Carb experts...advice? HELP..

[inline6]

Call up Pro Systems! It may like a SV1!

[Tuner]

Did anybody ask about the ignition timing? SB2 heads are particularly allergic to too much timing.

[BradH]

That photo appears to prove you have CAD.

Carburetor
Acquisition
Disorder

I'm a founding member of Carburetors Anonymous

There were more; sold one and parted out another

The goal is to get down to no more than two, and -- ideally -- only one

[stealth]

Did anybody ask about the ignition timing? SB2 heads are particularly allergic to too much timing.

Crank trigger 27deg.

[stealth]

Call up Pro Systems! It may like a SV1!

They suggested CNC-BILLET VENOM-VX carb. 1040-1050 cfm

With their 4500 metering blocks....bigger passages? Wasn’t sure what to make of that..

[stealth]

Thanks to Norms on here from cfs too

I’m trying get my arms around this....the help is appreciated

[ClassAct]

That photo appears to prove you have CAD.

Carburetor
Acquisition
Disorder

I'm a founding member of Carburetors Anonymous

There were more; sold one and parted out another

The goal is to get down to no more than two, and -- ideally -- only one

LOL. It's an addiction. Treat it as such!

[PRH]

I thinned out my “herd” some a few years ago.
I had a few carbs that were similar enough to others for their application that I let a few go.

What I have left is an assortment that will fit a fairly wide variety of combos.

[rustbucket79]

Hey thanks for the input.

I’ll have to check on the springs… I was thinking that too. I know the seat force is 250 but not sure open. I will note these heads use Jesel shaft rocker with all titanium valves (5/16 intake), and retainers. Should be pretty light. Also, very stiff double taper pushrods ½ at widest area.

I was pretty happy with numbers, but the dyno secession provided no real usable info other then tq and HP. The demon was just a backup carb to trial but ended up the dyno guy wanted nothing to do with the SV1 I wanted to work with. So I felt unprepared for using 4150 Demon. Maybe It’s a good carb?… not sure but after all the dram of a poor dyno secession and quite a few bucks spent on the engine itself, I want to be sure I have the right carb on there.

I really think this should be closer to 800 hp and don’t want to leave that on the table if there is something better. Curious too as to why it fell off so hard just prior to 7000 rpm. Min CSA is 3.12 on the head if I recall correctly.

That’s why I’m reaching out to all the experts on here. I value the insight and experience.

What made you choose this particular dyno? We are more than open to hearing what a potential dyno customer hopes to accomplish during his session so we are prepared for the day. Typically we have a half dozen carbs on the shelf to try, as a good comparison or verification that what the customer has is correct, or where they could be with a better carb.

I could pm you more if you like, but don't want to mention too many details on the shop.. Engine builder is well known in this area. Picked him by his reputation and on track performance... I was certainly let down

Where are you located...? I wish this place would have been prepared..

I certainly wouldn't mind hearing what happened, but the shop name is unimportant, we all have bad days or lack knowledge in certain areas......

I'm in British Columbia Canada so unlikely close to you.

[rustbucket79]

... given your results carb B was quicker with your combo...

Yes, because that's the only combo I'm concerned with. If it's faster on somebody else's car and slower on mine, then it's not the right carb for my application.

... The dyno is just another tool to use. Few of us have the resources to buy one ore more $1000+ (cdn) to try on the track. The ones that do, are quicker than the rest of us.

TBD on which one of these will suit my dual-purpose application best, or if I'll end up with one "street friendly" carb and another that's better on the track, but less happy on the drive to & from there.

Oh, I pieced together the four carbs in the background myself trying to keep the cost-per-carb down. Not saying they'll all work worth a sh!t, but at least I know exactly how they were built.
.
3.15.2019 - Carb Stable.jpg

I'm jealous! I always thought the Demon RS carbs were a great idea, but I would guess it would take some time to dial, in every Venturi and booster combo. My Dominator is so ancient it came with the slide in velocity stacks

[stealth]

... given your results carb B was quicker with your combo...

Yes, because that's the only combo I'm concerned with. If it's faster on somebody else's car and slower on mine, then it's not the right carb for my application.

... The dyno is just another tool to use. Few of us have the resources to buy one ore more $1000+ (cdn) to try on the track. The ones that do, are quicker than the rest of us.

TBD on which one of these will suit my dual-purpose application best, or if I'll end up with one "street friendly" carb and another that's better on the track, but less happy on the drive to & from there.

Oh, I pieced together the four carbs in the background myself trying to keep the cost-per-carb down. Not saying they'll all work worth a sh!t, but at least I know exactly how they were built.
.
3.15.2019 - Carb Stable.jpg

I'm jealous! I always thought the Demon RS carbs were a great idea, but I would guess it would take some time to dial, in every Venturi and booster combo. My Dominator is so ancient it came with the slide in velocity stacks

I’m going to have one for sale soon......too small for my combo

[inline6]

Call up Pro Systems! It may like a SV1!

They suggested CNC-BILLET VENOM-VX carb. 1040-1050 cfm

With their 4500 metering blocks....bigger passages? Wasn’t sure what to make of that..

Not sure but been there done that...I did what you did and screwed around on a dyno with a carb that was messed up and wasted money on dyno time trying to tune it. Finally gave up and called up Pro Systems and about 2 pulls it was right. This was a street strip stick shift Fox Mustang SB Ford 470whp.

[jmarkaudio]

Get a 2" Dominator adaptor and beat/borrow any Dominator you can. The 447 ran .05 quicker in the 1/8 with a 1250 over a 1050, we have not run bigger on that engine to see. My 461 has had up to a 2.800 throttle blade, 2,375 venturi carb on it... and no loss of power...

[PRH]

My Dominator is so ancient it came with the slide in velocity stacks

Mine too....... pre-HP.
After a little tweaking, it works pretty well too....... in its current configuration........ up to about 800hp.
Much above that, it would need metering blocks with larger diameter main wells.

They look tough with the stacks too!!

[340king]

My experience is that you bring your own known good MSD box or other ignition system to the dyno. A bad box will shave 50 to 100 hp off the engine and be unnoticeable otherwise. The power supply to the box is also critical. A well sorted dyno operation will have all of this taken care of. I would like to see some form of capacitors like you see in the car stereo world on the system to keep voltage constant, especially when using a battery charger to mimic an alternator. Just some observations from the cheap seats.

As for carbs, typically large carbs on smaller engines have to be jetted richer than a larger engine making the same HP. This is due to the signal decrease due to cubic inches. This tends to even out as RPM (airflow) increases and can lead to a rich condition at high rpm. I would contact John Dunn at JDR Carbs and see if he has a solution. He rebuilds and tunes existing carbs very reasonably.

Best of luck.