1956 Rocker Arm Nuts

[Alexander C.]

When I was setting the lash on my newly rebuilt heads, I noticed that more than a couple of the nuts were easier than they should be to turn. 1 of them is not very tight at all. I've searched on eBay and few times and I can't seem to find an NOS set of GM rocker arm nuts. All the ones that are close don't have the same taper on the bottom to fit into the top of the cup.

Anyone know where I can get these? I really would prefer good used original or NOS only.

Thanks!

[Edward M.]

Re: 1956 Rocker Arm Nuts

How may do you need. I have a set of 56 two barrel heads that have been off of the engine once since 1956.

Hydraulic lifters so they don't need to be adjusted once they are set.

I assume they are the same nuts. Anybody know for sure?

[Alexander C.]

Re: 1956 Rocker Arm Nuts

Ed, if they are the same then that would be great! I only need 4 or 5, the rest of mine should be ok.

[Edward M.]

Re: 1956 Rocker Arm Nuts

Ed, if they are the same then that would be great! I only need 4 or 5, the rest of mine should be ok.

I'll check the parts book when I get home tonight and confirm they are the same.
If they are, I'll get 1/2 dozen headed your way.

[Alexander C.]

Re: 1956 Rocker Arm Nuts

Awesome, thank you again!

[Edward M.]

Re: 1956 Rocker Arm Nuts

Awesome, thank you again!

Parts book confirms that 56 passenger car V8 and Corvette V8 rocker arm adjusting nuts are the same part.

As soon as the tornados pass, I go out to the garage and get 1/2 dozen for you.

[Joe L.]

Re: 1956 Rocker Arm Nuts

When I was setting the lash on my newly rebuilt heads, I noticed that more than a couple of the nuts were easier than they should be to turn. 1 of them is not very tight at all. I've searched on eBay and few times and I can't seem to find an NOS set of GM rocker arm nuts. All the ones that are close don't have the same taper on the bottom to fit into the top of the cup.

Anyone know where I can get these? I really would prefer good used original or NOS only.

Thanks!

Alexander-----


The original nuts used for your application were GM #3744341 or, possibly, GM #3836735. No matter as the GM #3744341 will work regardless of what was originally installed. The GM #3744341 are discontinued but replaced by GM #12557390. The latter are what I recommend that you use. In fact, I would recommend replacing ALL the nuts. These things are not expensive and why not have it 100% right?

[Stuart F.]

Re: 1956 Rocker Arm Nuts

Ed;

Hope the Tornados stayed away from you. Saw on the news this morning - really looks bad. Our thoughts and prayers are with all the folks in those areas. The last weekend storms in MO showed a number of old classic cars that were in garages that were hit too, i.e. 67 Chevelle, 53 Studebaker. Ouch!

I'm with joe on the rocker adjusting nuts. That's no place to skimp, specially since they are so cheap. I do recall the 55/56 era nuts were not too great. Recall early 55's had a set screw in the middle of the nut.

Stu Fox

[Alexander C.]

Re: 1956 Rocker Arm Nuts

I totally agree IF I could find an entire set to buy...

[John H.]

Re: 1956 Rocker Arm Nuts

I totally agree IF I could find an entire set to buy...

Alex -

Those things are available everywhere for about seven bucks per side:

http://www.summitracing.com/parts/SUM-G6800-K/

[Joe L.]

Re: 1956 Rocker Arm Nuts

I totally agree IF I could find an entire set to buy...

Alexander------


You should be able to obtain 16 of the GM #12557390 from any GM dealer.

[Alexander C.]

Re: 1956 Rocker Arm Nuts

Alex -

Those things are available everywhere for about seven bucks per side:

http://www.summitracing.com/parts/SUM-G6800-K/

I have a brand new set of those and they don't have the same taper on the bottom that the originals do. Are they ok to use with the original rocker arm balls?

[Jim L.]

Re: 1956 Rocker Arm Nuts

I have a brand new set of those and they don't have the same taper on the bottom that the originals do. Are they ok to use with the original rocker arm balls?

Taper on bottom? They install with the flat side down against the rocker ball. Or am I misunderstanding what you are saying?

Jim

[Alexander C.]

Re: 1956 Rocker Arm Nuts

My rocker balls have a small groove cut right around the center on the top. My nuts have a taper on the bottom of them which fits into this groove. I'll try and post some pictures. I'm sure I could use the newer flat nuts but it would be nice to have correct original ones.

[Joe L.]

Re: 1956 Rocker Arm Nuts

My rocker balls have a small groove cut right around the center on the top. My nuts have a taper on the bottom of them which fits into this groove. I'll try and post some pictures. I'm sure I could use the newer flat nuts but it would be nice to have correct original ones.

Alexander------


I'm not familiar with the design you describe although I do believe that some 1955-56 applications may have used a different style rocker ball and nut. I'll be very interested to see your photos. In any event, you don't suppose that GM changed the design later because the first style worked better, do you? No one ever sees these parts and I'd want, functionally, the best parts available.

By the way, have you checked your rocker arms and rocker balls for wear and/or damage? If they're original, they've been in use now for a LONG time. Check the rocker arm tip which contacts the valve. If there is any wear at this point, the rocker arm is not suitable for re-use. Wear does not mean "shiny", but it does mean if there is any grooving, AT ALL.

Also, check the rocker arm ball socket in the rocker arm. There must be absolutely no wear, grooving, spalling, pitting, erosion, or "black spotting" in this area. If there is any, the rocker arm should be considered scrap.

The rocker balls should show no evidence of any of the above described, either.