MS-3 2110 Buildup

[Max Welton]

So here's the next challenge on these. To form the seal I'm thinking an o-ring that fits into the groove in the TB and seals against the ID of the manifold. The manifold bore measures about 1.889", very close to the OD of the TB. The bottom of the groove in the TB is 1.815".

The o-ring also needs to survive the temperature at the top of the manifold. So can someone school me on o-ring tech and where I might something of this specific size?





Max

[Max Welton]

OK, here's what I found.

This site lists sizes in inches and has descriptions of various material properties. Buna-N seems to have acceptable properties, but the AS568 sizes don't have a size that looks like it would work.

http://www.marcorubber.com/sizingchart.htm

So I figured there would be a metric o-ring so ...

http://www.theoringstore.com/

So the metric sizes are by cross-section X ID. My ID is ~46mm and OD (actually the ID of the manifold bore) is ~48mm.

The Buna-N 70 comes in a 2.0mm cross-section with a 46mm ID and an operating temperature range -40 to 212°F

http://www.theoringstore.com/index.php? ... ts_id=1897

They also have a 2.4mm cross-section Buna-N 70, but only in 44.6mm and 47.6mm IDs.

http://www.theoringstore.com/index.php? ... =4a&page=2

So it seems like I should go with the 2.0X46.

They are so inexpensive, I have ordered four of the 2.0X46, 2.4X44.6 and 2.4X47.6 and see what seems best.

Max

[Piledriver]

Brilliant meets simple.

Same style would work w/eccentric inserts and some manifold machining on GSXR tbs.

[Max Welton]

So the correct o-ring size is N1.50X040. These are Buna-N 70s from http://www.theoringstore.com/ .



Max

[andy198712]

Nice one! Is it snug in the manifold?

[Max Welton]

Very. In fact I needed to use some silicon stuff to get it slippery enough to go in. Perfect!

Max

[Max Welton]

Sunday I attempted to button up the 2110 long-block. With 25 ft/lbs on the main case studs everything still turned fine. Somewhere between 25 and 35 ft/lbs the crank got hard to move.

Process of elimination revealed #3 (shown) to be the culprit. Nothing obviously amiss with the bearing saddle or the journal. Since I already had a problem with #2 of this bearing set, I have ordered up a set of KS bearings.





Max

[Max Welton]

So we found several problems lerading to the crankshaft binding. First, the #2 bearing halves each had a small bump (like a little pimple) on the ID. Then the #1,2 and 3 bearing saddles were slightly undersized. Steve took .0005 off each saddle and tried a STD journal crank in my case with my bearing and it spun fine at 40 ft/lbs. But when I got the case back, my new DPR crank was still binding up. Randy Bowen tried a STD crank he had and it was fine. So there's something not right about my crankshaft. I've sent it back.

Meanwhile I am thinking about throttle linkage. These motorcycle TBs are set up for cable operation so that's the direction I'm going. I'll be using 1/16" "wire rope". I have an idea for a progressive splitter. I can find cable hardware (sheaths and adjustors) all day, but I need a source for 1"-2" pulleys. Any suggestions?

I'm also trying to teach myself how to use something called freecad, but it's kicking my butt so far.

Max

[andy198712]

Very. In fact I needed to use some silicon stuff to get it slippery enough to go in. Perfect!

Max

that sounds perfect!

i've got gsxr this with fixed spacing but tempted to switch to the VFR ones.... pretty common and cheap on ebay UK

[gearheadgreg]

Meanwhile I am thinking about throttle linkage. These motorcycle TBs are set up for cable operation so that's the direction I'm going. I'll be using 1/16" "wire rope". I have an idea for a progressive splitter. I can find cable hardware (sheaths and adjustors) all day, but I need a source for 1"-2" pulleys. Any suggestions?

Hey Max!

If you haven't already figured out your cable linkage, you might try going into some of the plethora of bicycle shops around town to see what they've got, or better probably, is online. Otherwise, garage door places might have something along those lines, or a Farm & Fleet type store - one out east kinda near you I think.

Barring that - you could always have one made up pretty easily. I've hat Martin at The Machine Shop do some stuff for me - he's a great guy and likes doing the different stuff for small cars. (He races an Audi 5000 turbo Quattro staiton wagon, has a Mini in his shop, and a Saab Sonnett, etc etc)

[Max Welton]

Thanks Greg. Yeah, I get my 1/16" wire rope at the Big R out on 24. They sell it by the foot, as much as I need.

Randy Bowen has done some nice work for me in the past. I mocked up the injector stands for my squareback in wood and he created the stands in aluminum.

I actually have a linkage design in mind that will be progressive off the idle-stop then become linear somewhere around 1/4-throw. I expect this engine to be ferocious just off idle and I want the option to make the throttle less sensitive in that range and having nice fine control there might be nice.

I'll be able to think seriously about the engine room layout when I hang the longblock off the transmission. I'm still waiting for Steve Hollingsworth to send the crank back to me from PH.

Max

[gearheadgreg]

Ah, yes - Big R.

Randy's good on a lot of levels, I'm sure he'd do you right.

For progressive linkage, Porsche 944's came with a progressive cable setup, that most replace with an faster opening aftermarket setup.

Stock 944:



Aftermarket 944:




Additionally, when I switched from a two-stage progressive throttle body on an old water-cooled VW to a large single stage, it felt to jumpy. I was able to add more throttle spring and make it work just fine - just as an FYI.

[Max Welton]

Good info Greg. Thanks.

In other news, I just got off the phone with Jose at DPR. There's a NEW crank shipping on Monday. I'm hoping to assemble the short-block over Christmas week.

Max

[langsen]

So the correct o-ring size is N1.50X040. These are Buna-N 70s from http://www.theoringstore.com/ .

This o-ring idea is great. Before I order them I just want to make sure that 40mm is definitely the right size since earlier you mentioned 46-48mm sizes. Do you need to stretch it a bit I guess?

[Max Welton]

Yes, a light stretch to fit. The larger sizes were bunching up and making it harder to get the TB into the manifold.

Max