Frank, are you sure you don't want to be a profesional engine builder? I think the world would benefit greatly <img src="/forums/images/graemlins/lol.gif" alt="" /> <img src="/forums/images/graemlins/kewl.gif" alt="" /> Nice catch <img src="/forums/images/graemlins/cheers.gif" alt="" />

I wonder how accurately Frank's eye can measure tolerances and how accurately Frank's arms can measure bolt torque.

Should be darn close by now!

He better get it right, because I'm going to go on strike if I have to take that engine out again. <img src="/forums/images/graemlins/lol.gif" alt="" /> <img src="/forums/images/graemlins/cheers.gif" alt="" />

I almost followed him in the same mistake.

When I picked up the parts, he mentioned that he had torqued the mains to 48 lb-ft, but it didn't set off alarm bells at the time, so when I installed the crankshaft, I torqued it to 50 lb-ft. Sometime over the next few hours, I started wondering and first checked the OE bolt torque and was reminded it was 55-61 lb-ft.

That seemed ok at first glance, since it roughly compares to 48 lb-ft with moly lube, but then I realized it couldn't be right because the benefit of the main studs is the ability to increase the clamp strength - so I checked the ARP website for recommended torque on a 12mm 190k psi tensile strength fastener and found the 86 lb-ft value. After I stopped shaking <img src="/forums/images/graemlins/lol.gif" alt="" /> I called the machinist and to his credit, he immediately asked me to bring it back.

I don't like the delay, but it may provide a chance to massage the girdle and bores for a tighter clearance. A loose engine will make more power, but I'd rather have the main clearance between .002-.0025" if possible.

Anybody can make a mistake, so I'm not too upset - I'll see later today what he's able to do with it.

Frank

Frank,

I have had a similar problems with getting the mains done.

With the mains now properly torqued, ask the shop to shoot for the minimum number on the spec (not so easy to do).

To make the bore clean up all the way around it ends up to big since you canÆt bring the edges in. If you hit the max number the bore ends up round and pretty with the sides cleaned up but you can have too much clearance when assembled.

The only thing that works is a mild egg shape. It's only at the far edges. The bearings have this same taper to avoid pinching as the housing flexes.

Basically on a line hone / line bore the sides of the bearing bores are going to be large no matter what to get to the housing right verticly. ThatÆs OK since the loading horizontally is minimal.

In my experience if they hone the bore to the max number thatÆs in spec you can still end up with too much clearance on the mains. Granted the spec only allows for about .0005" of tolerance but in my experience that adds directly to your bearing clearance.

If you have a crank that's been polished itÆs likely that itÆs a couple of tenths under where it started. Combine that with max sized housing bores and you have a tolerance stackup that gets your mains out of spec or to the high side.

Getting the block done again should help; again ask if they can go to the low side of the spec. There is not a lot to work with. All you care about is the up and down dimensions.

I know on some motors they have select fit bearings available, does yours? On engines that donÆt have select fit bearings I have fine tuned the clearance by sending the crank out for ion nitriding. It takes about a two weeks to turn the part around costs about $120 and the crank should be lightly polished when you get it back.


It also adds about .00015ö -.0003ö per surface. Since there are two sides to a journal that drops the clearance by .0003ö-.0006ö and gets you a super tough bearing surface. I donÆt know if your crank is hardened or not or if you have select fit bearings available. I also have used coated bearings with good results. Get the clearances right without the coatings. The coatings thin out and burnish in on the vertical surfaces (they end up super polished and shiny) but stay close to full thickness on the sides.

Kevin

The factory bearings are select fit. They also have unified sets since most techs do not bother with the selection process.

Thanks guys - I think (hope) all is now ok.

The machinist just called and said he removed the crankshaft, cleaned off all the assembly lube, torqued down the girdle to 86 lb-ft and checked it with the bore gauge. It stayed exactly where he had honed it with no further bulging at the parting lines.

Next, he installed the crankshaft dry with plastigauge, retorqued to 86 lb-ft and checked the oil clearance. He says it's .0015-.002, with an average of .00175..... that's dead-on perfect to me. <img src="/forums/images/graemlins/kewl.gif" alt="" />

He's left the plastigauge on it for me to see, so I'm off to pick it up now.

The refreshing thing is that he said he felt really foolish about it. He didn't know how he arrived at that 48 lb-ft torque value and thanked me for calling him on it. I guess he values his reputation and really does try to do good work. <img src="/forums/images/graemlins/kewl.gif" alt="" />

Frank

This day has gone from sh*t-to-sugar in a big way. What I saw at the machine shop was really purty...... looked like .00175 on every main journal to me, so we installed the girdle and torqued it down while I was there and I brought it home to continue the checking.

One of the reasons I was originally showing .003" main clearance was the initial torque value.... but the other was because I was using 2 year old Plasti-gauge that had gotten brittle and dry, so I got a new pack for checking the rod journals.

First, the "stuff" - Wiseco forged pistons with full-floating pins/wire clips and 3SX H-beam rods with ARP-2000 bolts:


The stuff assembled:


The test fit on the rod journals was amazing...... every one... all six.... showed within a whisker of .0015" oil clearance:


That's about as good as it gets, and I think I like this machinist a lot. <img src="/forums/images/graemlins/kewl.gif" alt="" />

Frank

Those are some nice looking parts!!!!

I like part pictures!

Nice work Frank!