Tuning help with new carb on strong 408
You need to change the air bleeds. In board are for idle curcuit. If it's rich, you need go larger I think. Qf has a great tech line. I had the same problem. My 408 is much milder. I have a 750. Don't go cutting the carb up. It's designed to be fully tunable.
Yep, did do that, went up 2 sizes at the recommendation of QF tech. Was able to get some adjustment of the idle screws, but now am running into a problem with it randomly popping loud in the exhaust, about every half second. The idle screws were at about 3/4 turn out (gave me the highest vac) and I took them out another 1/2 turn and the popping went away. I will have some time to goof with it this weekend.
Yep!
I think the engine wants more air. Are you running a PCV? I dont see one.
No, I am not running a PCV. Think I will install one this weekend. However, with the 750 HP Holley I had been running, everything was just great. Racked up about 1500 miles on it.
Wide band O2!!!!!!!!!! How much of your transition slots are exposed? If too much it will idle rich & have hesitation when accelerating from off idle. Demons had a sweet air bleed right into the center of the carb to get the idle speed up & not expose the transition slots. Or the old school way is drill holes in the throttle blades.
Have not had the time to take the new QF off and check the slots. I had to do this with the Holley several times before getting perfect. However, maybe in my stupidity, I did drill the primary blades out. I stepped up a few times before everything was right with 3/16" holes.
I agree on the wideband. Be suprised how far off aome things really are
Agree!
Hi, i´m in the same boat with my AED 750. Even after completely removing the IAB´s (the outer ones in the carb body) it´s running pretty rich at idle. I will change the Idle feed restrictors in the metering blocks to smaller ones - i think that is possible with your carb, too.
Could be....have to keep in mind.
This thing must pull like a freight train with the heads and cam combo.....cool, i can imagine this can run 10s in the quarter if tuned properly.
Michael
Yes, it is really strong. Agree, should run in the 10's, but I need to cage it and get more room in the back for larger tires.....have not tubbed it yet.
Again before you start doing mods pull carb off & make sure the transition slots are not over exposed 1st!
Yes, on my adgenda!
He's right. No more than .04 of the slot should be exposed. You may have to drill a small 1/8 hole in each butterfly if it won't idle. It wants more air at idle. A result of a large cam profile
Agree, may be a last option after trying different air bleeds, pcv, etc.
I really hate to mention this, but what are the chances that PV is leaking?Right through the diaphragm.You wont see it in the mains.The intake floor might be wet.
I would put a plug in there until you get the idle sorted.
Jus saying
It is possible, when I start goofing with everything this weekend, will check.
The Dart is my first money pit....am also trying to get some brake issues sorted out on my second money pit (Roadrunner)......as many of you know!
