Ready for the off season

Pulling season is winding down so time to do a little R&D work. Did pretty good this season with my wd45 puller with the stock gleaner motor making 50hp on the dyno. Had enough for our 4500lb class but lacked power in 5500 so.. what's the thoughts for the off season? Well let's just start with what's the best I can make hp wise without stroking a crank and spending a bunch of money. Any ideas I would appreciate some help. Thanks

I'm running a tsx871 drilled out at the moment. What should I be running on it

Compression.

What's to gain if I do 4 1/8 bore with flat top pistons head and manifold work

Your compression is so low in a stock engine, you won't mill enough off of anything to gain anything significant. Don't wreck your parts by taking some bad advice. If I wanted to make some power and not spend any money,

1. Advance the camshaft. Currently the intake centerline is 112-113* atdc and this is to late. Closing the intake valve earlier will trap more air and build more cyl pressure. 1 tooth advanced (13.333*) will help, though it would be best to make an offset key, or cut a new keyway and get in the intake centerline 103-105* range.

2. The carburetor just plain doesn't flow much air, the venturi sits on the bottom bowl and has to shear air at a 90* angle from the bottom bowl with basically no short side radius. If you were to build a "tounge" on the roof of the barb bowl, you could force the air around a large radius and increase what the carb flows. I've tested several and they are 95-99 cfm of air stock, after I build the tounge and replace the venturi they run about 145 cfm. I either make the venturi or buy some from a carb parts place in Washington..... I'll have to find the name.

3. The manifold is terrible. Where the neck from the carb joins the runners, it's a sharp 90* corner. I don't care who bored the manifold how big, you can't draw air over a sharp edge. Knocking that corner back and radius it will help. For example a manifold flows about 115 cfm in stock form, a few minutes spent on the corner and 140 cfm, or spending time and welding the outside and cutting a larger radius and working the floor where it turns to join the head and 180 cfm is easy. I fill the top corner also, I cut the floor flat and wide, fill the top to keep the air condensed on the floor.

4. The head also suffers from corners with no radius. Blend the corners of the intake port, it's T shaped and radiusing the corners will help. Valve and seat work can help, but depending on what you can and want to do there's to many options to take time to explain now.

There's simple things that can be done with spending very little money. You'll get the most benefit from altered camshaft timing and the carb modification.

Edited by wi50 - 28 Sep 2016 at 8:24am

Filling the back, bottom corner of the bowil doesn't cure the problem, but it needs to be done when filling the top. When I do the back bottom corner I also build a vane leading in front of the emulsion tube. That little vane gave me a significant improvement on the flow bench.

But let's cover the important one, the top. Think about it like an upside down cylinder head port......the venturi base is like the valve seat. Stick your tounge out of your mouth and curl it up toward your nose. This is the shape to build on the top of the carb bowl, or roof of the inlet. Leave a gentle radius and a lead in angle.to the venturi. When done it looks like.the intake port of a high performance automotive cylinder head.

The venturi in a stock bowl is grabbing air from the roof of the bowl, or short side radius....this radius is really non existent in the carb, it's a sharp corner. Building this tounge with a large radius leading to the venturi would give us a "short side radius", and this is where the air is traveling, that back bottom corner is a dead area. But by filling both and shaping them correctly we can make out venturi or " orfice" much more efficient.

Let's say the venturi can flow xxx cfm, but the air is very turbulent atthe inlet, by doing the shaping of the inlet correctly, I can increase the efficiency of the orfice.

If I took a plate of steel and drilled a hole through it that was say 1.129" diameter, that hole would have 1 square inch of area. If I bolt that plate on the flow bench and draw 28" h2o depression on the bottom side of it, it may flow 85-90 cfm of air depending on conditions..... But if I bored a hole through a piece of material say 4" thick and shaped the inlet in a radius and the exit like a radius, tuba or French horn shape, but the choke point in the center was still that same 1.129" diameter and I drew the same 28" depression through that orfice, it would flow 180 cfm depending on how well it's shaped.

Your carb venturi is no different, shaping the inlet will greatly increase the efficiency.

This is why I make the venturi and make it longer so I maintain the choke point at the emulsion tube ending, but I can shape the inlet with aa more gradual radius leading to the choke point....stock venturies are not shaped very well.

So here's some free and good information that I spent a very long time shaping things differently and testing on the flow bench to learn. During the winter months I'll do some carb work for people, but I feel I've spent enough time getting it right that I don't need to give away all the information.

Excellent!