On a low boost, small blower application, say 5psi or less, at what point would you need an under blower referenced power valve carb “non blow through, boost referenced” with the port on the side?

I have a fully built 383 stroker with a dynamic compression that should be a little higher.

I’m running a nice Holley AED 750 HOHP carb.

I was going to go the Procharger route but I would lose me AC and power steering.

The Edelbrock 1551 kit lets you retain your accessories. I have done years of research on blow through applications, but now the whole draw through has me confused.

Can I get away with a normal carb on a small blower application?

The mod to reference the power valve seems simple as long as you don’t drill in the wrong direction.

 

You can use whatever carb you want, just modify it to boost reference the power valve. Its an easy mod depending on the carb, and you reference it from a vac port below the blower.

 

Even a vacuum secondary?

 

The secondary butterflies on a vacuum secondary carburetor open based upon the air velocity going through the primary butterflies, and engine load not vacuum. Will work fine, it will take some tuning.

You will need to run a bigger carb for the engine then you would na though. Say you put 7.5 psi out with the blower, the carb is now seeing an engine that's about 1.5x the displacement. Blowers don't like inlet restriction.

 

Thanks Ben. I have a 750 DP now. AED sells a nice blower 850 double pumper it’s the remote port for the power valve. What do you think about that?

 

I always run the smallest carb/throttle body I can get away with as a general rule for daily drivers. In racing it doesn't matter as much of course. We can measure intake manifold pressure to determine whether you need a larger bore. The smaller the bore the more control the driver has with the throttle sensitivity.

Next, I think you can monitor the power valve function using a wideband. Wideband will show enrichment a/f when the power valve opens. This should be easily to tell you whether it is opening or not, if the reference is needed, or working. Sometimes blowers will open the power valve naturally without a reference and sometimes not, I think from memory its been 20 years since my last carb blower engine though.

 

Sounds good brother. My car has a wide and. I can just run my 750 and see what the wife and says. If it’s opening or not. I can possibly modify this carb to reference the valve. I just watched a few videos on it. Seems straight forward. If that all fails, I can grab an AED 850 I mentioned above.

 

Sure, if the 750 ends up being a restriction go bigger later.

 

I meant “what the wide band says”

 

The carb will produce enough fuel for the air it allows to pass. It's just a matter of it passing enough air.