Inliners International Forums General Discussion Engines Correct rocker arms and shafts

I am completing a 235 chevy build and am confused? My head is a 56 and the rockers and shafts are shot. I have 2 other sets that I picked up , they all look alike huwever the numbers are different and I keep getting all sorts of information as to what belings, fits, works, etc.
Does anyone know what rockers and shafts belong with a 56 car head, what will fit, and can explain the different numbering systems on the various rockers. I could also use a good place to make a purchase of at a minimum shafts if not some rockers . Art

Patrick's will likely be a good source for replacing your worn components. And can answer any question you might have regarding interchangeability.

I tried Patric's and they had nothing.

You might want to contact Tom Langdon at Stovebolt6. I sure that me might be able to help or give you some suggestion.

Panelnut, I have a complete set of correct 235 NOS Rocker Arms and Rocker Shafts for sale. I sent you a PM. I am in South Jersey.

The block will determine witch rocker arms to use, off the top of my head I recall 58 / 59 being the change in oil flow restriction in block to rocker feed.

In theory 59-62 use the rocker arms themselves as a restriction.I believe this was done to prevent the oil feed restriction used previously from getting plugged with goo...When in doubt you can do what I have done several times.Take a .062 Holley carb jet and hand grind or file it so it's a light press fit in the rocker shaft oil feed tube..062 is the same restriction used in the rocker oil feed tube on 228-302 GMC's ....

I may be missing something here. The 55-57 blocks fed the rockers by way of the rear cam bearing. The factory drilled the bearing boss, installed a fitting and ran a steel line from the rear cam bearing to a spot in the upper middle lifter tally, near the top, and ran the line to that spot. The oil went up a drilled passage in the block, through a drilled passage in the head where the connector for the rockers has a copper tube that picks it up from the head and allows the oil to go into each of the rocker shafts. My understanding of the later 58-62 blocks is that gm illuminated the fittings and line off the rear cam bearing, and fed the oil completely through block drilled passage, if that makes any sense. As for the rockers, 55-57 specific rockers have not been available new for some time but the 58-62 were much more readily available. I have run the later rockers for a lot of my 55-57 motors and have not had any problems.

Well still confused, I looked at my gm parts manual. Both heads are from 1956. Each set of rockers look similar but have different casting numbers. Of those casting numbers, none of them are listed in the GM parts manual ??????????

Sounds like the differences have more to do with the oil routing in the blocks than the rockers. Just because there is a difference in the casting number doesn't necessarily mean the rocker design itself is any different than another. I would call Patrick and see if he could shed any light on interchangeability issues you might face. Its possible if there is a specific rocker required for your application, and non-specific rocker could be modified by grinding a slot or drilling a hole to make it work fine.

This killed me last night so i dug a little further. I actually have to go look at some of my blocks and see if there is any difference in the location of the oil hole to the head in the deck of the blocks. That is, is there a difference in either the placement or size of the block deck oil feed passage. If there is not, then it would appear that the difference lies in the head and the rockers. So, the heads starting in 59 apparently got a new drilled passage so if you are using a 55-57, and possibly 58 head on a 59-62 block, you may not get oil to the rockers, or enough oil to the rockers. There apparently was a special bolt that was drilled from the bottom up to just above where the threads ended and then cross drilled. This was done to the bolt near the oil tube pick up on the head. near as i can figure, this was done because the later blocks put more oil pressure and volume to the head and using an earlier head restricted this pressure and volume. The later motors also had the return loop on the rocker connector pinched off to keep this higher volume and pressure in the rocker shafts.
The 59-62 rockers are slightly different too. I have two new sets, one trw and the other sealed power. When you look in the hollow of the rockers, you will see that the oil groove is offset and does not intersect the oil hole that feeds the top of the rocker arm to drip on the valve stems, springs. When I pulled out a box of filthy dirty 55-57 rockers, those had the oil groove centered in the hollow and intersecting the oil feed hole. the best I can figure, was that GM wanted to solve the rocker oil feed problem from the earlier motors (you may remember the copper line and restriction valve kits that feed oil from the oil sender output or oil filter output to the side of the head)by putting more oil and at a higher pressure to the rockers, sealing the loop off, and making essentially a pressurized system. the offset groves must be to limit the amount of oil that would spit out of the rocker holes, with this now pressurized, so to speak, system so if the groove was to intersect, there would be a lot of oil spitting all over the place instead of trickling down over valve train to cool and lubricate. So it seems that if you are using a later block with an earlier head, you have to use a pinched off connector, the later rockers, and double check whether the rockers are getting oil pre-startup and if not, you may have to drill the bolt near the connector tube pickup at the head. Now the next question seems to be whether the later rockers, with the offset grove, can be used on the earlier head and earlier block. I think so because I think i have been using them for a number of years because the 55-57 versions have not been available new for a lot of years. Those are my thoughts anyhow. I have no pride of authorship here so feel free to correct me if my thinking and research have lead me astray.

I called Patrik's and the lady I spoke to could shed little about rockers except that they had none

I sent him an e mail however he gave me little information

Try http://www.rockerarms.com in Anderson, CA. I have traded with that group since they were originally in Torrance, CA. I have always had good success with their information and even bought some of their products. They even made up a set of High Lift Rockers plus the shaft set up for my grandson's 216. So far all has worked out fine.
Normbc9