Bad Habit, I reread the description of your problem from start to finish. Here are some idle rantings that hopefully will help the troubleshooting.

Is it correct that you can get past the mid-range miss/bog and above 4500rpm the boat runs fine, just lean. Or, is 4500 WOT? It feels like you may have two problems... fuel delivery/ carburation and the intake leak. Sounds like you are getting a grip on the intake leak, but the fuel/carburation is still elusive. I think I read you changed to high flow needle and seats? If so, did you adjust the float accordingly. Not sure about edelbrock carbs, but on qjets this is important. What it seems like is the power piston is not opening when vacuum drops, thus leaning things out at cruise speed. Are the plugs a decent color after idling, or is it lean there as well? Sorry if you have already answered that. If it is lean even at idle and you have reasonable fuel pressure, you must have a carb problem or massive vacuum leak. Your vacuum was on the low end, but did not sound outrageous (like a tulipped valve). Are you sure the power piston is moving freely and that the spring is in place under it? I think you can inspect this on the edelbrock while the engine is running.

Multiple problems are a *****! Sorry for your trouble,

BT :cool:

The bog is ever present at least under 4500....The miss happens at cruise between 3000 and 4200 or so. I can over come by staying below or above this range. I have not re-set the float for the hi-flow needle and seat kit. But I will call edelbrock and get their specs...As far as the power piston I think that would cross over to the metering rod springs. I think I have read that you can check the operation of the rods. I have not checked this but did change the springs to the ones that operate the easiest/quickest....What should I be looking for on the rods/power piston and their operation? The plugs seem to actually be VERY rich running ON THE HOSE... LOTS of carbon and strong gas smell. BUT this was before I got the intake situation corrected/plugged. I havent' checked them at idle since I sealed the gap on the intake. SOOOO If I'm not lean at idle then what does that lend itself too? Tommorow will be (weather permitting) install of the new pump and fuel lines....I will re-set the float and get ready for anouther 2hour trip back and forth to the lake to check this thing out :mad: I can't thank you guys enough for all your help so far. I won't go on and on about how little I have left for all this (money:( ,patience and time.) Suffice to say it's people like you guys that make this board and sport special.....I will update a.s.a.p. and KEEP THE IDEAS COMING!!!!!

BH

Do yourself a favor and check the anti-syphon valve operation and the screen behind it when you put the pump in. If you don't already know, this is an in-line checkvalve that is typically located at the outlet of the fuel tank. It often looks just like a brass 90* elbow. Causes boaters lots of trouble and is easy to fix.

I have not worked on edelbrocks, but am fair on a qjet. Qjets have the same power valve. Reading Dennis Moores section on edelbrock it say "you can remove the cover and watch the operation of the power piston as you rev the engine." If the power valve is not moving, it would lean your engine out at cruising range. This power piston is what moves the metering rods up under low vacuum (throttle open). That is, the spring moves the piston up when the vacuum drops. A lighter spring will make the cruise a/f ratio leaner... at least on a qjet and I think on yours as well. A heavier spring will make the cruise a/f ratio richer.

The gas smell at idle is probably your idle mix circuit is tuned too rich, but I wouldn't worry about that for the moment. Rich is good. I am really leaning toward the anti syphon valve or a clogged screen.

I was going to change my needle and seats last week, even bought them (qjet), but chickened out. This is a fairly sensitive change and needs to be handled properly from the float setting standpoint and fuel pressure standpoint. Doing this stuff wrong would probably result again in a rich or flooding condition, so that is not your problem.

Anti-syphon valve and screen or any other filter you have not yet replaced.

BT :cool:

And please, dont assume that the bead of caulking you ran has fixed the intake leak problem. You could still be leaking between cylinders or to the lifter valley. Pull it off and do it right. Im just learning quadrajets and cant wait to hear the end of this story.

Hey Formula31, how you been? I have a book from "HP BOOKS" that is dedicated to Rochester carbs, particularly qjet. Let me know if you need any specific info.

Dave :cool:

Bad,

Sorry to state the obviouse, however I have never heard of so many problems sealing an intake manifold. You took the right path by using red rtv sealant, and a thin bead should have eliminated any casting imperfections period. You also may need to check your bolt length's, even if you properly torque the intake if the bolts are bottoming out you will never seal the leak. This is also possible with the carb bolts.
Typically there is never any one fix for dialing in a motor other than a good deal of patience. Don't second guess your effort, and don't jump around the motor. No short cuts.
Start at the top and check each and everything you have assembled. You understand white plugs mean lean, correct the intake leak (by the way starting fluid usually raises the idle) and then you may need to re-jet the carb.
As already mentioned I don't agree with only 4 p.s.i. for fuel pressure I want 7-8 minimum, check pump, supply line and clamps, and tank vent to be sure there is no restriction.
You will beat this problem!

When you say the plugs are white, do you mean the electrode and ground strap are white or do you mean there is no color on the white porcelain? These new reformulated fuels just dont put color on the plugs.
Sorry if this was already covered, I didnt read the whole thread.

Float setting 1 9/32 with 5 psi. 1 5/16 with 8 psi fuel perssure .The springs you should be using are Orange-red will not raise piston uitil vacuum drops to 5". I am running Orange-red spring .065-.047 rods for now,.113 jets in both front and rear.I'am useing the Edelbrock # 1466 needle and seats at .110 and useing the leanest pump shot and have no problems.My plugs to some would seem like they look white but with a tad of tan on the porcelain but my heat line is on the curve of the ground strap.:cool: ps I still don't think you have a vacuum leak,but if I thought the vacuum was realy to low and I was going to check for a leak on the top side of the gasket only ,just run a bead of water buy the ports and if it is on the top side it will be sucked in with no guess work ;)

Got off the phone with Edelbrock Tech. THEY say float level (inverted)should be @ 7/16" and that float drop should be 1-1/4". Also stated that Min Fuel Pressure should be 5psi with 6-1/2 the max....Ive gotten 2 answers from their tech on fuel pressure though. First time it was 2lbs min @idle and 4lbs@ W.O.T. Anyways the fuel pump should be on today. As far as springs Im currently running the plain springs which is the richest quickest setting. As far as the plugs the porcellen after a run is WHITE not just some of it ALL of it. The ground strap is clean as a whistle with a spot about 1/16" off the base having a slight line. Funny thing though at idle on the hose the plugs are RICH big time. It's at speed they are lean....As far as dialing in the motor I dont' look at this as what im doing...Isn't that what you do after major changes or when setting up a new motor...This thing ran GREAT for the first 40 hours!!!!!! THEN with no changes and with no warining I got the bog under hard acceleration and miss at cruise Along with the "GHOST PLUGS!) Anyways hopefully I can get everyone here some updates on my little soap opera a.s.a.p.
Thanks again everybody you are my life-support right now...Because I think unless I hit the jackpot or get this fu**ing problem child fixed SOON(Ive been on this problem for 10 months now) My wife (family for that matter) will want a divorce:D

BH

Could you post a pic of your plugs? It sounds like your running fuel thats just not leaving color on your plugs. You need to get a spark plug magnifying glass thats lighted. If your really lean, you will get a white buildup on the strap.
Heres a link. Theres a good section on reading the color ring at the base of the porcelain.
http://www.strappe.com/plugs.html

I went through this last year when I put a new carb on. I kept going fatter until it started losing perfromance and still no visible color. The new fuels, especially the reformulated fuels we get in major urban centers do not leave color for many hours.

Maybe your chasing a problem that has nothing to do with the color of your plugs?

Just an update...I put the new Fuel pump on and installed a liquid filled gauge inline near the carb inlet....I had a good freind come over to lend a hand. Well sadly I hate to say that we didn't make much progress. We did rule out a few things though....After the pump change I noticed no change in the bog/backfire on a hard quick throttle jab...He however noticed that the carb was DUMPING fuel into the carb...The backfire we assumed was coming from the TONS of excess fuel...Well we decided to re-set the float drop to 15/16" as listed in the book. It had been at (their tech dept decision) at 1-1/4. I went from the stock 98 jets in the primary to the smallest I had which was 92. I changed the springs and rods to the slowest/leanest ones I had from my trick kit. The plugs had been BLACK and carbon filled AT IDLE ON THE HOSE. Well now the plugs were just very rich but not totally black. So A little progress there. But I shoudn't have had to adjust the damn thing THAT LEAN! The bog seemed to totally disapear and the backfires were ALMOST gone. Matter-of-fact I went about 20 or so quick throttle jabs without any bog or backfire.....BUT after letting the damn thing idle for 30 min or so I started to get the backfire back a LITTLE more. I noticed the carb was leaking fuel into the secondaries. I couldn't really tell were but it looked like it had to be from the gasket that connects the upper and lower parts of the carb. The fuel was starting to puddle in the corners of the rear of the carb. Not much but it was there..I replaced that gasket and re-checked the needle and seats (back to stock),float levels and everything else I could see. But when it was back together NO CHANGE:hothead: I got a reply back from edelbrock that said the carbs could only handle 5.5 lbs!!!! This was after my new pump was reading 6lbs....Well I am getting tired of all this bull so I bought a Holley 750 vac. sec. Model 4010. Bought it off a fellow board member here. Supposed to only have about 30 hours on it..I figure Doing this will hopefully make all the holley lovers happy since it means taking off the Edelbrock:D And rule out one more possible problem (whats left?:confused: ) Just wanted to update everyone on the status of my "problem child". I will post when I get the carb on....Any suggestions on starting points for jets or sec. springs? Here is the carb I bought thoughts on this also..Thanks again you guys are the only thing keeping me from murdering this kid:p

BH

Well lets see. Where to begin:rolleyes: Since my last post I have made some definite progress. Well I installed the new Holley 750 and right away got rid of the bog going from cruise to W.O.T. Matter of fact I have some serious prop ventilation at about 4000rpm's W.O.T.! Picked up over 1.5mph. Jetting was for a bigblock with 74 primary jets and 76 secondary. I actually got some color on the plugs. Not very much but a little. If upped the secondary's to 82 and the primarys to 78. Plugs look PERFECT!!!. The mid-range power Ive picked up is awesome. The cruise miss was still present but at a smaller rpm range (3600-4200). I had a moment:) and thought since I had tried everything else I wired the Drew Shotguns wide open and WHOLA.....the miss was GONE!
I spoke with Drew and he said that ANY miss would be magnified 25 times with the shotguns based on the way they work. He said the miss probally was so small that it took the Shotguns to make it noticeable. Anyways I set the Shotguns on the loosest setting and set the closed positon to where it was actually open about 1/4". Now everything sounds great...SOOOOO Let's see Ive got the "miss" figured out,Picked up lots more torque and power, got rid of my bog at cruise not to mention got my plugs/motor running with the correct A/F ratio. Only ONE problem remains. I still have the severe bog going from idle to w.o.t. I have checked the float levels, no change. Advanced base timing to 10,12 and 14 with VERY little effect. Going from stock 8degrees to 10 made a VERY slight difference. I bought the 50cc pump and installed the biggest cam for that pump. It made a small difference. Noticeable but still small. I'd say going to 10 degrees initial and the 50cc pump MAYBE took 1/2 of the bog away. I have no idea what to do next:confused: :confused: :confused: :confused: I have to ease in to the throttle to get the boat to accelerate of the line even if its just a slight acceleration. After about 2-3 seconds Im o.k. Now sometimes during this way of accelerating I get a stumble/surge/cough sometimes I just get a slight bog then its ok. Sometimes I get a smooth transition. Now if I slam the throttle then I get the SEVERE stumble. If the boat is not in gear I can get a VERY slight bog on a idle to W.O.T throttle stab. Everynow in then a backfire. I was wondering if my problem could be anything Im overlooking:confused: I have checked and double checked EVERYTHING I can or anyone else here has thought of. I have one last thing Im concerend MIGHT cause the problem..........THE ALPHA SHIFT INTERUPTER.......COULD this be giving me any of the symptoms Im having??????????? As always ALL HELP IS GREATLY APPRECIATED:) :) :) Any thoughts AT ALL are welcome. Thanks

Randy
"Bad-Habit"

Randy,
You changed to a 50 cc pump , right? But did you change the squirters? Holley makes different size nozzles fpr this, and you can put 5 gallon pumps on , but there is only so much that will go though the squirters.
Because with the stumble and backfires off idle , it certainly sounds lean.
Another thought is the check valve in the accel. pump. If that's leaking or missing it will severely effect the amount you shoot:rolleyes: ( excuse my terminology:D :D ) And again this would be MOST noticable coming off idle.

Just a few more ideas. Cal (mopower)

Yeah I changed the pump. The squirters no. Actually I don't think you can on the 4010. But from what Ive read the squirters only determine the volume of the shot. I mean the cam/pump determine how much is shot the shooters decide at what rate and volume the fuel from the pump is shot....At least thats what my Holley book says...

BH

OK , the 4010 may not have replacable nozzles...I'm not sure about those:confused:
This did help a friend of mine on his. He had , what sounds like the same thing as you , only not quite so bad. He could accelerate normally , for the most part. But if he really hit it , he would get a stumble and occasional backfire:( . His carb had the removable bowls and metering plates , 4560 I believe.

did anyone check the pick up tube in the tank for a restriction? i had this problem before, it showed up on the pyros, and after some searching, i found a collection of debri in the 90 coming off the pick up.surging , lean condition, and loss of power prob solved.

better put a vacumn gauge on that puppy cause you are suckin air someplace!!!!!!!!!!!

Pulling between 14-1/2 and 15-1/2 pounds. Guage moves around between these two......

BH

this may sound stupid....but check your bolt lengths. Being that you've changed from stock bolts to ARP and have changed manifolds your bolts may even be bottoming out....just a thought from a similar experience with World Products heads and stock GEN VI head bolts......

mighta found my problem....using square bore carb on spread bore manifold...maybe you have a similar situation. I did'nt know that there is a special adaptor made for using such an application...but for the price difference I just bought new intake manifolds made for my carbs. Maybe you're dealing with a similar situation? Good luck.. Glenn

No Glenn I made sure when I first bought the manifold...Luckily the "Brock" a.k.a the Brick:D and the Holley both use the same intake pattern. Right now Ive gotten everything pretty much licked execept for the bog/stumble though its only off-idle though..By the way glad you didn't order the adapter! Lots of problems getting the mixture correct and less power for sure!!

BH

That is interesting about the spreadbore intake. I have 502 merc dual plane intakes with spreadbore pattern, although they have the holley and qjet bolt patterns. I was thinking I could bolt holleys right up with no adapters or anything. Is that not true? I run qjets now. I haven't purchase holleys yet and this may impact my desicion cause I am not buy new intakes (again).

BT :cool:

Years ago I had a 73 Mach 1 with a 351 HO with a spredbore Motorcraft 4v. Ford used a Holley bolt pattern then for all of there carbs. It wasn't working well so I switched to a Holley 780 squarebore. The secondary throttle blades interfered with the manifold so I put a short spacer under it. The carb worked perfectly right out of the box, no jet changes at all. I have to wonder though about the high performance potential of a standard Merc manifold.

When I look at the pattern from the square bore gasket laid down on top of the manifold with the spread bore hole I get the feeling theres a whole lotta dead air space around the sides of the intake thats not moving any air...its gotta affect the venturi effect of all the flow. My front 4 plugs are lean as hell...and the back 4 look like black spray paint with #86 jets on all four. I've been told that the adaptors dont work well unless you put attitional spacers below them etc.....so why go thru all that and stiff fight problems? I also question the performance ability of the stock qjet intakes....So I'll just shotgun the whole problem with the new intakes. I won't find out the results for a couple weeks though...they will be delivered the day I head south on a motorcycle vacation....so I'm bummin about that. I'll let ya know how it turns out. Glad to hear the holley at least solved some of your problems BH....I shoulda stuck with them I think! By the way...the factory electric fuel pumps that came with those only put out about 3 1/2 lbs.....Glenn

BAD-HABIT, Looks like you have this thing about licked.
I haven't worked on a holley 4010 before, but I definitely would check the squirter nozzle. I have fixed alot of cars and boats with replacing the squirter size. If they are replacable, then look at them and there will be a size# printed on it, like 26 or 28. I have even drilled them out before and the bog has always went away. The bigger 50cc pump puts more fuel in, but in a longer time fram. You need more fuel sooner. I think if yours are smaller like the # I stated above ( and a lot of holleys have those ) your would see a huge improvement with a 40-45. That is why you noticed a slight improvement when you increased jet size, you made it richer.
Take a look at it and see if it can be removed and let us know.

hey Bad,

i am running a similar motor. Vortec 355, airgap intake with an edelbrock carb. You are correct, the vortec motor has a different theory with the intake gaskets and design. The intake gasket is more of an o ring held in place by a plastic frame. the mounting bolts are vertical and it only has eight bolts with one on each side of the water jackets. Rtv is used to seal up the front and the back of the intake.

i would use the gm bolts and they are rip off. I believe the new gasket system is designed because of the cast heads and the aluminum intake that most vortec motors have. It allows the dissimilar metals to expand and contract at different rates. The reason why there are no bolts in the center where the egr gasses are for most sbc heads is that the vortec heads are solid. Vortec car motors use the computer and not the egr system to meet smog emissions.

It sounds like your holley is working for you. I think if you can get your intake sealed up nd some locktight on the intake bolts you should be ok.

I have had the stock vortec gaskets factory bolts locktight holding my intake on for about a year and a half. I have heard that the black rtv was made to seal vortec intakes. I don't know if this true. I have heard that there are some better intake gaskets available today.

I think you have found one the weakness of the vortec motor designs. the other thing that I would watch is your block water pressure. Too much water pressure on the intake gaskets could make a milkshake.

Does your intake have the rear cooling holes? Are you using them? You might have a cooling problem that is heating up your intake manifold unevenly. Does this problem occur after a hard run?

Good Luck, Just some thoughts.

Same Problem
 

Did not read the entire thread, but had similiar problems as you with a holley. After changing almost the entire engine and ignition system, and all the MSD, found my problem was a defective power valve in the carb. Ticked me off, since I spent nearly $1000 bucks and numerous hours.

BH...I checked all those power valves (informally) by sucking on them...granted I'm no expert on sucking on things...but they appeared to be working fine and were the blowout proof type. Maybe a proper test with the right equipment would yield different results .....

formulaF302,

I tried a square bore carb on a spread bore intake and I was not happy. I tried an adapter and got the same results. for me I will always match the carb with the intake.

I think Bad said he was using an air gap intake. I have had had excellent results with my edelbrock air gap intake.

My .02 and a few weeks in the garage.

Well guys.........

I just finally got the other carb that Formula302 sold bolted on my combo, and it is working waaaaaaaaayyy better than the old weber carb. I'm super happy so far.!

but.....

i've also got the same stumble when you crack it from idle hard. It recovers quickly, and takes off, and it's only from an idle. I'm going up today to work on it, and am hoping that maybe adjusting the accelerator pump will help it. Just got it running yesterday, so i didn't have time to work on that part, was more concerned about jetting.

On the subject of jetting, i'm up to 81 jets in the primarys, and the plugs are still bone white. Does this sound like a lot? Every jump i've made (i started at 73's) has made an improvement in performance, so i'm assuming I need to just keep going up....?

i hafta admit tho, glad i trashed the weber.......this carb works sooooooo much better.:p

I don't know if those carbs I sold you guys woulda had those stumbles or not on a hard take off....at the time I was running props that would broke loose on a hard take off...so all of my takeoffs were rather slow events with the tabs all the way down with twin engines. The electric fuel pumps that came with those cargs were only abut 3 1/2 lbs as I recall though in case that helps you at all... Glenn

Forgot to write back in, Glenn........ I got the stumble cleared up by moving the pump cam to the first hole. That took care of it. Runs perrrrrrrrfect now. Still dialing in jetting tho. Does anybody know, if the primarys and secondarys both have power valves, should they be jetted evenly? I'm at 82's all around, and it seems to run pretty terrific, just didn't know if the secondary's should be richer than the primary's? I'm gonna try and play with it more this week.

Thanks Glenn........cured my problems.! Now if Badhabit can get his fixed...

Yea they have power valves front and rear....Stock they are the 6.5's....I think that most times jetting is higher in the rears.....

BH

When you dump the sticks, the throttles open and your vacuum falls to almost atmospheric. The idle and main jet circuits will almost completely stop flowing fuel. At this point the accelerator pump and power valve are what lets the motor accelerate.

The larger accelerator pump squirters will allow more fuel to flow. You can fine tune this with the various pump cams, but you have to have enough flow through the squirters first or it will always be lean.

The accelerator pump can only deliver fuel for a short period of time, then runs out. Hopefully, by the time the pump runs out, the motor is pulling enough vacuum to establish flow through the main jets. The 50 CC pump will maintain a larger flow volume and for a longer period of time, but will also run out eventually.

The power valve is there in case the engine is heavily loaded- the vacuum will be lower that for a normal running condition. The power valve opens at a specific vacuum level, and stays open until vacuum returns to normal. The number on a Holley power valve indicates the point at which it opens- I think a 6.5 will start to open at about 13 lbs vacuum.

I would first verify that the main jets are approximately correct, check the pump squirter nozzles for size number and operation. and the power valve does not leak by applying a vacuum (haha)

If it stumbles during the acceleration only, and the main jets are even close to correct, it is probably the nozzles. They are cheap and are right at the top of the carb, next to the air filter screw hole. Be careful not to drop it, and watch for a small seal underneath. I have gotten away without that seal so don't worry if it's not there. I would buy the next 2 sizes larger than the one you have.

See if there is a 4 digit 'list' number stamped in the air horn area- for example 8410, and post it. Holley has a listing of these with all factory jets, nozzles, etc that the carb was built with.

Good luck!
Bulldog aka Ronnie

That's kinda the problem.........the squirters aren't adjustable on the 4010 Holley....... :(

Yeah this is the downside of these carbs I think. Outherwise I think its a GREAT carb. I think you can drill the shooters out if need be........Ive got a couple of books that describe the procedure.

BH

do you have a adjustable fuel pressure regulator by any chance? If so could it have slowly adjusted through engine vibrations?

I would also change the fuel filter, and check the pump diaphram if its got one +clean out fuel lines.

Silicone gasket sealer is what I would use, as its compressible and formes a good seal.

Everything else I can currently think of has been said.

No regulator....Fuel filter/seperator changed,pump diaphram changed(new fuel pump) and fuel lines cleaned out...........Still working on the stumble.

BH

Did you check fuel flow? I read that fuel pressure can be fine but flow still bad.

Can you post a pic of where you think the leak is, and have you tried surfacing the mainfold with a flat file, as this works quite well and doesnt require expensive machining. Move the file forward and sidwards at the same time to achieve a perfect flat. then file again but at a 90% angle across the previous filed grain, and repeat till no low spots are present. they are visible as areas which dont catch the file.

Have you siliconed the manifold as yet?

agree it may be fuel starvation
 

Recall that there may be a filter (sock) and/or a check valve in the fuel tank. Sometimes these get partially plugged and may cause these symptoms when you need the fuel most.

KM