Blow through 1776

[John S.]

For sure, I should be able to make it to carcraft tomorrow and at least get some jets. What are you going to use as the carb pressure cover on your dellorto?

I have a CB one with no hole, yet.

[John S.]

Man I'm glad I don't live near those places. I'd be so poor if I could just drive over and get stuff!

But your trans core issues would be solved. Lol

[AdamStrahan51]

When I bought mine I got 2 of them, the “sand system” and a side entry one, the sand system one is the one I’m going to use. My thinking is that if it comes in straight down into the carb it wouldn’t cause any unnecessary turbulence, instead of coming in the side. I may be right, I may be wrong. I just wish I didn’t have to use 2 90* elbows to get all this poop to line up.

[AdamStrahan51]

So my AFM (AEM UEGO air/fuel) will be here Sunday, and picked up some 145mains and 180air today as a starting point

[AdamStrahan51]

If anything I’ll end up with a collection of jets and I’ll be able to tune it for where I take it

[AdamStrahan51]

https://youtu.be/73LuBuhLgAA

[buguy]

It's alive!!

[Clonebug]

Revving in neutral is not an indicator of the jets being correct.
When I ran a 34 pict-3 blow through it ran perfect in the garage with stock jets. As soon as I took it out on the road it fell on its face and went dead lean. I went from a 130 main all the way up to a 170 main to get enough fuel to pull 11 lbs. boost through 4000 rpm in third. Then it leaned out again.
It took almost 3000 miles of messing with that carb to finally get it to run pretty good.
I was never really satisfied with it though and went to FI after 2 seasons and 7000 miles.

[AdamStrahan51]

I know under load it’ll be different, It revs smoother with the bigger jets, I didn’t want to put it under load until I installed the AFM. Just wanted to hear it sound better then with the 115mains. I also ordered the 33mm mod rings, and bigger venturis. Just gotta wait on CB perf. And the wonderful USPS. I’m just happy there’s a lot of knowledgeable guys here to lend a hand. Makes it less discouraging when a question arises

[buguy]

Oh man if your waiting for CB AND USPS, you may as well find another project to do for the next couple weeks!

[Clonebug]

One thing I found to increase fuel was to extend the float bowl vent up into the top hat. You might want to do that before you get too far. The float bowl needs to see the higher pressure above the venturi and sometimes without an extension it doesn't see it.

[AdamStrahan51]

The problem with the USPS is through rain, hail, sleet, and snow they will deliver... but .7mile down a dirt road not a chance. “Sorry we missed you” notice in the mailbox.

As far as increasing the fuel, isn’t that what the mod rings, and the turbo emulsion tubes are for? Supposed to make tuning it easy. I don’t know, that’s why I’m asking. Any advice is welcomed

[Clonebug]

I used a Bocar 34 Pict-3 carb for blow through. I never used a mod ring. I did modify my emulsion tubes by soldering a couple holes shut but I should have tried them as stock.
You will have to try different settings and jets. It just takes time. If you have a wideband that will help a lot but figuring out what changes what is a time consuming process.
Make sure you make the top hat and intake plumbing easy to take off because you will be doing some jet changing in your quest for more power.
I pulled my carb so many times I could pull it....rejet and reinstall in less than ten minutes.

I found the issue to be I kept turning up the boost therefore changing the tune. It's an addiction I tell ya........

I recommend staying at about 10-11 lbs. boost unless you have excellent ignition control. Intake temps will be a major factor at anything over 8.0 lbs of boost. You need to either cool it down or retard the timing enough to stop detonation.

An example is.....at 13 lbs boost with the carb I was down to 18-20 degrees timing and still seeing detonation at warmer summer temps. Spring/fall and winter was ok. Intake temps would be 170 degrees. I had MS-1 ignition only..... after the second week of turbo.
With my current setup of FI, intercooler and WI combined I can do 25 lbs. boost at 25 degrees of timing.... and my intake temps are at or near ambient.
Cold air is denser and can hold more fuel which makes more power....add timing to that and you make even more power for the same amount of boost.

I realize FI is not that cheap but I found after messing with a carb for two years... the money it cost in down time, screwing around changing jets and frustration....along with the detonation cracking a couple sets of P/C's...it ends up being a pretty good deal.

Don't take this wrong.....I'm just stating that I've been there...done that...and realized once I got FI...I should have done it right away.

Jets and related parts are not cheap either.

Keep track of what it costs to do it......it does add up.

[Chip Birks]

Holly red, with holly boost sensitive pressure regulator. I’m planning on picking up some jets. Any suggestions on a starting point?

I don't think a red is gonna do it in a blow through arrangement. Max pressure out of that pump is what, 7psi? Your carb wants 3psi above ambient to function right? So you'll that gives you pump for about 4psi of boost before it won't keep up anymore.

[AdamStrahan51]

I’m definitely thinking I’ll go EFI at some point, but my wife’s reasoning is “why do you need it if this works” so... after enough messing with it she’ll see why. That’s how I’m going to end up with long travel take her for a ride through the woops in my brothers x3 then take her in the Baja. As far as the ignition system, magnaspark with the black box. Thanks for the heads up with the fuel system... it should do for now, gotta focus on getting it tuned up before I get carried away with going faster. Got my AFM, and picked up a few different sized mains, and idle jets.