Re: h vaccum?

Posted by ChadS on September 07, 2009 at 16:41:46 from (4.224.78.147):

In Reply to: Re: h vaccum? posted by CJ_1080 on September 07, 2009 at 10:43:40:

Rethink your hitch, as well as the carburator issue. If you run the H carb, they had two sizes of venturi options, small and a 1/4 inch bigger ID. M carb, you need a 25 or less. Venturi ID sizes are measured in 32nds of an inch, so when you see the two digit number, in the ID of the venturi, it means, (for example) 25, which is 25/32. Keeping the venturi size smaller than the biggest setup,,,
Will increase vacuum pressure, increase manifold air speed.
You need fast air speed to keep the air moving into the cyl when its lugging the hardest.
If the air speed is too low, it becomes dead air beacuse it pretty much loses its ability to draw, and mix the fuel that enters the cyl. It goes flat rpms drop faster.
Higher manifold vacuum pressure is associated with air speed, faster air speed, the higher the manifold pressure, faster, higher quality conditions inside the manifold and port create better conditions to enhance torque when the rpms are pulled way down, the carb butterfly is wide open, the air speed has to be matched up for the rpm ranges.

CJ, in your case, your target rpm for tuning will be from 1000 rpm to 1800 rpm. If your tuning it to run 2500 rpm, and on the track its running 1800 and less, tuning it at 2500 doent do much good, if it never sees it while its working under a load.

The other H was tuned for low rpm operation, his air, fuel were dialed in to run low rpm, and thats what you need to duplicate in your tuning.

40 degree distributor will kill you!
(more on that later)

Chassis adjustments, If your hooking that well, to the point of stalling, you dont have to touch anything in the engine to gain distance. A chassis adjustment is meant to balance the chassis. 18/20 hitch spec setup takes power on a good track.

If your stalling, you need to drop the hitch height 2 inches, if it goes further down the track, but still stalls, drop it downm another inch, but dont move the hook point back further away from the center of the rear axle centerline,,,

Once you have the chassis loosened up to the point of tire slippage, its now time to start looking at proper weight placement to get your chassis to LIFT the front end when the slightest load to the drawbar is applied, what goes up, must come down,,,,, when the front end drops if your air pressure in your tires are good, the hitch will lift the sled pan off the ground releasing its grip from the soil and putting all the weight on your rear axle and carries it till, you either stall, spin out, or full pull.

I suffer most cases from the opposite with my Super H puller. I spin out bad. I idle it down, to try to let the tires grab a bite to gain lift, but either the track is loose, and the best cut tire in the world is useless against a brand new tire in this case, or when I get to a soft spot, it spins and the front just bobs.

The first thing I will tell you is, I have never ran weight behind the rear axle on this tractor. I lightened the nose up quite a bit,,, and relied on the engines power to acclerate and hope it sticks, but 5 out of 10 times, it will spin with the front end down.

On a good track, I get it figured out pretty quick,,, as do most drivers, on the loose sandy tracks,,, Im three weight classes heavier than usual, just to try and get a bite to harness the massive torque this litte Super H stroker makes,,,, but, Ive exhausted my search for tires, for fast gears, power is not a problem, its in my chassis adjustments I have seemed to have seen many times on others, but dont have on my puller. It tells me that my front is heavy, need to move weights behind the rear axle to create a better counter balance for the lifting leverage that the chassis creates during the act of pulling.

Other optins I have considered, is changing the angles of the drawbar to create lift off the chassis by making brackets that have attaching points above the rear axle centerline, then rebending the drawbar, so it drops lower in the front and at an upwards angle to the hook point. When the front is up, the drawbar should be level with the ground, and pulling off the high points above the rear axle, actually making the front seem lighter, without changing weight. I can see this in my head, but have not got that far to redesign.

Oliver pullers already know this about the hitches, oliver hitches are one of the best pulling hitch design in stock form, vs IH, and it comes down to how its attached to the rear end, and how it creates lift. Its why olivers are hard to beat, but if the same basics are used, it can increase the pulling effect off a tractor. NATPA banned any part of the hitch above the axle centerline to even the odds, so this is a reasoning for my belief, If I can adapt an Oliver 88 hitch on the back of my H, would it pull better........... ChadS

Replies:

• Re: h vaccum? CJ_1080 19:25:06 09/07/09 (0)

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