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Author Topic: Milwaukee Midget  (Read 2231297 times)

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Offline fordboy628

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Re: Milwaukee Midget
« Reply #5595 on: February 20, 2016, 03:59:08 AM »
midget,


1/   The inlet ports are slightly better, ~ 1% or so.   The shape of the curve is pretty much the same.
2/   The exhaust ports though are worse, ~ 8%.   A significant difference.

I'm not yet sure why the exhausts vary so much.  I ground these valves before testing, so the margins are thinner, but I'm not convinced that is the difference.   I'm going to have to carefully measure the port's mcsa to try and get a handle on the difference.   So even though these heads are the same casting number, they might be from differing "batch lots".   I'm going to carefully check them over for production date codes, if any.    This would be a good question for Steve, how to "decode" any production casting codes.


 :cheers:
Flowtestboy
Flowtestboy: though the 4 valve may behave differently and this head may be different, a lot of people seem to think that exhaust ports are TOO BIG to start with and that continually hogging them out and putting in bigger valves is counter productive. Some of this is to allow bigger intake valves ( making the exhausts smaller that is) but also just that the flow dynamics of the exh port and attached header/exh pipe can benefit by the smaller port/matching pipe. The flow may increase on the bench but what does the HP do? this is of course the question. In your experience with similar configurations, which I know is extensive,what do you think the 8% difference might do on a running engine? (my comments above are primarily associated with 2 valve v8s so may not apply at all) Just asking.  :-D ( methinks question answered with dyno time..... :evil:)

Jack,

I see this every day that I run flow tests or simulations.   The presumption that some modification is going to perform the same from one engine type to another, is a giant mistake.   Even when the engines are quite similar, differences occur.   Just because a certain porting modification works on a V8 Pontiac, doesn't mean it will work on a V8 Olds.   Too many variables.    The flow and performance differences between 2 valve and 4 valve engines are quite large, basically for the same reason.

On this Rover head, the ports at the manifold face are actually quite large.    Where the ports are divided internally however, the minimum cross sectional area is pretty small.   I believe that this is where the peak flow is being choked off.    I want to finish some flow demand simulations prior to any "enlargement" of the mcsa though.     "Hogging out" the ports is EXACTLY what I do not want to do, because that will turn this experiment into a 11,000 rpm "screamer".

One of the other factors that limits valve size is the valve centerline spacing, obviously something that is "fixed".   And the use of a 75mm/75.5mm bore diameter also restricts the maximum diameter of valve that can be used.

The 8% less exhaust flow significantly alters the flow ratio between intake and exhaust.    I have a certain flow balance % value in mind for this engine.   That percentage usually works well with the same cam grind on both intake and exhaust.    Flow balance % below that value typically requires different cams from intake to exhaust.   I can usually make anything work, given enough development time and dollars.    But knowing the data values ahead of time, allows a more "thoughtful" approach to the cam(s) selection.     On any project that is funding "challenged", it just makes sense to try to make the best choices on the first shot, something that some forethought allows for.   "Development" always occurs on the dyno after "initial engineering".    The trick is to use the "initial engineering" to eliminate the poor or bad choices.   I've also called this process the "evaluation and planning stage".

The bottom line is:  Engines DO NOT CARE about numbers and percentages, flow rates, etc, etc.    The end focus is to produce bhp as opposed to information.   But the "information based approach" works better, in my experience.

To hit my target, I want to use a gunsight rather than throw a dart.   It just works better for eliminating piles of shiny, useless parts.

Next time we meet up, I tell you some "tales of the drag shop".    You're buying.
 :cheers:
Flowtestboy
Science, NOT Magic . . . .

I used to be a people person.  But people changed that relationship.

"There is nothing permanent except change."    Heraclitus

"Only two things are infinite, the universe and human stupidity, and I'm not sure about the former."     Albert Einstein

Offline jacksoni

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Re: Milwaukee Midget
« Reply #5596 on: February 20, 2016, 11:54:19 AM »
So, taking all this planning into account, the lower flowing head gives you an opportunity to -maybe- adjust the flow ratios/percentages more to your liking. I was not suggesting to "hog something out">  :-) (others do). Indeed hitting the planning target is the best starting point. I think in prior posts on this thread you have pointed out how some"guru" ported a head and lost flow and performance. But you also point out that flow numbers don't always tell the story and bigger isn't necessarily better. Air speed, turbulence etc and many other factors are important and need to be looked at. Which of course you are doing.

I look forward to the opportunity to listen to tales and indeed, I'm buying- happily.  :cheers:

I look forward to seeing flow results with the different shaped valves.
Jack Iliff
 G/BGS-250.235 1987
 G/GC- 176.245  2018
 G/GMS-182.144 2019

Offline Milwaukee Midget

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Re: Milwaukee Midget
« Reply #5597 on: February 20, 2016, 03:13:50 PM »
So, taking all this planning into account, the lower flowing head gives you an opportunity to -maybe- adjust the flow ratios/percentages more to your liking.

I see your idea, Jack.  Yes, it could be that the anomalies inherent in the second head might play to our advantage, were it not for one thing.  The cam bearing surface is damaged on the second head.

I was able to pick it up as cheaply as I did because of this problem.

The casting numbers are the same, and Mark's going to better suss out the reason for the differences. 

Once the reason is determined, we'll need to be cautious with our experiments on the second head to be certain we'll be able to repeat/apply any shaping and sizing information to the original casting.

British castings . . . the more things change . . .
"Problems are almost always a sign of progress."  Harold Bettes
Well, I guess we're making a LOT of progress . . .  :roll:

We are NOT rebuilding . . . We are reloading.

GOD SAVE MG - The Queen can take care of herself!

Offline fordboy628

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Re: Milwaukee Midget
« Reply #5598 on: February 21, 2016, 07:15:27 AM »
Chris,

THANK YOU!!


For giving up most of your Saturday to help out my son.  I'm sure he appreciates it.

As do I and Mrs. Fordboy.

Thanks for a great gesture of friendship.

 :cheers:
Mark
Science, NOT Magic . . . .

I used to be a people person.  But people changed that relationship.

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"Only two things are infinite, the universe and human stupidity, and I'm not sure about the former."     Albert Einstein

Offline Milwaukee Midget

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Re: Milwaukee Midget
« Reply #5599 on: February 21, 2016, 10:08:10 AM »
I just drove the truck and ate the patty melt.  :wink:

You and Junior are always welcome.

 

"Problems are almost always a sign of progress."  Harold Bettes
Well, I guess we're making a LOT of progress . . .  :roll:

We are NOT rebuilding . . . We are reloading.

GOD SAVE MG - The Queen can take care of herself!

Offline fordboy628

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Re: Milwaukee Midget
« Reply #5600 on: February 22, 2016, 05:47:10 AM »
midget,

I got a flow test strategy mapped out in my head, along with the other voices . . . . . . . . .

Give me a call on my cell phone after 8am . . . . . . .   I'll try to move your voice to the front of the line . . . . . .

 :cheers:
Thinkyboy
Science, NOT Magic . . . .

I used to be a people person.  But people changed that relationship.

"There is nothing permanent except change."    Heraclitus

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Offline Milwaukee Midget

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Re: Milwaukee Midget
« Reply #5601 on: February 22, 2016, 08:34:29 AM »
midget,

I got a flow test strategy mapped out in my head, along with the other voices . . . . . . . . .

Give me a call on my cell phone after 8am . . . . . . .   I'll try to move your voice to the front of the line . . . . . .

 :cheers:
Thinkyboy

As long as one of those voices isn't Jay Cutler - I certainly wouldn't want to be dealing with a bi-polar Bear . . .
"Problems are almost always a sign of progress."  Harold Bettes
Well, I guess we're making a LOT of progress . . .  :roll:

We are NOT rebuilding . . . We are reloading.

GOD SAVE MG - The Queen can take care of herself!

Offline jacksoni

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Re: Milwaukee Midget
« Reply #5602 on: February 22, 2016, 06:22:05 PM »
So, taking all this planning into account, the lower flowing head gives you an opportunity to -maybe- adjust the flow ratios/percentages more to your liking.

I see your idea, Jack.  Yes, it could be that the anomalies inherent in the second head might play to our advantage, were it not for one thing.  The cam bearing surface is damaged on the second head.

I was able to pick it up as cheaply as I did because of this problem.

The casting numbers are the same, and Mark's going to better suss out the reason for the differences. 

Once the reason is determined, we'll need to be cautious with our experiments on the second head to be certain we'll be able to repeat/apply any shaping and sizing information to the original casting.

British castings . . . the more things change . . .
Got it. How badly damaged are the cam bores? some folks may still have the tooling to rebore. I had to do that with my head after investing a bunch in it and finding the bores were significantly out of round and small to boot. What is the bore diameter? There are some cutters available that might do it. Not remembering the source right now but if you have the diameter, I'll dig some if you are interested.
Jack Iliff
 G/BGS-250.235 1987
 G/GC- 176.245  2018
 G/GMS-182.144 2019

Offline fordboy628

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Re: Milwaukee Midget
« Reply #5603 on: February 22, 2016, 09:29:28 PM »
So, taking all this planning into account, the lower flowing head gives you an opportunity to -maybe- adjust the flow ratios/percentages more to your liking.

I see your idea, Jack.  Yes, it could be that the anomalies inherent in the second head might play to our advantage, were it not for one thing.  The cam bearing surface is damaged on the second head.

I was able to pick it up as cheaply as I did because of this problem.

The casting numbers are the same, and Mark's going to better suss out the reason for the differences. 

Once the reason is determined, we'll need to be cautious with our experiments on the second head to be certain we'll be able to repeat/apply any shaping and sizing information to the original casting.

British castings . . . the more things change . . .
Got it. How badly damaged are the cam bores? some folks may still have the tooling to rebore. I had to do that with my head after investing a bunch in it and finding the bores were significantly out of round and small to boot. What is the bore diameter? There are some cutters available that might do it. Not remembering the source right now but if you have the diameter, I'll dig some if you are interested.

The cam bores are not THAT bad.   A proper size and length Sunnen honing mandrel (~25mm - 28mm ?) would fix it up.   BUT, the cam "ladder" would need to be cut .005"/.010" prior to honing.   Not too difficult, but the "average" engine shop would NOT be able to do it.   Alternatively, for a shop with an older Tobin-Arp cam boring machine, after the aforementioned "ladder" surfacing, the boring back to size would be a piece of cake.    The only shop that I know that has a Tobin-Arp cam boring machine is Apex Automotive in Bensenville, IL.   And theirs has been out of service for years because of a broken part that is no longer available.

This is why dealerships junk modestly damaged heads, and just bolt on all new stuff . . . . . . .

 :cheers:
Fordboy
Science, NOT Magic . . . .

I used to be a people person.  But people changed that relationship.

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"Only two things are infinite, the universe and human stupidity, and I'm not sure about the former."     Albert Einstein

Offline Milwaukee Midget

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Re: Milwaukee Midget
« Reply #5604 on: February 22, 2016, 09:32:53 PM »
Jack, thank you.

Mark has already started some machining on the test head, so it's not likely we're be able to backtrack, but if we could, this is what we'd be facing -

Essentially what would need to occur would be mill the top of the head and the flat of the cam ladder, make a 24 1/2 mm align hone the length of the head through both sets of cam journals and corresponding cuts to reset the cam seals on both ends.  We'd need to take most of it out on the head side and a touch from the cam retaining ladder.  It's probably doable, but we're already in uncharted waters converting from hydraulic to solid followers and unknown cam base circles.  Yeah, we'd need to shim the valves either way, but sticking with these stock dimensions to begin with gives us a better chance of success.

We have a friend who keeps saying "it's complicated". 

I disagree.  Truth is, it's simple.

The problem is that we're the ones complicating it!   :wink:

Mark called today - some preliminary flow tests on the offer-up head are under way.  We'll see what the different valve shapes provide, but it's likely the shaping necessary to get this head where it needs to be for what we're looking to do is not too extensive.  I'm liking the 'less-is-more" idea, and seeing as this head is used in much larger applications with success, scaling it back probably means simply getting the flow angles right, cautiously adjusting the cross sections to meet the flow demands and then choosing a cam profile. 

There is an issue with the valve seat where it meets with the casting in the bowl area - this is on both heads.  There's a bit of a lip, but simply smoothing it out creates an ugly angle of flow.

I'm certain Mark will chime in when he's done with his taxes - poor bastard.

He's heading back to flow world on Thursday. 

EDIT -

Oh, well, it seems he DID chime in.

Makes sense - much more fun than dealing with Uncle Sam.   :cheers:
"Problems are almost always a sign of progress."  Harold Bettes
Well, I guess we're making a LOT of progress . . .  :roll:

We are NOT rebuilding . . . We are reloading.

GOD SAVE MG - The Queen can take care of herself!

Offline fordboy628

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Re: Milwaukee Midget
« Reply #5605 on: February 22, 2016, 09:37:54 PM »
midget,

Did some of the flow testing this AM and got some decent results with simple modifications.    I'll post them up once I have them downloaded from the portable cauldron.    Spent the afternoon cutting the valve seats for the oversize REC valves.    Without motorcycle size cutting tools, that became a major project.    Got the head cleaned up and re-assembled, but ran out of time to test.    Will continue on Thursday.

Just to whet your appetite, Intake now 151 cfm;  Exhaust now 120 cfm; both on head #2 with STOCK size valves.

 :cheers:
Flowtestboy
Science, NOT Magic . . . .

I used to be a people person.  But people changed that relationship.

"There is nothing permanent except change."    Heraclitus

"Only two things are infinite, the universe and human stupidity, and I'm not sure about the former."     Albert Einstein

Offline Milwaukee Midget

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Re: Milwaukee Midget
« Reply #5606 on: February 22, 2016, 09:40:33 PM »
Less IS more!
"Problems are almost always a sign of progress."  Harold Bettes
Well, I guess we're making a LOT of progress . . .  :roll:

We are NOT rebuilding . . . We are reloading.

GOD SAVE MG - The Queen can take care of herself!

gkabbt

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Re: Milwaukee Midget
« Reply #5607 on: February 22, 2016, 09:49:07 PM »

Less IS more!

Depends on what is being discussed!!!!!

Sorry.....couldn't help myself.  :-D  :-D  :-D

Gregg
« Last Edit: February 22, 2016, 09:50:40 PM by gkabbt »

Offline fordboy628

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Re: Milwaukee Midget
« Reply #5608 on: February 23, 2016, 06:46:19 AM »

We have a friend who keeps saying "it's complicated".  

I disagree.  Truth is, it's simple.

The problem is that we're the ones complicating it!   :wink:


Well, I admit that you can:  "Just bang 'em together and get 'em out the door."

In fact, I know several engine professionals who do just that.   Some of their clients are happy, some are not.    They respond by saying:  "You can't please all of the people all of the time."

There are, however, alternate choices, depending on the results you want, and how much of a "deep thinker" you might want to be.

As I have mentioned a time or two previously:    "It's complicated."   "Both ways work."   "More or less."   "Eventually."    Decide for yourself whether I put those comments in this order for a specific reason . . . . . . . . . .

"Ya pays yo money, and ya makes yo choice". . . . . . . . .

 :dhorse: :dhorse: :dhorse:
Nolongeraboy
« Last Edit: February 23, 2016, 06:50:19 AM by fordboy628 »
Science, NOT Magic . . . .

I used to be a people person.  But people changed that relationship.

"There is nothing permanent except change."    Heraclitus

"Only two things are infinite, the universe and human stupidity, and I'm not sure about the former."     Albert Einstein

Offline fordboy628

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Re: Milwaukee Midget
« Reply #5609 on: February 23, 2016, 06:48:45 AM »
Less IS more!

Ahhh . . . . . . . .

NOT in porn . . . . . . . .

Just sayin'

 :dhorse:

 :cheers:
M
Science, NOT Magic . . . .

I used to be a people person.  But people changed that relationship.

"There is nothing permanent except change."    Heraclitus

"Only two things are infinite, the universe and human stupidity, and I'm not sure about the former."     Albert Einstein