Main bearing clearances?!

[mk3-4-me]

ok ya ill take 2 there 2morrow. Man if its just a rod out of spec, that would be dandy! lol
.
then i can still see me driving my car by sunday now! if i get the rod back by at least 12 2morrow...

i let you guys know!

 

[mk3-4-me]

Ok well I didn't take the rods in yet, instead I put a known in spec rod on the number 6 journal and torqued it down, and got the same reading... So it's deff the #6 journal that's out of shape... looks like I do have to wait another week!

 

[mk3-4-me]

I'm having him weld and regrind the journal... It's $125 to do it. I'll have to find the specs of what the journal should be for .25 undrsized.

 

[mk3-4-me]

ok i was looking on TSRM http://www.cygnusx1.net/Supra/Library/TSRM/MK3/manual.aspx?S=EM&P=83 and the crank pin diameter spec are:

STD : 51.976 - 60.012 MM
U/S 0.25 : 51.725 - 51.735 MM

I just wanna make sure that the 0.25 specs is what i need. All my other journals are 0.25 undersize so im still gunna be using that spec.

Thx im leaving right now to take it there again.

 

[IJ.]

If it spun a bearing that Rod needs to be resized before you go any further.

 

[mk3-4-me]

I took all the rods in wen I got it all balanced and he said it was still round and in spec...

I told him to resize it If it was bad... Took it home right after I heard it knocking.. So idk

 

[Devin LeBlanc]

Hes wrong unless it didn't spin, does it have cross hatch marks on it?

 

[IJ.]

I took all the rods in wen I got it all balanced and he said it was still round and in spec...

I told him to resize it If it was bad... Took it home right after I heard it knocking.. So idk

Do you actually know what a "Spun Bearing" is or are you just using the term to describe normal rod knock?

 

[mk3-4-me]

Ya the bearing spins cause of material that's grinded away cause of low oil pressure... And when the piston gets pushed down, that material that was lost causes a lil gap and that when the rod comes down and hits the journal... Sorry for the messy description, lol but thats what a guy I work with explained to me because I asked him... And he builds 10 sec cars, and low 7 sec 500whp busa... Lol so I'm sure he knows what a spun bearing is... But I'm just satin that's what I went by...

And no the cross hatching marks weren't there anymore, that's y I took it back to him and told him to resize it... That's when he said he personally checked it and it's still in round... I wanted it resized trust me... I'll have to take it inso
Where else and see wat they say...

 

[IJ.]

The bearing touches the crank for whatever reason, usually no oil pressure this causes the locating tangs on the bearing flaten out and the bearing shell sticks to the crank and spins inside the Rod, if it's spun a bearing the rod HAS to be resized.

 

[mk3-4-me]

Ok well ya trust me that's what i thought! Lol I'll just take it in somewhere else then... And ya that's a better description of it... Lol

My bearing was toast though! I could feel a sharp edge on one side if I dragged my finder across it... Like only Is was really ground away! Lol

 

[IJ.]

Can you get a pic of the back of the dead bearing?

 

[Devin LeBlanc]

I would bring all the rods and the crank to another reputable machine shop and go .50 undersized. If its done properly there is nothing wrong with it, though you can hardly trust any machine shops now a days

 

[mk3-4-me]

well all my other journals are within spec, being .25 undersized... so im just havin hiom weld and regrind it to spec.

and yes ill get a pic when i get a chance.

 

[Devin LeBlanc]

Are you using stock rod bolts or ARP's?

 

[mk3-4-me]

eagle rods with eagle arp 2000's... i read a post somewhere where IJ recomends 55 ft lbs with 30wt oil. so thats what i went by, and i did 105 ft lbs for the arp mains with engine oil. what do you think about that?

 

[Devin LeBlanc]

I think that you should use ARP moly lube and go by the specs that came with them, and if your using ARP's they all need to be re sized.

 

[IJ.]

I would bring all the rods and the crank to another reputable machine shop and go .50 undersized. If its done properly there is nothing wrong with it, though you can hardly trust any machine shops now a days

Can't go that small on the journals without having the Crank reheattreated, the induction hardening on a stock crank is very shallow, only about 12 thou deep.

 

[mk3-4-me]

thats what i read to... so thats why im stayin .25 undersize... are there any stores that sell moly lube? i went to an advance auto by me and they dont have any...

 

[IJ.]

Castrol LMM grease IS Moly based and what I've used to assemble engines for 30+ years, 1/10th the cost of tubes in a 500gram tub.