Clearance issues...

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lbhsbz

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« Reply #50 on: May 11, 2011, 11:11:52 AM »
Brad you need to determine the main journal diameter before it can be shown whether the journal has been properly cut or if it is actually undersize as originally believed. The actual dimensions will determine the path taken. Regardless, it is fixable. Anything may be fixed in a machine shop.  8)
Getting back to the point as originally perceived and discussed (debated) by me and your reply: If in fact the mains are 0.027" undersize, then whether they provide any clearance or not on paper is moot and the reference data you provided is too-little-too-late. The fact is that if there is a measured 0.0015" of clearance and IF the journals are -0.0027" then simply turning them to the high side of specification would give the main clearance desired by the OP.  It really IS that simple. Ever hear of the K.I.S.S. method?   We are building a day cruiser engine, not a swiss watch F1 engine.

LO
Yeah, I know, but if we start with high aspirations chances are better that we'll end up with something that stays together then if we start with compromises.  Might as well do it right the first time, then there won't be a second time.


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Nordie

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« Reply #51 on: May 11, 2011, 11:58:10 AM »
I gotta bribe HomeBlown57 to come back over with his micrometer and measure my parts.



.....someone better run with that one.

it's a good thing i read things literally, and dont hardly ever catch the hidden motive  ;) I would recommend Ron as well! Seems like he knows what he's doing  ;) Pun intended, or not!


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lbhsbz

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« Reply #52 on: May 11, 2011, 12:05:35 PM »
it's a good thing i read things literally, and dont hardly ever catch the hidden motive  ;) I would recommend Ron as well! Seems like he knows what he's doing  ;) Pun intended, or not!

So...then one could assume that Ron knows his way around Brad's parts?

Nordie

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« Reply #53 on: May 11, 2011, 12:09:56 PM »
Like the back of his hand  ;D  ;)  :thumbup:

Brad also knows that ron enjoys Diet Dr. Pepper whatever that means


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lbhsbz

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« Reply #54 on: May 11, 2011, 12:33:50 PM »
The carbonation makes his parts tingle.

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« Reply #55 on: May 11, 2011, 12:34:51 PM »
Carb KLEEN makes his parts burn! But cleans them thouroughly


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lbhsbz

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« Reply #56 on: May 11, 2011, 08:42:05 PM »
So brad...did you find your tape measure to get a size on that crank?

lbhsbz

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« Reply #57 on: May 25, 2011, 12:34:28 PM »
Updates?

Brad @ SCJB

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« Reply #58 on: May 25, 2011, 12:39:08 PM »
nope.....i still havent had a chance to get HomeBlown57 over with his bore gauge and mic's

i got bored the other day and threw some plasti-gauge in the mains...... they came out to .002

i gotta figure out if its the block or the crank.....because different shops did each one......so ill be sending the wrong piece to the shop that did the work.
  • Boat #1: 1978 Liberty
  • Boat #2: 1982 Eliminator Sprint

lbhsbz

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« Reply #59 on: May 25, 2011, 12:58:24 PM »
I once threw plastigage in a .020 over bearing with a .010 under crank....said I had .0016" clearance when in reality I had .007" interference.  Plastigage is worthless.....

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« Reply #60 on: May 25, 2011, 01:01:01 PM »
Plastigage is worthless.....

I agree with you....it was purely out of curiosity.
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« Reply #61 on: June 01, 2011, 01:27:26 PM »
HB57 just came by and we measured everything out. the block is off on mains 4 and 5. 1-3 are good.

Heres what we got:

Crank Main Journals are all consistently 2.71875 ( about .0032 over from std)

Block Bores are as follows: (Should be 2.937-2.938)

1 = 2.9375
2 = 2.9375
3 = 2.9375
4 = 2.9360    <-- the cap they replaced
5 = 2.9365

we put all 4 sets of bearings in the #1 main and torqued them down and they all came out to 2.7205 (0.00175 clearance), except one set was 2.7210.

I'm gunna take the block back to the guy tomorrow and tell him to fix #4 and #5

then I'll get a set of .030x's (if i can find them). that will give me about .00275 clearance if they get #4 and #5 to match 1-3.

  • Boat #1: 1978 Liberty
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Luckie Stiff

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« Reply #62 on: June 01, 2011, 01:37:28 PM »
Good news. Even though you're in the "acceptable" range on 4 & 5, good call on getting that shit taken care of. Big River?
"Don't you realize that there are already enough people in the world to hate without you putting so much effort into giving me another?"

HomeBlown57

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« Reply #63 on: June 01, 2011, 01:54:44 PM »
Lucky,
What do you mean by "acceptable range" on 4 and 5?

lbhsbz

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« Reply #64 on: June 01, 2011, 02:06:21 PM »
Picking nits here, but you've got to work the numbers right to understand what's really happening.

If your crank measures 2.71875, the it is exactly .0302" UNDERsized....which is close to perfect.

The block disturbs me.  I'm not sure how they did what whey did and ended up with different diameters without dicking up several more aspects like alignment (between all the journals as well as main bores going straight Down the block.  Did you measure to the cam bores at each end of the block?


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« Reply #65 on: June 01, 2011, 02:06:37 PM »
skip. if i get 0.031 bearings, that will give me .00275 clearance on 1-3 which is a little on the tight side, but close enough......if i dont fix 4 and 5, that will give me .00175 on #5 and .00170 on #4. WAY too tight.

thus not in an acceptable range. ;)
  • Boat #1: 1978 Liberty
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« Reply #66 on: June 01, 2011, 02:09:24 PM »
Pat: no, we didnt measure anything with the cam. ......and thanks for the undersized correction. I'm still getting the hang of all this....and im a little dyslexic to boot.  :screwy:
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lbhsbz

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« Reply #67 on: June 01, 2011, 02:18:43 PM »
Before letting anyone fix anything, you've got to measure the crank to cam centerline distance at both ends of the block.  Line boring a block twice will most likely result in excessive timing chain slop.....you can get .005 and .010" undersized chains, but depending how far they moved up the crank centerline....even those
Will be to long

IRRebel

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« Reply #68 on: June 01, 2011, 02:33:04 PM »
Do you think that maybe they line bored it BEFORE changing out the cap(s) (discovering it was bad) and didn't do so after that? Be willing to bet both #4 and #5 were replaced.......I'm with Pat, can't figure how they physically did that...... :screwy:

Good job catching it though!  :thumbup:
Ray
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« Reply #69 on: June 01, 2011, 02:50:09 PM »
Lucky,
What do you mean by "acceptable range" on 4 and 5?

My bad, I had a moment of dyslexia there.  :banghead:
"Don't you realize that there are already enough people in the world to hate without you putting so much effort into giving me another?"

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« Reply #70 on: June 01, 2011, 02:52:05 PM »
skip. if i get 0.031 bearings, that will give me .00275 clearance on 1-3 which is a little on the tight side, but close enough......if i dont fix 4 and 5, that will give me .00175 on #5 and .00170 on #4. WAY too tight.

thus not in an acceptable range. ;)

Yeah, I did bad math, it's been a looooooooooong 5 days filled with lots and lots of yellow bellies, I think my brain is starting to work again...
"Don't you realize that there are already enough people in the world to hate without you putting so much effort into giving me another?"

lbhsbz

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« Reply #71 on: June 01, 2011, 03:30:13 PM »
Before you ask him to fix it, ask him how he plans on fixing it...and more importantly, how did it end up like this in the first place.  Ask him what to do about the timing chain lenght issue?  Ask him how out of round those bores will be?  I'd stand there and watch him, because I'm willing to bet he's gonna go at with a flap wheel on a die grinder if you leave it with him, and while the thing might measure out OK, it won't be anywhere near round.  Also, before you bring it back to him, bolt the rear cap down again and see if the thrust surfaces come close to lining up with those on the block.  There is a lot involved in swapping caps and line bore/honing a block....you have to look at all of the things that can possibly go wrong, and have the "machinist" explain what steps he will take to prevent these things from occuring.  If you're not happy with his answers, take your shit elsewhere.  If he makes you feel stupid while you're asking him questions...take your shit elsewhere. 

I'm not posting all this because I've had "experiences" with automotive machine shops, I'm posting this because I don't want to see you waste more time, and possibly money, and end up with something that's the same or worse. 

I'd almost be inclined not to return the shop that let something like this out the door.  The money you paid him...well, chalk it up to the price of education. 

Understand that:

when they do work on the mains, they have to first machine a small amount off of the bottoms of the caps to make the holes smaller, but they also go out of round.  After all the caps are torqued back on, the mains are bored, but you can't move a hole, keep it the same size, and keep it round, so the machining procedure involves an interupted cut, which encourages tool deflection, which makes the hole even more not round and screws up the finish.  Additionally, with a boring bar as long as it needs to be to do the job, it too will flex.  It is not a "set it and forget it" operation.  It requires a real machinist who can monitor and make changes during the process to keep things going smoothly, not just a guy who knows how to machine stuff.  This is why a lot of shops don't deal with main bore work...cuz it's a pain in the ass.  The shops that DO still deal with it either have no clue how/are too lazy to properly do it, or are very expensive because all that attention to detail and time costs $$.  And regardless of who does it, the crank centerline moves a little closer to the cam centerline every time you do it...so generally after having been done (especially poorly) once, it'll make a good boat anchor, since the timing chain will have enough slop to hook your shackle too.

« Last Edit: June 01, 2011, 03:34:36 PM by lbhsbz »

IRRebel

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« Reply #72 on: June 01, 2011, 03:43:44 PM »
All that being said, and true, would that not also screw up the bore centerline being perpendicular to the crank centerline?

What can be done about it?  ???

Ray
"Life's journey is not to arrive at the grave safely in a well preserved body, but rather to skid in sideways totally worn out shouting 'Holy Shit what a ride!"---Crewcheif22 AKA Keith

lbhsbz

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« Reply #73 on: June 01, 2011, 04:19:21 PM »
All that being said, and true, would that not also screw up the bore centerline being perpendicular to the crank centerline?

What can be done about it?  ???

Ray

Measure it up and see if it's fixable, if not, stop wasting time and money and find a new block that doesn't need main bore work.  They're out there...I had one.  The mains were untouched and perfect.  took me 4 blocks to find it.

HomeBlown57

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« Reply #74 on: June 03, 2011, 07:32:51 AM »
This is a sincere question coupled with my opinion. I can't imagine the machine shop removing more than .005 from the caps to begin the process. (could be wrong) after honing back round this should only raise the crank .0025. I don't know what they use to register the new crank centerline. I just can't believe that .0025 would matter. I wonder how much the block moves and mishapes during operation. Agreed, if you start in the wrong place it probably won't get better. BUT, I  would rather have round holes .0025 higher than an out of round hole in the wrong spot. As for lining up the bores with the "NEW" crank centerline .0025 (new crank location) at 45 degrees (new crank location in regard to the existing cylinder centerline) at 7" (rod plus pin height) is about .020 degrees.
My opinion;
I have a tough time swallowing .020 degrees having ANY impact on anything.
My question;
Does this amount really matter?

On the other hand, I do see the impact of having a loose timing chain. Although, if we run the calcs on a 3" timing gear moving the crank .0025 only results in less than 1/2 a crank degree. When degreeing a cam I am always satisfied if I am within 1/2 a degree. If you subscribe to the theory that the cam will use the play in the chain (rotate forward and backward based either on the the chain springing or valve springs pushing the cam forward) the most impact that could have is 1 degree total.

Ok, I'm done.

 


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