IH Cub Cadet Pulling and Hot Rodding

[jpiper]

Wyatt and Frank,Nichol's performance
http://geocities.com/nicholsperformance2002
http://www.geocities.com/nicholsperformance2002/page6x.html

 

[wcompton]

Since titanium has a lower coeff. of thermal expansion, do you guys typically tighten up your lash settings?

 

[dkirk]

Todd,

I have a personal stash of welch plugs that I've accumulated over the years. Haven't bought any in a long time. Would think that any small engine, tractor, or carburetor repair shop would have some. Madson's would be my first try.

 

[wcompton]

re: my 4:32 post, it looks like lash can be tightened up .003 with Ti valves, this would give a little more lift & duration . . . .

 

[bmoore]

Wyatt,
I understand how decreasing the lash will increase the duration. How does it increase the lift?

 

[fmorski]

Bruce:

The lift of the valve is directly related to the lash. Lash is the distance between the lifter and the valve stem. The narrower the space, the higher the valve will be pushed and therefore increasing the open height and duration. The duration is increased since the lifter contacts the valve sooner and stays longer.

If Wyatt reduces it by .003" than the lift at the valve is increased by that much. THe duration can be calcualted if you know the original specs at the spec lash/clearance. You would also need to know the ramp data on the cam as that would also have some bearing. Regardless, the reduction in the clearance/lash will increase both furation and lift as Wyatt stated.

 

[bmoore]

Frank,
Thanks for explaining.
I already knew that. If the lift of a cam lobe is .500", that is the difference between the base of the lobe and the maximum height of the lobe. Subtracting a lash of .010", that would give a total lift of .490" at the valve, even though the cam is actually rising the full .500". (These numbers are just out of the air, since they make the math easy.)
I posted the question this morning. Last night on the open forum, I mentioned trying some beverages that my neighbor brought over to show his appreciation for me clearing his drive a few times. Sue and I tried a few of them. Maybe more than a few. My brain might have been a little fuzzy this morning. Good thing it wasn't a weekday.

 

[cmccarty]

Gentlemen, I know this shows my lack of engine knowledge, But......does an increase in valve lift of .003" make a statistically significant or even a measurable difference in engine performance?

 

[wcompton]

Charles, it depends on the situation, for simplicity's sake, if you look at a cam map (a diagram of a cam in an X-Y plane) you can think of the area under the cam profile as the amount of air available to the cylinder. The amount of lash is a negative vertical shift to the map, so minimizing lash minimizes this shift.

I guess it's like comparing a blueprint of a room to a cam map, adding 3" to one side of a 10'x10' room doesn't add as much area as adding 20'x20' room.

Sorry if my explanation is poor, I was never real good at 'splainin' stuff.

 

[gmcchesney]

Ok, you guys have talked me into a 3 angle valve job.What should be the seat angle be for both the intake and exhaust valve? Also the face width, this will be for a K301 pulling engine.
Thanks
Gary

 

[tmorrow]

has anyone tried jumping a 122 cub cadet, from the spark plug before

 

[tschweizer]

Tyler, I think you might have to expand a little

 

[wcompton]

Question on carb spacers-
How do you folks that pull arrive at the correct carb spacer length?

Reason I ask is because dealing with a single cylinder engine, even up to 9000 RPM this makes for an awful long pulse length to take much advantage of any pulse scavenging. On something say, a Formula 1 V10 engine, the intake runner length can be tuned to take advantage of intake pulses to give volumetric efficiency over 100%.

 

[dfrisk]

WYATT - I should have My book on the technical aspects of Ferrari's F1-2000 edition F-1 car in about a week, maybe 10 days. The article I saw in Car & Driver Mag. said the intake trumpets on those engines vary in length pnuematically six different times while accelerating from 12,000 to 18,000 RPM to correct the tuned length. Neat factoid is they can accelerate 25,000 RPM per second with no load. The 3.0L V-10 only makes 803 HP @ 17,500 RPM, 253 #/ft. of Tq @ 15,500 rpm, 18,000 RPM redline. Whole engine only weights 200 Kg. Bore is 96 mm & stroke is 41.4 mm. Csaba Csere did the book review for His editorial in the new issue! Author is Peter Wright, former technical director for LOTUS Engineering.
If You want to take some notes when I get it let Me know! ;-) Lot of aerodynamic features are explained in the book as well but I don't think they apply to Your project!

 

[farmall gray]

A little update on my carb problem. I took the welch plug out and it was clean inside. I ran some tag wire through all the passages just to be sure. The float level was a little high. That 149
had a #26 carb on it when I got it, but the engine I rebuilt for it had the #30. Just for giggles, I stuck the #26 on it to see how it would run while I was working on the #30 carb.
It fired right up and idled smooth and I didn't even have to adjust it much. So I know there was something wrong with the #30. I'll put the #30
back on and try it tomorrow.

 

[farmall gray]

I decided to try that carb again tonight. I still cant get it to idle with the #30 carb.
It just acts like it is not getting enough fuel
at idle. It will almost idle for a short time but
gradually loses speed and stalls unless I choke it a little or burp the throttle.
I can't find anything physically wrong with the carb.
I have checked and rechecked everything. I even tried swapping needles, jets, etc efrom the #26
carb. I'm starting to think that maybe with the
hotter cam that it doesn't have enough vacuum
at low RPMs to make the idle circuit work. I have a #30 carb from a 1650. My next step is to put it on and see what it does. I'm really getting tempted to just clean up the #26 carb and put it
on permenantly.

 

[dkirk]

Todd,

Could the throttle shaft be so worn in the #30 that an air leak is occurring? You have ample vacuum at idle with that cam - I don't think that is the problem.

Wyatt, if you send me the engine speed at which you want optimal inlet ramming, I'll respond with 3 different inlet duct lengths that will all perform nicely.

 

[wcompton]

Dave-
I ran numbers and the 2nd, 3rd, and 4th harmonic were waaaay too long. Maybe I'm doing something wrong with the numbers, with these low RPM's I was getting the 4th, the shortest, at 19 inches . . . . and beyond that the return is so small that it didn't seem worth the trouble.

I guess that's why I asked the question, being that a stock engine running 3600 RPM, the intake valve works at 30Hz, at sea level the wave from the valve would be quite long, not to mention how the wave would get longer with altitude and under the negative pressure of any intake restrictions like the air cleaner.

(I'll send you my information)

(Message edited by wcompton on February 12, 2004)

(Message edited by wcompton on February 12, 2004)

 

[farmall gray]

Dave,
I had put a new throttle shaft kit in it. Anyhow,
I figured out the problem. The problem is the calibration of that particular carb. There was a
small hole going in to the chamber between the 2 threaed parts of the main needle. I figured out how the idle circuit works. This hole is drilled in from the top air cleaner screw hole and another hole is cross drilled from the air horn.
What this hole did was to weaken the vacuum to the idle circuit leaning it out. I noticed that the other 2 carbs didn't have this hole. So to try it, I stuck a round toothpick in through the air cleaner screw hole plugging that small hole.
Viola! it idles fine with a little adjustment of the idle mixture screw. If I pull the toohpick out, it dies. So I took the carb back off and
plugged the hole with JB weld. I'm waiting for the JB to set up, but I know it will cure the problem. You guys that said it had a vacuum leak
were right, but the vacuum leak was designed into the carb by kohler!
Whatever engine combo this carb was calibrated for, it sure didn't work with mine.
It must have been for an engine that had a very strong metering signal at idle.

(Message edited by tmarkle on February 13, 2004)

 

[dkirk]

Todd,

Excellent! Nice diagnostic and we all learned something to watch out for.

Thanks for that.