Northstar rebuild: Will style (Page 24/119)
Will JUN 08, 01:58 PM
the crank will have more mass than drill balanced crank, but because the mass will be closer to the axis, it will have lower rotational inertia. It won't rev any higher, but it will accelerate faster.
cptsnoopy JUN 08, 02:38 PM
It will be interesting to see how much material if any you need to remove.
WAWUZAT JUN 08, 07:47 PM

quote
Originally posted by AkursedX:
Lowering rotating mass=higher revs?

Lowering rotating mass doesn't mean higher RPM ... it means getting to those higher RPMs faster.

Will JUN 09, 12:32 AM

quote
Originally posted by cptsnoopy:

It will be interesting to see how much material if any you need to remove.


Quite a bit. Stock rods are 680ish grams, Eagle rods are 530ish grams.

cptsnoopy JUN 09, 01:22 AM
my bad, i thought you had already run the Eagle rods.
Will JUN 09, 12:49 PM
I had a an ebay crank drill-balanced to run Eagle rods with stock pistons.
The Ross pistons are a few grams heavier than stock, making the crank slightly underbalanced.
I have the crank that was in the engine that I originally swapped into the car. It is pristine and all the journals are within 0.0002 of spec, even after 100K miles. I'm going to be lathe balancing that crank. I have a third crank which will remain stock for comparison.

Both of the balanced cranks will be lighter than stock obviously, but I predict that the lathe balanced crank will be heavier than the drill balanced crank. HOWEVER, I can show through physics that it will have a smaller moment of inertia, despite being heavier.

[This message has been edited by Will (edited 06-09-2005).]

cptsnoopy JUN 09, 03:44 PM
ok thanks, it makes sense now.
Nashco JUN 14, 10:40 AM

quote
Originally posted by Will:

This is the second time tonight I've written this. WTF, Cliff?


FYI, this is a bug that is a result of very long posts. I had the same thing happen before when I wrote a very long post; when I redid it, I cut/paste it, the problem was repeatable. I then paste half of the post at a time and it worked fine...I'm not sure if it's a function of number of characters, or if the computer gets really confused by so much useful information.

Thanks for all the info Will, this is great documentation.

Bryce
88 GT

Will JUL 14, 07:57 PM
Piston ring issues.
For future reference, when ordering Total Seal rings for use with custom pistons, get the rings FIRST, measure how thick they are, then communicate that info to the piston MFG so that the piston grooves may be cut to the right width.
Ross cut the piston grooves in my pistons to 0.0605, which is exactly on spec for 1.5mm piston rings.
The Total Seal rings came out a bit under spec in thickness, giving me 0.0034 side clearance on the top rings and 0.0038 on the second rings. This clearance should be down around 0.0015 for top rings and 0.001 for 2nd rings.

To the credit of the company, Kevin took the rings back and gave me credit for them, even though it's been a year since I bought them.

I just ordered a plasma moly set of stock replacement rings 0.25mm oversize from Sealed Power through Summit. Federal Mogul part number E943K-25mm. My bores are 0.005 over, so the 0.25mm oversize (0.010) rings will give me a bit of extra room to file-fit the gaps, since the stock replacement rings are supposed to be pre-gapped.

I'm also considering making a ring lapping fixture. Rings are cast in a certain diameter, and are flat in that diameter only. When squeezed down to bore diameter, they are no longer as flat on the sealing surface (bottom surface for top ring and top surface for second ring).
So take a piece of bar stock bigger than the bore and face a shallow dish into one end at the finished bore diameter and about 2/3 - 3/4 the depth of the ring. Squeeze a ring into that and lap it flat at bore diameter to get a better seal than unlapped rings.
Pain in the tail, but worth a couple of ponies.

Will JUL 21, 10:42 PM
Drilled out the oil drain back holes in the lower crank case today.

The tops of the ones opposite the crank sensor are slightly over 9/16, but the bottoms of those same holes are smaller than 1/2"! Ran a 9/16 drill all the way through those to open them up.
The holes on the same side as the crank sensor are all 15/32 or so at the top, but larger than that at the bottom (which is kinda strange since oil flows downhill...). I drilled one of those out to 9/16, but the other two took a little more attention. They are not centered on the main webbing, so I had to use a 0.550" end mill to center on the main webbing adn plunge as far as possible before sending the drill all the way through.
The result is that all 6 holes have now been enlarged to 9/16". The next step will be to do the same to the oil manifold, BUT I will need to look at it very closely as drilling the holes in it out will put the edges of the holes VERY close to the edges of the seal groove that holds the seal that maintains pressurized oil to the main bearings. Would not be good to have that seal fail!

Getting closer...

The Sealed Power rings arrived. They are not as thick as I'd like, averaging 0.0579" for the top rings and 0.0581 for the nd rings, but they are overall about 0.001 (top) and 0.0015 (2nd) thicker than the TS rings. They are also more consistent than the Total Seal rings. The SP rings have a thickness variance of 0.0002 across all 8 top rings and 0.0002 across all 8 2nd rings. No single ring had more than 0.0001" variation in thickness across the 4 points I measured.

The TS rings had as much as 0.0003 thickness variation in one ring and 0.0007 across the set.

The Sealed Power rings are still too thin for my tastes...
I will call on Monday to see if they have a set of 1/16" rings for a 262 Chevy. My bore is 3.667 (3.662 stock) and the 262 bore is 3.671. I will then use a surface grinder to thin the rings to 0.0590 top and 0.0595 2nd.

I also have access to a plater, so if nothing else can work, I can plate the non sealing surfaces of the rings up by about 0.001 or a bit more and touch them with the grinder to maintain consistent thickness.

[This message has been edited by Will (edited 07-22-2005).]