Not the Mercdog again

[larrycavan]

I pictured the hole being closer to the front wall than it actually is. I doubt that placing it 180 degrees the other way is going to matter at all. What you might consider is coming off the orifice board with another board that meets the front wall and is parallel with the floor. Just cut the inner end on an angle matching the angle of the orifice board, put a support strip inside the front wall for the other end to sit on. Lave the exit hole on the angled board where it is. Cut a new one in the new board where ever it suits you. Install the baffle.

Reason being is you can locate the orifice parallel to the floor and the baffle will distribute air more evenly to the orifice.

I left mine on an angle and installed the baffle parallel to the floor. Doesn't seem to matter. Bench calibrates in with a .54 Cd and my orifice is not sharp edged.

[Old Grey]

Exactly what I was thinking. I think the hole being 180º out helps me because I can put the baffle lower without affecting the orifice, and that makes the 3" top box unnecessary.

It is a good looking bench, hence the reason to fix it, it's just under the skin it's subtly flawed.


I should post pictures of the faults so that we can have a guessing comp.

[RACEPUMPER]

Your right grey, that bench looks really pro. I have seen one of these with a single orifice and deck plate style access port. The basins were only used for direction change and depression was adjusted with a big old variac. It had the big baffle box on top. pretty much everyone with these has done this mod. Search the old forum it's all in there. The PTS is the best design by far, the smaller superflow and saenz are like your mates bench inside. Keep us posted.
Jim

[larrycavan]

Looks good. Tweak it, hook up your FP1 and you're good to go.

[Old Grey]

Looks good. Tweak it, hook up your FP1 and you're good to go.

The looks are actually the deceptive part because it looks good, but it has quite a few problems.

This looks like a straight forward fix, until you realise that there are no screws holding the 2 panels together. I don't know what possessed me to run a magnet over the box, but I'm glad I did because there's lots of screws missing - screws on the front are 18" apart -.


Other classics are, the switches on the front are open on the back, cables not sealed, not painted internally, and that adds up to a lot of air leaks.

There's no hard problems, just heaps of them.

Another question, I read that people are changing the bowls for ¼" Alum disks, but it doesn't say why, just wondering if bowls matter?

[Tom Vaught]

MEMORIES

Think most people went down the MERCDOG path at one time or another.

The electronics packages available are so much better today vs during the early days.

Good Luck with your project.

Tom Vaught

[larrycavan]

It's just a valve. All it needs to do is seal when it's shut. It's best if it can't flutter in the breeze though.

Whoever built that cabinet wasn't much for attention to mechanical details. It's like anything though....there are always things you look at and say "I can do that better".

I didn't put my switches on the front plate because it just seemed to me to be a potential for a leak area. I put mine on the back board. There are no wires inside the the plenums on mine. I also put a little breaker box on the back of mine and came out of that to switches.

Doing it again....I would devise a spring loaded rotating disk with a lock and proper seal. Something quite rigid and squared edge orifices. It doesn't matter what your orifice Cd value works out to be.

[larrycavan]

I want to give you a little tip on something else as well. Everyone is so big time into automation but make no mistake, there's information to be had by manually controlling the flow...IF you know what to look for.

Let's say you do a lot of a particular type of cylinder head. When you get one that wants more turns on the flow control knob than is normal......there's a problem with that port and you need to be checking it out. Automating test pressure control could hide that.

A flow bench is a tool..nothing more...nothing less. As time goes on you get a feel for your bench and the more things you actually feel, the quicker you notice when something doesn't feel right.... That's a major plus IMO.

Perhaps with automated test pressure control you can hear the motors spin up more and that will tip you off....don't know because I don't use it. I don't find it a challenge to turn that little knob and I'm not in a big rush when I'm flow testing. A few seconds here or there isn't going to make any difference to me.

[Tony]

.

The story goes that someone(Warspeed) built this Mercdog bench around Feb 2004 to Aug 2005 -

Not guilty your Worship.....
It was definitely not me, the faults were all too evident even in the very old days long before this Forum even started.

I still have a bench with a very large vertical rotating turret, but it always flows in the same direction (having two test holes).
Sealing the turret was never a problem, direct air pressure plus a big spring does that.
It also has a very large effective settling chamber ahead of the orifice, which makes a very big difference.

It has absolutely nothing in common with the original Dog design.

[Malvin]

Tony
It also has a very large effective settling chamber ahead of the orifice,

That is interesting to me