Rod Cap Nut Torque Spec Problem
Thread Starter
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Mountain Pass
Joined: Sep 2012
Posts: 219
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Rod Cap Nut Torque Spec Problem
Hello all. I hope this post finds you well and you bestow your wisdom upon me. 
So, I have a 1995 Ford F250. I'm building the engine to go back into it. I'm building a bare bones 7.3 Powerstroke. So, far I've muddle through all of the problems that i've encountered so far until now.
I've install all of the pistons, connecting rods, and caps. Now I'm going back to torque all of the bolts that secure the caps to the connecting rods. The torque specs that I've found have been in 2 stages. Stage 1 53ftlbs and Stage 2 80ftlbs.
I torqued everything to 53ftlbs and then torqued everything but two bolts to 80ftlbs. The only reason I haven't torqued those is because I can't reach them and I can no longer spin the crank. I used oil and assembly lube througout my entire process, so I can't see anything being seized up. In fact, i could turn the crank just fine when everything was at 53ftlbs.
Have I done something wrong? I'm afraid to keep trying to turn the crank in fear of breaking the crank bolt off.
Is it ok if only two bolts are not torqued to 80ftlbs? Should it be that tight?
Any thoughts or suggestions would be greatly appreciated.
Thanks!
So, I have a 1995 Ford F250. I'm building the engine to go back into it. I'm building a bare bones 7.3 Powerstroke. So, far I've muddle through all of the problems that i've encountered so far until now. I've install all of the pistons, connecting rods, and caps. Now I'm going back to torque all of the bolts that secure the caps to the connecting rods. The torque specs that I've found have been in 2 stages. Stage 1 53ftlbs and Stage 2 80ftlbs.
I torqued everything to 53ftlbs and then torqued everything but two bolts to 80ftlbs. The only reason I haven't torqued those is because I can't reach them and I can no longer spin the crank. I used oil and assembly lube througout my entire process, so I can't see anything being seized up. In fact, i could turn the crank just fine when everything was at 53ftlbs.
Have I done something wrong? I'm afraid to keep trying to turn the crank in fear of breaking the crank bolt off.
Is it ok if only two bolts are not torqued to 80ftlbs? Should it be that tight?
Any thoughts or suggestions would be greatly appreciated.
Thanks!
Laughing Gas
Joined: Aug 2006
Posts: 1,249
Likes: 11
From: oklahoma
If you can't turn the crank. I'm guessing you have something wrong. Go back through and make sure you don't have a rod cap on backwards
To start with
Did you keep the rods and caps together when you took it apart?
To start with
Did you keep the rods and caps together when you took it apart?
Hotshot
Joined: Feb 2009
Posts: 10,410
Likes: 77
From: Plankinton, SD
Definitely step back. Rods all in the right way also? There is a chamfer on one side of the big end that goes to the outside on each journal. Crank been turned? New undersized bearings? Bearing clearance checked?
Thread Starter
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Mountain Pass
Joined: Sep 2012
Posts: 219
Likes: 0
Ok. Just a question. each bearing has what appears to be something like a "notch". The pistons and rods only go in one way, and the bearing will only fit one way on the rod side. However, the cap can be placed such that the notches lline up from the cap and the rod or vice versa. Does that make sense? I've just been lining up the notch from the rod and the cap.
Is that incorrect?
Are my torque specs correct? 53ftlbs and 80ftlbs?
Is that incorrect?
Are my torque specs correct? 53ftlbs and 80ftlbs?
Thread Starter
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Mountain Pass
Joined: Sep 2012
Posts: 219
Likes: 0
Ok. To further muddy the waters, I read that the torque specs for the rod cap bolts is 70 lb-ft. I'm just not quite clear what the correct specs are for these rod cap bolts. Does anyone have the source of truth? Unfortunately, I don't have a Haynes manual to give me the exact value. The main reason that I don't own that manual is because I'm usually able to find all of my values out here. Ha-ha!!!
Thread Starter
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Mountain Pass
Joined: Sep 2012
Posts: 219
Likes: 0
Also, which could be the culprit, I realized that I mixed up the rod caps. I didn't realize that would be an issue until now.
Could that be my problem?
Is it a problem that's solvable?
If so, please advise.
Thank you all so much in advance.
Could that be my problem?
Is it a problem that's solvable?
If so, please advise.
Thank you all so much in advance.
Lead Driver
Joined: Apr 2016
Posts: 7,221
Likes: 1,342
From: Bahstun
take the rods out and send them out to be resized unless you can match them up 100% again correctly
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Lead Driver
Joined: Sep 2002
Posts: 9,573
Likes: 2,037
From: North Texas
52 and 80 from the FSM here - https://www.thedieselstop.com/faq/94...an/stjmain.htm
IMO, start over on the build. Remeasure everything, that is a huge oversight.
IMO, start over on the build. Remeasure everything, that is a huge oversight.
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Laughing Gas
Joined: Aug 2006
Posts: 1,249
Likes: 11
From: oklahoma
Yes that is a problem. They have to stay together. You may be able to see the number if they have them on the side of each rod and cap ..If not as stated before you will have to have them resized
Thread Starter
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Mountain Pass
Joined: Sep 2012
Posts: 219
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10-4. Back to the drawing board. Thanks for the info guys. I'd rather everything be spot-on correct from the beginning than regret it later. Would it be worth it looking into some upgraded rods and pistons? I'm plan to throw a little power at this build, but not a ton. I would be over the moon at 400HP.
Hotshot
Joined: Feb 2009
Posts: 10,410
Likes: 77
From: Plankinton, SD
I dont mean to be rude, but in my opinion any extra money would be better spent on hiring somebody to build the motor. I think you are in a little over your head. You can take that as me being a d#$k, or just passing on advice. That's up to you, I'm not trying to be one.
Thread Starter
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Mountain Pass
Joined: Sep 2012
Posts: 219
Likes: 0
I dont mean to be rude, but in my opinion any extra money would be better spent on hiring somebody to build the motor. I think you are in a little over your head. You can take that as me being a d#$k, or just passing on advice. That's up to you, I'm not trying to be one.
Lead Driver
Joined: Apr 2016
Posts: 7,221
Likes: 1,342
From: Bahstun
Always mark bearing caps before removal with paint, scribe or punch
Have some plastic ziplock baggies and or bins around for parts
keep camera handy to document process
keep some engine rebuilding books and magazine near toilet for future learning
don't rush and ask as many questions as needed
Have some plastic ziplock baggies and or bins around for parts
keep camera handy to document process
keep some engine rebuilding books and magazine near toilet for future learning
don't rush and ask as many questions as needed