The Stovebolt Site Forums The Shop Area Engine Shop External oil line on rebuilt 235

I need help in understanding the engine from my 1950 COE. I know it is rebuilt because the serial number is overstamped and the engine had been painted green. The block casting codes indicate that is is a 1958 235 cu. in.(3738307) with date code G298. The head casting code is 3836848 which would indicate a 58 to 62 head. So clearly this is a rebuilt later engine. The original valve cover has been retained (two acorn nuts hold it on) and there is no oil cap (this is a cabover, so you must fill the engine oil by opening the cap on the draft tube).

The odd part is that there is an external copper oil line going from a tee at where the oil pressure line hooks in. This line wraps around the back and enters the head above the distributor, which I presume is to supply oil to the rockers. Why was this done, does anybody know?

Another issue is that before we removed the engine for restoration, I did a compression check and got readings from 105-110. At the time I thought I had the old splash oiler and thought this was OK. I learned later, when I did the compression check, I did not remove the spark plugs, so perhaps the readings would have been higher if I had done it correctly. If I had done the compression check correctly, would the values had been higher? Knowing that I have a later 235 I am concerned with those readings. I need to determine if a rebuild is in order before the cab is put back on. Thanks!

The external line was added most likely because the passage in the block/head that would normally send oil to the rockers is plugged. Rather than fix it correctly, it was simply bypassed.

How do you check compression without removing the spark plugs?

Cletis,
What I meant was I removed the plug for the cylinder I was testing, but not the others. When I moved to the next cylinder, I replaced the one I had tested. Thus, when turning the motor over for testing, the starter was fighting the compression of the whole motor, rather than just the one I was testing. Does this make sense? Now, the engine is on a stand, and I can't test is correctly. I would think my true values are higher than I came up with. At least the values (105-110) are close to one another.
Kent

OK, now I see it. And you could be right about the readings being lower.

Ditto on the reason for the external line. It's a quick way to compensate for clogged internal oil passages, and there's not much of a downside to the change, other than being easy for one of us oldtimers to spot. Most folks who didn't grow up around stovebolts won't know the difference.

The compression pressure readings you got are OK, but you'd probably get a little higher reading with all the plugs out and the throttle blocked wide open. Don't sweat it, just do it differently next time. Be sure and adjust the valves before you check the compression- - - -a tight valve adjustment can affect the readings more than leaving the plugs in. As long as your compression readings are within 10% of each other, actual pressure numbers don't mean much. You can get totallt different readings, pressure-wise, from different gauges.

I usually plug my compression gauge into the shop air line to check it for accuracy occasionally.
Jerry

Thanks for the helpful comments. I plan to run the motor a bit after it is placed back in the frame, just to be sure there are no leaks or other problems, before proceeding with replacing the cab. I promise I will do the compression check correctly,(after adjusting the valves). This is what is so fun about this hobby, you learn so much (and I started from about zero knowledge).

I suspect that the rebuilder was some sort of established firm. A shade tree mechanic would not have bothered to overstamp the serial number with another number. They had to retain the old valve cover because a more modern 235 would have the oil filler/breather and it would be too tall to fit under the floor cover (doghouse).
Kent