Tight crank?

Anonymous · Post by **Anonymous** » Tue May 24, 05 6:47 pm

Just fitted the crank into my 360. Initially, it wouldnt turn even with the mains caps only torqued to 12ibs.
I then loosened all bolts until I isolated main cap no2 as the culprit. re torqued all caps a second time and crank spins with socket on the crank bolt. Is this normal?

Dave-R · Post by **Dave-R** » Tue May 24, 05 7:02 pm

The caps have room to move around a bit. Make sure you have them sitting with everything flush.

Spin the crank after locating each cap before torquing down. Spin it completely a few times before installing the rear main seal. Make sure that thrust bearing is flush with no step.

When done right the crank should spin by hand with very little effort. You should also have a lot of oil on the bearings first. I mention that just in case.

Dave-R · Post by **Dave-R** » Tue May 24, 05 7:06 pm

And you have checked all the clearences haven't you?

Anonymous · Post by **Anonymous** » Tue May 24, 05 7:22 pm

Dave, I havent checked clearences but the crank is a fresh regrind with new Clevite bearings from a reputable machineshop.
I noted that the caps have more than one position. I got a mate to turn the crank whilst i adjusted the caps. The crank span fine with all mains except no 2. When i repositioned n0 2 it span fine albeit, with a socket on the crank bolt. I couldnt turn it by hand although theres not much to grip onto!

Alex · Post by **Alex** » Tue May 24, 05 8:24 pm

It should spin by hand with oil on the crank journals, if it does not something is wrong.

It is essential you make sure the surfaces the bearings fit into are spotless, any dirt behind the bearing will kill the clearences.

Make sure the caps have the correct orientation as they are machined to fit only one way

When you torque the crank, tighten numbe two and four, make sure the crank rotates freely, then tigten one and four, check the crank rotates freely once again, now tigten number three finger tight, get a soft hammer and whack the nose of the crank rearwards, now use a bar to press the crank forwads as hard as possible and while the pressure is on torque number three down.

the crank should spin freely, now bar the cran backwars gently and check the thrust end play.

Job should be a good un!

If you did not centre number three the crank will be tight and the thrust will be destroyed in minutes.

Good luck

Dave-R · Post by **Dave-R** » Tue May 24, 05 8:32 pm

And what if the bearing has not been sized right? Or the #2 main is out of alignment with the others?

You HAVE to check clearences. Without physically measuring you have no idea if you are assembling a bomb or not. Borrow the tools to do it. Or buy some plastigauge. Look not only for clearence but also for taper.
Has the mains been align honed?

I think you need 2 or 3 thou clearence on the mains. You will have to look it up. Use a micrometer to measure the crank and an inside micrometer inside the bearing at 90 degrees to the parting line. The difference between the two measurements is your clearence. If you can't get the tools Plastigauge will do. Follow the instructions on the packet.

Are the oil holes in the crank chamfered?

You can check crankshaft alignment by installing only #1 and #5 bearing shells and caps so the other journals are touching nothing. Torque the caps up and then put a dial gauge on #3 journal. As you spin the crank check how much the gauge moves. You want less than 2 thou variation if possible but you can get away with 4 thou.

Dave-R · Post by **Dave-R** » Tue May 24, 05 8:35 pm

Oh and did i say check for taper on the journals? make sure the journal is the same diameter at several points along it's length. The spec is in your workshop manual.

I have found instructions for using plastigauge. If you need them I will scan them and email it to you.

Dave-R · Post by **Dave-R** » Tue May 24, 05 8:37 pm

And what Alex said above too!

Dave-R · Post by **Dave-R** » Tue May 24, 05 8:43 pm

BTW I only know the above because my crank is damaged and I have been reading up for when the new one gets here.

Anonymous · Post by **Anonymous** » Tue May 24, 05 11:28 pm

Wow, just got back from the pub and read the posts. Pretty much scared me to death! I put a lot of faith in the machine shop. I'm aware (not least from reading Daves crank posts that the thrust face position is crucial. I'l follow the above instructions and post back.

Anonymous · Post by **Anonymous** » Tue May 24, 05 11:35 pm

Just read it all again, wish i hadnt started. Alex, in your sequence you dont mention torquing no5 cap. The caps and bearings are all correct and very well lubed. I'l try it again tomorrow. Hopefully i just need to sequence the job correctly.

Matt · Post by **Matt** » Wed May 25, 05 12:08 am

You can't trust the machine shop . I've been on the receiving end of mistakes by a couple of very reputable establishments. You have to double-check everything yourself , at least with plastigauge. It's cheap , & it works.

Anonymous · Post by **Anonymous** » Wed May 25, 05 7:02 am

I've got plastigauge so i can try that.I havent had time to set it up according to alex's instructions yet.
The crank turns over easily with a socket and short extension bar. My 318 (sat on the garage fllor) cannot be turned by gripping the flex plate and that is a engine that has a worn crank. Just a point of comparison as I havent built one of these motors before.

Alex · Post by **Alex** » Wed May 25, 05 7:36 am

Typo mate, 2-4, 1-5, 3 is the sequence.

Anonymous · Post by **Anonymous** » Wed May 25, 05 8:08 am

Just to add my two penneth. Before I put the pistons in my newly machined engine, I could turn the crank by hand from the crank nose with all caps torqued down. It wasnt easy but it was definately do-able