Crank clearance issue

[86 t-tops]

So I’m trying to build a motor… first time for me…

I’m checking my crank clearance, using green plasti-gauge and it appears to be too tight…

.0015 inches on #1
.001 inches on #2
Less than .001 inches on #3, #4, and rear

It’s a stock 302 block, bored over to 306, and I’m installing a Probe Street Fighter 306 bottom end kit (28 oz balance) that came with the crank and bearings. I’m also using ARP bolts for the caps (torqued to 70 ft lbs as per ARP instructions).

From what I’ve read my options are the following,

1. Have the crank measured and turned .001 to provide me with the clearance needed.
2. Have the block line honed and check clearance again
3. Purchas some .001 oversized bearings to provide me with the clearance needed

I’m think of going with option three since it won’t require me taking the block into the machine shop.

I have a spec sheet on the crank and can post any info from that if necessary. Again this is my first attempt at building a motor, sorry if I’ve left any key info out of this post.

Any feedback is appreciated.

Thanks

[toofast306]

Are you sure you're reading the plastigauge correctly? I've never seen plastigauge accurate to 10,000ths of an inch.

[86 t-tops]

Are you sure you're reading the plastigauge correctly? I've never seen plastigauge accurate to 10,000ths of an inch.

I believe so but will try and post some pictures as well.

I was able to compare the thinkness of the plasti-gauge to the scale provided for #1 and #2 crank journals. The other three all had the plasti-gauge wider than the smallest measurement on the scale. This is why I said less than .001 of an inch as I'm not really sure what the measurement was.

I'll take pics and then try it again...

Thanks

[86 t-tops]

I've uploaded some photos for the plasti-gauge and placed them in an album called Clearance Issues. I don't believe I've done this wrong... plasti-gauge placed from front to back on each journal and the caps torqued down to the specs provided by ARP... again the crank and the bearings came in a kit from Probe...

[toofast306]

Is there any dirt or burrs on either the bearings or the block? Did you tap the bearings in with a hammer?
I had some dirt/debris issues with some of Probe's products in the past...

[Tailites]

is the clearance wrong on every journal?

[86 t-tops]

I have washed both the block, bearings, and the crank a couple of times, surfaces are smooth.

I did not tap any of the bearings with a hammer. Just pushed them while aligning the tabs on the bearings. Should I hit the ends with a hammer to ensure they are seated?

The clearnace on the #1 cap is tight but acceptable at .0015, the rest show not enough clearance (photos available in my albums).

Thanks for the help.

[Tailites]

dont hit anything with anything...bearings fit...period

if the tolerances are out...

then something needs either machining or a different size

[Blackmare]

Hope it's ok, linked the pics from your album to make it easier for the others to help you.

http://www.torontomustangclub.ca/forums/attachment.php?attachmentid=1260&d=1404355619

http://www.torontomustangclub.ca/forums/attachment.php?attachmentid=1259&d=1404355571

http://www.torontomustangclub.ca/forums/attachment.php?attachmentid=1258&d=1404355540

http://www.torontomustangclub.ca/forums/attachment.php?attachmentid=1257&d=1404355443

http://www.torontomustangclub.ca/forums/attachment.php?attachmentid=1256&d=1404355413

[ZR]

I'd have the crank miked and if ok, block align honed.

[86 t-tops]

Thanks for linking the photos... Have to figure out how to do that one day...

I won't hit anything with anything....

Going to double check the clearance before I do anything... Nothing is simple...

Perfect temp to take the t-tops off and go for a drive... Think I'll do that first...

Thanks

[86 t-tops]

Double checked my clearance again... placed plasti-guage across the entire lenght of the bearings... very similar results. #1 journal is .0015 while the others are all consistently the same width but too tight... just less than .001 inches of clearance.

Going to order a set of overzied bearings that will give me an extra .001 clearance and put me close to .002 clearnace in total...

[Tailites]

make sure the thrust bearing in the middle has the proper clearance end to end also

[Scott]

Double checked my clearance again... placed plasti-guage across the entire lenght of the bearings... very similar results. #1 journal is .0015 while the others are all consistently the same width but too tight... just less than .001 inches of clearance.

Going to order a set of overzied bearings that will give me an extra .001 clearance and put me close to .002 clearnace in total...

So I only have had one coffee so far today, but if your clearance is too tight and you are after additional clearance to get closer to .002, I think you are after undersized bearings, not oversize? What do the experts say that do this for a living?

[86 t-tops]

End to end clearance noted...

As for oversized or undersized bearings the way it was explained to me was the term relates to the crank... so oversized bearings are for an oversized crank since they allow for additional clearance. If you have a crank that has had the journals reduced in size, say by .001, then you get undersized journals since your journals are now smaller or undersized.

I found this a little confusing so I read several post about it over and over until it sunk in... not sure if it sunk in correctly but the bearings I've ordered will provide me with .001 clearance, which is basically what I need.