Im building a GSR engine with a LS crank. Crank has been balanced and micropolished. Block mains are untouched.

Block codes: (1) D D C D D (5)
Crank codes: (1) 3 2 2 2 2 (5)
Bearing Colors: (1) Black, Brown, Green, Brown, Brown (5)

So I ordered the oem bearings and plastigauged them to be certain everything is in spec. Turns out everything is really tight. Tighter than I like on a turbo motor.

Clearances: (1) .0010", (2) .0010", (3) .0012", (4) .0010", (5) .0010"
And thats with a crappy plastigauge, +/- a few ten thousandths.

[spec range]
Mains 1,2,4,5: .0009 - .0017"
Main 3: .0012 - .0019"

I thought using the codes would give me middle of the spec range clearances? I usually aim for the loose end of the range for a turbo motor. To get that I'd have to use the thinnest Honda bearings to get near the loose end of the range. But that sucks, it means I have to order all new bearings and ditch these. Whats the point of even using the codes? What do you guys think?

 

Clerances on the tighter side of the range generally make for a longer lasting engine. They're the main bearings anyway, all they do is support the crank while it spins. The rod bearings are the ones that really take a beating.

If you wanted a specific clearance you should've had everything measured while it was at the machine shop, before ordering the bearings. That's basically all blueprinting is.

 

Your assumption is correct about the sizing being in the middle of the range.

Are you using main studs or the OEM bolts? This could affect your readings.

Also did you use lubricant on the bolts or studs while torquing?

Did you have the bearings in correct and make sure everything was super clean?

Was the block and the crank the same temperature?

 

1.) Original main bolts, how many times can they be retorqued?
2.) Using ARP Moly lube on the threads and washers. main caps 1, 5 (56ftlbs), mains 2,3,4 (49ftlbs)
3.) Yes Im pretty sure the bearings were in correct. The mains and journals were cleaned by hand with paper towels and brake cleaner.
4.) All parts are being built in a room that is about 60*F and have been there for weeks.

So im fairly sure all the measurements are not skewed. And all of them are consistently tight too.

 

First off you are not supposed to use moly lube on the OEM mains when torquing. Use regular oil.... this might be the reason why, you could be overtorquing.

OEM mains are like headstuds. They are supposed to be replaced during a rebuild.

 

Also, do you know if your torque wrench has a good calibration?

 

This is the 3rd time this engine has been rebuilt over its life so maybe its time to invest in main studs. The torque wrench is just a regular craftsmen wrench about 3 years old. I take good care of it tho. I dont even know where I could get it calibrated.

 

Well I am applying my thinking to headbolts vs. studs.
With normal bolts if you apply moly you WILL shoot past the correct torque that you actually want. The bolt will move too smooth. Honda has already calculated the friction loss from not using a moly lube....

 

If you send me your torquewrench I can check the cal. I should be able to cal it too if needed....

 

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by 91SiZ6 &raquo;</TD></TR><TR><TD CLASS="quote">Clerances on the tighter side of the range generally make for a longer lasting engine. They're the main bearings anyway, all they do is support the crank while it spins. The rod bearings are the ones that really take a beating.

If you wanted a specific clearance you should've had everything measured while it was at the machine shop, before ordering the bearings. That's basically all blueprinting is.</TD></TR></TABLE>

You might want to rethink this theory.

 

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by PHDZINE &raquo;</TD></TR><TR><TD CLASS="quote">

You might want to rethink this theory.</TD></TR></TABLE>

Let him run it that way..... it is only a z6 anyway....

 

Alright I cleaned the moly lube off all the main bolts and thoroughly cleaned out the holes. I used motor oil this time and it was still tight.

I bought a set of ACLs which of course are equal to Honda Green bearings. Those brought the clearances further from the tight end but still tight (.0012~.0014). I guess Im going to have to order pink and reds. I dont get this.

Anybody want to buy some unused bearings

 

tepid1 is right about the arp/oil thing.I wouldn't use main studs with what your doing.You could replace with new oem bolts but its probably not necessary.If the block is cold , the clearances will measure small.Everything should be around 70 degrees (and not sitting on a cold garage floor).If the acl's measure .0012-.0014" with plastigage I'd say your good to go.I never comfortable measuring tenths with plastigage.

 

It's generally accepted that tighter clearances are for better reliablity and looser is for for higher reving. The crank spins on the mains but the rod journals take the vast majority of abuse so the extra clearance provides more oil for a "cushion". When I said "on the tighter side" I thought it was obvious that I meant the tighter side of OEM specs...maybe not. If you disagree, feel free to explain why. I used a .0015" clearance on all of my bearings for a middle of the road clearance. Only time will tell how long it lasts.