Connecting Rod Bolt ?

[kmac530]

So not to knock the Studebaker engine design, but does anyone else have an issue with the rod bolts on a Stude V8?

I have built dozens of VW motors from 1200cc 36hp rebuilds to 200+hp 2274cc Weber IDA 10 second drag bug motors and everything in between. Also Toyota 8rc, 18r, 20r and a 22r motors. And 4 SBC from 265ci to a 383. Then I have even built a few BBC including my ElCo's 396/402 a 454 and a blown 468 750hp monster.

I do not prefer this rod bolt design. The bolts fall into the motor and are just awekward to deal with. I have had rods with actual bolts thru the cap into the rod. I have had studs that are screwed to the rod with nuts on the studs to hold the cap on. I have had bolts in the rods, similar to the Stude design, but they press in or have a type of knurling that grab into the rod and hold it in place while you fiddle with the caps.

I like removeable rod bolts, I just wish these were tighter and held their position better.

Am I missing something positive in this design, or do others not prefer it as well?
What good points are there in this design?

No life and death problem here, just curious.

[StudeMichael]

I have never had an issue with rod bolts. On the small end you are supposed to tap the nut with a hammer and then torque it again. It is amazing how much more it will turn after a few taps.

[Roscomacaw]

Personally, I've never had issues with them. Maybe I just don't know any better.

[StudeRich]

They usually are a bit snug in the rod, I wonder if your Rods have worn and oversize bolt holes, maybe from running too loose.

There should have been PalNuts (locknuts) on the Rod Bolts.

[kmac530]

Yes there are pal nuts on them. They were PLENTY tight. I did not use a torque wrench to remove them {can you even check torque on removal?} But they were VERY tight nuts. The rod bots sho no sign of wear at all, no markings or shiney spots or rubs. Same in the rod holes, no flared edges, shines or mis-shapes at all.

The bolts do not just fall out neccesarily, but when I am sliding the caps back on, if there is any bind at all the rod bolts just push backwards out of the rod. Just seems to easily by every other motor I have built.
I guess it is just me.

[StudeMichael]

The bolts do not just fall out neccesarily, but when I am sliding the caps back on, if there is any bind at all the rod bolts just push backwards out of the rod.
[/QUOTE]

There is something major wrong with that!

[kmac530]

All 16 rod bolts have the exact same issue? The exact same tension on the fit? The motor has only 70k on it and the bearings look GREAT, not like they have been replaced great, just in great shape great.

There has not been ONE single mark inside of this engine like someone has been inside of it, no sign of an overhaul or any serious repairs.

What would be "major wrong with that?"

So you guys are saying to remove the big end rod cap bolts from the rods I should have to pound {obviously I realize that would damage them} or press them out and not be able to push them out with the palm of my hand just with hand pressure?

[SilverHawkDan]

Kmac,
I would recommend you replace the rod bolts. First all bolts are torqued to a "stretch" tightness. Therefore rod bolts were designed to be a use once and throw away item. Although most if not all of us have used them more than once. I suggest you buy the Chevy 3/8" rod bolts from ARP. A few dollars more than others but you are getting a quality performance tested bolt assembly. You will find they have a slight interference fit in the rod and a snug fit in the cap. On my Bonneville 259 engine I tried the new ARP "Wave Loc" rod bolts. They have ribs that lock into the cap to keep things true even at high RPM's. The only problem with them is they are harder to get out of the caps when you disassemble the engine. You have to work them out. They are also torqued to 55 foot pounds instead of 35 like the stock bolts. For a hot engine I would recommend the Wave Loc but for all other applications the standard ARP bolts are great. And yes I have used them more than once in a stock application. Afterall I do drive a Studebaker don't I.
Dan

[kmac530]

Yes you do Dan...and a couple of COOL ones to boot.

[PackardV8]

Yes, there's a problem with your rod bolt fit in the rod. The Stude bolts are designed as an interference fit in the rod, same as most other V8s with which you're familiar.

No, they shouldn't be loose. Never seen that.

Maybe, Dan and I'll have to disagree on a couple of his statements:

I suggest you buy the Chevy 3/8" rod bolts from ARP.

Don't order Chevy rod bolts. ARP has a specific part number for Studebaker rod bolts. Make sure you order nuts at the same time. I ordered 16 rod bolts and that's what I got - no nuts.

BTW - when rod bolts are replaced, the rod big end bore must be resized.

First all bolts are torqued to a "stretch" tightness. Therefore rod bolts were designed to be a use once and throw away item.

This is confusing torque-to-stretch with torque-to-yield. All bolts which are tightened to a given torque figure stretch a bit. This doesn't mean they can't be reused several times. A few years back GM and other manufacturers developed a different technology in which bolts were designed, manufactured and when installed are stretched to a yield point. Those can't be reused. However, guaranteed, Studebaker and most other older engine design rod bolts can be reused in a stock engine more than once without a problem. I'm often in a major local rebuilder shop and they ship a dozen engines a day out the door with the same bolts they came in with.


jack vines

[SilverHawkDan]

Jack,
Thank you for the clarification. I was not aware of the Stude specific part number. I used the word stretch to keep it simple. What apparently has happened to his rod bolts is with repeated use or more likely over torqueing, the bolts are no longer the correct dimensions. Otherwise if the rods are not damaged then the bolts are. I too have used stock (older) rod bolts multiple times. That is why I differrentiated between HiPo and stock use. Since all metal has a usable life, bolt manufacturers recommend replacing them esspecially in a high stress use. Of course they recommend rod bolts be replaced every time. They sell bolts. I do know that we used the same rod bolts in Top Fuel Engines for only a few times or if the engine had any bottom end failure all bolts, rods and mains were replaced. That is about as high stress as you can get. 40 lbs. of boost and 90+% nitro breaks things. That said I think each person building an engine should weigh the few bucks a set of rod bolts cost verses the damage if the bolt fails. I bet there are a dozen opinions on this subject. See Jacks comment on modern bolts.
Dan

[Chicken Hawk]

When in the parts business, I recommended to alway replace the rod bolt unless you knew they had not been taken apart a few times and know they had not been over tightened but let's face it; probably NO ONE knows that after all these years.

ARP has Studebaker V8 Rod bolts and recommends 50 pounds torque with ARP lube and 60 with 30 weight oil. I also advised to have the rods rechecked to see if they needed to be resized as the ARP bolt fit really tight. Phil Harris at Fairborn sells the ARP bolts, also ARP main and head studs.

Stock Stude rods are to be torqued to 52 to 54 pounds according the the shop manual. I never replaced the small pal lock nuts after the rod nuts were torqued.

Ted

So not to knock the Studebaker engine design, but does anyone else have an issue with the rod bolts on a Stude V8?

I have built dozens of VW motors from 1200cc 36hp rebuilds to 200+hp 2274cc Weber IDA 10 second drag bug motors and everything in between. Also Toyota 8rc, 18r, 20r and a 22r motors. And 4 SBC from 265ci to a 383. Then I have even built a few BBC including my ElCo's 396/402 a 454 and a blown 468 750hp monster.

I do not prefer this rod bolt design. The bolts fall into the motor and are just awekward to deal with. I have had rods with actual bolts thru the cap into the rod. I have had studs that are screwed to the rod with nuts on the studs to hold the cap on. I have had bolts in the rods, similar to the Stude design, but they press in or have a type of knurling that grab into the rod and hold it in place while you fiddle with the caps.

I like removeable rod bolts, I just wish these were tighter and held their position better.

Am I missing something positive in this design, or do others not prefer it as well?
What good points are there in this design?

No life and death problem here, just curious.

[PackardV8]

They were PLENTY tight. I did not use a torque wrench to remove them {can you even check torque on removal?} But they were VERY tight nuts. . . . . The bolts fall into the motor and are just awekward to deal with.

I recommended to alway replace the rod bolt unless you knew they had not been taken apart a few times and know they had not been over tightened but let's face it; probably NO ONE knows that after all these years.

You and Ted together may have diagnosed the somewhat unique problem you're having with the bolts being loose.

I also advised to have the rods rechecked to see if they needed to be resized as the ARP bolt fit really tight.

X3, Ted. Guarantee, after installing and torquing ARP bolts, the rods will need to be resized. After fifty years and 100k miles, most Stude rods should be resized for a precision stock rebuild, even when reusing the original bolts. I always replace the OEM nuts with ARP nuts on all rebuilds.

jack vines

[kmac530]

Jack would you happen to have the part number for the Stude specific ARP rod bolts? I am on the ARP website and I dont see even one Packard or Stude section. They have Renault and Suburu, Opel and Vauxhaul, Alfa Romeo, BMC/Triumph and Rover....yet NO Studebaker? WHAT?

[Chicken Hawk]

Phil Harris at Fairborn has them but if you need to talk to ARP, their number is: 800-826-3045

Ted

Jack would you happen to have the part number for the Stude specific ARP rod bolts? I am on the ARP website and I dont see even one Packard or Stude section. They have Renault and Suburu, Opel and Vauxhaul, Alfa Romeo, BMC/Triumph and Rover....yet NO Studebaker? WHAT?