998 big end bore size

[850RS]

I appreciate the collective wisdom of the forum and I’m hoping that you guys might have this info or could maybe point me in the direction of a manual that does have this info.

I’m upgrading the con rod big end bolts on my pre A+ 998 race motor to ARP bolts which are spec’d by ARP for .0055 stretch. To get that measurement it took 55 ft lbs of torque. I’m looking to have the rods checked to see if the bore is in spec or if we need to hone to get back to the correct big end bore size.

Does anyone know the correct bore size for the 998 con rods?

I looked through all of the workshop manuals and I don’t see this information anywhere. I appreciate any help.

Also- anyone know if there are any clearance issue with running the ARP bolts on the 998 con rods? I can’t see any interference from the block, cam shaft, or the gearbox casing. My gearbox casing is currently disassembled so I can’t confirm if the ARP hardware will interfere with any gears. I can’t imagine the clearances would be that tight that swapping bolts would cause an issue.

[Ronnie]

I appreciate the collective wisdom of the forum and I’m hoping that you guys might have this info or could maybe point me in the direction of a manual that does have this info.

I’m upgrading the con rod big end bolts on my pre A+ 998 race motor to ARP bolts which are spec’d by ARP for .0055 stretch. To get that measurement it took 55 ft lbs of torque. I’m looking to have the rods checked to see if the bore is in spec or if we need to hone to get back to the correct big end bore size.

Does anyone know the correct bore size for the 998 con rods?

I looked through all of the workshop manuals and I don’t see this information anywhere. I appreciate any help.

Also- anyone know if there are any clearance issue with running the ARP bolts on the 998 con rods? I can’t see any interference from the block, cam shaft, or the gearbox casing. My gearbox casing is currently disassembled so I can’t confirm if the ARP hardware will interfere with any gears. I can’t imagine the clearances would be that tight that swapping bolts would cause an issue.

Try a PM or email to 251 Eng on this forum.

[timmy201]

I'm using ARP bolts on a 1098 crank with no clearance issues to the gearbox/cam etc. You should be fine with a shorter stroke 998

[850RS]

Thanks for that suggestion, Ronnie. I’ve sent him an email.

Appreciate you confirming the clearance, Timmy.

[251 ENG]

998 con rod bearing housings size is 1.7705" - 1.7710"

[850RS]

998 con rod bearing housings size is 1.7705" - 1.7710"

Thanks Simon! Appreciate the info!

[850RS]

Simon gave me a great tip about trying to find a bearing catalog as they sometimes have this info included. I found on the ACL website that if you search the bearing part number in their catalog it will give you all the important dimensions.

Here is the page for the rod bearings for 998s
https://www.aclperformance.com.au/details/4B2201H

And here is the main cap page
https://www.aclperformance.com.au/details/3m2203h