Just installed a Innovate XD-1

Went for a spin and here are the results…
At idle it is at 12
At 50 mph cruise 11
Light acceleration off of idle 13 to 14
Medium acceleration and lugging the motor at low rpm: 14 to 15 and spiking to 16
Nailing it starting at 1500 rpm: 18 or even more (I got off of it quick).
Nailing it slowly and taking 3 or 4 seconds to get my foot to the floor: 10 to 10.5
What should I try to take care of the lean condition when nailing it? The secondaries are squirting. Could the powervalve be the problem?

Here are the specs…
427 BB
Crane hydraulic roller #139731, 226/234@.050, 288/296@adv., .587/.610 lift; 2,500-6,000 RPM
AFR 305 BB Rectangle heads; 119cc
RPM Air-Gap 2-R Intake
10:1 compression
BG Speed Demon carb 750, mechanical secondaries
Manifold vacuum at 900rpm = 10
POWER VALVE 6.5
Main Jets Pri: #76
Main Jets Sec: #83

 

Bigger squirters and bigger jets would be a start

 

Hi Thanks Motorhead for the reply. I always enjoy reading your posts and help to everyone.

I have .040 squirters in it now. Isn't that about as big as they go? Maybe a bigger pump cam? With the jets, if I go bigger the cruise is going to get even richer. I'm at 10.5 to 11 now. Is this even too rich? Should the aim be around 12.5?

 

Trying to tune with these O2 sensors is not easy. Make sure you are not looking at spikes caused by electrical intereference. If you can send that gauge back and get the LM1 with the data logging and RPM input you will be much better off and be able to see more what is going on,

Here is a graph of mine over 2 minutes, the first part in cruise, then idle and the 1st amd 2nd WOT to 3000RPM. Mine is not tuned properly either .

 

The first thing you need to do is get corresponding vacuum readings at all your test points. This will give you more data about what is happening inside the carburetor.

Looking at the data you have I would say that idle is OK to a little rich. Your 50mph cruise is way off to the rich side. This is where that vacuum gauge will help to see if that power valve is opening. I would say the primaries are way rich at part throttle. Lets see, you got 76 in the primaries. I would go to 72's.

Light acceleration is a little rich but I think you can live with it. Moderate acceleration is too lean, it needs to be down around 13.5 to 14. Some of this could be weak accelerator pumps.

The two WOT readings are proof that you have an accelerator pump problem. Part of this could be the throttles not getting all the way open. Make sure that the throttles open 100% WHEN PUSHING THE GAS PEDAL. If they don't this cheats you out of a lot of accelerator pump shot.

With idle vacuum of 10 that power valve may need to go. It almost looks like its running on some power valve at 50mph. Is that a two stage PV? You may need to go from a 6.5 to a 5.5 or 5.

Make sure the floats are set right. Low float level will cause the mains to start up late causing a lean spot between off idle and cruise. If this thing has adjustable air bleeds you may need to go a little bigger on the mains to help lean out that cruise metering.

BigBlockk

Later.....

 

Okay... thanks. I'll take some vacuum readings and get back with the results.

 

cruz was rich

 

This thread got me fooling around with my setup today. I am in the same boat as you but have been there much longer. My idle is around 14 now and my cruise is around 13 or so and I can live with that. What I have been unable to do is correct the lean condition on WOT. This problem goes back to the previous carb I had on the 406ci which was a 750 Holley with a ProForm main body. I just looked and I had the secondary jets up 92 trying to fatten up the WOT. THe jetting did not seem to matter.

Now the 825 Race Demon I thought would solve the problem or at least be better and run a little richer at WOT but it does not. I bumped up the squirters from 31 to 35 and not much change, I am going to jet up 4 sizes in both primary and secondary but I doubt there will be much change. I tried to buy some size 40 squirters today but the shop didn't have any.

I taped a vacuum gauge to my window today and I have about 13 inches at idle and it goes near zero at WOT so I doubt I need to change my 6.5 power valve should not need to be changed.

BigBlockk seems to know what he is talking about, I wish I could figure it out

Maybe I need to change the pump cam, it is the pink one I have in there right now

 

Wayne, post your most recent air fuel measurement from the dyno day. From what I remember, you need to jet up a few sizes. Does your Demon have 50cc accelerator pumps? You might need them and a accelerator pump cam kit to get it right at WOT. Also, have you adjusted your accelerator pump linkage properly? I think the common idea is to have about 15 thou additional travel on the pump arm at WOT.

 

Race Demon has 30cc pumps, heres my dyno run, he punched it at around 2200RPM and you can see it goes straight to a lean condition and very slowly seem to drift closer to what is acceptable

 

I'm trying to find a page at barrygrant.com for parts to speed demon carbs... like accelerator pump kits.. pump cams.. jets...etc. Anyone have a link to the goodies? Jegs carries brantgrant but it is hard figuring out what is needed there... Is there a page at barygrant.com that lists parts to their carbs?

Found this page but still no luck finding pump kits and cams.

 

It uses Holley parts, cams, pumps, squirters, air bleeds, jets, you name it they are the same as Holley, almost bought the Holley cam kit today

 

Okay.. I installed two 50cc accelerator pumps. That took care of the lean problem when nailing it. If I nail it real quick at low rpm though it will go way way lean. This is just the nature of the beast with mechanical secondaries isn't it?

Going to try some smaller jets in the primary side to get rid of the rich (11.5) cruise. Also put in a 5.5 high flow power valve.

 

Good point, I was thinking the same thing about mechanical secondaries, no one seems to have the answer

 

The engine should go cleanly from idle to WOT without stumbling or blowing black smoke. This is what the accelerator pump is there for. If it is going lean out of the hole with the big pumps you may need to open up the shooters. The size of the pump dictates the volume of the shot but the pump cam and shooter size dictates the rate of the shot.

BigBlockk

Later.....

 

A good source for carb parts: www.blp.com

Did you drop the primary jetting? If so, you need to compensate on the sec. side. The accel pump shot won't last long so if you've got a lean window that is fairly large you need more gas for a longer period of time. Ever thought of putting in some smaller high-speed air bleeds? This will tend to make the sec. side "come in faster" because of the decrease in the amount of air it's getting. Sometimes speed shops will you borrow an air bleed kit and then pay them for the bleeds you used.