Still Having problems with the PROBLEM CHILD-Lean/miss/stumble/backfire!!!!
06-13-2003, 01:23 PM
#61
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Originally posted by formulaF302
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
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
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
06-13-2003, 03:29 PM
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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
BT
06-13-2003, 04:06 PM
#63
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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.
06-13-2003, 06:19 PM
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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
06-13-2003, 09:29 PM
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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.
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.
06-13-2003, 10:36 PM
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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.
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.
06-13-2003, 10:59 PM
#67
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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.
06-13-2003, 11:41 PM
#68
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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 .....
06-14-2003, 12:37 AM
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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.
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.
06-14-2003, 09:18 AM
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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.
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.
