Author Topic: deck height measured over the pin differant side to side?  (Read 660 times)

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Offline 1340evo

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deck height measured over the pin differant side to side?
« on: May 01, 2021, 11:12:11 AM »
Anyone had this, I can't find a spec. in the manual but its ".005 differance on the front cylinder and ".006 differance on the rear cylinder?
Although looking at the pistons, they are contacting in the bores at 12 and 6 ??


Online Ohio HD

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Re: deck height measured over the pin differant side to side?
« Reply #1 on: May 01, 2021, 11:30:45 AM »
No spec that I know of.

But now all you have to do is figure out is the crank out of squire to the deck, are cylinders not parallel top to bottom, the piston bin bore not parallel to the piston crown, bent rod, rod big and small ends not parallel to each other. Also is the difference the same at the piston when at the bottom of the bore.

So, 0.005"? I wouldn't even be concerned unless you can verify that the piston skirt isn't parallel to the bore during it's travel top to bottom of the cylinder. The piston crown only needs to not hit anything. Of course if you find out it's the piston crown, then you only need deck the piston square to the pin bore.
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Offline 1340evo

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Re: deck height measured over the pin differant side to side?
« Reply #2 on: May 01, 2021, 11:49:00 AM »
At the bottom, best I can do is square the ends of the old pins in the lathe, put a bolt through them both and bolt them together in the small ends to get them straight  :teeth: it slides through so guess it's in-line. But at the bottom, because of the clearance in the bearings and the length of the rod, it shows fine to the machined surface.... ??

Just put a piston in the bore off the engine, and I can get about .008 pushing it side to side.. but its hard to measure?, measure at 90 deg to this over the thrust faces and it hardly moves anything.

Online Ohio HD

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Re: deck height measured over the pin differant side to side?
« Reply #3 on: May 01, 2021, 11:58:04 AM »
To blue print a motor you have to start at the beginning. Otherwise you're just working through all of the factory tolerances and wear that the miles created.
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Offline kd

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Re: deck height measured over the pin differant side to side?
« Reply #4 on: May 01, 2021, 12:08:42 PM »
I donít think putting the gauge block on the piston is the best way to measure. If you use the cylinder deck for the block it will be a more true surface. Measure both sides and see what you get. Expect about .001 or so. It probably wonít be perfect.
KD

Online SP33DY

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Re: deck height measured over the pin differant side to side?
« Reply #5 on: May 01, 2021, 12:38:38 PM »
I check the rods for straightness at the crankcase deck using a long gage pin.

I got them from Vermont Precision Tools. 0.7910" x 6.500" for Evo, and earlier engines,  0.9270" x 6.500" for TC and M-8.

Offline 1340evo

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Re: deck height measured over the pin differant side to side?
« Reply #6 on: May 01, 2021, 12:42:20 PM »
To blue print a motor you have to start at the beginning. Otherwise you're just working through all of the factory tolerances and wear that the miles created.

The bottom end has just been re-built with all new bearings, so should be right.

I've tried it both ways with the stand on the piston measuring the deck, and with the stand on the deck measuring the piston.. same both ways...

Online Ohio HD

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Re: deck height measured over the pin differant side to side?
« Reply #7 on: May 01, 2021, 12:49:57 PM »
To blue print a motor you have to start at the beginning. Otherwise you're just working through all of the factory tolerances and wear that the miles created.

The bottom end has just been re-built with all new bearings, so should be right.

I've tried it both ways with the stand on the piston measuring the deck, and with the stand on the deck measuring the piston.. same both ways...

I think it was T-Man that stated in an article, he never saw a factory crank shaft bore to deck surface in a Harley that didn't need to be corrected. So just putting bearings in a motor only puts it back to the factory tolerances at best.

You can check the rod against the deck as SP33Dy said, But it only gives you that measure of one degree out of a 360į rotation of the crank.

As KD stated, there will be some variation, and the measuring technique is crucial to getting it right. The cylinders need to be bolted to the case, and a solidly attached indictor mounted on the cylinder as the fixed surface.

Also if the crank isn't trued correctly, you'll see issues with parallelism.


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Offline 1340evo

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Re: deck height measured over the pin differant side to side?
« Reply #8 on: May 01, 2021, 01:09:54 PM »
yes, I think you ar right. Using plastic pipes to hold the cylinders down is not working. Also putting the gauge on the pistons not the best as they are not exactly flat.
I'm off to make some Ali spacers and a better gauge mount so I can do it like you show abouve.
I've just re-done it from the cylinder top and did get it out side to side, but only by .003

will get some better gear made first....

Put this post on hold ;)

Offline kd

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Re: deck height measured over the pin differant side to side?
« Reply #9 on: May 01, 2021, 01:55:48 PM »
The plastic fittings are OK to use. Tightened down is tightened down and the plastic has less chance of scarring the cylinder gasket surface.  Lots of us use the plastic fitting including me.  Some of us also made the tool like Ohio showed in his pic.  Most deck tools are large fur auto use and too bulky to fit the twin cam use.
KD

Offline 1340evo

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Re: deck height measured over the pin differant side to side?
« Reply #10 on: May 01, 2021, 02:07:39 PM »
okay, checked from the top of the cylinder, it's just under .004 side to side differance on both... guess thats not bad ??

Has anyone ever checked both sides, or is it just me thats anal :)

Offline 98fxstc

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Re: deck height measured over the pin differant side to side?
« Reply #11 on: May 01, 2021, 02:32:25 PM »
I was about 0.004" side to side on my twincam when I did my rebuild
I had a Darkhorse crank which I checked at 0.0001" so I figured the crankshaft bore was not square to the deck but I would live with it   :dgust:


Offline 1340evo

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Re: deck height measured over the pin differant side to side?
« Reply #12 on: May 01, 2021, 03:08:43 PM »
yes, they re-built my crank and measuring the pinion they said it was just in limit at .0015... TBH, I measure it better than that, but will have implication... mind you, its better than it was at somethink like .018 LOL

I've mailed them and see what they say.. its the best builder in the UK so knows what he's doing.. guess sometimes things are not made 100% in the first place ... I'm happy at 0.10mm especialy as it's rubbing up on the thrust faces and no where else...

Offline wfolarry

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Re: deck height measured over the pin differant side to side?
« Reply #13 on: May 02, 2021, 06:07:02 AM »
I wouldn't worry about .005.
If you really want it to be less have the gasket surfaces cut. It's not unusual to see the liners move or the gasket surfaces not true on a motor that has some miles on it.

Offline 1340evo

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Re: deck height measured over the pin differant side to side?
« Reply #14 on: May 02, 2021, 07:51:27 AM »
I'm thinking is the rod end bent a bit as .004 over that distance, I'm sure it would bind up?

Online Ohio HD

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Re: deck height measured over the pin differant side to side?
« Reply #15 on: May 02, 2021, 08:02:37 AM »
You said a guy just rebuilt the lower end, and that he's the best builder in the UK. Wouldn't he have checked the rods for being bent while rebuilding the crank?

I think you're way over thinking all of this. You're most likely seeing the factory stack up of tolerances.
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Offline kd

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Re: deck height measured over the pin differant side to side?
« Reply #16 on: May 02, 2021, 08:31:57 AM »
If this builder is as good as you say he's probably a busy guy.  He also may record his measurements and could still have them.. The fact that the front and rear combustion chamber volumes match up with different deck and head CC measurements (remind him of that) makes more sense now.  I wouldn't be surprised if it was a purposeful calculation and the way he reached his goals without extra machining.

Like the others are saying, the tip in the deck measurement across the wrist pin could be engine case deck surface machining, case distortion, and line bore for a few. If it has performed without catastrophic failure up to this point, and the fact that both pistons have the same deviation, you could take the average between the left and right + & - measurements and use that for your quench calculation for  head gasket thickness choice and feel comfortable they are even in both cylinders. The valve pockets are front and rear so the only other concern may be the cam lift and valve size if you are changing them. I think it's great that you are doing all of this.  It is always best to check everything before assembly.  You will know what you have and be more comfortable with it in the long run.
KD

Offline 1340evo

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Re: deck height measured over the pin differant side to side?
« Reply #17 on: May 02, 2021, 08:32:05 AM »
Yes, I'm sure he did and I'm sure you are right. He re-honed the rod bottoms, fit new pin, did bearings both sides and timing chest bearing. Balances and trued the crank to the pistons... I've mailed him so see what comes back... .004 may be what they work to??

He only did the bottom end and didn't assemble the cylinders as I wanted to paint them first. But he will have the measurements for sure.
Yes, its been with him 5 months!!

Also .004 on the top, becomes .0026 on the sides ;)
« Last Edit: May 02, 2021, 09:44:21 AM by 1340evo »

Offline 1340evo

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Re: deck height measured over the pin differant side to side?
« Reply #18 on: May 04, 2021, 10:57:17 AM »
they think .004 is okay over the piston top?

Anyone else had experiance of this??

Online jsachs1

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Re: deck height measured over the pin differant side to side?
« Reply #19 on: May 04, 2021, 01:48:29 PM »
I'm thinking is the rod end bent a bit as .004 over that distance, I'm sure it would bind up?
If you're nervous about a bent rod. Use or make a mandrel wider than a wrist pin, with the same OD as the wrist pin. Install in small end of the rod. No cylinders on the case. Rotate the flywheels until the mandrel touches the case top. You can use thin feeler gauge strips under each side of the mandrel to see if its contact to the case top is equal. If NOT: than use a thicker or thinner feeler gauge to find the difference on the side in question.
If the rod is bent, you can straighten it easily. Look in the "Home Made Tools Section":. I think I have a picture of a rod straightener I've made back in the day.
John

Offline 1340evo

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Re: deck height measured over the pin differant side to side?
« Reply #20 on: May 04, 2021, 02:20:49 PM »
I'm thinking is the rod end bent a bit as .004 over that distance, I'm sure it would bind up?
If you're nervous about a bent rod. Use or make a mandrel wider than a wrist pin, with the same OD as the wrist pin. Install in small end of the rod. No cylinders on the case. Rotate the flywheels until the mandrel touches the case top. You can use thin feeler gauge strips under each side of the mandrel to see if its contact to the case top is equal. If NOT: than use a thicker or thinner feeler gauge to find the difference on the side in question.
If the rod is bent, you can straighten it easily. Look in the "Home Made Tools Section":. I think I have a picture of a rod straightener I've made back in the day.
John

Hi, thanks. I did that as I say above, but using the 2 old piston pins bolted together LOL.. it worked... ansd it was fine although you can kind of get it to read what you want due to play in the rod. The builder checked this also and said it was fine. He just didn't check at full stroke the other way?
At .004 he's saying there is no problem and to run it.. do you agree?

Online jsachs1

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Re: deck height measured over the pin differant side to side?
« Reply #21 on: May 04, 2021, 02:46:08 PM »
Short answer- Yes, it's a Harley. Mine, I'm anal, I'd straighten it, cause I can. :smile:
John

Offline 1340evo

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Re: deck height measured over the pin differant side to side?
« Reply #22 on: May 04, 2021, 02:56:56 PM »
Short answer- Yes, it's a Harley. Mine, I'm anal, I'd straighten it, cause I can. :smile:
John

Me too.... I have the old pin and two big screwdrivers that will go through the bore, but what does side loading the crank pin bearing do and can you damage it or the honed rod end?

Offline kd

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Re: deck height measured over the pin differant side to side?
« Reply #23 on: May 04, 2021, 02:59:02 PM »
Remember that .004 across the top is .002 average.  Pull out your feeler gauges and check the .002 blade.  :wink:

Like John said, some of us are just OCD about this stuff.  Especially if building a close tolerance hard run engine. Unfortunately for me I fall into that category.   :crook:
KD

Offline 1340evo

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Re: deck height measured over the pin differant side to side?
« Reply #24 on: May 04, 2021, 03:13:22 PM »
And .004 over the top is .0026 down the side due to the 3:2 piston shape, and then only 1/2 of it thats not given over to rings... so .0016 in all.. so not a lot, maybe running in will correct that LOL

But, does it make the rings run on a point in Stead of a face????  :missed:
« Last Edit: May 04, 2021, 03:21:51 PM by 1340evo »