Doh! Well, lets call that one a brain fart... At least the bigger squirter making a very noticeable difference in the stumble gives me an indication it wasn't getting enough and not too much. I'll slow down and go one at a time. Makes sense unhooking the secondaries to isolate the primaries, thanks for suggesting that. I'll proceed as such (although unfortunately it's raining and supposed to continue most of the day, so no testing may take place I'm afraid... ) One thing to remind you of Del, when you said "see rpms where the secondaries open", this is a mechanical secondary carb. They open as soon as my right foot tells them to!
I like the disconnect the secondaries idea too. That way you can wack it open and not worry about feeling where the secondaries are. Would also test from different starting rpm's and keeping a log. So what happens at 1000, 1500... etc. Make a change and do it again. Also do not forget the cams. I spent half a summer on tuning mine. Also with carbs you are never done. ou: Just a side note I ended up with 37/41 nozzles. Yes I have given up on gas millage. Also surprised that the problem occurs at over 2000 rpm. Make sure that you have the .015 clearance on the pump arm at full throttle.
Gas mileage?? What's that?? I did check the pump arms, they are good. I sincerely hope it doesn't take half the summer, especially since summer just ended! I think with all the good input I'm getting here and the reading I've been doing, I'm not too far away from getting it set up. I should've started learning more before just blindly asking here, but this place has always been a bit of a crutch, so I guess it was a knee jerk reaction. Regardless, im confident we'll get it squared away.
Shawn, Get one of the guys on the board to build you a Q-jet. Then you will get something resembling gas mileage:grin::grin: The Q-jet offers plenty of performance for the street. It is possible to get that out of the Holley, but it takes some time. You have to lean it down and then play with the power valve passages so that it is lean when it needs to be and rich when it needs to be. I use a -6AN hook up for both my Q-jet and 1000DP, and I can literally change carburetors in 15 minutes or less. It is no big deal.
My fuel system is all AN, it very much resembles yours. I did that just so I could play with a q-jet in the future actually. But I'll need to dial in the Holley sooner or later, might as well do it now. And I couldnt care less about fuel mileage in this car. It's about the Smiles per gallon! But I still may play with a q-jet in the future, though I'll have to have my intake machined as its a square bore sp1.
shawn : no what i meant was after ya hook the link back up you can visually see when then link starts to pull the secondary's open which in turn ramps up the right side pump cam . just check rpm at that point , some guys adjust the link by bending it and there are also dif links you can buy . then there is the pump cam selections that will allow you to further tune .
Brief update. So I disconnected the secondaries and went to see what it felt like. Kinda hard to judge as it was new for me. For the sake of comparison, I got home and jetted them up from 82 to 85 and went again. Car ran much better, didn't seem obnoxiously rich. To be fair, I kinda got excitable and didn't pull the plugs. Hooked up the secondaries, the stumble was unchanged. So in an effort to make a small change, I jetted the secondaries up to 90's, and went down the road again. Still stumbled, but noticeably (albeit slightly) less than before. So it was in the right direction. Before I make any more changes I'm going to pull a few plugs and see how they look. Once the stumbles gone, I'll consider it a win, but I'm thinking this cars getting an a/f gauge in the near future just to have something a bit more concrete to go on. But that's later. I'll check the plugs out and report back when I can. Thanks for playing along gents!
Where did you go to with the secondary nozzles? Classic symptoms needs more from the pump! I love my AFR gauge.
shawn - just think of us as jerry jones , direct ya , tell ya what to do , without getting our hands dirty . except no big money and the PC is kinda our luxury box . but we learn too . good info for me if i run into someone that has a similar problem . and all this is why when i set up a holley to sell i put it right back to oem specs as close as possible and thats how i list em . i'm not guessin what some combo needs . so thanks for doin' all that dirty work n swearin' for us . hey , any power valve # info ?
Secondary nozzle I bumped to a 35 from a 31. That was hands down the largest improvement regarding eliminating the stumble. A little voice in the back of my head is saying to go a few sizes larger on it since it's been the most effective change thus far, but before I order more parts Im going to tweak the jets since I have all I could need of them on hand. I wish you guys were paying me what Jerry Jones pays his guys!!! Haha. Havent pulled the power valves, although im almost positive they are original to the carb which according to holley makes them 6.5"s. Im trying to decide if the difference between 6.5's and 5.5's would be dramatic enough to contribute to the problem, but Im not ruling anything out as I know these carbs can be finicky. At this point I want to rid it of the stumble, and I'll work on optimum tuning for power next. I may gamble and order a couple 5.5's and perhaps a larger squirter for the rear since that had the most dramatic affect on the stumble, but despite the parts being inexpensive I hate to just throw money at a problem without dertermining the cause first. Anywho, its a very wet day here today so the buick will be grounded, but as soon as I can give it a blast enough to get a decent plug reading I'll report back.
I still say 50cc pump on pri side. Absolutely cured my stumble on both Holley and Demon dbl. pumpers. Zero hesitation now.:TU:
no history for me as far as 50cc front pump , but i was worried about the 30cc rear pump on carb being too small . shawn - 6.5 PV is the most common valve , used on almost all standard use carbs - 600's right up to the 850's . some of serious dirt guys go down into the 4 range on their carbs . just checked back to my holley tech info - he told me front PV 4.5 - but he also told me no rear PV ?
You have a two circuit carb. Idle and main. Idle is controlled by the Idle feed restrictors, idle air bleeds and the idle screws. The mains are controlled by the main jets and the hi speed air bleeds. Then there is the transition. The lower side of the transition is the realm of the transfer slot. This is mainly for small throttle changes. Then there is the transition to go from idle to big throttle changes. That's what the accelerator pump is for. The main thing controlled by the pump system is the rate of delivery unless you change the pump volume. The rate can be changed by cam or shooter size. Main point here is bigger jets do little for the transition. Need a new service where you can rent a complete Holly service pack. All the parts you could ever need. I think it would take $500 to stock the system. Pay a rental fee plus cost of any parts used.
Wouldn't that be the ticket! I'll tell you what, the 50cc pumps worked so very well for my application that I kept them setup on both carbs in case I want to swap them out.
say no more...it's the eddy heads right. you should just take those off and send them to me. I will "give" you my Iron heads to bolt on. that should cure all the problems. I guarentee it. :Brow:. been reading this a while now. sorry your having problems shawn. thought I would lighten up the mood a bit. GL and send me those heads:laugh:
Oh man, you'd do that for me??!! What a guy!!! :bla: The problems arent really that big a deal, Im not overly worried or frustrated about it. I just look at it as a valuable lesson in another facet of these cars I need to learn. Heck, a little bit of me might even be enjoying the tinkering, as morbid as that sounds. Besides, the car isn't un-driveable in the least. It still fires up and runs, pulls like a mad man, cruises fine, and wastes the tires on command through 1 and 2. Casual driving you'd never know it was having a problem (but whats the fun in "casual" driving?! Haha). But thanks for offering to take the REAL problem off my hands buddy!! :TU::laugh:
Shawn, I'm thinking part of your problem is the fact that you are running a 4 speed. It loads the engine differently than a torque converter. I would definitely look into the 50cc pumps, I have them front and rear and 37 squirters. I have no flat spots anywhere.
http://pages.ebay.com/link/?nav=item.view&id=161840245403&alt=web If you buy a 50cc kit, Get one with the heavy arm, 1st pic, not the light style, 2nd pic with spring exposed. Geometry is perfect with the heavy style, not so great with the lightweight one. You don't want to have to start bending arm to start out with.:shock: Abt. $36 shipped is what I've been paying.
check holley #20-11 kit . that's everything you'll need . $50+ at summit . two will put ya over $100 and give ya free shipping . some nice used kits on e-bay sometimes .
