Have a new blue print crate motor with a brawler 670 carb. Idle is very rich afr reads 8.9. I know I have a new fuel pump that is putting out way to much pressure at 8 to 10 psi. But my question with car shut off and cooled down the left primary main or high speed air bleed is full of fuel all the others are not. Float levels normal. So maybe debris or gasket issue.

 

The needle and seat will have a heck of a time controlling that much fuel pressure. Fix that first then see what happens.


JIM

 

Quick Google search shows your carb is supposed to be at 6.5#
agree with above, it’d be hard to make any adjustments when you’re prob pushing fuel past

 

Under Pressure! Doon Doon Doon Doo Doo Doon Doon!

 

Yes on 6.5 psi new pump arrives Wensday.

 

A Regulator might have been the better option here.. I have a stock replacement pump and still needed the regulator for my quick fuel holley type carb.

 

ok installed another pump today and pressure looks much lower.. Gauge bounce sucks but best I can tell is 5 to 6 psi. Idle mixture adjusted to 12.5 right now. Idle mixture screws out 1/2 turn. But now have lean off idle stumble in park.

 

ok drove vette today. Vacuum at Idle 18 hg , in gear 16 hg, cruise 16hg, acceleration 4hg
AFR idle 11.5 Cruise 14.4 Acceleration 12.5
Did not perform wot yet has hestiation when accel and is new engine. idle mixture screw out 5/8 turn.

 

Does that carb have an adjustable accel pump? Some do, you can move a lever for a larger shot off accel

 

Yes has a 30cc shot right now. Pink cam on #1 set.

 

Did you check the transfer slot exposure? The mixture screws are not really "in the zone" and you are still too rich. It would be good to do a full basic set up of the carb. Lars has a Holley setup paper that would help. Drop him an email and ask him for it. (not a PM).

 

is your timing set right? And vac advance connected to manifold vacuum source instead of ported?

 

It is great that you have a Air/Fuel meter available because without one it gets very hard to get the jetting perfect. I bought one and was surprised at how close the last carburetor's jetting was after being pre-set at the builder's shop.

Shouldn't you be taking a bit easier on a "new" engine in the first place. I tend not to abuse them for a few hours running time and a WOT run at this point might not help the engine.

Did you set up the timing curve in your new distributor? If the timing curve is not set up for your engine then you might have issues. I would certainly get a Timing light (with the timing ****) and see what the engine timing is set to currently. I use a timing light that allows me to see exactly where the mechanical, centrifugal and vacuum advance units all work.

For example I have a 427 bb running high compression and I have a fairly conservative timing curve that gets full timing 36*-38* by 2500 rpm, if I was not careful and set it up or used default settings my engine might develop a detonation issue. Getting the best timing curve to handle things like high compression and raised Pistons have a big affect to the timing my engine is happy with.

It would be worth your time to check/verify the way your distributor is set up. I bought an MSD billet Distributor with mechanical tach drive to use and it was easy to set up. Now I have had to disable all the various advance mechanisms and lock out the base plate and set the engine to 15*. This allows the Holley Stealth Sniper to take control of the engine's timing as well as the fueling issues. From the Holley EFI software I can make any changes as I get to design the timing curve I use which is best for my 427.

 

Distributor set up on allen distributor machine 36 degrees all in at 2500 rpm. Vacuum set to manifold vacuum. transfere slots were way out of adjustment. I have only done halt throttle pulls too shoon for WOT.

 

don’t want to derail the thread, but just saying, if you built your motor right, which I’m sure you did, you don’t need to worry about waiting for WOT pulls. Especially if you use moly rings

edit, I looked back and saw that’s it’s a crate motor. I’d probably baby it too, no idea what clearances or materials they use.

 

got back to adjusting carb today. transission slots were way off and accell pump out of adjustment. My idle mixture was still to rich at 9.7. had to close rear idle mixture screws to be able to adjust mixture, right now I have 12.5 idle mixture. idle air bleeds are at 70 and idle fuel restrictors are at 32 which is factory setting.

 

I have yet to have one of these carbs not have a flat spot out of the box off idle no matter the combination,Big Block, Small Block, mild, wild, It doesn't matter. Increase the squirter size,(I just drill them out with a number drill) and if that doesn't do it, get a 50CC pump housing, and diaphragm and a more aggressive pump cam (I just modify the pump cams to do what needs to happen)

 

Did you sort out the issues with the Brawler carb? I also have a Blueprint crate motor that included the Brawler 670 purchased 12/2024 and see similar idle richness and off idle stumble. Transfer slot square. Best vacuum at 1/4 to 3/8 idle screws . I increased the accelerator nozzle to a 37 and an orange cam to cure the stumble. I don’t have the benefit of a wide band for afrs but drivability is pretty good now.

Still living with the idle screws way in. Before fooling with the accelerator circuit, I tried changing the ifrs to .028 and could get the idle screws to 1/2 to 5/8 out best vacuum. Made the stumble worse at the time and went back to the .032s. Was going to mess with the ifrs again and ran into your post and what you may have found.

 

Costs more than brawler, but Some folk seem to be having success with a different vacuum secondary squarebore Holley 4150
Off-Road Truck Avenger 0-90670

https://www.holley.com/products/fuel.../parts/0-90670