I've got a rich bog WOT off idle. Holley can't figure it out..
447 FE, 11:1 Comp, Comp 308R solid roller, MSD Pro Billet with 6AL. Motor only has about 500 miles on it.
1000 HP with annular boosters, upside down black front and red rear in 2, 52 shooters right now. 50cc pumps. 3.5 PV's. transfer slot's good. stock jetting.
idles at 700 RPM. 6" vacuum, 18 deg at idle 36 deg at 2500. 3600rpm stall converter, 4:11 gears.
Issue: when you go WOT from a stand still it will rev up to about 2k then stand still, some times it will clean up some times not. also will do this during a brake stand, will not spin tires on pavement. It pukes black smoke when it does this. If its on dusty pavement it wont bog and just blow the tires off. Ive tried all the cams and shooters, any less than a 37 and it will backfire through the carb. Going up in shooter with a front heavy cam provided the best results but far from great, right now with an upside down black and a 52 shooter has the least bog. Timing changes didn't do anything positive. tried higher idle, didn't change anything. Tried idle mix screws, no positive changes.
If you are moving more than 5-10 mph and hammer the throttle it will blow the tires off.
I think the boosters are coming in before the pump shot it done causing this, but im not sure how to fix it. this is my plan and my ideas:
1- I will be replacing both 50cc pumps with 30cc to see if it changes anything, also changing the secondary to the same as the front.
2- custom grind a carb cam to the profile i need
3- change the air bleeds to move the fuel curve.
Any ideas would be greatly appreciated.
First, I think 18 initial is plenty, although little more is a little better to bring up idle vacuum, also, if your converter allows it, don't be afraid to let it idle a little higher too. That's a big cam. Are you running vacuum advance? If yes, make sure you are setting initial with it unhooked, and if the vac advance port is alive at idle, may want to consider running manifold vacuum to the advance. I generally do NOT do that, but in your case, it could help. If you are mechanical advance only, no issues, but I want to make sure that you aren't at 18 with vac advance, and when you drop the hammer it falls out to something much lower
Second, I think you are bathing that motor in fuel, in fact, it's not good for it. I have experience with the 1000 Holley and I generally set them up with 30 cc pumps and .028-.031 shooters. Often I will use a blue cam on the front to get a low vacuum motor to hit a little harder as well, but even that is rare
Next, I think your PV is too tight, so you douse it heavy and fast with your big pumps and shooters, then it has to get below 3.5 inches of vacuum before it gets fuel again, so it goes lean with dirty plugs. I would be running 5.5 PVs and only if it was rich at part throttle cruise would I drop to a 4.5 and even then, only on the primary. In fact, I'd likely go 5.5 primary, back to stock jetting with 84s and if your version has a rear PV, you could plug it and go 90s out back, but not required. it just helps during hard launches because the PV can become uncovered easily
Finally, don't expect that 80513 HP to behave perfectly even after you get it back. We call those "high IFR" metering blocks, and they can be a pain in the butt. Somehow, with the IFR up above float level, they can be sloppy and cause transition issues and odd behavior when crusing. This isn't your problem yet, but may be after you get it dialed in. What I do then is get an early primary metering block off an old 600, drill all the orifices to match the 80513, but with the lower IFR block they clean right up. Again, not your issue, but come back if it gets fussy driving easy after you fix this
Last comment, always good to check every plug and every plug wire, especially the ends, to make sure you don't have some secondary issue, check firing order, etc. Just good housekeeping as you troubleshoot. Hope this helps