Milwaukee Midget

[Stan Back]

Those rockers are very purdy for that old cast inon clunker -- are they stock?  (Sure!)

Stan

[Milwaukee Midget]

The Rockers are Harland Sharp.  They're bushed, not needle bearing, but I have a couple of friends who run them and swear by them.  About half the cost of Tiltons, and the factory will sell direct.

Good eyes, Graham.  The seals are only on the intakes, and I'm trying to scrounge an ignition system.  I'll keep you posted.

Tzoom, I don't know what David Vizard would think, but his former partner at APT, David Anton and I had a great conversation about cam selection for the 970 for next year.  One problem he brought up, and I had not thought through, is that with my rod to stroke ratio, I may have issues with the valve opening faster than the piston moves out of the way.  To complicate the issue, I need to get the compression up to ~13.5-14 : 1.  It will be a balancing act.  If I use flat top pistons, I'm at ~ 12.5 : 1.  There's plenty of meat to skim off of the head, but that doesn't help with potential interference.

Right now, no big deal - I've got all winter to figure it out.  I just want to get this 1275 screwed together for September. 

[Dr Goggles]

Right now, no big deal - I've got all winter to figure it out. . 

Heard that before!!!....great to see the progress Chris.

[Milwaukee Midget]

This week has been crazy.  This will be a little off topic for a minute, but bear with me.  I'm stage managing a show at the Harley-Davidson museum on Friday, and between advancing that show and editing our next CD, I've been distracted.  

The show is a fundraiser for Guitars for Vets, an organization I do volunteer work for.  Their mission is to get guitars into the hands of physically and mentally disabled veterans, and to teach them to play.  It's a music therapy approach, and to steal their tag line, they're "putting the healing power of music in the hands of heroes".  I think it's worth taking some time out to help.

http://www.guitarsforvets.org/G4V/Home.html

The block is finished, but I'll have to pick that up next week, tap the oil galleries, send it back to get the cam bearings installed, and get the pins fitted onto the con-rods.

My cam came back this week, and I was a bit disappointed.

Threads we're bunged up.  It looked like it was chucked up in a drill press.  It was well prepped for shipping, and obvious that it left the shop that way.  I was able to chase 'em out, but now I've got a 5/8 fine thread die that I'll probably never use again.  The profiles look really good, though, and if this is my only complaint, then I've got few worries..

Anyway, on with the show.

[Milwaukee Midget]

Quick update.  Mocked up the rockers tonight.



Hmmmm . . .

'bout a hundred ways to do this wrong - that was my last count, anyway.

I think I've got it right, but I'm going to sleep on it and look at it again this weekend.

If I do have this right, here's the problem.  The exhaust is on the right.  To line it up with the valve, clearly it will need to be shimmed between the post and the rocker.  That's no big deal.

The intake is on the left.  It's perfect, and that's the problem - it is flush against the post, and will require a shim to prevent it from rubbing.  A thin one will still get me pretty close to center - probably close enough that it won't be an issue.  Still, I can't help but think there's something not quite right.

Hmmmm . . . the oil holes in the shaft.  Hmmmmm . . .

And that's why I'm going to sleep on it.

'night, all.   

[Geo]

Chris,

Looking good!  Glad to see something beyond the body.

The cylinder head, valves, rockers  are left - right - right - left - left - right - right - left.  Swap the two on the exhaust.

The valve position to the rocker stands are far - close - close - far - far - close - close - far.

Geo

[Milwaukee Midget]

Thanks, Geoff – Tried that last night, but the problem is now a different issue.

Here's the combination that gets me my alignment from 8 to 1, from the passenger side (and I should qualify that - this is a left hand drive Spridget)
 
Left – Left – Right – Right – Left – Left – Right - Right. 

I’m reminded of “The Hokey-Pokey”, but that’s not what it’s all about.


It’s more like “The Chicken Dance”.



With the rocker all the way up, it hits the pedestal.  And with a valve a tad shorter than stock, with the rocker at the maximum of its upper excursion, the valve does not completely seat.



I’m deciding between clearancing the rocker and clearancing the pedestal.  The rockers are pretty beefy, but simply clearancing the pedestal might not give me enough room – I might still have to clear the flange on the pedestal nut.

So much for the notion of “bolt-on performance”.
   

[Tzoom]

This brings back memories of the Mk IV Sprite I had in England.   It was a 1275 and its gearing was fine for the twisty roads in the area where I lived where you didn't get much above 45 mph but on the motorway going to London it would be turning 4500-5000 rpms at highway speeds.  The Brits built a strong little engine but I marveled that the thing held together sometimes.  What do you figure this engine will be turning at speed when you get it finished?   

[Milwaukee Midget]

Well, the plan is

23" tires
4:22 rear
7530 RPM =
122.mph

That will be the I/GT engine, built to 970 Cooper specs, but that's next year.

This year, I'm running this 1275 (the head I'm working on right now will be a part of both engines) at the USFRA event, and if I can make a 100+ mph pass, and the car tracks true, I'll walk away satisfied.

Funny you should bring this up - I've owned 4 MG's over the years, but have never driven a Midget!  My only experience behind the wheel of a Midget will be on the salt. 

I've got to believe that they are a riot on the twisties.  I know my MGB is.

[Tzoom]

I've got to believe that they are a riot on the twisties.  I know my MGB is.

It was a blast but it could also get pretty exciting.  The car didn't have a whole lot of torque so steering with the back wheels was rare and it wanted to push in the corners sometimes.  Those English hedge rows don't look lethal but they are mostly built on 3 or 4 foot berms.  I had the car against one once.

I guess I'll get to see you run at Bonneville.  I'm going out for WoW and staying over for the Shootout if Max comes.   

[Milwaukee Midget]

E-mail correspondence with Harland Sharp -

Me -

"I'm running into clearance problems with rockers and the pedestals.
 
Here's what's happening - These are in my photobucket account.


 
The head is a 12G 940 casting - open chamber 1275 MG.  The valves have NOT been offset.  In order to get alignment with the valve, the dog leg on the rocker wraps around the pedestal.  Alignment with the valve is spot on, but what happens at full upward extension of the rocker is that it hits the pedestal.
 
 
 
The problem is that at full upward extension, and with a racing valve that's actually .040 shorter than stock, the valve will not completely seat.


 
Do I have this set up right?  It was the only way I could get the rollers to align with the valves.  Do I have the right components here?  Are there any issues in clearancing the inside of the dogleg that are common to this application?  Do I need to do some grinding?"

This from Harland Sharp -

"The way the bodies are designed the smaller offset side should be against the stand, but you also want the rollers lined up on the valve stems so if flipping them around gives you better alignment then do that. As a result you may need to trim the rockers and or the stand a little. I’d focus on the stand first and if you can’t get enough clearance from it then take a little off the rocker."

 

COMMENTS, ANYONE?

[Dr Goggles]

I'd happily comment but I'm pretty sure after SSS's cuss-mangulator had had it's way with what I wrote it wouldn't make very much sense.....

I think what you have is a SIMPLE BOLT-ON MODIFICATION , that can be fitted with few tools in just a couple of hours by a competent home mechanic in your own garage.These parts have been designed and tested in our workshop and are guaranteed to fit, if in any circumstances they do not fit we will refund your money without question AS LONG AS THEY HAVE NOT BEEN FITTED TO A MOTOR.

I feel your pain brother. There is I think a part of the brain that reassures you when you see something that says" do that, and everything will be OK" , when everything is not OK that part of the brain releases huge amounts of stress hormones which throw absolutely everything into confusion, this confusion soon gives way to an acute sense of lateral thinking and rapid problem solving .....ususally "it's not gonna fit, I'll hit it with this pipe wrench ( where's the ball pein when you need it?) .......

The most annoying type of advice you can ever get is " try this , if that doesn't work then you may like to try this...." invariably trying one way excludes the possibility of trying it the other way ....because you've already wrecked it......

Sorry I couldn't be anymore help.....

[Seldom Seen Slim]

Dr. G, if there was a way I could exempt Aussie-talk from the curse-word filter -- I'd do it just so we could enjoy the colorful phrases that arise from the Antipodes.  Sorry that you feel restrained -- I'll try to cut you some slack once in a while.

[maguromic]

I am no expert, but when we had the GMC on the Spintron machine we noticed that if the roller was not perfectly lined up on the tip it tended not to roll properly but rather slide across the tip. In a horsepower limited engine like the GMC and your MG engine, valve train stability means allot.  Maybe Dynoroom will chime in.  Tony

[Peter Jack]

It sure wouldn't bother me to radius those sharp corners on the pedestals. I'd leave the base of the pedestal full size. The easy way to accomplish it would be to use cartridge rolls. If you haven't used them before get them and a mandrel from an industrial abrasives supplier. Once you start to use them more and more uses will appear.

Pete