How does this work? Ive noticed that the main bearings are selected by size and etched into the block but when I buy a set of ACL Mains you dont get to select any sizes. Does this mean that the mains tolerance will be less than ideal with the uprated bearings?

Cheers

Andy

 

Andy, The selective sizes marked on the crank webs are for production build only and selective bearings are not serviced by Fuji Heavy. Standard bearings are the only ones to use either genuine or aftermarket type. Clearance will have to be established by the fitter using plastigauge or similar and the usual tricks to obtain the considered optimum clearance.

We have found that only low HP European engines will stand a crank grind. Even though you can buy STI oversize bearings it NEVER works on anything above 240 HP as the crank goes soft after a regrind and failure comes around again really quickly.

In any case, cranks aren't expensive on a Subaru in relation to the cost of a complete strip and rebuild again after the 2nd failure.

Does that help? David API Engines

 

Thanks David.

So even Subaru cant select mains as per the crank markings?

I just had the crank polished, its all within tolerance and wasnt really scored as I stripped the engine the moment big ends 2 and 3 let go. Is it necessary to plastigauge it up given that Ive got new ACL bearings and the crank is in good shape?

 

yes..

then swap them about and get them as good as you can.

David

 

Do plastigauge have distributors? I notice that the only retail pack they sell direct doesnt include the size range Im looking for.

 

Hi !, Plastigauge is a small packet of thin strips of squashy plastic type material. When you buy a packet there is a paper 'gauge' in the packet which gives you instructions on how to use and measure. It's really simple and one packet will firstly do many engines and secondly do anything from a mower to a tank.

There is no issue with correct size.

David API

 

I had a very nice chat with Mr Plastigauge. When I mentioned the clearance ranges I was going for (0.01-0.03mm on the mains and 0.016-0.044mm on the bottom ends) he seemed surprised and sold me a retail pack of the motorbike engine gauges (PL-X on the website) that nicely covered the range.

Do Scooby engines have tighter tolerances that ur average motor then David?

 

Yep ! Sure do. Piston to bore clearance standard is .0008" :- eight tenths of a thousandth of an inch. Not large if you get my drift. I don't have bearing clearances off the top of my head, it's just the piston clearance that I remember. Maybe another will advise before I get to the paperwork on Monday.

David

 

does someone know where i can buy some plastigauge?

many thanks

 

Sorry Jonnnyboy, just caught up with this one. We have it at the works. l'll try to remember to look it up and post for you tomorrow Friday 9th.

David APi Engines / APi Impreza