Well I learned something on my truck this week. It is a 59 235 that is in my 47 3600. When I rebuilt the engine I was very careful with everything I did except that I used the same valve train rockers that came off this engine. I did notice that the coupling between the rocker shafts had an overflow tube going down to the head. I pinched it off. I have had the truck running for about 500 miles and was getting some oil puffs at stop lights and when starting it hot. I have overhauled many engines over the years and never have had this happen. I suspected that I had the old style low pressure rockers like on a 216 or older 235. I had investigated the difference in the earlier and later high pressure rockers so I purchased a set from T Langdon and switched it out on Tuesday this week. I was correct in my suspicion of the wrong rockers that were on my 59 235 originally. After I installed the new rockers on my engine, I don’t see any smoke whatsoever! I believe I was getting too much oil in my valve train and even though my head has new guides, valves, springs, valve seals (on the intake valves), and it was planed and maga-fluxed for cracks. The later 235’s have a 11/32 oil passage going to the head instead of a 1/16 inch orfice and have the groove in the rockers in-line with the hole, it must have been quite the oil sprinkler under the valve cover. It was very oily and looked like it was over oiled. After installing the new rockers that have the offset oil groove not inline with the oil hole, I ran the engine with the valve cover off. It just oozes oil out each hole not spraying out. I have ran the truck several days now and no more puffs of oil at stop lights or starting it up hot. I so glad I was able to get the right rockers for my 59 235. NO MORE SMOKE.
Great Story and info to add to the ‘bolt. My ‘59 also had the wrong rockers installed and it took me quite awhile to figure it out. The overflow tube however was not pinched off so no puffing going on. I was chasing a low oil pressure issue. Thanks for sharing!
One of our ‘bolters Pre ‘68 Dave, has a great website that covers the differences.
Last edited by Phak1; 10/01/20231:09 PM.
Phil Moderator, The Engine Shop, Interiors and Project Journals
1952 Chevrolet 3100, Three on the Tree, 4:11 torque tube Updated to: ‘59 235 w/hydraulic lifters, 12v w/alternator, HEI, PCV and Power front Disc Brakes Project Journals Stovebolt Gallery Forum
One of the major differences besides the oil supply tube configuration is the position of the lubrication groove in the rockers. The later model rockers have the groove offset from the holes in the shaft so the shaft retains more pressure and the spit holes in the rockers dribble instead of squirt. Those seemingly minor differences can add up to become major gremlins! I'm working on a couple of possible modifications to the valve train that should make those differences a moot point. 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!
I found that info from pre '68 Dave and that's what got me chasing this problem. I put an oil gauge on the head above the side cover originally when I fired the engine up. I had no oil pressure there. Thats why I pinched off the overflow tube to see if that would help, it did not. After the new offset rockers were installed, I have 16lbs of oil pressure at the side of the head and oil just oozes out the rocker holes. I never ran the engine with the valve cover off with the old set of rockers because I did not want oil everywhere on my clean engine. Now with the right rockers it's not a problem. Normally my engine has 35-40 pounds of oil pressure idle cold, and driving it maintains that pressure. A hot idle is about 15lbs at 400rpm.
It's possible to ream the older style rockers for bronze bushings and offset the lube groove in the process. That cures the "too much oil" problem nicely. One piece of the tubing below is just barely enough to convert a set of 12 rocker arms.
"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!
I went with one of our car clubs on a leaf color peeping tour today. We traveled 120 miles. My truck ran great. I asked one of our members to watch my tail pipes and after we stopped for lunch he said nothing visible came out of my pipes. Yahoo!
