Valve adj. for power

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Model T Ford Forum: Forum 2009: Valve adj. for power
Top of pagePrevious messageNext messageBottom of page Link to this message  By tyrone thomas on Sunday, December 06, 2009 - 08:53 pm:

can the valves be adjusted with less clearence to hold valve open longer?


Top of pagePrevious messageNext messageBottom of page Link to this message  By tyrone thomas on Sunday, December 06, 2009 - 09:09 pm:

maybe there just is'nt enought to make a difference.


Top of pagePrevious messageNext messageBottom of page Link to this message  By Thunder on Sunday, December 06, 2009 - 09:16 pm:

Nope.... Any overadjustment, will leave the valve open, causing a loss of power. Remember, its only a 20 hp engine. There are a few "free horsepower" secrets, like balancing, but why not a cam, a "Z" head, and a good exhaust?


Top of pagePrevious messageNext messageBottom of page Link to this message  By David_Cockey on Sunday, December 06, 2009 - 11:40 pm:

Reducing valve clearance will increase the valve open time. This can increase peak power and torque at high engine speeds, and reduce power and torque at lower engine speeds. This can result in a slower accelerating car when driving since a T only has a two speed transmission. Exceellent information on Model T camshaft profiles and valve timing at the Tulsa Model T club website.

If the valve clearance is reduced sufficiently the valves may not completely close when the engine is hot. This will quickly result in burned valves.

I have no idea how balancing an engine increases power.


Top of pagePrevious messageNext messageBottom of page Link to this message  By Thunder on Monday, December 07, 2009 - 01:10 am:

Better balance... Higher RPM...


Top of pagePrevious messageNext messageBottom of page Link to this message  By David_Cockey on Monday, December 07, 2009 - 01:50 am:

The driver may run higher rpms with a better balanced engine because it feels and sounds better, but better balance by itself. won't make the engine capable of higher rpms.


Top of pagePrevious messageNext messageBottom of page Link to this message  By Thunder on Monday, December 07, 2009 - 07:10 am:

ok...


Top of pagePrevious messageNext messageBottom of page Link to this message  By Fred Schrope on Monday, December 07, 2009 - 09:27 am:

Thunder
I agree


Top of pagePrevious messageNext messageBottom of page Link to this message  By Seth Harbuck - Shreveport, LA on Monday, December 07, 2009 - 09:50 am:

Valve clearance:

When valve lift isn't but 1/4", tighter valves are bound to produce more power because they open further.

But valves get longer, especially exhaust valves because they run hotter than the block they run in, so don't get crazy with this on exhaust valves.

Balance and power:

An engine that shakes because of lack of balance will have less power than one that doesn't. Shaking requires energy and it is a loss - it isn't being added to crankshaft torque. Thunder is correct.

Seth


Top of pagePrevious messageNext messageBottom of page Link to this message  By Erich Bruckner on Monday, December 07, 2009 - 12:58 pm:

What about better balance leading to less self destructive forces of torsional and friction losses. Perhaps no increase RPM, but less power going to those forces(it's probably a small amount) and increased performance in the longevity arena?

Erich


Top of pagePrevious messageNext messageBottom of page Link to this message  By Frank Harris on Monday, December 07, 2009 - 01:50 pm:

Dave is correct but so is Thunder. Balance will not make it run faster but it will let it run faster.

In other words, you chicken out and back off when it vibrates and the result is that you go slower.


Top of pagePrevious messageNext messageBottom of page Link to this message  By Seth Harbuck - Shreveport, LA on Monday, December 07, 2009 - 02:42 pm:

Racers that intend to win spend the money to have their engines balanced. More power = more speed.


Top of pagePrevious messageNext messageBottom of page Link to this message  By David_Cockey on Monday, December 07, 2009 - 06:14 pm:

The amount of power that goes into shaking the engine is very, very small compared to the output of the engine.

There are other good reasons to have a well balanced engine - durability and general pleasantness.


Top of pagePrevious messageNext messageBottom of page Link to this message  By Hal Davis on Tuesday, December 08, 2009 - 01:13 pm:

I don't know that it is so small. Engines are heavy and then they shake the whole car. That's a lot of mass! Then there's the acceleration part of it. Something shaking back and forth is accelerating and decelerating an awful lot. You'd have to make some assumptions to crunch any numbers, but I would guess that vibration can rob a significant amount of energy from an engine.


Top of pagePrevious messageNext messageBottom of page Link to this message  By Seth Harbuck - Shreveport, LA on Tuesday, December 08, 2009 - 03:14 pm:

As much as a T can shake and as little power as it has, it probably isn't very small. The argument isn't how small it is, it's whether or not vibration saps power.

It does.


Top of pagePrevious messageNext messageBottom of page Link to this message  By tyrone thomas on Tuesday, December 08, 2009 - 03:33 pm:

Ah, excuse me, the tread is about adjusting the valves with a smaller gap and getting tons more power. :-)


Top of pagePrevious messageNext messageBottom of page Link to this message  By Seth Harbuck - Shreveport, LA on Tuesday, December 08, 2009 - 05:11 pm:

Yes, you are right - sorry that I contributed to the thread derailment. Please accept my apology.

Tons more power would probably be more easily found by adding a shot of nitrous oxide with the appropriate amount of fuel to go with it.


Top of pagePrevious messageNext messageBottom of page Link to this message  By bob wood on Tuesday, December 08, 2009 - 07:27 pm:

I am no expert mechanic, I can only report what worked for me. I have two T's. A 25 speedster with the Chaffins perf. cam and a 19 roadster with the stipe 280 cam. The speedster valves are all set at different gaps by the timing of the opening and closing of the valves. The roadster is set all the same because it is a new cam, not a regrind.
Our club is fortunate to have an expert mechanic, Dave, who is especially fond of T's. I ran my speedster with a rebuild, 6:1 head, distributor, Chaffins dual exhaust, Winfield 1 1/2 inch carb for about 6 months before the crank failed. Dave supervised the re-do of the speedster engine and spent a day setting the valves with a degree wheel. Bottom line, when I did the first test drive it felt like the car jumped. Not only was acceleration better, it also sounded smoother, and wanted to run away on top end.
There is a great article in Murray Fahnestock's book The Model T Fordowner, "The Fine Art Of Valve Timing and How To Acquire It" on page 293.
I think the book is available fom Lang's. There was an article in the Vintage Ford detailing this approach, but I don't know which volume. If you have the CD it should be easy to find.


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