Dual pulse for a 781?

[pigpen]

I just picked up a bb781 62t/61x and it looked like the cases have been tapped for dual pulse but when I got the motor one line pulse fitting is capped and the only one was ran. It's still running oem 38's. Would it be in my benefit to run dual pulse?

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[nucleus_coolins]

Im running oem 38s on my new dasa 771. It was also tapped for dual pulse lines, but I just left one capped and used the one pulse line it was using before. Its been working great but im also curious can you add another pump to the oem 38s to use the 2nd line? I never researched it that much, just set it up how it was before.

 

[Quinc]

I dont think it will matter much with 38's. I would run both if you upgrade to 44's.

 

[yamanube]

I don't think you could possibly run dual pulse lines with OEM 38s....

 

[stagesrt4]

just run single pulse

thats how i ran my 38s on my BB781

didnt switch to dual pulse till i install my novi's

 

[pigpen]

Ya I wasn't sure it was even possible with 38's since one is just a "slave" carb.

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[jetpilot36]

use at least 44s. 46s if you can. dual pulse and dual pickups are nice because if one cylinder acts up, its easier to diagnose.

 

[JMew03]

All the engines I currently have are like that. Only one is actually running dual lines.

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[Vumad]

Pretty sure you can add a fuel pump to the slave carb. You can turn a slave carb into a primary carb if you change the plates out, so it makes sense you can run them as 2 singles or dual pulsed duals. Its only a benefit if you are racing and running wot for extended periods. Ive b3en lead to believe by my esperienced racing friends that the slave carb can start to run a little lean when pushing high rpm flr extended periods. This conversation reguarded my limited sxr, nkt a modified superjet. I have a limited superjet and have had no issues running wot, although i havent gone out of ky way to try tk blow it up.

 

[Jet_jase]

Just switched from dual 38's to a single novi 48 and my twins where using 2 pulse lines.

 

[pigpen]

Just switched from dual 38's to a single novi 48 and my twins where using 2 pulse lines.

Did you have the plate changed on the slave carb?

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[JetManiac]

Oem dual 38s were designed with single fuel pump and slave carb setup on the front. They work great as designed for 701 to 781 ported BB motors.

If you wanted to add a second fuel pump and pulse it can be done, but the slave carb has the restrictor to regulate fuel pressure built into it. So if you remove and install second fuel pump then you will need to add a restrictor in return line after the Y to keep fuel pressure similiar. However, I recommend not messing around with it unless you are an experienced tuner and are willing to experiment.

 

[sj762]

Once you take that plate off the front carb to put on fuel pump you have no fuel lines for in and out

 

[pigpen]

Oem dual 38s were designed with single fuel pump and slave carb setup on the front. They work great as designed for 701 to 781 ported BB motors.

If you wanted to add a second fuel pump and pulse it can be done, but the slave carb has the restrictor to regulate fuel pressure built into it. So if you remove and install second fuel pump then you will need to add a restrictor in return line after the Y to keep fuel pressure similiar. However, I recommend not messing around with it unless you are an experienced tuner and are willing to experiment.

Think I'll just run the single then, not looking to complicate things. Lol

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[nucleus_coolins]

Some great info in here! Thanks guys