Carb experts...advice? HELP..

[stealth]

Why do you think you are having issues with the carb? Seems like the motor is topping off at around 5700. I'm thinking valve springs. What's your valve spring pressures and what's the recommended valve spring pressures for the cam?

What sort of power were you expecting? 738hp isn't too far off what I would think this combo could do. I'd think maybe 800hp or so would be really good.

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.

[NormS]

At the top end of the power curve, some engines are very sensitive to the flow restriction of the intake system, sensitive to A/F ratio, and to total ignition advance. If the carb is too small(CFM), if the A/F is going rich, and there is too much or too little timing, the result is reduced peak HP. If that SB2 intake is well prepped, I doubt that it is the issue. More plenum volume added, by way of a carb spacer, may pick it up, considering the CID of the engine. So if the engine was 'seeing' the intake system as being too restrictive, I think it is more likely that the carb was the issue.

[stealth]

This is not my intake but shows what a GM 699 looks like with the long plenum. I am using this part number intake, just not mine in the pic.

[BradH]

... I'd rather start with something I know is built for the combination then continue to sort out this one.

Now.. what do I need and from whom?

FWIW, I give 1 vote for NormS (like PRH suggested) and 1 for AED, since I've done a little work w/ them recently.

And, yes, the "prehistoric" 850 annular that Norm built for Dwayne has always made really good power & torque when we've used it during my dyno testing w/ Dwayne. "And not a speck of billet..."

[PRH]

Frankly, there is enough questionable data on the dyno sheet where I wouldn’t consider any of it to be “reliable”....... including the tq/hp numbers.

Take it somewhere else....... start fresh.

I’d be surprised if Ceralli’s hasn’t had any experience with an SV1.
He might be able to shed some light on what kind of tuning challenge it might be.

[af2]

Why do you think you are having issues with the carb? Seems like the motor is topping off at around 5700. I'm thinking valve springs. What's your valve spring pressures and what's the recommended valve spring pressures for the cam?

What sort of power were you expecting? 738hp isn't too far off what I would think this combo could do. I'd think maybe 800hp or so would be really good.

If it was springs it would simply take a shyt. Needs carb .

[jmarkaudio]

Numbers look weak for a 2.2. We did a 447 with smaller heads, 691 intake with a Dominator top welded on, made 830 HP. A little more compression and cam, but you should be in the higher 700 range. What part of the country, what is the DA in your area? And a bigger carb would be my suggestion as well.

[stealth]

Near Allentown Pa...

Yeah...I think is weak too... thought I would start by getting correct carb and redyno...love to get this to someone with skills

[MadBill]

That 22 HP nose-dive from 6700 to 6800 RPM is a big red light. (assuming the engine wasn't being throttled back during that last 100?) Typically a pull is continued to at least a few hundred past the peak, where an air turbine would narrow down the cause of such a drop-off. Unless the cam lobes were formed with an angle grinder, there no way the valve kit you describe shouldn't run to at least 8500. [By way of comparison, the SR Mike Jones* provided for my nostalgia 495" Can Am BBC (270°/273°, 0.723"/0.700") is specced to run to at least 7500 RPM with 2.3"/1.88" steel valves and 240# seat force.]

Also, not a red light,(maybe a flickering yellow...) but commonly with a split duration cam like yours, more exhaust than intake lift is indicative of a "shelf grind" using the same lobe design for both intake and exhaust -not an optimal plan. Also, most well-developed engines end up with significant less exhaust than intake lift. I wouldn't rush to change it just yet, but I would suggest contacting *cam king or some similar specialist and comparin their suggestions to your current specs. Obviously if they digress, the further out, the more a swap would pay dividends...

[stealth]

Numbers look weak for a 2.2. We did a 447 with smaller heads, 691 intake with a Dominator top welded on, made 830 HP. A little more compression and cam, but you should be in the higher 700 range. What part of the country, what is the DA in your area? And a bigger carb would be my suggestion as well.

Thanks,

How big? Do I need to consider welding up for 4500?

[rustbucket79]

Why do you think you are having issues with the carb? Seems like the motor is topping off at around 5700. I'm thinking valve springs. What's your valve spring pressures and what's the recommended valve spring pressures for the cam?

What sort of power were you expecting? 738hp isn't too far off what I would think this combo could do. I'd think maybe 800hp or so would be really good.

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.

[rustbucket79]

I guess we've been lucky so far, having sold a dozen or so of them and zero complaints as of yet.

As I said, it goes on 90% of the 4150 style engines on it's final pull, using the same sweep as I use with the customer's carb, and the graph mimics the previous test, at a larger number for both hp and torque. Occasionally I'll rejet if it's the correct application, but bottom line it's a well designed carb out of the box.

Even on a tunnel ram, a pair of them on my lil 406 has decent throttle response and loads nicely before the pull.

That's why I asked about on-track testing vs other carbs, rather than standard dyno tests. I've had two carbs that made virtually the same HP & torque on the engine dyno, but you put them on a car and one carb (the one with smaller venturi and much better booster signal) ET'd .2 better and pulled 2 add'l MPH because of improved shift recovery. It's not that the dyno lies, but it doesn't tell the whole story.

My interpretation of your dragstrip test is given your results carb B was quicker with your combo, but on a different combo or if you changed gearing and/or torque converter, carb A might be quicker. 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.

[stealth]

Why do you think you are having issues with the carb? Seems like the motor is topping off at around 5700. I'm thinking valve springs. What's your valve spring pressures and what's the recommended valve spring pressures for the cam?

What sort of power were you expecting? 738hp isn't too far off what I would think this combo could do. I'd think maybe 800hp or so would be really good.

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..

[BradH]

... 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

[ClassAct]

... 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

That photo appears to prove you have CAD.




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