The Stovebolt Site Forums The Shop Area Engine Shop 235 Engine fitting ports

Can anyone advise me as to what 2 different fitting ports are used for on my 235 engine? The first one is in the head just underneath the valve cover. Its about 1/8 pipe thread on the passenger side of the engine. Most of the pictures I've seen the port is just plugged as is mine. I seen some that have an angle fitting and a solid line towards the firewall and wrapping around the back of the engine. Where does the steel line go and why do most engines not have it? The second port is on the drivers side of the engine towards the back of the block. When I bought the engine it had a block heater attached to this port. I removed the block heater and I'm almost positive that port goes into the water jacket. What has me confused is when I removed the 1/4 pipe fitting the block was full a black sledge looking grease. I don't know why a water jacket would have a sledge like that but I guess anything is possible. I primed the oil pump with a drill and had the engine running briefly and it does not spray any oil so I am sure its not an oil port. Anyway I just plan on plugging this port and calling good, I was just curious what it was used for.

Thanks

A photo or two would confirm locations, but I think I understand.

1. "The first one is in the head just underneath the valve cover. Its about 1/8 pipe thread on the passenger side of the engine."
This plugs a hole to an oil passageway/journal. I think others have posted that this hole/port was needed by the factory to drill a hole inside the head. The "access port" was then plugged. That hole could be used as a cob-job attempt (via a non-GM "upgrade" kit) to get more oil to the rocker arms (the steel/copper line you refer to)?
https://www.stovebolt.com/ubbthreads/ubbthreads.php/topics/1100613/top-oiler-question.html

2. "The second port is on the drivers side of the engine towards the back of the block. When I bought the engine it had a block heater attached to this port. I removed the block heater and I'm almost positive that port goes into the water jacket. What has me confused is when I removed the 1/4 pipe fitting the block was full a black sledge looking grease."
This is hole into a water/coolant journal. Water can be drained out of the engine/block from that hole. The black sludge is simply gunk in the water/coolant - it can "crud up the coolant passages in the block". This has been recently discussed.
https://www.stovebolt.com/ubbthreads/ubbthreads.php/ubb/showflat/Number/1248905/Searchpage/1/Main/182515/Words/%2Bdrain/Search/true/re-water-jacket-plug-in-235.html#Post1248905
https://www.stovebolt.com/ubbthreads/ubbthreads.php/topics/1248679/part-name.html

The port on the passenger side on MY 235 head is where the water temp sensor is screwed in. I have no idea if that is where it actually belongs...but that is where it was when I bought the truck (and I need the front thermo port for dual aftermarket intake manifold heating water, so I have no plans to change it).

[EDIT] Crap, I'm all mixed up. I meant to say DRIVER side of the head!

Perhaps I'm talking about a different hole... in this pic, the hole I am talking about is the one that is vertically oriented, next to the #5 intake valve, just outside of the valve cover gasket surface.

235 Head

Dave,

That is the port for the coolant temperature sender. I do not know if that is one of the ports/holes referred to in the original post. It is not one of the ports that I tried to ID.

"A photo or two would confirm locations, but I think I understand." Maybe one of use it correct?

Well, at least I installed one thing in it's correct location!

Tim has it right. Small fitting on the passenger side of the cylinder head. Makes sense its just hole drilled to access another part of the head that needed a hole and then plugged later. Its no surprise people try to pipe more oil to the top end of the engine. When I primed the oil pump with a drill after several minutes I seen a very unimpressive amount of oil making it to the top end of the engine. Is there any aftermarket high flow oil pumps available for the 235 engines?

Jonald,

Are you referring to a low-pressure of high pressure 235 engine.

If it is a 1953 engine, what is the Engine Serial Number?

Read back in this thread about top oil volume at low vs. high speeds by Jerry.

Ed

I'm working on a conversion to run small block V8 gears in a stovebolt pump housing. It requires fitting a spacer about 1/4" thick between the pump body and the end plate to accommodate the longer gears. That should flow about 15-20% more oil and help with the chronic low pressure problems the splash-oiler engines have, and raise the pressure slightly on the full pressure engines with a bit of excessive bearing clearance.
Jerry

The plug on the side of the head was how the factory drilled across for oil access to the rockers. On a 55-58 235, the rockers are fed oil via the rear cam bearing. So if you pulled the side cover, you would find a steel line that ran from the back cam bearing boss up to a fitting just below the boss that you are referring. Oil was metered through the head to the copper rocker connector. That oil is supposed to dribble out from the rockers, not spit. Oil dribbles from the dribble hole on each rocker to lubricate the rocker arm adjuster ball and push rod cup, and the spring and rocker arm tip. If it is spitting, it misses those vital parts and hits the inside of the valve cover. It’s not all that uncommon to see a reduction in oil flow to these motors through a combination of a worn cam bearing allowing pressure to bleed off, and a clogged line. The aftermarket came to the rescue by selling little kits that took oil from the oil sender port on the driver side or the output of the oil filter (which dumped the clean oil directly into the pan where it was instantly diluted with dirty oil anyway) and ran it into that drilled passage which is a direct feed to the rockers. The 55-58 rockers have a groove inside the rocker that directly intersects the dribble hole. If you had to replace the 55-58 head with a later 59-62 head, you had to use the drilled bolt and plug arrangement to cut the oil flow to the rockers so that it would not spit but dribble.

For the 59 and up, gm changed the oiling system to create a sort of pressurized system to the rockers . Those blocks do not have a steel line from the rear cam bearing but use a drilled passage directly up from the main feed. The metered oraface for the later head is larger than the earlier head. For these motors, it’s the same issue, the drilled passage gets clogged so you used one of those little copper kits. The rockers are different for 59-62 in that the groove inside each rocker is offset from the dribble hole, and the rocker connector copper tube is pinched off.

Those aftermarket copper line kits were small lines. The reason for the small lines is that with these bypass motors, if you used too big a line you bled too much pressure from the mains starving the main and rod bearings. If you have a an issue with the rockers getting oil, and you want to install one of these kits, and your motor has a bypass oil filter, consider running the line from the output of the filter to the fitting on the passenger side of the head. Running it this way keeps the number of sources tapping oil pressure from the motor to one (as opposed to two, the oil filter and the aftermarket line) which helps keep the pressure up and has the benefit of providing the rockers with clean filtered oil.

Since the bypass filter output is a gravity drain back to the oil pan, plumbing a rocker supply line that way will result in no flow at all. Looks good, but it won't flow any oil.
Jerry

Dragsix, welcome to Stovebolt.com

VERY nice write-up.

My only question is: were both 1956 truck and car engines drilled the same for camshaft oiling? I thought (perhaps mistakenly) that oiling of the camshaft on 235 truck engines did not change until 1956 (and the 1955 truck engines could not use hydraulic lifters)?

Again, welcome to Stovebolt.com

I have not (in the over 40 years that I have been playing and racing these motors) seen any 55 motors that did not have the steel line arrangement for feeding the rockers. That being said, I also do not remember just how early the earliest 55 235 I have ever seen is, lol. Could be early 55 motors (with a 54 casting date) could be a leftover 54 stick motor and thus use a different arrangement. The 55 blocks are a little bit of an animal unto their own in that Chevy was still designating specific blocks for stick motors and a different block for powerglide equipped motors in the passenger car line with stick motor blocks not drilled for hydraulic lifter use. My understanding is that 235 truck motors did not ever get a powerglide, only a stick trans, thus, solid lifters only. What this means is that you can retro fit a 55 powerglide passenger car block with solid lifters, but you cannot retro fit a 55 stick block with hydraulic lifters. This changed in 56 for the passenger cars in that all 235 motors from 56 forward came with hydraulic lifters. Now I don't know about the truck motors from 56 forward as I do not have any in my stash of motors so I cannot say whether the truck motors continued using block not drilled for hydraulic lifters (would love to know the answer to that though). Same for the rocker oiling. I cant imagine that the 56-58 truck motors did not use the steel line arrangement. I can say that 59 and up 261 blocks did not, they used the same upgraded direct from the main oiling as the 59-62 passenger car blocks.

Hotrod Lincoln, the oil filter is not exactly gravity drain into the pan. You are right though, it is to a degree. The input is pressurized from the oil sending unit port, albeit, a bleed off of the pressure. So there is some gravity drainback in that configuration just because of the way the filter hangs. When you run it to the side of the head for the rockers, that condition is eliminated, it is pressure in, pressure out. I have had one of Charlie Baker's bootleg offy sideplates on various of my 55-58 motors for many many years now. The side plate did not fit with the 55-58 steel line installed. I removed the line (installing plugs at either end of each boss) and ran the oil output to the side of the head and fed the rockers clean pressurized oil, just enough to allow the rockers to dribble. I raced and beat that motor, and others in the same configuration, for years (just recently removed one that I built that way in 1985 as a running motor to put a very modified 261 in and the rockers on that motor look as nice as the day I installed them all thouse years ago. Again, though, you always have to double check the work and make sure all of the rockers are getting sufficient dribble pressure, especially No. 1 and 6 cylinders and that the stock style canister seals can handle the pressure. It’s been hit and miss with me although I switched to a remote spin on using small lines a number of years ago (I am not currently running any filter on the 261 bypass style motor).

Also, you might have noticed that the 55-58 rocker connectors have an open loop, while the 59-62 and closed up. The 55-58 loop is open because the engineers expected excess pressure and volume to bleed off through the loop. Unfortunately, when the motors got old, a restriction was sometimes needed to keep sufficient oil to the rockers. Many many mechanics pinched off the open loop in an attempt to gain a little more pressure and flow with an older engine. I do the same.