Im changing the sump on my ST170 as its a bit rusty, i thought i may as well fit some ARP conrod bolts whilst im there, are the ST170 bolts the same as the standard 2.0L zetec? Is this possible from under the car and what does it mean when it says i may need to ream the rods?
Is there any point fitting new bearings whilst im there also?

 

I would not do this unless you have a good reason , ARP's are stronger than std so that you could rev the engine harder without risk of failure , but if all else is std then would not go to the expense .

Also replacing the bearings might cause more problems than cure , you could do the big ends fairly easy in situ but normally if the bearings need replacement then the crank needs grinding or at least very carefully measuring to make sure it is ok and a quick journal polish , if the only problem with the car is the sump then just do the sump , as I have said before "if it aint broke dont fix it !!" sometimes engines are best left alone as they have "run in" change anything and this is not the case , dont get me wrong a well built engine is good , but doing anything "half cocked" sometimes causes more issues than you started with and doing the bearings from under the car would be classed as half cocked if you do not measure the crank first .

When it says reaming it means accurately opening the bolt holes to a pre determined limit , using a drill is not good enough , you may well need a 9.1 mm Ream or whatever they recommend and again not something you would want to do without some engineering understanding .

 

Thanks fella, the engine is not standard and the rev limit has been raised so i wanted the ARP's for peace of mind. Sounds like allot of hassle

 

It can be mate , if it was making noises or when you drain the oil you see debris would be looking more like a crank grind , which is a crank out job , I have to say if it is running ok then would leave alone unless you are prepared to strip engine completely which is ok but then you say where do I stop replacing bolts , and the costs of gaskets and seals

Looks like you have a nice car , the other option is to build another engine with your goodies in it and swap over a weekend , then you have something stronger but also have a spare that you know is a good one as well .