ARP main studs

[carolinaturbo]

I purchased new arp main studs for my engine. Tapped the holes and installed them. Found the rear and ft studs hitting oil pan. Looks like they are too long or something. Has anybody else seen this problem? Thanks. This is a 20bolt non 109 block. Studs are 123-5401.

 

[turbo nasty]

Common....I used a big ball peen and massaged the area that hit...with the round peen side of the hammer

 

[278cikiller]

I purchased new arp main studs for my engine. Tapped the holes and installed them. Found the rear and ft studs hitting oil pan. Looks like they are too long or something. Has anybody else seen this problem? Thanks. This is a 20bolt non 109 block. Studs are 123-5401.

You might have the fronts in the back and the backs in the front, I seen that happen when the motor in the car and you have to take the pan off , you have to pry the oil pan over the studs at the front of the motor to get by the fly wheel.

 

[Spooling]

I assume that you are having your block "line-honed" after installing studs?

 

[fastblackracing]

It is very common for the stud and or the nut to hit. I use the twelve point nut to gain clearance and you can trim the stud length a bit if needed. The studs change the clamping force on the bearings and and it is common to have the block align honed when changing. You can probly get away with just installing the studs but you really need to check your bearing clearance to make sure you dont cause yourself a big problem.

 

[turbonut85]

I assume that you are having your block "line-honed" after installing studs?

It is very common for the stud and or the nut to hit. I use the twelve point nut to gain clearance and you can trim the stud length a bit if needed. The studs change the clamping force on the bearings and and it is common to have the block align honed when changing. You can probly get away with just installing the studs but you really need to check your bearing clearance to make sure you dont cause yourself a big problem.

X2 on the align hone....someone installed studs on a motor I bought without doing the align hone....10k miles later I had copper showing on 1/2 of each cap bearing......get it align honed or get just bolts.....just my .02 ---Keith

 

[S10xGN]

I don't recall the set number, but I'm pretty sure two of them were 1/4" shorter than the rest. Those go in the rear. It's kinda hard to tell in this pic:

 

[SCOOBY DOO]

Take the block to a machine shop and ask them to check the main saddles with an elongated inside mic. You'll likely find the measurement has "tightened" up with the studs. Same rings true using ARP fasteners on the rods.

 

[jasjamz]

Shorts in the rear like posted above

 

[TurboBuRick]

X2 on the ball peen message.

 

[williambavila]

Line bore or your going to be doing this again and buying a crank

 

[PSID6]

You will actually see your main bearing clearance increase with studs. Roughly .001 which is huge,this is a big no no without having the caps cut and a proper main line hone done.

 

[earlbrown]

Measure and write down your bore dimensions with the stock bolts.... the put the ARP's in and see if it's still the same dimensions.

My 4.1 block showed no change with the stock bolts and the ARP's.


Based on my first hand experience with a bore gauge I'm betting the vertical clearance is greater than spec and the caps need to be hand lapped 1/2 thou

 

[TurboDave]

Measure and write down your bore dimensions with the stock bolts.... the put the ARP's in and see if it's still the same dimensions.

My 4.1 block showed no change with the stock bolts and the ARP's.

I had the same experience in assembling my (on the engine stand) block. Measured all the mains with the stock bolts, and then with the ARP studs. Saw no change.

 

[bryesh]

Another vote for studs vs. bolts not making a significant difference. My experience was that as the bearing cap is tightened the clearances will change up until a certain point. Above that preload (maybe 70% of recomended final torque) the clearances did not measurably change. I overtorqued as well maybe 110%- 120% and there was still no measurable change in the bearing clearance.

Classical hand calculations (ie Shigley ) will yield identical clamping forces for a bolt or stud at a given torque.

 

[fastblackracing]

I think the bigger issue here is unless you are adding steel main caps there is not much to be gained from just adding studs. The stock caps will break or the block webbing will split first, the bolts usually survive. And changing bearings or adding studs without checking your clearance is just foolish, changing fastener type will change clamp load, how much depends on a variety of factors but if your gonna build an engine and not check all of your clearances you are just asking for it.

 

[fastblackracing]

Here is a pic of some still good main bolts, but everything else let go. I know its not a v6 but same story. A set of studs would not have helped this engine one bit.

 

[bryesh]

As far as the clamping force of fasteners goes, there is a lot of scatter no matter what a person does. Even the exact same installation, using the exact same techniques will result in different clamping forces. So in reality, a spectrum of clamping forces nust work. If not then there would be a lot of failures.

I am interested to know why people think there are major differences in clamping force between a bolt and stud, torqued to the same value with all other things the same. All of the analysis methods I have found do not show such differences. Common references such as Shigley, Nui, Bruhn do not consider weather the fastener is a bolt or stud. I also looked into an AIAA paper entitled "An Evaluation of Common Analysis Methods for Bolted Joints...", which compares these methods and others (esa, nasa, other papers) and there seems to be no differences while analyzing clamping force between studs and bolts.

Is this just from personal experience?

Thanks

 

[fastblackracing]

Thread angle, fine thread vs coarse thread plays a part, the hardness of the fastener plays a part in how much it stretches, with a bolt you have friction under the bolt head and the threads which are torquing into soft cast iron. With a stud no torque is applied in the block threads, and you have friction at the nut, washer and stud all of which are harder than the oem stuff. It all applies pressure to the main cap differently. I have measured the main bearing bores with a precision dial bore gauge reading to .0001 [one ten thousands of an inch] with bolts and studs at different torque values and could see how the bore size changes. It all comes down to stretch and friction and how its applied to the fastener.

 

[fastblackracing]

As far as the clamping force of fasteners goes, there is a lot of scatter no matter what a person does. Even the exact same installation, using the exact same techniques will result in different clamping forces. So in reality, a spectrum of clamping forces nust work. If not then there would be a lot of failures.

I am interested to know why people think there are major differences in clamping force between a bolt and stud, torqued to the same value with all other things the same. All of the analysis methods I have found do not show such differences. Common references such as Shigley, Nui, Bruhn do not consider weather the fastener is a bolt or stud. I also looked into an AIAA paper entitled "An Evaluation of Common Analysis Methods for Bolted Joints...", which compares these methods and others (esa, nasa, other papers) and there seems to be no differences while analyzing clamping force between studs and bolts.

Is this just from personal experience?

Thanks

I just know what I personally learned out in my shop, but I would like to check out the sources you refer to, do you have any links for these?