I would have finished checking the 1954 235 engine but 2 different starters smoked. 4 compression strokes per cylinder test and then rest for a few minutes. I need to rebuild the starters anyway. Per 12-21. As far as the engine rings and or valves leak. I have never heard this engine run. Oil is ok not green or brown. Jims Automotive Machine in Brunswick has 2 of my 848 heads he is machining for me. I plan on having him machine this 235 and if needed install a set of 30 under for the crank that I purchased from The Filling Station. Thoughts.
My guess is #2 is going to be a valve, probably exhaust, not rings. Try getting #2 to TDC on the compression stroke and then applying compressed air through the spark plug hole. Listen for the leak at the exhaust pipe and the carb with the throttle open.
Ignoring #2, I'd accept the +- of the other 5 cylinders at near the average of 114 psi. Not great, but servicable.
'57 GMC 102, Original 347 V8, HydraMatic, 3.08 rear gear, added A/C, disk front brakes, HEI, AFB carb, '98 Honda Black Currant paint. T-boned and totaled 10/12 '52 GMC 152 Stake Bed, Original 228, SM420, added A/C, HEI, disk front brakes, '67 Chev 3.55 rear gear. Gets used as a real truck.
Be sure the valve clearance has been adjusted before trying a compression test. I've seen a tight valve give a false compression test reading on several occasions. Ditto on the cylinder leakdown check- - - -it will give you a much more accurate idea of what's going on. I use an air pressure regulator to adjust the pressure to 100 PSI with no air flowing, and record the pressure with the air connected to each cylinder. For instance- - - -90 PSI at the cylinder = a 10% leakdown rate. A good cylinder will score somewhere in the mid to high 90s. Air leak at the exhaust port- - - -bad exhaust valve, air at the carburetor, bad intake valve- - - -air at the oil filler, bad piston rings. Bubbles in the radiator- - - - -leaky head gasket or a cracked cylinder head or cylinder wall. Jerry
"It is better to be silent and be thought a fool than to speak and eliminate all doubt!" - Abraham Lincoln Cringe and wail in fear, Eloi- - - - -we Morlocks are on the hunt! There is nothing noble in being superior to your fellow man; true nobility is being superior to your former self. - Ernest Hemingway Love your enemies and drive 'em nuts!
Ok sounds good. Ordered a leak-down test from Amazon. Can’t have too many tools. Will report my findings. The Filling Station is sending me a rebuilt starter for 12 volts, I asked and it’s built to work pre. 55. So the flywheel should not be an issue.
Good luck with that. There's no need to do anything to 6V foot starters as long as you have a 139 tooth flywheel- - - - -just put 12V to it and go. Put this switch on the 6V starter to bypass the ignition resistor.
The resto-ripoff places count on taking money from gullible people who don't know when to ask the right questions. Jerry
Last edited by Hotrod Lincoln; 10/02/202612:08 AM. Reason: Fat fingered that one!
"It is better to be silent and be thought a fool than to speak and eliminate all doubt!" - Abraham Lincoln Cringe and wail in fear, Eloi- - - - -we Morlocks are on the hunt! There is nothing noble in being superior to your fellow man; true nobility is being superior to your former self. - Ernest Hemingway Love your enemies and drive 'em nuts!
New question. For the production year 1954 I noticed in the specifications that the engine had an early production and a later production. The early production camshaft has small journals, and the late production has the same journals as the 261. I cannot locate what the specific date this change occurred. Can anyone help clear this up.
I think Jerry had a short between his keyboard and chair. That should be 139 teeth.
'57 GMC 102, Original 347 V8, HydraMatic, 3.08 rear gear, added A/C, disk front brakes, HEI, AFB carb, '98 Honda Black Currant paint. T-boned and totaled 10/12 '52 GMC 152 Stake Bed, Original 228, SM420, added A/C, HEI, disk front brakes, '67 Chev 3.55 rear gear. Gets used as a real truck.
New question. For the production year 1954 I noticed in the specifications that the engine had an early production and a later production. The early production camshaft has small journals, and the late production has the same journals as the 261. I cannot locate what the specific date this change occurred. Can anyone help clear this up.
Thanks
Shady
That change actually involves "early 235" spray oiler engines, (1941-53) which ran the same cams as the 216. All the full pressure 235s I've ever worked on had the large journal cam. Jerry
"It is better to be silent and be thought a fool than to speak and eliminate all doubt!" - Abraham Lincoln Cringe and wail in fear, Eloi- - - - -we Morlocks are on the hunt! There is nothing noble in being superior to your fellow man; true nobility is being superior to your former self. - Ernest Hemingway Love your enemies and drive 'em nuts!
If oil doesn't bring it up, no 2 probably has a burned or stuck valve. Pour some Marvel Mystery oil down the stems of both valves on No, 2 and let it set a few days. Carbon on the stem will keep them from sealing properly. If you have a burned valve, it will get worse in a hurry and you will soon have a dead miss.
This test was performed with a quality decibel meter with the upper limit set at 80db, and my new leak/ pressure tester. The psi setting for the test was 90lb. This old boy does not hear as well as he used to. Rocker shaft was removed, tapped on the valves and they are springy. Marvel Mystery Oil soak the top end for a few days.
If I am reading the leakdown test results in your pictures correctly cylinder 1 is the most significant problem and the one noted to have a leak into the intake system. Cylinder #6 is marginal. Before you tear the whole thing down check the #1 intake valve to ensure it has lash (maybe adjust to have exccess lash). Just because you have some leakage past the rings doesn't mean the engine needs to be torn down.
Cylinders #4 and #5 results look strangely high pressure (low leakage)?
