Milwaukee Midget

[fordboy628]

Just out of interest are any of the heads you are testing offset valve ones ?

Yes.   Both Swiftune heads use 1.48" inlet valves combined with 1.22" exhaust valves.     As this combination will not fit the standard valve spacing dimension, I suspect the exhaust valve has been offset by the usual .050".

Midget's Longman head uses a 1.48" x 1.15" valve combo.    I'm pretty sure it is at the standard spacing.

The other Longman head uses a1.48" x 1.22" valve combo.     Would have to suspect that it also has an offset on exhaust.

When I get some time this week, I'll measure the valve spacing centerlines for several of the heads I've been flow testing and post up the results.

OK.  Some measurement results just in:

Std 1275 cylinder heads, valve spacing center to center:     1.340"/1.345"
Swiftune cylinder heads,  valve spacing center to center:     1.370"/1.376"   so +.030"/.75mm spacing

The intakes (1.475" valve) remain centered, the exhausts (1.215") are moved outboard from the cylinder centerline.

I have heard of offsets in the .040"/1.0mm to .050"/1.27mm for exhaust, AND, for intakes. (1.50"/1.53" dia valves!!!!)   My understanding is that the double offsets with the giant valves are only used on LARGE bore sizes, such as 73.5mm.


Fordboy

[fordboy628]

Warning Will Robinson!!   Warning!!

Below are photos of a $5000.00 (approximately . . ) Swiftune cylinder head currently seeking employment as a . . . . . BOAT ANCHOR . . . . . preferably in the Royal Navy!!

 

Uhhmmm, don't let anyone tell you that sinking the valves into the chamber roof is NO PROBLEM.    On this late style "sculpted" 12G940 cylinder head, the valve depth combined with an overcut larger than what Swiftune originally machined into the chamber, has opened a "defect" into the water jacket . . . . . . .    This particular valve is about .03"/.75mm deeper than the other valves.   Combined with a .06"/1.52mm larger "overcut" this "valve job" found water.

BTW, the defect has been "picked at" just to see how extensive it might be.    The "water" was discovered at speed, in competition, after a 400 mile tow . . . . . .

That particular valve is .021" deeper than the chamber depth . . . . .   (measurements taken with the head inverted)   and you can see how heavy the "overcuts" were made.

If you are going to modify your head in this manner, you might consider ultrasound checking the thickness of the casting FIRST.   Or not . . . . .

Checkitfirstboy

[Milwaukee Midget]

I could see that having a negative impact on compression. 

But Mark, this challenges the accepted adages, the common knowledge, the benchmarks, the standards that all racers know to be true . . .

1 - "Bigger is ALWAYS better!"

and

2 - "The more you spend, the faster you will go!"

To my favorite heretic!     

[grumm441]

I could see that having a negative impact on compression. 

I don't know, as it builds up steam...

G

[Milwaukee Midget]

Just use higher viscosity water.

[fordboy628]

But Mark, this challenges the accepted adages, the common knowledge, the benchmarks, the standards that all racers know to be true . . .

1 - "Bigger is ALWAYS better!"

Ahhhh, you do know it's racing, not porn, right?


F/B

[WOODY@DDLLC]

You sure it's not a secret transfer port? 

[fordboy628]

You sure it's not a secret transfer port? 

Maybe a double, super secret, transfer port?     Injecting only one cylinder, so as not to be obvious . . . . . . .

[Buickguy3]

  How about some Ni-rod? Works for me.
    Doug 

[Peter Jack]

 How about some Ni-rod? Works for me.
   Doug  

I agree Doug. If the head has enough material to completely remachine I'm sure I could repair it with a complete preheat to red but it would likely cause some distortion. Otherwise I'd sure try a conventional localized repair.

Pete

[fordboy628]

 How about some Ni-rod? Works for me.
   Doug  

I agree Doug. If the head has enough material to completely remachine I'm sure I could repair it with a complete preheat to red but it would likely cause some distortion. Otherwise I'd sure try a conventional localized repair.

Pete

I'm game to try and repair the head, but the owner is not.    In addition to welding/brazing the defect, the head needs 8 valve seats to restore the high-lift airflow.    And, after having a bad experience with a dropped valve seat and the resulting blown engine & gearbox (couldn't get it shut off fast enough and it's a Mini . . . .) he doesn't want to risk another expensive debacle.    That is understandable.

BTW, I did not install the valve seat(s) that caused the problem.

Yeah, I know properly installed valve seats shouldn't be a problem, but sometimes client confidence in a repair trumps everything else.    What engine builder can guarantee a totally trouble free repair?      S*** happens when engines get over-revved and over-heated . . . . . . .

Auto racing is the ultimate "Caveat Emptor" sport . . . .        Well, except for thoroughbred racing . . . . . .

Fordboy

[jacksoni]

Well, if the owner is making an anchor out of it, maybe he would donate it to your upcoming Chris-Craft restoration project- if it had any other features making it worth repairing. :-P

[fordboy628]

midget,

Entered your data in to my copy of Bonneville Pro.    Attempting to duplicate your 2013 results based on your known data.

First pass through the data cruncher says it's not possible for an 1810 lb car to go 118.7 mph with 95.1bhp . . . . . .         even with an origami pilot . . . . . .   

Will need more accurate input data.   :| 

F/B

[Stan Back]

I saw him running over on #3.  I sorta goes south.  Every map I see, south looks downhill.  Maybe that's it.

[Interested Observer]

Fordboy/Midget:
Doing the calculations with the parameters as listed below, the results are also as listed below.  While the frontal area, drag coefficient, and driveline efficiency are estimates, they seem to be reasonable values, and show that the actual results from the salt can be consistent with predictions.  (Previous encounters with Bonneville Pro here on the forum have shown it to be less than confidence inspiring.) 
After Speed Weeks last year you guys vowed to distill the area and drag coefficient from the results, but I don't remember ever seeing them.  Did this ever get done, or is it considered proprietary info?
So, for what it's worth:

Speed   118.7   mph
Area   15   sq-ft
Cd   0.45
Aero drag   215    lb
Weight      1810   lb
Tire pressure   60   psi
Rolling drag   28   lb
Total drag   243   lb
Hp aero      68
Hp rolling     9
Hp total      77
Driveline eff.   0.9
Engine Hp at Bonneville   85.6
Engine Hp at Sea Level   93.4