Northstar rebuild: Will style (Page 99/119)
Will APR 01, 09:48 AM

quote
Originally posted by La fiera:

All those setbacks and frustrations will dissapear once you fire her up and hear it rumble! Glad is coming along good!



Yeah, once it's running I'll be able to leave frustrations FAR behind!
Trinten APR 04, 01:54 AM
Pretty cool stuff, Will!

I'm always envious of people who have the space and ownership/access to machining equipment. Not to mention the knowledge to use it effectively. I fully admit, in theory I'd love the ability to prep a block correctly and do all of this instead of having a shop do it, but if I had the equipment, I would be hard pressed to find the time to practice to get good enough to trust anything serious being made...

So I will accept my faults in this matter and continue to be envious.

Looking forward to seeing it done!
Will APR 06, 12:04 PM
Ready to put the right head on:



The Cometic head gasket:



Even though the embossments make it feel like a stack of notebook paper, there are only three layers of steel. This one is has a 0.036" compressed thickness



Head ready to go on. I'm not sure what the smudges are... it came back from the parts washer that way. I've cleaned the deck with alcohol and WD-40, but the smudges don't come off... I didn't try prep-sol, but I might on the other head.



Gasket in place



I'm using stock replacement Fel-Pro bolts. They have an micro-encapsulated sealant coating on the threads and a solid lubricant coating under the heads



11x2.0 is a pretty coarse thread. Alan Johnson told me to tighten my prior ARP studs to 70 ftlbs. While bolting on the heads for trial purposes last summer using the factory torque sequence (22 ftlbs + 60 *+ 60* + 60*) I saw numbers as high as 90 ftlbs on the bending-beam torque wrench. I wanted to tighten the 11x2.0 bolts to give the same clamp load as the ARP studs. I could find online calculators that would give me torque vs. preload for 7/16-20 thread, but nobody has a calc that can do 11x2.0, so I had to derive the torque to pre-load formula and set up a spreadsheet. I double checked my formulas vs online calcs for 7/16-20, then duplicated the math for 11x2.0 and came up with.... 65 ftlbs. It turns out that the increase in "ramp angle" of a coarser thread is canceled out by the decrease in pitch radius at which the applied torque shows up as "wedge force". More friction comes from the conical aspect of friction, since the thread form angle is 60 degrees, while the ramp angle is only 2.3 (7/16-20) to 4.5 (11x2.0) degrees.



Head installed



Close-up of the spacers I used under the upper row of head bolts



Head in place



Cams and lifters in place



Cylinder head and sprocket mods for the 4x cam sensor



Close-up of a couple of ooopsies when modifying the sprocket. I'll check it against the stock timing of the other bank's exhaust cam using a degree wheel.



Put a lid on it and it's starting to look like an engine.

[This message has been edited by Will (edited 04-06-2021).]

Will APR 07, 12:44 PM

quote
Originally posted by Trinten:

Pretty cool stuff, Will!

I'm always envious of people who have the space and ownership/access to machining equipment. Not to mention the knowledge to use it effectively. I fully admit, in theory I'd love the ability to prep a block correctly and do all of this instead of having a shop do it, but if I had the equipment, I would be hard pressed to find the time to practice to get good enough to trust anything serious being made...

So I will accept my faults in this matter and continue to be envious.

Looking forward to seeing it done!



I'm looking forward to it being done in a big way.

I have access to generic machine tools where I'm doing this, but I don't own them.

I had another shop do the block prep, as that's rather specialized to an engine machine shop... and I've had multiple shops before fail at honing the Northstar bores correctly.
La fiera APR 08, 10:39 PM
Hey Will what's the story with those aluminum spacers on the head bolts? If those spacers don't have the same density as the heads that discrepancy density will affect their expansion rate and you may end up with loose bolts or pulled threads. I'm pretty sure you already took that into consideration, but I just ask to make sure.
ericjon262 APR 09, 04:16 AM
My larger concern, would be that the longer bolt will be under less tension for a given LOA stretch, thus resulting in a lower clamp force, but judging by the statements made in one of his above posts, he's already accounting for that and more.

------------------
"I am not what you so glibly call to be a civilized man. I have broken with society for reasons which I alone am able to appreciate. I am therefore not subject to it's stupid laws, and I ask you to never allude to them in my presence again."

cognita semper

Will APR 09, 10:37 AM

quote
Originally posted by La fiera:

Hey Will what's the story with those aluminum spacers on the head bolts? If those spacers don't have the same density as the heads that discrepancy density will affect their expansion rate and you may end up with loose bolts or pulled threads. I'm pretty sure you already took that into consideration, but I just ask to make sure.



The heads are '93-'99, which were use hydraulic bucket tappets and are better balanced for N/A performance. The block is a '06-'11. The spacers are required to adapt the older heads to the newer block.
In '00, GM reworked the top end of the engine to use roller followers. One of the changes was to use longer head bolts. They changed the dies that form the sides of the block to allow the outboard head bolts to go deeper into the block. They did NOT change the die that formed the valley, so they were not able to make the inboard bolts go deeper... so they had to make the boss on the heads taller. The spacers simulate that.

Any aluminum alloy is fine. The differences in thermal expansion are not enough to worry about... especially since it's already a steel bolt in an aluminum block & head.



quote
Originally posted by ericjon262:

My larger concern, would be that the longer bolt will be under less tension for a given LOA stretch, thus resulting in a lower clamp force, but judging by the statements made in one of his above posts, he's already accounting for that and more.




If a 2" bolt needs to be stretched .005 to achieve the correct preload, then a 4" bolt will need to be pulled .010. When you pull by torque, that's not a consideration. The shank of the bolt will wind up, but that doesn't reduce the torque that makes it to the threads. GM pulls by angle to achieve a desired compression on the head gasket. With a MLS gasket that doesn't really compress, or at least doesn't compress the same way as the factory gasket, I can no longer use GM's procedure and have to rely on bolt torque instead.

//

I ran the numbers and QuarterMaster's 0.890" thick flywheel will work with PTT's clutch in the 282 bellhousing, so I ordered the QM flywheel. It has an inboard shoulder for holding the bolt heads, instead of an outboard shoulder. That will make cutting a flexplate to fit much easier. That flywheel should ship on Monday. I hope I can still return the PTT flywheel.
ericjon262 APR 09, 04:14 PM

quote
Originally posted by Will:

If a 2" bolt needs to be stretched .005 to achieve the correct preload, then a 4" bolt will need to be pulled .010.



True, this was my point, % stretch determines load.


quote
Originally posted by Will:

When you pull by torque, that's not a consideration. The shank of the bolt will wind up, but that doesn't reduce the torque that makes it to the threads. GM pulls by angle to achieve a desired compression on the head gasket. With a MLS gasket that doesn't really compress, or at least doesn't compress the same way as the factory gasket, I can no longer use GM's procedure and have to rely on bolt torque instead.




also true, not 100% sure where I was going with that post now that I re-read it. that being said, it is important for that thread pitch be considered for tightening bolts, as a finer pitch thread with require less torque to achieve the same stretch, so it would be possible to over torque the fasteners. You also seem to have already accounted for this in one of your other posts. it is quite amazing how such simple changes like gaskets and bolts affect an assembly procedure. we've mentioned two variables here, but there's many others that also can be significant, like bolt material and proper lubrication.

------------------
"I am not what you so glibly call to be a civilized man. I have broken with society for reasons which I alone am able to appreciate. I am therefore not subject to it's stupid laws, and I ask you to never allude to them in my presence again."

cognita semper

Will APR 09, 04:41 PM

quote
Originally posted by ericjon262:

also true, not 100% sure where I was going with that post now that I re-read it. that being said, it is important for that thread pitch be considered for tightening bolts, as a finer pitch thread with require less torque to achieve the same stretch, so it would be possible to over torque the fasteners. You also seem to have already accounted for this in one of your other posts. it is quite amazing how such simple changes like gaskets and bolts affect an assembly procedure. we've mentioned two variables here, but there's many others that also can be significant, like bolt material and proper lubrication.




Well... yes and no. 7/16-20 has a ramp angle of 2.25 degrees and a pitch radius of 0.203". 11x2.0 has a ramp angle of 3.76 degrees, but a pitch radius of 0.191. The preload depends on 1/cos^2 of ramp angle, so small changes to small ramp angles don't change preload much, and the greater "wedge force" coming from the smaller pitch radius makes up for the greater ramp angle.
The frictional term from the "taper lock" related to the 120 degree cone formed by the 60 degree flank angle (thread angle) is actually more significant than the "wedge friction".

Ooops... I just realized that I didn't include under-head friction in my spreadsheet... but it affects both equally, so it won't wreck the estimate.

[This message has been edited by Will (edited 04-09-2021).]

Will APR 10, 11:58 AM
https://www.fiero.nl/forum/.../000121-13.html#p493


quote
Originally posted by Will:

I spoke with AC Delco about plugs... they said that the stock is the ONLY thing that they make with that head style.

I spoke with Autolite. They said that the stock plug is the coldest they make.

I spoke with NGK. Their tech guy was able to hook me right up with exactly what I need.

Lesson: For oddball spark plugs, call NGK and don't waste your time with anybody else. They've got their act together. The tech guy was asking me about compression ratio, power adders, etc. It sounds like they have a more modular way of making plugs that allows them to put whatever guts they want in whatever head style they want.

The stock plug is a TR55GP, stock number 3403
-T is head style and thread size
-R is for resistor
-5 is for heat range
-(2nd) 5 is for extended gap (.060 stock)
-GP is for platinum

The part number the NGK tech gave me is TR6GP, stock number 5141. The 6 is the heat range and there is no extended gap option. This plug will come out of the box with ~.040 gap and can be gapped as high as .050. Even with the higher compression, the GM DIS should be able to fire .050 gap.
Carquest warehouse an hour away has them, but the local CQ won't be open tomorrow, so I'll have to run up there myself... d-oh. If I'd have taken care of this yesterday, he could have had them for me this morning.

There's also a TR7IX stock number 3690 if the 6 heat range isn't cold enough.

And the local Fisher/Federated Auto Parts can have them for me tomorrow.




Got a set of NGK TR6GP's (5141) on the way from CarQuest.