View Full Version : 164 compression readings

06-06-2007, 03:16 PM
I just did a compression test on my 1940 Champ 164 . My readings ran from 65# on one cylinder, with a reading of 120# after oil was injected, and 100-120# on the rest. My question is - what where the compression readings when new?

John Kirchhoff
06-06-2007, 04:05 PM
Sounds like that one cylinder has tired rings, or possibaly one ring is broken. The others sound pretty even, which I think is more important than the actual reading (within limits, that is). The temperature of the engine (hot pistons fight tighter than cold) and the condition of the battery, cables, etc (cranking speed) can have a great effect on readings you get. If you checked with the engine stone cold, you might try getting it warmed up and then check to see if the low one is still considerably ower than the rest. If it is, it's probably needs rings. If the pistons is just a bit more loose fitting than the others, warmed up it might tighten up and not be that bad at all. If it's still low, you might pull the head and look at the cylinder wall on that cylinder. Sometimes, but not always, a broken ring will scratch the cylinder at the broken spot. As far as the orginal readings went, I'll bet dollars to donuts the compression readings were higher when the engine had 10-15,000 miles on it than when the engine was brand spanking new. It takes a while for the cylinders to get polished up from use and form a tight seal.

06-06-2007, 04:28 PM
I would definitely SECOND that!! Studebaker always used Perfect Circle Chrome top ring, Ring Sets in their line installed and replacement engines. Those hard rings for sure, require a good break-in period!

quote:Originally posted by John Kirchhoff

As far as the orginal readings went, I'll bet dollars to donuts the compression readings were higher when the engine had 10-15,000 miles on it than when the engine was brand spanking new. It takes a while for the cylinders to get polished up from use and form a tight seal.

Studebakers Northwest
Ferndale, WA

06-06-2007, 05:54 PM
Thanks guys. I guess I should of asked what is the reading on an engine properly broken in. I thought that the 110# reading in two cylinders and three at +/- 10% was o.k. I would hope that the higher reading with oil squirted in the cylinder would indicate a worn ring rather than a broken one (fingers crossed). I did the test with the engine stone cold and will re-test with it warmed up to operating temp. I just got the car started and notice that it blows blue pretty good out the exhaust. Otherwise the engine sounds very good with no main, rod or other abnormal noises.

Neal in NM
06-06-2007, 08:37 PM
According to my Motors Truck Repair Manual a ratio of 6.5 to 1 is 110 psi, 7.0 to 1 is 120 psi, 7.5 to 1 is 130 psi, and 8.0 to 1 is 140 psi. This table is an approximate. Neal

06-06-2007, 10:07 PM
Thanks Neil - that's what I wanted to know. My shop manual states the 164 has a 6.5 to 1 ratio. With readings around 110# in five cylinders it appears they are about normal, but the one a 65# has a problem with rings. How far can a cylinder be bored before an oversize piston is required? Can just honing this one cylinder and new rings be enough if the wear is minor? In other words, can I fix just one cylinder if the others are o.k.? Thanks for the feedback fellows.

06-06-2007, 10:09 PM
Sorry that should have been "Thanks Neal."

John Kirchhoff
06-07-2007, 09:39 AM
Were ir me, and I was going to ring the old gal, I'd pull the head and take a gander at the cylinder walls. At the top of the cylinder, there should be a ridge just below where the top of the piston ends its travel. The ridge is formed by the cylinder below the ridge being worn from ring travel while the area above is pretty much unworn. The depth of the ridge will give you a rough idea of how worn the cylinder is. If the ridge is quite visible and feels sharp or square edged to the touch, then boring and oversized rings would probably be advisable is you plan on doing any serious driving. If the ridge feels more like a "bump" to the touch, then the cylinders are probably serviceable without boring. (Just a tip, but if you close your eyes you can feel things better.) To get an idea of the amount of wear, take a ordinary piece of paper and fold it over once. Lay it on a flat surface and feel the difference in height. If the ridge is something like this, rings alone would probably be fine. Fold that paper over again so that you have four layers and feel of that. If the ridge feels like that, then it's probably boring time IF you plan on doing a lot of serious driving.

If the ridge is very pronounced, you'll probably need to remove it with a ridge reamer before you remove the pistons. If you try to force it past the ridge, the rings will catch and you can break a ring land on the piston. If you are just going to ring it, the "bottle brush" cylinder hones work better than the three stone jobs since the little balls will follow the cylinder walls better since cylinders usually wear barrel shaped.

Cylinders can be pretty badly worn but when ringed with cheap, "soft" cast iron rings, they'll do a pretty good job for you. Once in the middle of combining, I had a piston burn through one side down to the middle ring. It scored up the cylinder wall pretty badly but being pressed for time, I seriously honed it out (WAY over tolerable allowances), stuck in a new piston and rings and went back to work. When cold, I could hear piston slap on that cylinder, but when warmed up it disappeared. I've run that thing for many years since with no problems. What I'm trying to say is, unless you drive a tremendous number of miles and do it like a maniac, a simple ring job will probably do everything you need. You may use a little more oil than you would with a fancy, expensive bore job, but you can buy a bunch of oil for what that bore job would cost in money, time and trouble (pulling the engine, etc).

Anyway, this is just my opinion. I figure if one is going to spend money, they are best putting it where it will do the most good. Given the choice between a high dollar bore job with new pistons and rings and retaining the same old barely adequate brakes or a simple ring job and spending the money saved on better brakes, I'll go for the latter any day. The bore job may get you up to speed slightly faster but the better brakes will get you stopped faster. Most people don't die from acceleration but instead from that sudden decelleration when they hit something.

Neal in NM
06-07-2007, 09:49 AM
That question is a can of worms!! People can be very opinionated about this topic. Without seeing and measuring the cylinder no one can say for sure what you can do with it. The biggest problem is the lack of a lot of aftermarket support. For example if you look at a SBC there is a ton of aftermarket parts for them including .005 over piston rings. Yes you can hone it over if it is not too bad and diamond cut piston rings (if you can find them) to fit but you will probably have more piston skirt slap. It really depends on what your final objective is. If you want to band-aid it to sell or until you have the moneys to fix it properly or is it to be a daily driver? Like I said without seeing it or having a hard measurement in my hands I would not speculate as to what you can/should do. It could be as simple as a broken/missing ring with no cylinder wall damage. Neal

06-07-2007, 11:05 AM
The car will be driven in the summer (pretty short here in MN) - and then only on the occasional Sat-Sunday. It probably won't see anything over 55mph and will probably see <1000 miles per year. Right now it's going through a almost total chassis/body restoration by me. I did find in the shop manual that the compression on the engine should be about 100#. The car sat for 7-10 years without starting so I'm beginning to suspect a bad ring -either stuck in the grove from carbon or gum - since I now realize that the other cylinders are about normal. Anyone have a procedure or product the would recommend for cleaning out carbon and sludge from the cylinders?

Thanks, you guys are great!

John Kirchhoff
06-07-2007, 12:53 PM
The old way of cleaning carbon out of an engine was to have it running and then pour ATF into the carb until it died. Then restart it and blow cumulonimbus clouds of smoke for 15 minutes afterwards. It didn't remove much carbon, but it did make you feel as though you were doing something constructive and killed any mosquitoes that were unfortunate enough to be within two miles of your car.

If you haven't driven the car much since wakening it up after its long sleep, just running it may eventually get the ring to sealing again. I've seen stored bikes with a couple of low compression cylinders have normal readings after being run a week or several hundred miles. Sounds to me that at this point, getting the old gal spruced up and running is more important than the low compression cylinder. If that cylinder doesn't improve and causes problems in the future, it could be pulled with the engine in place. You don't want to get yourself overwhelmed with fixin' at this point.

06-07-2007, 01:53 PM
Yes, I remember using that stuff. The great clouds of light gray smoke and the stink of burning light kerosene. And your right, it did make one feel great about doing something to restore the zip in the old buggy.
The main thing with the Champ right now is getting then suspension, brakes, exhaust, rust and dents taking care of and holding off on any engine work until Winter. I'll want to pull, if necessary, and reinstall the engine before I reinstall the front sheet metal. Your thought about running the engine to see if the rings will free-up is a good one. I've only run the engine so far on three occasions for about a total of five minutes - the engine hasn't even been fully warmed up. So I think I'll run for half hour or so at fast idle and see if that helps.

Neal in NM
06-07-2007, 06:41 PM
Your assumption of a stuck ring may be correct if the engine has been sitting for a prolonged period of time. There is a very good chance it will free up when you start seriously using it. I personally would pour some sort of penetrant in the one cylinder which is performing poorly and let it set for a week or so. When I bought my truck I poured Risoline down each spark plug hole and let it set before turning the engine over by hand and it seems to run fine. Just remember if you do put penetrant in the cylinders and let it set it might be wise to change the oil as this will thin out your crankcase oil. Neal

06-07-2007, 08:21 PM
I experienced relief from stuck rings in my Lark. It had 'sat' for maybe 30 years, with a newly rebuilt engine. At first it smoked quite a bit, but after about 300 miles it quit smoking and pinging and now works as it should.

Tom Bredehoft
'53 Commander Coupe
'60 Lark VI
'05 Legacy Ltd Wagon
All three Indiana built OD cars

06-28-2007, 01:56 PM
:DA quick update - I poured a little Rislone in the weak cylinder and the rest in the crankcase after removing an quart. I let the car sit for about a week and then ran it for a half hour or so a couple a times. I rechecked the cylinder and lo and behold the reading was a perfect 100. Hurray! It's still burning a lot of oil so I guess the oil control rings are either badly worn or still hung up. One more question. Reading the replies regarding piston slap, in the old days we use to knurl the pistons to increase the skirt size. Is this done anymore? Thanks again guys;)

06-28-2007, 03:10 PM
Greetings, cortica37

Glad to hear the rings freed up and you currently have good compression. FWIW, most all old Champion 6-cyls burn oil by sucking it up past worn intake valve guides. The oil system design sprays oil onto the lifter/valve interface to lessen the noise. When the intake guide wears out, and they all do, this oil in the tappet chamber is sucked up into the intake and that's where the smoke comes from.

Once a Champ owner opens up that buzzing little anvil, there is no stopping point on the repairs and they cost as much as a V8 to rebuild. The limited use you describe, don't bother. Keep driving it and don't look behind you, because large repair bills are hiding in that blue haze.