Are my connecting rods machined wrong? Which way to install pistons? - 460 Ford Forum
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post #1 of 10 (permalink) Old 09-29-2012, 04:37 PM Thread Starter
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Are my connecting rods machined wrong? Which way to install pistons?

I am putting together a 545 stroker and I think that the rods on my stroker kit are machined with the chamfer and tangs on the wrong side but I wanted to get a second opinion. I'm going to try and attach some photos but not sure if I have sufficient permission yet.



1st photo shows the original rod cap (right) to the new one (left). Both have the lettering at the top of the photo but the large chamfer and bearings are on the opposite sides.



2nd photo shows where I was installing the rods and ran into trouble. I can't get both connecting rods on the crank because the large chamfers are on the inside instead of the outside. You can see that the lettering and bearing tang is outboard like it is supposed to be but the chamfer is on the wrong side.

I wanted to see if it is ok to just flip my connecting rods around and put the bearing tangs facing inboard instead of outboard. That would put the larger chamfer on the correct side but would put the bearing tangs on the wrong side.



3rd photo is my pistons. They are 40 cc dish Mahle forged pistons. I am pretty sure that the relief is an exhaust valve relief but I want to make sure. There aren't any markings on the piston to tell me which side goes foward so I'm just lining up the relief with the exhaust valves (front of the engine on cylinder 1-4 and facing back of engine on 5-8). The heads are edlebrock RPM and it seems like the exhaust valve is the one that would hit rather than the intake.

Last edited by cvfracing; 09-29-2012 at 04:40 PM.
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post #2 of 10 (permalink) Old 09-29-2012, 05:35 PM
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Cool

  • The valve relief in your aftermarket forged pistons is an intake valve relief, not an exhaust valve relief.
  • On your OEM stock rods with the cast production pistons with offset pin, 4 rods are fit to the OEM pistons one way and the other 4 rods are fitted the opposite way; assemble in the engine block accordingly.
  • On your aftermarket rods with forged pistons, all rods go on the same way. In this case, the chamfer on the con rod big end should be on the same side and directly beneath the intake valve relief on the forged pistons.
Then check your bearing tangs.

Paul

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post #3 of 10 (permalink) Old 09-30-2012, 08:54 AM Thread Starter
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Paul,

Thanks! That helps a lot. I set up my aftermarket rods & pistons like you described and everything seems right. The only problem is that it puts the lettering and tangs on the inboard side of the engine instead of facing out towards the freeze plugs. All the traditional wisdom out there says to keep the lettering and tangs pointing towards the outside of the engine but I can’t do that and still get the chamfers on the conn rods to line up correctly with the radius on the crank if I do that.

I guess that is just a chevy thing??? Does this photo look right? You guys are AWESOME!! Some punk at Summit racing would have given me bad advice…even the mechanic who did my machining was saying to install based on the tangs / lettering.

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post #4 of 10 (permalink) Old 09-30-2012, 09:37 AM
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your piston valve relief correct location ? intake on top right side ? if so

you have the rod installed on piston wrong , turn it around
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post #5 of 10 (permalink) Old 10-01-2012, 09:04 AM Thread Starter
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The intake relief on the pistons is in the upper right (rearward on cyl 5-8 and forward on 1-4). I don't think that flipping the pistons on the rods will help...that is the way I had them for the first set of photos.

I gone over this a hundred times in my head and a dozen times with the actual parts. I don't see any way to put the rods in such that the tangs and lettering are facing outboard towards the freeze plugs. If I put them in so that the lettering and tangs are correct then the bearings are wrong (ie with the small chamfer and bearing hitting the radius on the crank).

I think they put the large radius and tangs on the wrong side. Does anyone see any issue running with the bearing tangs facing inward as long as the chamfer is correct and the bearings aren't hitting the radius in the corner of the crank Journal?
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post #6 of 10 (permalink) Old 10-01-2012, 09:58 AM
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On my stroker cleveland using chevy rods the tangs were installed inboard and ran fine for years.
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post #7 of 10 (permalink) Old 10-01-2012, 11:02 AM
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It makes NO difference where the bearing tangs are. It makes EVERY difference where the large radius chamfer is. Don't obsess about the tangs or lettering.
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post #8 of 10 (permalink) Old 10-01-2012, 11:54 AM
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Yep, large chamfer toward the cheek of the crank.

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post #9 of 10 (permalink) Old 10-01-2012, 12:03 PM Thread Starter
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Thanks Guys!!! That makes me feel a whole lot better! I would hate to screw this up. It's my first engine build and I am totally amazed at how many things are easy to screw up! (piston rings upside down, pistons or rods in backwards, bearings in wrong and so on)
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post #10 of 10 (permalink) Old 10-01-2012, 03:27 PM
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Quote:
Originally Posted by cvfracing View Post
Thanks Guys!!! That makes me feel a whole lot better! I would hate to screw this up. It's my first engine build and I am totally amazed at how many things are easy to screw up! (piston rings upside down, pistons or rods in backwards, bearings in wrong and so on)
the 2nd pic show the rod needs to be turned around if the piston is in the bore correct
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