark plug hole? Should I have the valve cover off for this procedure? Fred, I'm old with limited computer skills. My kids, however, will be coming in a couple of weeks and I am quite sure they could shoot and post video. Thanks for the guidance on buying parts.

 

It helps to have the valve cover off so you can see that both valves are closed, while you verify TDC by looking in the spark plug hole. Or find TDC on #1, test it, turn the crank clockwise 120 deg and follow the firing order. 1-5-3-6-2-4. In two complete turns you'll have them all.

Speaking of which, have you checked valve clearances? That could be your compression problem if there isn't clearance.

 

Thanks. Valve clearance was not checked. I know it was mentioned before as something that should be done along with the tune-up, but the engine was running and starting so well that I never made it quite to the bottom of the list of suggestions I was given. It would be great if something simple like valve lash adjustment would improve my poor compression numbers.

 

I don't think the pistons should need to be removed to check the wear of the cylinders. Once the head is removed the cylinders can be checked. In my experience, most of the wear in the cylinders is very near the top.
Also one check to see if the rings are causing the low compression is to squirt some oil in the cylinders before the compression test. It the numbers come up a lot, the oil is sealing the rings temporarily. This oil test should work well on a six cylinder as the top of the pistons should be level and oil go all the way around, unlike on a V8.
From my Ford manual your engine 215 6 cylinder overhead valves, 101 hp. is supposed to have 130 psi compression at sea level when new.

 

Several mentions have been made of the need to find TDC for each cylinder in order to do the compressed air test and also to check valve clearance. Am I correct in thinking that TDC is reached for #1 cylinder when the timing mark and pointer are matched up? Please forgive my ignorance. I should have learned these things from my Dad, but now of course it's too late.

 

Yes, but the pointer and mark also line up at 360 deg from TDC on the compression stroke. So you need to look at the valves as you turn the engine CW, watch the intake close, then keep turning until the marks line up. Or put your thumb over the plug hole and feel when pressure blows it off as you crank it.

 

Thanks Ross. I should be good to go now. It may be a few days, however, before I have a chance to get back to thinking about my truck as some family things are coming up.

 

Today I was able to repeat the compression test and do some of the things that were suggested. My data today was a little different from the other day. I'm not sure why. First the spark plugs:




As you can see, they have changed color quite a bit. Last time they were very black. This time the color is improved, but there seems to be some deposits beginning to form. When I rechecked the gaps, there were little pieces of crud that crumbled off. I drove the truck hard before removing the plugs, but I thought I did last time too.

I took another compression reading and also added oil into each cylinder and repeated the test. The results below show my original reading, today's reading, and today's reading with oil:

#1 80-72-98, #2 88-68-88, #3 70-65-80, #4 62-62-90, #5 62-68-90, #6 80-80-90.

Do these numbers suggest anything to anyone? Cylinder #2 stand out to me as kind of an outlier--maybe a valve issue?

I took the valve cover off and this is what I found:










I'm not sure if my 65 year old valve train looks good or bad. It should be noted that my truck sat from 1967 until 2012 without being driven. Since 2012, it's been driven about 800 miles.

I wasn't able to do the compressed air test because my air supply didn't have the right fitting to connect to my compression gauge. I did, however, check the valve lash for #1 cylinder. It was .022 for the valve closest to the radiator. The rocker arm on this valve was solid, but most of the other rocker arms on the other valves had quite a bit of "wiggle"--maybe as much as .010. I only did the first valve because I really wasn't sure what I was doing. I believe valve lash for my engine is supposed to be .017.

Any thoughts or suggestions? I'm thinking (hoping) that maybe valves are a big part of my low compression and ridiculous oil consumption.

 

All things considered, I wouldn't say that a lot of sludge. When you say "wiggle" on the rockers, is that side-to-side or up-down or twisting them?

I think what your engine needs most is to run it! Change oil filters frequently (500 miles?) to get rid of the sludge. If you want a #60 jet, pretty sure I have one.

The front valve is an exhaust. The manual tells the simplest way to set valves: