Wanting to install OE cross bolt caps

[frnkeore]

Out of curiosity, how would the bolt hole(s) for the thrust main be modified to account for the front to back deviation and still allow it to fulfill its intended purpose?

Regarding #3 thrust, it appears that either the cap is drilled off center or the block saddle is. I'm guessing the cap is. The below will need to be done on a milling machine.

Measure the cap first, using calipers, measure the thickness of the bolt hole, to the side of the cap. If both sides are within .005 - .007, then it's good. Then do the same to the block bolt holes.

To fix the cap, put it in a precision vise, indicate across the bottom, to insure it's parallel and indicate the center of one bolt hole, on the X axis. After that, indicate the center of the of the cap, on the Y axis and "0" it. You will be at the center of the cap and where the center of one bolt should be.

Using a sharp, long 1/2" end mill (make sure it can go all the way threw, w/o hitting the vise bottom) and plunge threw the cap hole. Move over to the other hole, 3.680" and do the same. To insure that there is bolt clearance move .010 more in the Y axis and plunge again.

If the main saddle is off center, then you have to disregard the Y axis above and match the offset of those bolt holes, by measuring the offset and matching that on the Y axis.

Also, the circular cuts on both saddle and cap, are very close tolerance. The dimension is .913 - .915 so, check that also.

[Urgefor]

That is what I was assuming the modification would be. Thank you for clarifying.  I take it that means for the thrust bearing cap to do its job, an elongated bolt hole isn't much of a concern as long as the mating surfaces between the cap and saddle are able to achieve the desired clamping force to keep the cap from shifting when the bolts are torqued to spec.

[JacksFordParts]

Almost All the old schools guys I've talked to about this have told me you only need to do #2 and #4, they never had a problem with #3

[frnkeore]

That is what I was assuming the modification would be. Thank you for clarifying.  I take it that means for the thrust bearing cap to do its job, an elongated bolt hole isn't much of a concern as long as the mating surfaces between the cap and saddle are able to achieve the desired clamping force to keep the cap from shifting when the bolts are torqued to spec.

Yes.

One other thing, if you use the center cap, is that after the center cap and saddle surfaces are inline with each other, you will have to accurately locate the threads in the cap, to the cross bolt hole that will be drilled from the outside of the block, to be sure that when the threads engage, they don't pull the cap off to one side or the other, decreasing the thrust clearance to much, so make all the side holes 1/32" over size and spot face them.

It won't be easy to do and the machine shop will need to know what they're doing.

[XR7]

I agree with Jack, the caps that need help are #2 and #4, that is where most blocks start to crack between the cam and crank bores when run hard at high HP & RPM. Easier for the machine shops to do a good job on the conversion and not have to deal with the thrust alignment when changing caps and all the work that goes with it. One of the two stocker blocks have just the number 2 & 4 cross bolt caps.

[pbf777]

I take it that means for the thrust bearing cap to do its job, an elongated bolt hole isn't much of a concern as long as the mating surfaces between the cap and saddle are able to achieve the desired clamping force to keep the cap from shifting when the bolts are torqued to spec.

      As stated previously by another, yes, basically slotting of the bolt hole in the cap as needed is done for alignment; but be aware that particularly since we in this day and age are expecting power levels beyond that which the O.E.M. engineered the block for, loss of material sums particularly in these sort of high load/stress areas are not appreciated.  As for example I have witnessed FE caps split thru the bolt hole column in the past even with only the O.E.M.'s bolt fastener preload value (though I believe the bolt engineering is part of the problem!  ) and most today will switch to a stud of higher strength creating even greater compressive forces coupled to the greater operational pressures!   

      Also of note:  Even if not swapping the main-caps it is often encountered with the implementation of a stud fastener in place of the O.E.'s bolt that interference of the studs' shank and the bold hole I.D. (and it would be nice if ARP could better control the run-out alignment between the studs' shank to threaded sections!  ), and should be inspected for; as this can not only create difficulty in acquiring the proper thrust-cap location front to back for reasonable bearing/crank thrust clearance value, but also this issue can cause force to the caps right to left which can lead to distortion of the main bearing bore and/or creating a greater deflective load from the vertical pull on the threaded bores with the possibility of aiding in breakage of the block casting through the bolt holes!   

      Scott.

[Urgefor]

Thanks for the info regarding replacement of OE bolts with studs Scott.  I was definitely not aware of that issue and now I know that I should make a decision regarding main studs in relation to installing a different set of main caps.

[Urgefor]

Posting this here as well.  Any information is appreciated.

I haven't heard back from Billet Speedworks after sending a message via their contact page on their website and leaving a couple voicemails on the number listed on their site.  Anyone know their current status?  I'd place an order via their website and be willing to wait, but I'm not sure what to think about the lack of response from them.

[Urgefor]

Good news everyone!!!  (in my best Professor Farnsworth voice)  Finally got in touch with Billet Speedworks.  They will be machining caps in a few weeks with availability being mid August.  Responses I received from resellers ranged from "we can't get them" to "we've had them on backorder since last December".  If you have been thinking about ordering a set, now would probably be a good time.   

[pbf777]

     Maybe!   

     Scott.

[Urgefor]

Just got the shipping notification today from Billet Speedworks.  Main caps are finally on the way. Better late than never.