ARP studs/ Out of round main bearing bores

[Jbird988]

Have a engine here that has arp main studs and with these studs torqued down I will have .003 clearance which is including the measuring of the bearings and the size of the crank main journals on the X axis. The Y axis I get .0015 clearance with bearings and crank journal taken into account which that is what I want for clearance. With the engine in operation I know the X will close up some which I know that is why bearings taper down on the ends. Asking how much the X axis closes up during operation is probably a loaded question and I normally don't get hung up on measuring at the parting line but how critical is it being that much off compared to the vertical clearance? Should I be having the mains resized?

The main bores by themselves are .0015 bigger on the X axis than the Y and on the Y it is actually .0005 tighter with the studs than what factory spec is which should help keep the bearing crush given the bores are larger on the X?

[bentvalves]

sounds like a perfect candidate for line hone.

what engine are we working with?

[Jbird988]

sounds like a perfect candidate for line hone.

what engine are we working with?

It is a Toyota tacoma 3rzfe 2.7

[bentvalves]

aluminum block likely? (wrong/cast iron) what is the application?

what are you using to measure the housing bore?

[Jbird988]

aluminum block likely? (wrong/cast iron) what is the application?

what are you using to measure the housing bore?

It is a iron block. Application is a daily driver that may be getting a turbo later on hence the studs now. It would be a mild tune. Lots of guys been running these engines around 100% stock internals with 10-12psi reliably.

[Jbird988]

aluminum block likely? (wrong/cast iron) what is the application?

what are you using to measure the housing bore?

Using a brown&sharpe dial bore gauge.

[BillK]

The instructions that come with every set of ARP main studs I have seen always tell you that align hone will most likely be required. I dont see a kit listed for that engine but here is a link to the instructions for the 3SGTE kit: https://tech.arp-bolts.com/instructions/203-5404.pdf Pretty sure the "FOOTNOTE" is the same in all of their main stud kits.

[bentvalves]

put the O.E fasteners back in and measure.

then, put the O.E. fasteners back in and button the engine up.

[Jbird988]

The instructions that come with every set of ARP main studs I have seen always tell you that align hone will most likely be required. I dont see a kit listed for that engine but here is a link to the instructions for the 3SGTE kit: https://tech.arp-bolts.com/instructions/203-5404.pdf Pretty sure the "FOOTNOTE" is the same in all of their main stud kits.

Arp didn't make a stud kit aimed at this engine but they do have a stud in production that is the right size needed for it. I could see issues with .003+ out of round for a few reasons but .0015 and that closing up by .001? maybe a little less while engine is under load. Hate to make a 8 hour round trip to drop the block off at a shop if a main bore job is not needed so figured id gather some opinions. I feel like I'm probably sweating this for no reason but I've been wrong before.

[Jbird988]

put the O.E fasteners back in and measure.

then, put the O.E. fasteners back in and button the engine up.

I actually did do that which the vertical clearance was factory spec and measuring at the parting line was .0005 large. The crank needs to be ground and I was getting the numbers lined up to tell them what diameter to grind it to. I hear what you are saying about leaving the O.E. bolts in but was looking to go ahead and do all the preventative maintenance stuff now.

[Jbird988]

put the O.E fasteners back in and measure.

then, put the O.E. fasteners back in and button the engine up.

I actually did do that which the vertical clearance was factory spec and measuring at the parting line was .0005 large. The crank needs to be ground and I was getting the numbers lined up to tell them what diameter to grind it to while hoping to avoid a main bore job. I hear what you are saying about leaving the O.E. bolts in but was looking to go ahead and do all the preventative maintenance stuff now.

[modok]

I think it is fine as-is
Restoring the housing to round would reduce the horizontal clearance, but also increase the vertical clearance, and that which isn't helpful, unless you get thicker bearings.
It could be fine tuned further, but just honing it round would not be much improvement.
Honing it round and back in spec then using .001" under upper shells.... might be nice tho.