This thing will idle like a dream, and cracking the throttle hard sounds good, but just off idle, around 1500 or so its rough as hell, and looks like its dumping way too much fuel while looking down in the carbs. Too much fuel pressure?, floats seem OK but maybe, what?? I read thru alot of posts and still I'm a little lost. Help!!
Check the power valve in the carb. It may be blown and dumping fuel. What setting do you have the accelerator pump lever in? Flatman
2 new power valves, 4.5s in them, 48 jets and the acc. pump in the middle hole. There on a regular Offy intake, seems i read somewhere where this may affect pressure due to height of manifold??
Are you running a stock pump? They usually provide enough pressure for two carbs. Are you running tandem or progressive linkage? Flatman
Stock pump, a new one, and tandem linkage. Also, the vacuum advance was hooked up to manifold vacuum, which I thought was wrong, its now on the rear carb, could this maybe be causing this?
The stock distributer needs the ported vacuum, so you were thinking right . However, with two carbs your vacuum signal will be about half of what the distributer needs to see as you are running tandem. I have the same set up, but plan on getting a mechanical advance distributer from GMC Bubba, then I don't have to worry. I don't think this is causing your overfuelling problem though. The accelerator pump bridges the gap between the idle circuit and the main circuit so you don't get a flat spot. Try shifting the pumps to the lean hole and see how it runs. The main jets will only pass fuel according to the air passing through the carb, two carbs=half the normal airflow per carb. Flatman
The stock pump puts out around 3psi, which shouldn't be too much in the way of pressure. Are you 100% sure of the float levels? These things are prone to flooding. Mine have this tendency to leak fuel all over the manifold externally A regulator certainly wouldn't hurt, but probably isn't nescessary. How did you sync the carbs? Flatman
I tried 97's, 94's back 20 years ago. I couldn't stop them from dribbling fuel on the manifold either. That's when I started to carry a fire extenguesher. I would say power valves are the culprit(off idle,the vacuum drops, they will pour fuel in) I helped it a little by replacing them with plugs,and jetting up(94) to #56 jets. It ran a little rich at cruise though. I finally 'solved 'the problem by switching to a wcfb four barrell. No, not as cool looking , but runs nice,and with power... good luck...
Are the power valves the early style or did you buy off the shelf valves? My buddies flatty had this problem with BG powervalves. We even went to 3.5's to keep them from openning too soon, but in the end we swapped them out for a plug and a stock PV and it responded very well to the change. We ended up jetting it way down also. I would start by dropping the vacuum advance distributor because that can be causing a headache in it's own. We've never had any issues with fuel pressure and it's running the stock pump. I don't think I'd chase that route. Hope this helps...
I sync'ed them by ear, I loaned my uni-sync, well we all know how thats goes, anyway I guess I should pull the airhorns off and check 'em yet again. I don't have any external leaks at all. I've put 94's on alot of motors over the years and have never run into this. What do you recommend for float settings?
The float level, measured between the machined surface of the bowl cover and the top of the float, should be 1 11/32" for the AA-1 and 2100 carbs. The 2110 sets at 1 15/32", and the IHC truck 2110 sets at 1 5/16". The float drop should be 1 7/16" for the AA-1 and 2100 carbs, and 1 3/4" for the 2110 carbs. this is measured with the float hanging freely from the bowl surface to the bottom of the float. I'd try the lean accelerator pump link setting (hole closest to the throttle shaft) and drive it, see if it makes a difference. Flatman
Block off the power valve on the secondary carb, and use a progressive linkage. I did this on my AV8 and all problems were salved. Leave the 4.5 power valve on you primary carb. I use an original Eldelbrock Sling Shot so height has nothing to do with it. Contact Vintage Speed for advice on 94's, Charlie is a great source.
Well, I've reset the floats and checked the PVs, no change. This thing run fine before, the front carb is the one orginally on it, and the rear come off my F1, so I know they were both good before. What the hell??