car comes out of the hole hard climbs to about 4500 bogs real bad then smooths out and revs the rest of the way. only does this under load. I'm think the air door on the secondaries may be hanging up. or maybe the advance weights are sticking some and the advance isn't coming in fast enough. o No: any ideas I can't figure it out. 430ci crower 530in-560ex lift 304in 312ex duration cam offy single plane manifold (single 4bbl) 800cfm q-jet ("v" hanger) secondaries holley blue pump set at 5psi with return style regulator hei dist w/msd 6al headers/no exhaust 3500 stall th350 390 gears initial timing 14 deg 34 total
David, The ignitionmans always saying what a natural rev-limiter, the stock in cap coil is to the HEI. Do you have the MSD conversion kit to run the seperate chrome (MSD 8200) coil? Other things to check are float level and fuel system in general, you may be running out of fuel. Checking the timing advance/rate is easy with a light. Hope that helps.
adam I'm not sure on the rear rod size I'll check tonite after work. Larry the car revs to 6500 np its just goes hard bogs/hesitates then takes off again its still the coil in the cap but its a hp one from accel.
David, If it revs to 6500 after bogging, I think it is safe to say your ignition isn't the problem. There are only two things that control the rate at which the secondary air valves tip in. The spring adjustment at the air valve shaft and the vacuum break on the passenger side front of the carb. If you push the air valves in with your finger(engine off), they should snap back closed. Make sure the vacuum break is holding vacuum. With the engine idling, the vacuum break should hold the airvalves closed, you should not be able to push them in with your finger. If you can, the vacuum break is defective and allowing the airvalves to flop in instead of gradually tip in, this will result in the dreaded bog.
cool I'll have to check that out I've got a spare pulloff rear rod size is CL .0667" edelbrock number 1954
.0667 was the thinest I could find if you know of a source for a smaller rod I'll try them out thanks
.0337 at 90 degrees...the power tip. I may have to try these out on MY car first:Brow: :Brow: I just pulled them out of the yard this past weekend.
If you can't find any, I may be able to help you out with these particular ones. Also..... check out www.carbsunlimited.com for choices on rods AND hangers. Hangers are important just as rods are. This is the page on CarbsUnlimited. http://www.carbs.net/rodshang.asp
found a set of cc's today .0303" checked air doors everything seemed ok took it for a test drive and it still bogs. I'm running 5psi of fuel pressure should it be higher?
finaly figured it out the advance inside the distributor was all rusty and sticking little sandpaper little grease all better. runs way better with those CC rods in there though might even pick up a little at the track. thanks everyone for your help.
Larry, Post juming here but Itn't that vacuum break the first thing most removed on a Q-jet? I believe even the HotRod article has you remove that. Ya remove all vacuum thingy's, break or bend the tap on the shaft so it is now a manual carb and take off the air vein gurad thingy for better flow. Other tip I remember was to double/triple stack the carb spacers if you could. 4 hole for low end and open ones for top end. Don't remember much more than that, read it so long ago. Matt uzzled:
you can take out the choke for better flow if you don't do any cold weather driving the air doors on the secondaries have to stay or the carb won't work properly.
Matt, That vacuum break is very important to secondary action. Without it the airvalves will flop in and the engine will bog big time. Some guys will drill out the vacuum orifice, and back off on the spring adjustment, to make the air valves tip in sooner. But most engine combos need some damping from that vacuum break. The airvalves effectively size the carb to the motors demand. High stall converters and high numerical rear gearing want the secondaries in sooner. In that case a mechanical secondary carb might be a better choice.
