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FE Power Forums => FE Technical Forum => Topic started by: DuckRyder on December 14, 2019, 04:33:52 PM

Title: Scat Crankshaft block interference - Subtitle “why can’t anything be easy"
Post by: DuckRyder on December 14, 2019, 04:33:52 PM
(https://photos.smugmug.com/photos/i-82nvgP9/0/7e871681/X3/i-82nvgP9-X3.jpg)

I seem to recall someone else having this issue, question is, how critical and will it affect the balance? Can I just make a couple of blocks to spin the crank on and decrease the outer diameter using a file of un married parents and then clean up the shavings really well, or do I need to seek out a machine shop to fix it?

Title: Re: Scat Crankshaft block interference - Subtitle “why can’t anything be easy"
Post by: philminotti on December 14, 2019, 05:36:02 PM
I had that exact problem.  Pond block and Scat crank.  I had the oil slinger flange turned down a bit on a lathe.  No problem.  But I do suggest doing it right, ie. on a lathe.  Pretty common area of interference.
Title: Re: Scat Crankshaft block interference - Subtitle “why can’t anything be easy"
Post by: philminotti on December 14, 2019, 06:20:11 PM
And one more thing... In my limited experience of building two FE's with nearly all aftermarket parts, nothing EVER fits like Legos.  Everything needs to be massaged.  Intake to oil pan, balancer to bellhousing!  Good luck.
Title: Re: Scat Crankshaft block interference - Subtitle “why can’t anything be easy"
Post by: DuckRyder on December 14, 2019, 06:24:24 PM
I’d be nice if something went my way every once in a while...

I guess I will go throw myself on the mercy of the only decent machine shop I know Monday, I expect he will be nonplused that I got this crank somewhere else, but maybe he will do it for me before christmas...
Title: Re: Scat Crankshaft block interference - Subtitle “why can’t anything be easy"
Post by: My427stang on December 14, 2019, 06:50:15 PM
I had one like that too, if you think you can shape it, go for it.  It's so close to centerline that the small amount you remove won't change balance

As I turned mine, the slinger was egg shaped, I wonder if they had a run that wasn't machined properly
Title: Re: Scat Crankshaft block interference - Subtitle “why can’t anything be easy"
Post by: DuckRyder on December 14, 2019, 07:12:37 PM
I actually think mine is egg shaped too... It’ll spin 3/4 turn...

If my guy will do it that is probably the best... you know I’m fumble fingers and that could be bad...
Title: Re: Scat Crankshaft block interference - Subtitle “why can’t anything be easy"
Post by: cjshaker on December 14, 2019, 07:48:51 PM
Since you'll be removing the same amount of material around a 360 degree radius, it shouldn't affect balance at all.
Title: Re: Scat Crankshaft block interference - Subtitle “why can’t anything be easy"
Post by: My427stang on December 14, 2019, 09:02:58 PM
Since you'll be removing the same amount of material around a 360 degree radius, it shouldn't affect balance at all.

They aren’t too big, they aren’t machined round, which means metal has to come off one side...after balancing.  Not enough to matter that close to centerline anyway
Title: Re: Scat Crankshaft block interference - Subtitle “why can’t anything be easy"
Post by: DuckRyder on December 15, 2019, 06:18:44 PM
Now that I'm actually looking at it, its obviously egg shaped, egregiously so...

I make the slot in the cap 3.48-3.50 and the slinger in the 3.30... range... but being off center... well you know the story...

If I have him turn it to the lowest spot it is going to be a vestigial oil slinger (in other words quite small) and I'm not sure if that is going to cause me any issues or not...

I suppose if I take 3.30-3.35 or so and cut it in half that will give the the radius and that amount from center line should work while leaving it egg shaped...

In other words small and round or somewhat larger and egg shaped.?.... Which is preferable...?

Bonus points if you can tell me how they get like that, seems like it would take real work to machine it elliptical... <shrug>

Title: Re: Scat Crankshaft block interference - Subtitle “why can’t anything be easy"
Post by: My427stang on December 15, 2019, 07:00:34 PM
As long as it doesn’t hit at either end of thrust it will be fine
Title: Re: Scat Crankshaft block interference - Subtitle “why can’t anything be easy"
Post by: philminotti on December 15, 2019, 08:03:45 PM
If you're anything like me, your rear main seal will leak either way. ;D
Seriously though, I noticed your crank is knurled... Did it come that way?  I bought my Scat crank in 2006 and it didn't have that.

Phil
Title: Re: Scat Crankshaft block interference - Subtitle “why can’t anything be easy"
Post by: DuckRyder on December 15, 2019, 08:22:14 PM
lol,

Yeah, I it didn’t leak a drop before so I’m sure it will this time.

It did come knurled so I guess that went my way...
Title: Re: Scat Crankshaft block interference - Subtitle “why can’t anything be easy"
Post by: Falcon67 on December 16, 2019, 11:24:57 AM
And one more thing... In my limited experience of building two FE's with nearly all aftermarket parts, nothing EVER fits like Legos.  Everything needs to be massaged.  Intake to oil pan, balancer to bellhousing!  Good luck.

LOL, not just an FE thing either.  One of the reasons when I decide to update the rotating assy, I'll buy the whole deal from a known vendor. 
Title: Re: Scat Crankshaft block interference - Subtitle “why can’t anything be easy"
Post by: pbf777 on December 16, 2019, 11:46:32 AM

If I have him turn it to the lowest spot it is going to be a vestigial oil slinger (in other words quite small) and I'm not sure if that is going to cause me any issues or not...

    No problem, as the slingers' intended propose was engineered in the time of the "rope" seal era.     ;)

Quote
In other words small and round or somewhat larger and egg shaped.?.... Which is preferable...?

     I would prefer to prior, particularly as the machining effort to the block, producing a professional and accurate result would be more difficult.      :P

Quote
Bonus points if you can tell me how they get like that, seems like it would take real work to machine it elliptical... <shrug>

      No, it's just Chinese   ::) 
   
      I imagine that the seal diameter may not be elliptical, but perhaps just machined off center from the main journals, as this surface is machined earlier in the roughing process, and apparently the crankshaft is re-fixtured for the cutting/grinding of the mains, and not replicating the previous effort.      :o   


     Scott.
Title: Re: Scat Crankshaft block interference - Subtitle “why can’t anything be easy"
Post by: frnkeore on December 16, 2019, 12:39:48 PM
What needs to be done here, is to take the crank to a regular machine shop and have them put a 20 deg chamfer, on the back side (flywheel side) of the slinger, of about 1/2 the width of the slinger.
Title: Re: Scat Crankshaft block interference - Subtitle “why can’t anything be easy"
Post by: frnkeore on December 16, 2019, 12:43:13 PM
Let me add:

Take the picture of this, to the machine shop and he will know, just what your problem is and just what to do.
Title: Re: Scat Crankshaft block interference - Subtitle “why can’t anything be easy"
Post by: My427stang on December 16, 2019, 01:49:14 PM
I would certainly ask the machinist, but I would not necessarily turn it round again.  Everyone has a technique, but a chamfer like Frank says, working the high spot just enough to miss, etc.  This isn't a huge deal, my gut says that it skipped a minor machining process.  The one I had was a quick and easy fix
Title: Look at where the knurls are in relation to possible seal surface..
Post by: mikeelikee on December 17, 2019, 12:45:00 PM
is this crank offset improperly?
Title: Re: Look at where the knurls are in relation to possible seal surface..
Post by: blykins on December 17, 2019, 12:50:19 PM
is this crank offset improperly?

The lip of the seal actually rides toward the front of the engine so the knurls are not misplaced.
Title: Re: Scat Crankshaft block interference - Subtitle “why can’t anything be easy"
Post by: DuckRyder on December 17, 2019, 05:04:13 PM
It is at the machine shop...

Title: Re: Scat Crankshaft block interference - Subtitle “why can’t anything be easy"
Post by: DuckRyder on December 20, 2019, 05:32:00 PM
Things you’d rather not hear your machinist (or Doctor) say:

"It was really bad"
Title: Re: Scat Crankshaft block interference - Subtitle “why can’t anything be easy"
Post by: My427stang on December 21, 2019, 08:36:32 AM
Things you’d rather not hear your machinist (or Doctor) say:

"It was really bad"

Certainly when things are measured in thousandths it was likely off by tenths, but despite it being shoddy and not right, the slinger isn't a critical dimension like a journal.  When you get it back you should be off to the races. 

FYI - Although I have always liked FM bearings and generally start with them for the rods, I have found them loose lately.  When you check your rod clearances, if you don't like them, consider a set of narrowed Clevites.  I strayed from Clevite a long time ago, but their numbers seem to be coming in better than the FMs on the BBC stuff
Title: Re: Scat Crankshaft block interference - Subtitle “why can’t anything be easy"
Post by: DuckRyder on December 21, 2019, 08:58:24 AM
I have the crank back, though I haven’t pulled it out and re-cleaned it yet.

I’m hoping Sunday for getting back to work on it.

They had a factory 390 (or 360) crank in the shop so he made the oil slinger identical to the OE crank except that it turned out slightly smaller in OD, I’m fairly confident it should be fine from here on.

I have Clevite for the mains, but still King for the rods, if for some reason they come out off on clearance, I’ll try the Clevite.

I will give SCAT the credit on the crank that the mains and rods were all very concentric I checked all of that, just haven’t gotten around to the rods themselves.

Edit To Add: Big props to Scotts Machine Shop in Fayetteville GA for fixing this and fairly quickly. Theses guys always do a good job if you need something in the ATL area.