Connecting rod bolt head issue

[67CarGuy]

9/7/2020 Update: Mystery solved! Jack, aka Packard V8, answers the question (that you didn't think to ask) on Page 2. Thanks to all for your help!


So I'm working on rebuilding a small block chevy, 400ci. Crank in, cam in, pistons in, but I can't for the life of me figure out how to get any of my sockets to fit fully onto the bolt heads that hold the big end of the conn. rods together

The webbing on the bottom of the conn. rod is too tall, or at least appears to be too tall, for my socket to get all the way down on to the head. What gives? Do I need a special thin wall socket set?

I'll try to add a photo here soon. This is the first engine I've ever assembled, so I'm learning as I go. Any help is appreciated!

 

[bob15]

What rod bolts are you using? Also stock rods or aftermarket?

A picture or two would be real helpful.

Do your rod bolts look like these:

 

[toplessHO]

normally rod bolts are held captive by the T or D shape.
shown above are the 6 point and 12 point nuts
normal thinwall 6 and 12 point sockets should fit.

 

[LXCam]

I’ve had to use 1/4” drive deeps before in this situation. Don’t think that ain’t sketchy at roughly 65ftlbs.

 

[OccupantRJ]

Be brave. You won’t die if you grind the OD on an inexpensive socket for it to clear.

 

[Milan]

The top of the rod bolt is interference fit. It yours is loose there is a problem.

 

[gearhead1]

Be brave. You won’t die if you grind the OD on an inexpensive socket for it to clear.

+1, I’ve done this many times. Bent wrenches, etc...

 

[BillK]

The webbing on the bottom of the conn. rod is too tall, or at least appears to be too tall, for my socket to get all the way down on to the head.

I have never had a problem using a 3/8 drive deep 9/16 socket. I have one of those rods in my hand right now and my 9/16 Snap On deep socket fits fine.

 

[67CarGuy]

What rod bolts are you using? Also stock rods or aftermarket?

A picture or two would be real helpful.

Do your rod bolts look like these:

Bottom right is our winner, folks!

 

[67CarGuy]

I have never had a problem using a 3/8 drive deep 9/16 socket. I have one of those rods in my hand right now and my 9/16 Snap On deep socket fits fine.

I'll give this a try when I'm next getting into it... hopefully this weekend while it's quiet.

Thanks for the suggestions, all - I'll let you know how it goes!

 

[bob15]

Can you post a picture of the issue? I'm still having a hard time understanding why your socket won't work.

 

[ScottsGT]

Bottom right is our winner, folks!

Stupid question..... Are you using a 12 point socket??

 

[67CarGuy]

Well, this just shows how long I go between updates.... I've been working on other projects, and without a vehicle for this engine to go into, I haven't made much progress since our last episode (almost a year, yikes!).

I did purchase a thin-wall socket from Harry Epstein, but didn't double check the size, so the one I got is too large. What is it they say about measure twice...?

Yes, I am using a 12 pt, deep well socket, but it's hitting the webbing of the connecting rod before the two halves ever start to really pull together. I know this engine has been put together before, so I'm feeling ridiculous that I can't even get these things more than finger tight, let alone torqued to spec.

Photos to come shortly. Yeesh.

 

[67CarGuy]

This is as far as I can get my 12 pt socket to go.

Another view:

And a view without the socket:

And one more for good measure:

I understand the proposed solution of grinding down some of the socket... I'm just trying to understand if that's the *only* solution, just the most common, or.... ? I get the feeling that one of you is going to point out something really obvious and I'm going to be slapping my forehead for not figuring it out months ago.

Edit: And I see that my photos aren't showing up... boy, you think something is simple... okay, let's try this another way...

 

[American Locomotive]

Wow yeah that's tight. Whoever designed that rod was definitely a goober. I don't think you have much choice except to grind down the socket. I feel like that clearance would be cutting it close for some thin-wall sockets too.

 

[TonyJ]

Are those the rods the motor had in it when you got the motor or are those a set that you bought ? If you bought them I’d call the place that sold them to ya or the manufacturer of them and see if a special socket is needed with their brand rods.


Tony

 

[Samuel D]

If you remove the nuts and measure the width inside the webbing with the internal jaws of a calliper, what sort of number do you get? It’s a little hard to see how close the socket is to fitting in the pictures.

 

[Packard V8]

Those aren't Chevy rods and nuts. Whose rods, bolts and nuts are you using?

jack vines

 

[67CarGuy]

They're Crower rods on a Crower crank, with (I think) Crower hardware. The rest of the engine hardware is ARP, I know that. The rotating assembly was all together in a previous engine, but that was before my ownership.

I'll pull one off and throw some calipers on it, see what I get.

Tony, you may be on to something with going straight to the source... I'll see if Crower has anything on their website about clearances, special 12-pt invisible wall sockets, etc.

 

[Samuel D]

Couple of other thoughts. Snap-on sockets are particularly thin-walled in smaller drive sizes. You might even get away with a 1/4" drive socket in a pinch, depending on the torque. The risk of damaging a 1/4" drive socket from high torque beats the certainty of damaging one by grinding.

I’d also try a 14 mm metric socket just in case it fits the nut. You never know, and if it does, that will give you another fraction of a millimetre of clearance to the ribs.

 

[Wakefield]

delete

 

[Wakefield]

Are those the rods the motor had in it when you got the motor or are those a set that you bought ? If you bought them I’d call the place that sold them to ya or the manufacturer of them and see if a special socket is needed with their brand rods.


Tony

I guess that is the most likely

 

[Indexmill]

Please do let us know how this turns out.

BTW, if you must reduce the OD of a socket, better to turn it on a lathe than try to grind it with a bench grinder.

 

[67CarGuy]

Please do let us know how this turns out.

BTW, if you must reduce the OD of a socket, better to turn it on a lathe than try to grind it with a bench grinder.

Man, you really know how to take the fun out of a job And I just bought a bench grinder, too!

Even though I have the full set of pistons installed, I may remove one and bring it my local machine shop and see what they say. While I don't intend to pay them to do the remaining build, they have likely dealt with this sort of thing before... If not, I'll track down a 1/4 drive socket that might work. Maybe this year will be the first I order from Harry Epstein 2x!

I'll definitely update when I have more info. Crower should be contacting me today too, so we'll see what they say.

Thanks to all for the helpful thoughts and suggestions so far!

 

[Packard V8]

Most likely, those bolts and nuts were never designed to be tightened with a socket and torque wrench. They probably need a box end and a stretch gauge.

jack vines

 

[67CarGuy]

Aha! Jack, thanks a bunch. I've done some more research in the past few days and all the other sources agree with you - you're a genius!

In all seriousness, thanks. This looks to be the correct answer. And now I get to buy another tool

 

[Packard V8]

Glad I could help.

FWIW, I made my own stretch gauge. Good enough for one-time use.

jack vines

 

[Samuel D]

How does a ring spanner fit if a socket doesn’t? Surely you’ll run into the same lateral clearance problem, only worse?

 

[Packard V8]

Those are special head 12-point bolts and sometimes require buying the matching "ring spanner" and stretch gauge.

jack vines