Milwaukee Midget

[wobblywalrus]

Midjet, the Whitworth stuff is described by bolt head width rather than shank diameter like UNC and UNF.  The Whitworth threads have a 55 degree included angle and rounded crests and roots.  The UNC and UNF threads have a 60 degree included angle and flat thread faces.  Whitworth and UNC or UNF are not interchangeable - even if they have the same shank diameter and thread pitch.

This is my source for fine pitch metric and Whitworth fasteners:  www.stainlessautomotivefastenings.co.uk   

[Rob]

And Rob, Thanks.  Are you going to be able to make the rescheduled Lake Gairdner event? 

I need to try Chris, if they go ahead and move the event to January it'll be the last one I am able to attend.

Cheers,
Rob

[fordboy628]

Midget,

Have done some research & measurement on some BMC valves in my pile of bits.  Numbers are as follows:
Cooper 'S'  std.   (REC #103)  o/a/l   3.525"/3.530"  race type profile
Cooper 'S'  'long' (REC #105)  o/a/l   3.570"/3.575"  race type profile
1275   std.                             o/a/l   3.570"/3.580"  stock type profile

All of these are std. flat faced valves, no rimflo.

For comparison FORD F/Jr. lengths are 3.850" std & race, also with an option for 3.950" RACE ENGINE LENGTH.  Longer valves really help the valve spring packaging........

Also: ANY notion of cam follower or pushrod weights?   Have followers been 'lightened' as per usual BMC race/Vizard practice?

Fordboy

[Milwaukee Midget]

Woo Hoo - the head has returned from its California vacation.  A bit of clean-up and I'll get some pics posted.

FB, a sample pushrod weighs 54 g, and a call to Phil at APT turned up a 44 g nominal weight for the lifters.

The lifters are the Phosphate Coated 62-65 Hrc Hardness HD units that APT sells.  The only modification that I made to them was to take a wire brush on a Dremel to the inside to make sure they were clean.

In the version of the Vizard manual I have, he suggests not bothering with the lightening - his claim is it's only worth maybe 50 rpm, and the loss of durability isn't worth it.

Now I suppose you're going to ask if they have the oil holes?  Well, the picture on the APT site shows holes, but to be sure, I threw a little oil down the pushrod hole and snaked my new boreometer after it, and watched the oil level drop, leaving just a small puddle in the bottom of the lifter.  Can't see the holes, but I didn't see any cracks!

I'm thinking I can snake this sucker up through the drain plug and check the cam lobes.  Kind of a British colonoscopy.

Misplaced my calipers - I've got to clean up this pig sty, but eyeballing with a steel ruler, valves are just shy of 3 9/16.

[Milwaukee Midget]

Found the calipers - In my kit with the Colortune, feeler gauges and timing light - don't ask - 3.527.

Oh, and the installed height is actually 1.450. 

Somewhat less brutal, but I'm guessing these Kow springs are looking better.

I'll drop by and bother Clint again at C&S tomorrow afternoon, and check pressures at 1.450 and .950.

Chris

[fordboy628]

Midget,

British colonoscopy sounds like an excellent idea, but make sure Rick Santorum approves in advance because it's a NECESSARY MEDICAL procedure to preserve the life of your baby.  I think he will approve if you agree to NOT enjoy it............................      

Don't bother explaining/apologizing for the condition of your shop/garage.  Wait until you see mine, it looks like a goat EXPLODED.

OK, the valves are the shorter Cooper 'S' length, but your installed height might work out alright.  Still have the option of the slightly less pressure valve spring.  Some questions pop to mind:

Is there room for a .030" spring shim/perch?  (Saves the head from being chewed by the springs.)
Is there .050"/.060" valve seal clearance at full 'net' lift to bottom of the retainer/keepers?
Is the actual net lift .490"?  If so, check valve spring pressure @ 1.450" seated & .960" open.  Adjust your dimensions to determine the
    spring pressures @ the actual dimension of use, rather than something 'close'.  If the springs are @ 275/290 #'s open, you are
    probably OK, 270/275 #'s was what I have used previously, and where I would start, BUT, I DO NOT KNOW THE NEGATIVE
    ACCELERATION ON YOUR CAM, MOMENT OF INERTIA OF YOUR ROCKERS, MASS OF PARTS, ETC, ETC.
    300#'s open pressure is the arbitrary line I did not want to cross, because it is out of the realm of my own experience.  The concern
    here is the contact pressure on the nose of the cam/lifter.  Again, I don't know enough about the specifics of the cam, such as nose
    radius.

IF IT APPEARS THAT THE SPRINGS ARE GOING TO WORK, DO NOT forget to check EVERY spring pair @ a standard loaded height of    
    about 75% full lift, for you, approx 1.070".  What you want to see is "even" (+/- 2#'s) pressures @ the checking height.  Don't freak
    out if they are uneven, they probably will be.  Separate the pairs, check inners & outers alone, and then 'match up' pairs for even  
    pressures.  HEAVIER PRESSURE PAIRS SHOULD GO ON THE EXHAUST VALVES.  This is because the piston is chasing the exhaust
    valve closed @ overlap, AND THE VALVE TRAIN MOTION IS CONTROLLED BY DIMINISHING SPRING PRESSURE @ THIS POINT.

I have some other questions about rocker clearance/geometry, as we discussed, but that is the next step.  Oil holes in the lifters is a good thing, as it allows the oil to drain out to the crankcase/cam, etc.

Let me see if I can duck away for a road trip to Milwaukee today/tonight.
 
Fordboy

[fordboy628]

Midget,

Assuming 1.340 installed height gets me ~ 125, .850 = 300 open, and a .750 coil bind.  Head should be back in Beerhaven by Thursday – I’ll be able to confirm that height and see how it goes together.

That's a 357#/inch spring rate.   Presuming that all the spring pressure numbers are correct & 1.450" is correct, then:
                                               @ 1.45" installed height that would give approx. 85#'s seat pressure.
                                               @ 0.96" open height      that would give approx. 260#'s open pressure.

That leaves room for an .030" hardened spring perch/shim which would add 10/11#'s to the above pressures, and.....  90/95#'s seat pressure   with   270/275#'s open pressure was my original recommendation.    Looks like a winner setup to me, just need to verify the pressures on a valve spring checker & 'balance' the springs.
 
Fordboy

Based on the cam card a few pages back, net valve lift = .490"/.492".   F/B

[Milwaukee Midget]

FB - sorry I missed the call.  I will make a clandestine Cheddar Curtain run next week - hopefully they won't sniff out the Cream City Contraband at checkpoint Wadsworth.

Chris

[DND]

Hi Midget

If your friend has and indactor with enough travel, you might want to see how much travel is in your springs past open as this will let you know how much you shim the spring and not get too close to coil bind.

Don

[fordboy628]

Midget,

I am hoping to have a 25cc burette by mid-week.  Already on the way from "Canada".   Will then be able to 'cc' the Longman head to determine the EXACT C/ratio.  Will also need to take some other measurements for valve/piston clearance calculations, etc, etc.   Bring all the head assembly bits and a sample head gasket.   Can also bolt head to the mockup to check rocker arm geometry, so bring rocker assembly as well.   Bring anything you think we might need or find useful.

Looking forward to your visit.  Stay on the racer's underground railway, ie, under the radar of the police who dislike 'cheese'.

 
Fordboy

[Milwaukee Midget]

Stay on the racer's underground railway, ie, under the radar of the police who dislike 'cheese'.

It's not the cheese - it's the purveyors.

[Milwaukee Midget]

Hi Midget

If your friend has and indactor with enough travel, you might want to see how much travel is in your springs past open as this will let you know how much you shim the spring and not get too close to coil bind.

Don

Hoping to have this all worked out by next weekend - it's crunch time - I have dyno time booked.

[fordboy628]

Midget,

Assuming 1.340 installed height gets me ~ 125, .850 = 300 open, and a .750 coil bind.  Head should be back in Beerhaven by Thursday – I’ll be able to confirm that height and see how it goes together.

That's a 357#/inch spring rate.   Presuming that all the spring pressure numbers are correct & 1.450" is correct, then:
                                               @ 1.45" installed height that would give approx. 85#'s seat pressure.
                                               @ 0.96" open height      that would give approx. 260#'s open pressure.

If all of this is correct or close, should be NO PROBLEM, as per previous posts.  Let's firm up a schedule to get this done early.  That way if/when the unanticipated surfaces, we can still finish on time.   Should be able to easily accomplish everything necessary, in the time available.   Am spending my saturday digging out BMC valve spring retainers, spring shims, spring perches, cc'ing plates, etc, etc, etc.  BRING YOUR VALVE SPRING COMPRESSOR AND SOME OF THE SPARK PLUGS YOU HAVE BEEN USING!!   Am willing to spend a day or so @ my buddy's machine shop in the unlikely event that something custom is needed.

Happy Easter!!   Noww where'ss thatt wabbit???   Come here, wittle wabbit................ 
 
Fordboy

[Milwaukee Midget]

Caution, FB, iamflagman runs 129 plus in a GTI, and the aero is worse than the Midget!

Chris

[fordboy628]

GTI?  Isn't that a german shoebox??   

Luv to all,
F/B