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 Post Posted: Mon Jul 04, 2011 3:20 pm 
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Well actually the blocks and tune I had came from tuner. I can only find one right now, I am going to have to do a good search of my shop to find the other. Things always seem to have a way of moving when you gone six months and you wife decided to clean your shop.

Here is the last log

Image

Basically, we were working on in, I deployed, came back and tuner for what ever reason went off the grid. So I never messed with it much after that. Could never get it to smooth out, pretty sure that rich condition up front was from the squirter pumps, it was that way with the weber plates also and I shaved them down. Not sure if something was up with the blocks or not.

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 Post Posted: Tue Jul 05, 2011 8:47 am 
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Bill what were the jets and main air bleeds on that run?

From what I see there I'd be trying both smaller MJs and MABs. 2 steps smaller on the MJ and .003 to 005 smaller on the MABs. The smaller MJ will take away fuel over all and the smaller MAB will add fuel back up top.

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 Post Posted: Tue Jul 05, 2011 2:27 pm 
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I would have to go back and check my records to confirm,

But I believe they were

86/96 Jets
.026 HSAB

When I find the other metering block, I will give them a try again. Going lower the .026 seems to be outside what I have typically seen.

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 Post Posted: Tue Jul 05, 2011 5:21 pm 
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Correction,

This is how it was set up

.052 t-slot
.026 hsab
.040 Idle Jet
.070 Airbleed
84front
96 rear

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 Post Posted: Wed Jul 06, 2011 10:05 am 
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Well I found the other block, so a test with those blocks will be in the future.

Curious as to why you think I need to drop the jet size? I can tell you the richness in the first 1.5 seconds was a result from the squirters, The condition existed with the weber stuff, and it did start going way until are started modifing the pump cams.

I plan on setting back up the way tuner had instructed and go from there.

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 Post Posted: Wed Jul 06, 2011 10:36 am 
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I would start with 93 square with no PV, jet it from there for best MPH on the track. Put the PV back in if you want to run it, then jet the down 4-6 to start. Go up or down as needed on the primary, leave the secondaries alone. If you find the cruise too rich or lean you need to balance the primary jet and PVCR to achieve that, leave the secondaries alone. Once you get the entire combination of jets and PVCR optimized then you can jet both up or down to handle different altitudes or major weather changes that shift the DA.


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 Post Posted: Wed Jul 06, 2011 2:24 pm 
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Bill this carb tuning stuff is a crap shoot, in case you haven't already figured this out. The changes I recommended are things that I have done with MY engine that changed the AFRs pretty much the way yours seem to need to go.

We know from experience that taking away from the MJ will take fuel away at all points down track. We also know that increasing or decreasing the size if the MAB will change how that fuel flows up on top end. More MAB = less fuel up top and LESS MAB will do the opposite. It's a delicate balancing act that won't be arrived at in a single change of any one item in these circuit(s) and I say circuits because a 2 circuit Dominator is still a 3 circuit carburetor, ie, idle, T slot and mains and all are interconnected though separate. O:) Figure that one out and you got the shitz down pat!!! \:D/

Jmark is correct in doing your tuning with jet square and NO PV. That way you know exactly what each quadrant of the carb is doing. Once you establish what it needs square (may even need stagger jetting) for best MPH, then put the PV in and work back to the AFRs that you had with the jet square. THAT will establish a baseline for future tuneup changes. Oh, and once you get there, WRITE ALL THAT INFO DOWN.

And on a final note, I realize that you are foot braking and need a clean low end but it's essential that you find what the engine wants down track and then work your low end/starting line stuff back to that up top.

And on another note, how much did you have to cut your pump cams to lean out the hit? :-k

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 Post Posted: Wed Jul 06, 2011 4:02 pm 
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A little note on the pump cams is have a pair of extra ones cause once you step over that line of clean take off it will bog and then you may have to start over again. This way you can file the ones you have and replace them after each test..
Yea I know PIA but it worked for me and Bill if you need one let me know as I have one that I filed to much for my package but my be ok for you...

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 Post Posted: Wed Jul 06, 2011 4:08 pm 
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Trust me Ken, I know this carb stuff is a crap shoot, I have spent alot of time finding stuff that doesn't work. ](*,)

Here is a pic of how much I had to take out. Everything I tried before messing with cam would not change anything. It occurred to me when I had the carb on the bench, When I actuated the throttle valve, the squirter would take nearly 2 seconds to empty.

Image

Here is a log how it currently is, before I started messing with the cam, the first 2 seconds looked like the first log I posted. It still needs some work, but definitely moving in the right direction.

Image

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 Post Posted: Sun Nov 20, 2011 12:18 pm 
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So my brain is working a little more about uneven transition between the blocks.

I was thinking of drilling them out to .250, then inserting a brass sleeve. Then drill out the sleeve to a smaller size. This way I would have a complete smooth transition between the blocks. Figure this is really the only way to really equalize each barrel is this. It annoys me to have to stagger the jets.

Whats every one think? Also in recommendations as to the final size of the channels?

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 Post Posted: Mon Nov 21, 2011 10:12 pm 
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No opinions?

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 Post Posted: Tue Nov 22, 2011 7:39 am 
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Isn't there an issue with the cu in the brass reacting with the fuel?

I like the idea. I'd do the same if I was in your shoes but with aluminum. McMasters has Al standoffs in 1/4" OD

A reamer would make a more accurate hole than a twist drill if you can access someone with or buy.

edit:
PS What size shooters? Since its lean - rich in the pump shot, have you tried larger shooters to let more delivered early?


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 Post Posted: Tue Nov 22, 2011 8:56 am 
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I have taken a different direction on this carb and went to a one to one ratio on the barrels and see what happens.

It just bugs me that I have to stagger the jets 8 sizes between the left and right rear barrels. In my mine the differant restrictions and unsmooth transistions doesn't deliver a consistant fuel mixture between the barrels.

Are far as using brass, I don't think there would be a problem. They make floats out of brass along with the needle/seats. So I don't think there is an issue with that.

The plan was measure the brass inserts that I have coming OD, then drill the blocks out a bit smaller. The the inserts actually measure .250, then I will drill it to .246. Then I was going to heat up the blocks in the oven, put the brass in the freezer, then assemble, I have a test block I plan on trying it on first to get the process down.

So no opinions on the final size, should I match the stake tube size?

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