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Author Topic: Inline-four crankshaft  (Read 201818 times)

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Offline Jack Gifford

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Re: Inline-four crankshaft
« Reply #270 on: March 09, 2016, 12:39:50 AM »
... If you are trying to maintain a some sort of relationship with the shop, I understand why you might be reluctant to push the issue though...
Yeah, there's always a "story behind the story". I have a "back door" relationship with a guy at the shop. If I went through the office, I'd have payed significantly more than the $1,600 (+ $215 mat'l). It's generally a good relationship, with the machinist visiting my shop often to witness how the parts are being used. The change for retainer clearance was a verbal deal- my mistake for not changing the print.
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Offline Jack Gifford

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Re: Inline-four crankshaft
« Reply #271 on: May 12, 2016, 12:16:14 AM »
Spin-testing of valvetrain has resumed, with the improved-design CNC'd cam followers. So far, the new 5 HP electric motor seems capable of powering one cam and valves (testing INT & EXH separately) up to my goal- 5,000 cam RPM, equivalent to 10,000 engine RPM.  I ran the EXH train for a considerable time, working from 6,000 up to around 8,000. Then briefly in the ballpark of 10,000 (per the pulley ratio, but didn't have a tach connected), but a change in sound caused me to quickly stop. The locknut of one follower's pivot stud had loosened, allowing the stud to quickly loosen. No real harm done (whew!) but I need to address the problem. I've changed to grade-8 locknuts with full 11/16" hex in place of 5/8" hex grade-5 (I had used the smaller hex because of the crowding). I'm reasonably sure that under-torqueing of the lock nuts caused the incident. So now I need to create a pair of custom-fabricated wrenches to be able to hold the pivot stud stationary while torqueing the locknut- which is more of a task than it sounds like, due to the limited space. I tried modifying a purchased crow's foot wrench but it wound up too weak for 67 ft.lb. of torque. To be contiinued...
« Last Edit: May 12, 2016, 12:33:48 AM by Jack Gifford »
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Offline Sumner

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Re: Inline-four crankshaft
« Reply #272 on: May 12, 2016, 09:02:29 AM »
Sure admire what you are accomplishing Jack  :cheers: :cheers:.  Keep the updates coming.  I feel you are doing the type of project that many of us dream of but never accomplish  :-) :-),

Sumner

Offline jacksoni

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Re: Inline-four crankshaft
« Reply #273 on: May 12, 2016, 10:21:17 AM »
Jack- I can't really visualize what sort of wrench you need but your mention of crows foot brought this to mind. I had to make something to tighten head bolts in my engine with the cams installed. Very limited space and giant PITA to take them out. Welded a 3/8 drive chunk of a crows foot to a 5/8 socket. Worked fine. I was torqueing to 75ftlbs (maybe not enough but not sure of the head castings and what I could go to. 1/2" studs
Jack Iliff
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Offline Jack Gifford

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Re: Inline-four crankshaft
« Reply #274 on: May 13, 2016, 12:05:34 AM »
jacksoni- I wish I had the option of a box-end, but I need an open-end to get onto the locknuts when the followers are in place.

In the interest of continuing the "spinning" I assembled it (with the new locknuts) by setting the clearances, precisely noting the rotational position of each pivot stud, removing the followers, torqueing the locknuts with a six-point socket (a multi-step process, since the stud sometimes turns with the nut), then re-installing the followers. Very tedious and not an acceptable procedure for the future- I'll definitely need to develop an appropriate open-end wrench deal.

After some validation at  about 6,000 RPM, spun it for awhile at 9,300, then 9,640- after which all seemed okay (turning the cam slowly with a wrench while monitoring the "feel" and sound of each cylinder's exhaust valve movement). But a short spin at 9,910 RPM resulted in a broken pivot stud. Not real surprising since there isn't much (or maybe none?) safety margin in my manufacture of these parts. I made them from grade-8 7/16-14 bolts, cutting the heads down to a 7/16" diameter hemispherical shape, then heat-treating to Rc-45. I admit to not attempting to calculate the shear stress that they would see- so I guess I'm lucky they "almost" sufficed. There was some collateral damage this time- the follower's ball-seat got beat up a little, so one of the "spare" CNC'd followers will get pressed into service. Once again the testing will be interrupted while I get the follower body shot-peened and heat-treated, and assemble wheels and axles into it. Plus investigating shear strength improvement of the studs- better material, smaller oil hole, etc.

P.S.- Hindsight truly is 20/20- I shouldn't have ignored the fact that the torque seemed to level-off at about 65 ft.lb. on the locknut of that one stud! :oops:
« Last Edit: May 13, 2016, 12:15:39 AM by Jack Gifford »
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Offline Rex Schimmer

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Re: Inline-four crankshaft
« Reply #275 on: May 13, 2016, 12:10:00 PM »
Jack, to quote someone, I don't know who said this, "people that don't make mistakes don't learn anything" or my other favorite, "When you learn by experience the test comes first that the lesson comes afterward". We are all learning so much from your build, not many people would tackle something this extensive. Keep it up!!!!

Rex
Rex

Not much matters and the rest doesn't matter at all.

Offline Jack Gifford

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Re: Inline-four crankshaft
« Reply #276 on: May 17, 2016, 12:11:09 AM »
I feel more "contented" now, as I usually do once I have a "plan of attack".

Started on a couple of crowsfoot wrenches for valve adjustment. They will look strange, since they both will rise from the crowsfoot part, up clear of cam stands, then out and down, so both handles will lie in the same plane as the fasteners. Normally with an extension on a wrench, two hands are required- one at the handle and the other at the drive end to hold the wrench from tilting sideways on the nut. With the handles co-planar I'll be able to work each of the two wrenches with just one hand- to hold the adjusting stud with one hand while I torque the locknut with the other.

I talked to ARP today- they have some "stock" 7/16-14 studs made of 8740 alloy which has a yield strength of 180 Ksi- they should be here in a few days. The studs I made weren't that strong (grade-8 bolts are nominally 120 Ksi) so I should see a significant increase in material strength. Plus, I'll EDM smaller oil holes through them, buying a slight increase in cross sectional area. The guy who CNC'd the followers says he will be able to CNC-lathe-cut the spherical shape onto the ends of them with merely carbide tooling, since ARP says the shanks don't exceed 39 Rc hardness.
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Offline Jack Gifford

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Re: Inline-four crankshaft
« Reply #277 on: June 09, 2016, 12:22:08 AM »
"Spintron" setup back together, with upgraded 8740 pivot studs, a new set of grade-9 lock nuts torqued to 67 ft.lb., and the two dinged-up followers replaced. The custom wrenches work "okay", but adjusting clearances is still a time-consuming pain in the neck. Just one brief run to about 3,000 cam RPM so far, to basically confirm the assembly. We'll see what I can break next... :evil:

P.S.- Couldn't get anybody with an EDM interested in doing the .050" oil holes, so I had to tackle drilling them. I "done good"- didn't break a single drill bit! A combination of very consistent US-made 8740 alloy and v..e..r..y slow feed- about .002"/second. Feeding the studs downward in the mill spindle to a stationary drill helped keep the drill point clear of chips. And probably some luck too. :roll:
« Last Edit: June 09, 2016, 12:34:06 AM by Jack Gifford »
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Offline tauruck

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Re: Inline-four crankshaft
« Reply #278 on: June 09, 2016, 01:40:00 AM »
Nice one!!. Well done. Now you know why other guys wouldn't tackle the drilling job. :-D

Offline Jack Gifford

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Re: Inline-four crankshaft
« Reply #279 on: June 10, 2016, 12:37:10 AM »
Gee... I failed to break the exhaust valvetrain at the equivalent of 9,960 engine RPM! Post-mortem looks okay; one valve clearance closed up about .001", which wasn't unexpected.  Got a couple of drops of oil out of the cam snout seal which I can't yet explain. :?

Should have the intake side set up and "spinning" in the next couple of days. :-)
« Last Edit: June 10, 2016, 12:39:59 AM by Jack Gifford »
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Offline Peter Jack

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Re: Inline-four crankshaft
« Reply #280 on: June 10, 2016, 12:52:54 AM »
It's always great to hear good news Jack!  :cheers: :cheers: :cheers:

Pete

Offline Jack Gifford

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Re: Inline-four crankshaft
« Reply #281 on: June 14, 2016, 01:25:10 AM »
Spin-tests finally wrapped up- success at almost the equivalent of 10,000 engine RPM (4,980 exhaust cam, 4,870 intake). Actual engine assembly to begin soon. The only machining left will be mounts for stuff driven off the rear of the cams- magneto, oil pump, and fuel pump.
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Offline Jack Gifford

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Re: Inline-four crankshaft
« Reply #282 on: June 29, 2016, 01:42:33 AM »
It feels good to FINALLY start actual engine assembly.

Verification of things isn't finished, though. With just the crank installed (no pistons/rods) I'll set up the cam drive, get the two cams phased together, and check valve-to-valve clearance during overlap. Then, hopefully, the 5HP electric motor will be able to turn the crank/cams enough to observe the whole cams/valve-train in action.
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Offline Jack Gifford

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Re: Inline-four crankshaft
« Reply #283 on: July 05, 2016, 12:25:04 AM »
Worst case valve-to-valve clearance measured all of .030"! :-o But changing from 108.5 degree lobe centerlines to 112.5 degrees (easy to do with dual cams) improves the situation to about .054". Surprisingly, engine simulator software shows very little change to the torque curve from the centerline change- if the software is to be believed. :? Anyhow, I'll be cautious and set them @ 112.5 initially, at least.
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Offline tauruck

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Re: Inline-four crankshaft
« Reply #284 on: July 05, 2016, 12:44:44 AM »
That looks great Jack. Long time coming but it sure looks worth it.
All the best. :cheers: :cheers: :cheers: