QuestionQUESTION: How can the rocker arms be identified? I have a 1948 to 1951 shop manual which gives numbers that are stamped on the rocker arm. HOWEVER, the engine I have is a 1955 and the numbers do not match. I am not sure of the difference between Inlet and Exhaust rocker arms. The book says there are 3 each of 4 types of arms; 3 RH exhaust , 3 LH exhaust, 3 RH Inlet, 3 LH inlet. If I don't have corresponding numbers, how do I assemble the rocker arm assembly? I can only think of trial
ANSWER: Unfortunately, 55 is a tricky year - you have to know whether the engine came out of a Powerglide car or a standard transmission car.
However, if the rocker arms have the numbers on them, we can figure it out.
If the numbers on the rocker arms are 9,0,3 and 4, it is a standard transmission engine. In that case, the arm with the 9 on it is for the exhaust valve on #1,3,5. The one with the 0 on it is for the exhaust valve for # 2,4,6. The one with the 3 on it is for the intake valve on 2,4,6, and the one with the 4 on it is for the intake on #1,3,5.
If the numbers on the rocker arms are 7,8,3 and 4, it is from a powerglide car, and the one with the 7 on it is for the Intake valve on # 2,4,6. The one with the 8 on it is for the intake valve on # 1,3,5.
The one with the 3 on it is for the exhaust valve on 1,3,5 and the one with the 4 on it is for the exhaust on 2, 4,6.
Be sure that the open ends of the two rocker shafts face the center.
I hope this is clear enough.
There is nothing sweeter sounding than a good running 235! But keep the RPM down - they are not high revving engines, at least not for long!
Dick
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QUESTION: Thanks for your previous answer. Now, one of the rocker arms has broken. It is #4 Exhaust. Thew #2 Exhaust pushrod has partially broken at the top, in the cup area. I set the clearances 0.005 over cold, then ran the engine at idle until the oil pressure lowered (about 40 min.) the set the valve clearances at I= 0.009 and E= 0.015. This was according to the 1951 Chevrolet shop manual. Any suggestions?
AnswerI can't see anything wrong in what you did. The specs are .006 hot for intake and .013 for exhaust, but setting them a bit wider than that certainly should not have hurt anything. All I can suggest is that you double check that you have them in the right locations, and replace the broken parts.
Did the engine seem to be running OK before the parts broke? Did the push rods line up with the rocker arms the way they should, with no mechanical interference which would tend to stress the push rod or rocker arms? Are the parts new, and from a reputable source?
It's a mystery to me - sorry I can't be more help!
Dick
