The Stovebolt Site Forums The Shop Area Engine Shop ? for the 235 engine guru's out there

I have a 58 235 that I can't get to oil the rocker assembly. It has just been rebuilt and has new oil pump. It shows good pressure on the gauge about 20 pounds idling and over 30 up to speed. My question is about the tube that comes up from the head to the rockers and then turns back down toward the head. It seems to me that the ones I have had in the past have had the loose end of that tube crimped closed. Is that right or does it make any difference? This one is open and smooth, it has never been crimped at all. Watching it run with the valve cover off there is no oil coming thru the tube, not even the open end. I have taken the rocker assy off and checked the tube and the passsage down thru the head and block as far as I could get a wire cable and it seems to be clean. Am I getting far enough down in the block or is there something else I should check? thanks!!

I had the same problem with my 57 235. I didn't have the block cleaned and I think the oil passage around the center passenger side head bolt was crudded up. Still don't know for sure. I had and extra head bolt and ground a groove through the threads of it and installed it in that hole. Fired it up and had oil to the rockers. I have also read about installing an unmatched head/ block combo & having to use a special head bolt to get oil to the rockers. Can't remember where I read it. Worked for me. I got about 5000 miles on it with no problems. I'll see if I can find the article with the answers. I have an 848 head on the 57 engine. Don't know the year of the head.

I believe that "special" head bolt is the one that is slotted on top, kinda looks like you could put it in with a big screwdriver. If you've got a regular head bolt in that position it will block the oil flow to the rocker rack.

slogoer,
I'm not real sure what you have or haven't done from your post. My question would be , have you pulled the side cover, removed the tube and fitting from the block and peeked in
there?


Stuart.

Here's a trick we used to use back when there were lots of 235's on the road, and oil starvation at the rockers was pretty common. Take the head bolt out where the oil passage comes up, the middle bolt on the passenger's side, and find or make a wooden dowel rod that's a snug fit in the hole. I modified a piece of broomstick. Fill the hole with clean motor oil, put the dowel in, and smack it with a BFH. The hydraulic pressure will clear out any crud in the oil passageway, unless it's really baked hard. I believe that head bolt has a hole drilled in it, or a grooved thread, also.
Jerry

Thanks for the info! I think the wrong head bolt is the problem but I haven't had a chance yet to look and see. If that is not it I will try the other ideas. What about the tube where it turns back down toward the head, should it be crimped on the end or not?? thanks again, slowgoer

slowgoer,
I have seen people mash this "overflow" tube in a effort to get more oil to come out of the rocker arms. I think if everything is clean and flowing properly then you don't need to restrict this tube.


Stuart.

What Jerry Said; just like a big plunger on your LOO but as another alternative,You can always TEE the oil press.feed line fitting on the left side of the block and run a line around and up to the pass. side of the Head,In the middle,Foward of the coil,and take out the plug from the factory and tie it in there. Wallah direct access to the oil feed for the rockers Regards Steve sr.

Thanks again for all the info. I plan to go Tuesday and try all this stuff. slowgoer

Again,the story of the special head bolt persists.There is one special head bolt,it's designed to restrict oil flow to the head when using a later head on an earlier block.Other than that,there are only 2 type bolts,long and short,listed for 216,235 and 261 from around 1940 to 1962.
The oil flow does not pass by the threads on a 235/261,actually check out a block and head to see the oil passages.

Every toolbox should have at LEAST one BFH.

You said you had this engine rebuilt. If you hapened to install new lifters without the groove around the outside you will not get oil to the rockers.

If the cam bearings were installed wrong you will not get oil to the rockers.

From 1938-62, only two head bolt part numbers are listed for 216, 235 and 261. Long and short except for a special drilled bolt, used when a 59-62 block is used with earlier top end* to reduce the oil flow to the rockers.

Note: Use with drilled bolt
Plug # 37 64 579
Install in block oil port near right center head bolt.
(This plug blocks the original oil path and sends it through the drilled head bolt)

· The cylinder head did not change but the rockers did.

Up until 1957 235/261 used an oil line that fed oil from the rear cam bearing and up around the head bolt. Keep in mind only Power Glide cars used and were drilled for hydraulic lifters. Starting in 1958 all 235/261 engines were drilled for hydraulic lifters whether they used hydraulic or solid lifters. At this time Chev got rid of the tube that ran from the rear cam bearing and now brought the rocker oil straight up the center from the lifter galley.

The plug on 1958-62 engines at the center under the side cover is used to block the hole necessary for drilling the oil path and is also where the restrictor orifice is on 1958 and 59 engines.(the restrictor orifice is the fitting for the tube on the 1953-57 engines that screws in the block at the rear)

The restrictor orifice was 1/16" up till 1958. In 1959 it was increased to 11/32". At this time because of the increased oil supply the rocker connector tube was pinched off and the groove inside of each rocker was offset 1/4" so it no longer lined up with the supply hole in the shaft to pressurize the system.

If you use 1958 or earlier rockers on a 1959-62 engine which have the groove inside each rocker in the center the oil has to easy of a path and will over oil the valves.

Because of this pressurized set up I do not like the aftermarket shafts that have a flat spot ground the full length of the shafts. This flat spot gives the oil an easy path to the groove and out the vent hole and also to just dump out the edge of each rocker. This can lead to oil use as the valve seals can't keep up with so much oil (I have a easy fix for this if anyone is interested).

The plug Chev sold to go with the drilled head bolt goes in the block on the top/deck next to the right center/drilled head bolt this blocks the original oil path and sends it through the drilled bolt.

Pre '68 Dave,

What is the relationship of the grooved lifters to the lack of oil to the rocker arms?


Stuart.

Dave, I need to find a good reference book for my 1957 235 engine. I have all the books for the 49 truck it's in, but need the specs on this engine. Is there a book that covers all early years of engines and the interchangability with the parts of them? Thanks

Starting in 1958 Chev discontinued the rocker supply tube behind the side cover that sent oil to the rockers from the rear cam bearing and brought the oil straight up the center through a new cast in galley. This new galley gets its oil from the lifter supply galley which ALL 235 and 261s know have even if solid lifters were used. If you do not use lifters that are grooved on the outside on these engines the oil is blocked by the lifters and can not reach the center rocker galley.

Pre '68 Dave,

Does this mean that a '58 plus block will not have a supply tube in the pushrod area?


Stuart.

That is correct. It is an internal passage.

Gee, so much for the "plugged little tube" theory!


Stuart.

Through 1958 they did have a 1/16" restrictor in the oil supply to the rockers which can plug up.

Up through 1957 it was the lower rear fitting the supply tube screwed into (under side cover).

1958 has it in the block right behind the plug where the old tube would have atached in the center of the block(under side cover).

1959 and up has a 11/32" restrictor in the same place as 1958 which is hard to plug.

Story time. In '65 while I was in the U.S. Navy, I had my '54 Chevy stored in San Diego. When I took leave, I drove from San Diego to Eureka, my home town. The "restrictor" plugged up at the start of the journey, and when I got home the lifters "were a clattering". I had Isky tubular pushrods in the engine and they were made with a tube that had hardened balls shrunk into each end. One end sat in the lifter and the other end in the rocker arm. When I took the rocker arm assembly apart, most of the arms were siezed to the shaft and the balls all fell out of the tubular pushrods. Nary a drop of oil to the top end for almost 1000 miles. At ease Sailor! :p

Stuart.

Just so you will know. I took the valve cover and immediately noticed the special head bolt was not in the correct position. It does look like a screwdriver slot on top of it. This one is a drilled bolt instead of the grooved threads. I made sure the drilled area was clear, installed it and now oil is flowing great to the rockers, even with the open ended tube. Thanks again for the info!! slowgoer

slowgoer,

The story of the special head bolt persists, and for good reason. You can bank on that!! :rolleyes:


Stuart.

But, the special head bolt is only on 57 and newer , right? I don't think my 51, 235 has that.

Glenn,

It should only be found on a 1959 or later engine that has had the original oil passage pluged to install an earlier head/rockers.
I wonder why slowgoers engine would have this. I wonder if it really is a 58 engine.

According to the casting numbers, the block is a 58-60 and the head is a 56. The head does have the plug in the side of the head. The truck is a 47. I guess this kind of stuff is what keeps it interesting! slowgoer

Slowgoer,
Thanks for the follow up. Too often, guys ask questions and find the solution to their problems, but never let the rest of us know what solved the problems. Glad to hear you getting everything lubed properly. I am even more happy about you telling us what fixed the problem.

Phil

If you check the casting date right above the starter I think you will find it ends with a 9 (for 59 etc),0,1,or 2.

I looked above the starter for the casting date numbers. The last three are B 4 8. slowgoer

Well it looks like your engine was cast Feb 4 1958.
That is early enough in the year to have the 58 oiling set up. I would sure like to see why you need the special head bolt.

Buy the way the plug that is used with the special bolt goes in the deck of the block and can not be seen once the head is on.

This one has a plug in the side of the head at the very top of the head just under the edge of the valve cover and is directly to the outside of the special head bolt which is directly outside of the curved oil suppply tube that goes up to the center of the rocker assy.. If you take the plug out you can see the side of the special head bolt. slowgoer

I just disassembled what seems to be an original 1958 235 engine,date code D298.Unscrewing the plug near the block right side center head bolt hole shows a drilled restriction of about.062.This restriction and it's passage into the drilled rocker oil feed in the block next to the head bolt hole, is below the threaded area in the head bolt hole.GMC's also use a .062 restriction to the rocker oil feed,it's a brass fitting screwed into the head on the external oil feed used by GMC's.
The restriction orfice can be located anywhere in the rocker oil feed,it only matter that it's there.Removing it will overoil the rockers and possible lower oil pressure to the bearings.

slowgoer, All 235s have that plug on the side of head. It plugs the hole the factory used for drilling the passage the oil takes from around the head bolt over to the rocker shaft connector tube.