Milwaukee Midget

[Milwaukee Midget]

Again, results below 6900 would be good to have.  Also, an actual loaded rolling radius or rollout measurement would be more accurate than the estimate used based on the 22” tire. 

Thanks for the graph.  It took me a minute to put it together in my slow-mo morning brain.

Yes, an extended graph, lower into the power range, would be nice.  The problem - at least as I understand it, and I'm sure Fordboy can chime in with a more accurate description - is that the impeller on the dyno is large for our application. 

T&T dynos a lot of large capacity drag engines, and while Superflow has available a smaller impeller which is better suited to high RPM, HP challenged engines, they simply don't do enough work on engines of less than 300 hp to make the investment worthwhile.

Your graph confirms that we are in the ball park, but if it's a home run, it will be of the scrappy, scrambling "inside the park" variety.  The additional power, lowering of the car, along with the lighter oils in the diff and transmission, resetting the toe in to 0, removing the front brakes, bicycle lube in the hubs, removing the front hub seals and a more aggressive driving technique - well, I'm optimistic.

A tail wind wouldn't hurt, either. 

Either way, this is going to be fun. 

IO, I'm grateful for your insights on this.  Thank you. 

[Milwaukee Midget]

Seems the electric water pump drive is keeping up - I'll know for sure next week, but I had it idling in the garage for about a half hour.  160 thermostat, never went above 175 on the gauge - same as with the engine driving the pump.  I've got some room to play there.

While the radiator sits lower than the water jackets in the head, I've got it plumbed in such a way that the return line on the back of the head and the overflow from the front of the head and the top of the radiator, along with the overflow tank are all above the head - I think that should minimize cavitation.  Any air should be shunted to the higher lines and then to the overflow tank.

Oh, and it DOESN'T LEAK!  No oil, no water - It's like somebody swapped in a Toyota engine while I wasn't looking.

Not too bad for a Brit motor built in the home town of Harley-Davidson.  

[Milwaukee Midget]

Jeez – it was just IDLING!

When I checked the cooling system this afternoon, I noticed the Midget seemed to be running a tad rough.  The exhaust pulses were not quite as aggressive as they had been, so I figured I’d check the valve lash.  These things are notorious for not maintaining adjustment – I’ve had issues before - and it’s dialed in a few thousandths tighter than before.  Additionally, on the advice of Tom at T&T, he suggested I not crank down the adjusters as tight as I had been.

I suspected something wasn’t right, so I took off the valve cover.

This is what I found . . .


Snapped right down the middle.  The keepers were still in place, and the valve was being returned by the inner spring, which actually stopped the valve from dropping out of the head.

It looks worse than what it is, but the rocker was also gnarred up through this process . . .



The roller still turns easy, and other than the scraping against the collar, the rocker appears to be usable.

While the spring was out, and after turning the piston toward TDC, I stuck my videoscope in the spark plug hole to see if there was any visible damage.  The valve turned freely, and the video inspection turned up no serious issues.  With the camera stabilized, there was no visible eccentricity in the rotation of the valve.

Yet after reinstalling the springs, and a new collar and keepers, and hooking up the compressor to the hole, a very loud air leak made itself present through the intake port.

I pulled the manifold and header, and checked for some sort of crack with the scope.  I couldn’t see anything, so I filled the port with WD40, turned up the air and submerged the camera back into the port.

It looked like Rover bubbling up from the sea in the television series, “The Prisoner”.  It was clear that the head had to come off.

My fear was a crack between the intake and exhaust ports – somewhat common when large intake valves are used in these castings.  But the head looked fine . . .



The piston showed no indication of touching the valve . . .



And the valve looks great . . .



Nothing in the combustion chamber looks broken, the springs are okay, and the valve stem is straight.

I called Mark – he was incredulous – but suggested I try relapping the valve.

Seemed to have helped quite a bit, but I’m still hearing a bit of hissing past the intake through the port.

So Sunday, I’ll tear it off again and try a bit more valve compound.

If I can’t get it sealed up, I’ll have an entry for sale.

Needless to say, this is not how I expected to be spending my weekend.

[gearheadeh]

Ahhhh man, This sucks! I;m cheering for you- Next time, don't put a jinx in making comparisons to other makes like "Toyota"

 

[Dr Goggles]

Crap.

We can say all we like about how this is just what the game is buuuuuttttt.

Sometimes swearing falls short.

[38flattie]

Damn Chris-sure hope you find the issue and make the salt!!!!!

[Stainless1]

MM, when you lap are you seeing wide and narrow areas on the valve or seat?

Good luck with the quest,
I'll see you and the Midget on the salt 

[Milwaukee Midget]

A night's sleep - well, a few hours, anyway - I'll pull the head again this morning.

I'm wondering now if when the collar collapsed, it may have compromised the guide, or perhaps caused it to shift.  The guide seal wasn't beat up, but I'm pulling it again, I'll check it.

Tom, thanks for the PM - If it is indeed the valve that's the issue, lapping it in the head is not the good move.

Stainless - everything looked concentric on the valve - I'll recheck the seat.

[Rob]

NOOOooooooooooo!

Wishing you the best Chris, this isn't the news we were all looking for! 

[jacksoni]

Ay, so sorry to hear. On the photo of the head, might just be the flash/lighting, but the seat shows shiny on the 6-7 oclock area next to the plug hole while the rest looks flat/carbon coated. Suggests the valve is bent though you felt the stem is straight. Need to carefully check. Good luck.

[RichFox]

Wouldn;'t something more aggressive like grinding the valve and seat or maybe a new valve be called for?

[jacksoni]

Wouldn;'t something more aggressive like grinding the valve and seat or maybe a new valve be called for?

This of course would be the proper fix but IIRC these are custom valves and unless has a spare already new is a no go. And today is Sunday. Need prevail on friendly head guy to do a valve job on it tomorrow so can load and be on the way. Tough row that one. Hoping valve not really bent and just a bit more lapping will do the job. However, fordboy and "everything is important" might pitch a fit.

I'd be concerned about the retainers. Why did it break? Are the lock angles correct (don't know about BMC but are they matching, not 7* in a 10* retainer or something).

[wheelrdealer]

MM:

Sorry to see but maybe it is better while you are still in civilization versus Wendover.

I don't have the experience all of these other guys do but I have mismatched valve spring retainers with a similar result. Although it was on one of them cookie cutter chevy engines. The other idea is did the retainer set or was it cocked and just vibrated loose. Retainers may be easier  to find than custom valves.

Good luck and good valve karma your way.

BR

[manta22]

What a bummer to happen at the last minute. Arrggghhh........

Regards, Neil  Tucson, AZ

[Milwaukee Midget]

Addressing the few questions -

MM, when you lap are you seeing wide and narrow areas on the valve or seat?

Just checked the seat - the polish is pretty concentric.

I also checked the face with a dial indicator.  We're at less than a 1/2 a thou on the 360, so at least that part is still aligned with the guide.

I'd be concerned about the retainers. Why did it break? Are the lock angles correct (don't know about BMC but are they matching, not 7* in a 10* retainer or something).

They're stock steel pieces - the angle, don't know.  Mark thinks the duty cycle was probably past the point of reliability.  The heck of it is, I have a set of titanium pieces, but the center spring perch is taller, and put too much pressure on the valve seat.

Wouldn;'t something more aggressive like grinding the valve and seat or maybe a new valve be called for?

Not sure, but I can say that a 1.48 BMC valve is a tough get on short notice.

I'm trying to upload a video of the air bypass through the seat from the port side, made with my inspection cam.  Yesterday, it shot out very aggressively.  Today, it looked like seltzer water - a definite improvement. 

Mark pointed out that this is all cold right now, and Vizard notes that there is quite a bit of warp in a valve at speed. 

It's my hope it's closer to solved than I think.

I'll get that video posted as soon as the computer lets me.

What a bummer to happen at the last minute. Arrggghhh........

Regards, Neil  Tucson, AZ

I'm not giving up yet.  My resources are a heck of a lot better for this engine on a Sunday in Milwaukee than they would be anytime in Wendover.

I was down to washing the car and putting it on the trailer.  Better now, better here, than there and next week.

That's my old buddy Dumb Luck.  Never know when he'll show - walks into the garage, and the next two days are spent addressing his concerns - sometimes for my benefit, sometimes not.