Problem with crank install on ka24de...

[kzracer]

have a 91 block that was untouched until i went to rebuild it with all stock components. went to install crank ground .050 under as it was scored pretty bad(from another engine). Crank spins perfect until center main bearing cap is tightened down close to torque specs. Then crank binds up and cannot move even with a large wrench on nose of crank.. all of the other main bearing caps are torqued to spec and crank spins free...torque down center bearing, crank binds. removed crank and bearings. Install original crank with std clevite bearings. Same issue happens. Crank binds when tightened on center bearing cap. Checked wear on center bearings for both sets (the original .050 under and the std size) and there is no wear from rotation on the block side center bearing, but there is wear on the girdle side center bearing. This is just from hand rotation, BTW. I checked the Girdle installed in block without bearings, and I found that number 1, 2, 4, and 5 main bores are not only perfectly flush where the girdle and block meet, but they measure 2.494" Center to center. Number 3 main bearing bore is different though. It measures 2.490" Center to center, and where the girdle and block meet at the parting surfaces, there is noticeable lip on the girdle.

Now the Question is.... Do I have the engine line bored to match the ID on the other Main bearing bores... Or do I junk the Block and start fresh...

[PapaSmurf2k3]

Could you try installing the ground crank with the standard bearings in only that 1 position? That should give you more clearance, no?

[kzracer]

thats a possibility... but sent crank off to machine shop to see what they say... good suggestion though and will keep in mind when I get block back...will post machine shop results in a couple of weeks

[PapaSmurf2k3]

Cool. Definitely let us know how you make out!

[kzracer]

Ok, after a looong 3 month wait... here is what I had done to the block. I had the top decked .010", I had new freeze plugs installed, and I had the shop Align hone the main bearing bores.... OK, but here is the good part. The shop had to send out the block to align honed because they didn't have the right hone to do it. Nissan KA24de main bearing bores measure very close to what I was getting, the shop said the the bores should be 2.497" in diameter, as you recall from my first post, the bores were 2.494" at the minimum. Since the shop didn't have that exact hone, they outsourced the job. Turns out that MOPAR small blocks all have the same main bearing bore diameter as nissan ka24de ones. So the mopar shop bored the nissan bores to dodge spec, 2.498". Got the block back, degreased the main bearing surfaces inside and out, degreased the original stock bearing shells, degreased the crank(original diameter, not ground, just micro-polished), and checked clearances with plasti-gage. After tightening the crank saddle down in the proscribed manner from the FSM, got a main bearing clearance of .0015" on the 4 outside main bearings, and got a center main bearing clearance of .0010". As I did not have time to final install the crank with assembly lube, I will find out if crank spins tomorrow. But so far so good, crank clearances spec out, so maybe some success later on Friday.

[PapaSmurf2k3]

Good deal. That sucks that it took so damn long.

[kzracer]

Ok... engine assembly problems continue.... Despite the fact that I had .001" clearance on the center main bearing, the problem of hand turning the crank when bottom end was buttoned up continued....AAARRGG! Ok, step back, what can cause this problem... a little google fu revealed that the crank was probably bent slightly. Didn't have a magnetic base dial indicator, so I ordered one from amazon for $26 delivered (got it in 2 days no less). Bolted it up to the block, ran the crank around supported by only the two end (front and back) main bearings. Lo and behold, runout on the crank on the main center journal was .00125", and with the bearing clearance only being .001" on the center main, that would explain the crank being frozen upon torque down. Now the process is to have the crank straightened... and here is an important question... is the Ka24de crank forged or cast? BTW, the second crank that I have (ground .050 under, with matching King bearings) is also bent, eff that machine shop, cause that crank is .0015" off center, as I tested both cranks because they both exibited the same binding. The saga continues...

[Harrythook]

Couple of really stupid questions. First the center (#3) main bearing is the thrust bearing, which in purpose eliminates end play when the crank is installed. Did you try installing crank with a normal main bearing in the #3 slot? Then check for rotational bind or drag?
Second is you stated you had the same issue with 2 different crankshafts. I am somewhat new to the KA motors but my experience is that when you have an issue with one part, and try another and end up with the same issue its usually not the part thats the cause.

Didn't have a magnetic base dial indicator, so I ordered one from amazon for $26

The one I use ran me around $400, but I am in the trade. Did you check runout on the rest of the mains?

There are many ways to determine if a crank is actually bent, and as stated I am a newbie with the KA so I dont know if this is a common occurrence. I do know that unsupported weight can cause deflection in a crank, by nature of counterbalance and design. And when your talking less than 1/1000 of an inch all sort of things can be going on there.

Just some thoughts.....

[PapaSmurf2k3]

I'm fairly sure the crank is forged.