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Edelbrock GURU's needed BADLY

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alaskanbowtie

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Edelbrock GURU\'s needed BADLY

Needing help,motor specs as follows:
350 .040 over
6.00" rods
Flat tops-gapless rings
isky cam @.050 214-224, degreed
Double hump heads with 2.05- 1.06 valves and "ALOT" of port work, Crower rollers
Dual Plane Holly contender ported and polished to match.
Headers and 2.5 duals.
Edelbrock 750 with 1/2" phenolic spacer.
it has the offroad kit and I have used several different jet combo's with no real good results.Still lagging and stumbles, well hessitates a little when you tromp it. Also at cruise if you stomp it it will kind of stmble a little then go. Right now it has .101 secondary jets and .104 primary with the biggest metering rods in the kit (fatest, less fuel) and orange springs. The accelerator pump is on the lowest setting which helped a little with the stumble off the line.
No vacume leaks and has a hi volume pump, getting plenty of fuel. Good accel ignition from distributor to platinu, plugs. So I'm going crazy with this stupid thing and I know it shouold be much better.PLEASE HELP anyone with similar set up. I don't know what to do next but go with a smaller accelerator pump nozzle to get the stumble off the line cured but I know other have this type set up with less of a motor and are having no problems?????
/forums/images/graemlins/1zhelp.gif /forums/images/graemlins/doah.gif /forums/images/graemlins/confused.gif
 
Re: Edelbrock GURU\'s needed BADLY

At what RPM is the stumble?? Is the truck auto? or stick?
Right off the only thing I see is that heads like your running are for very high rpm. If these heads are opened up "alot", then part of your problem may be that the air/fuel is stalling in the runners. This will cause a stumble you CAN'T tune out of. Bigger is not always better. The rods/jets will affect cruising and power acceleration. But the accelaerater pump has to discharge enough fuel to recover from vacuum loss. I would look more into the pump settings. more fuel/less pump duration.
 
Re: Edelbrock GURU\'s needed BADLY

My advice is get rid of the Edelbrock carb. A well tuned Qjet will work better.
 
Re: Edelbrock GURU\'s needed BADLY

What model of carb are you running. If its a #1407 I think you have a little too much carb for your engine. 750 cfm is a lot of air for a 350
IMHO A #1400 would be better.

If its a #1901 or #1902 (Q-jet) You should try adjusting the air valve.
 
Re: Edelbrock GURU\'s needed BADLY

Ditto Thunder. Also, you say no vac leaks-but did you check for a leak at manifold to heads joint?. They do tend to losen off on a recent build. /forums/images/graemlins/thumb.gif
 
Re: Edelbrock GURU\'s needed BADLY

stumbles a little from the get go and then at cruise, which can vary 2500 to 3500 the higher rpm is not a real stumble but more of a mild sputer/hesitation, hard to explain. These heads were ported by Brownsfield heads few years back (now known as AFR) and not for all out race but good street strip, not so much as to loose all the torque for street use. I have had several different carbs on it and the 600, 1406 ran good but was lacking so I bought the 750 which ran much better but had some stumbling problems which I've improved but still not able to get out completely , perhaps it is just to much carb for the motor and I won't be able to get it all out?? But I'm going to try everything first, I had hoped someone else wsa runninga tuned 750 on there 350 with good results that I could learn from there jet choices? /forums/images/graemlins/whistling.gif
 
Re: Edelbrock GURU\'s needed BADLY

I had same issues on mine with the 750 also I put a 1 inch spacer under the carb and cured my problems
 
Re: Edelbrock GURU\'s needed BADLY

have you checked your fuel psi, also what is you lift not duration of the cam. a good place to look is your cam and intake to see if the power band is correct for each other /forums/images/graemlins/dunno.gif
 
Re: Edelbrock GURU\'s needed BADLY

Did the Edelbrock book come with it? Call the E tech dept.

I think a problem like this is usually associated with the accelerater pump circuit. Most of the time it is not getting a big enough shot of fuel in those conditions.

What is coming out of the tailpipe when you romp on it? Black smoke would indicate a to rich condition. I am not sure, but those look like some mighty big jets.

Read the plugs too. I have never had much luck with platinum plugs....
 
Re: Edelbrock GURU\'s needed BADLY

Not real up to date with the Edelbrock carbs, would this be a carter style or a rochester style? I know the later model Rochesters have a secondary metering screw that everyone always overlooks. I have a JET 750 on my Vortec headed 350 and until I got it set right it would stumble out of the box. I'm now fighting it once more now that I got rid of my tail pipes. /forums/images/graemlins/hack.gif
 
Re: Edelbrock GURU\'s needed BADLY

[ QUOTE ]
Not real up to date with the Edelbrock carbs, would this be a carter style or a rochester style? I know the later model Rochesters have a secondary metering screw that everyone always overlooks. I have a JET 750 on my Vortec headed 350 and until I got it set right it would stumble out of the box. I'm now fighting it once more now that I got rid of my tail pipes. /forums/images/graemlins/hack.gif

[/ QUOTE ]

They are just like a Carter. I have owned a few of them and it seems like they work ok but usually after a few months they start acting up. I never had any problem from a well tuned Qjet and think they perform a lot better.
 
Re: Edelbrock GURU\'s needed BADLY

yeah it came with the book and I've been from big to small on the jets, (these being the smallest), but I think I will try this gasket & 1" spacer under it tonight to see if she runs a little better, I was running a little fat but with the last down size in jets it quit that but still stumbling I do need to look at the plugs to see what they are doing.I think that the stumble is because of to much from accelerator pump only because it improved when I lowered the setting on the pump rod to decrease the flow. I've talked with Edelbrock a bunch of times and only once did I get anyone with a brain the other guys went off a book and what it says should be about right which was all wrong on my motor. They tried to tell me to go with an 800 the first 3 times I talked to them, so I'm not real impressed with the tech department and Mr. Hamar who you can barely understand /forums/images/graemlins/angryfire.gif I'll look at the plugs tonight as you've said and see how they look also try to get the spacer on. The lift is 464-488 on this cam and I have a mild Tci converter which gives about 500 over idle. thx for some more insight I'll post after trying these things to see what I come up with /forums/images/graemlins/thinking.gif
 
Re: Edelbrock GURU\'s needed BADLY

I will try this tonight but it looks as if you have a Big Block which would eat up a 750, unless you are talking about a small block application you used it on??
 
Re: Edelbrock GURU\'s needed BADLY

yes its on a big block but i had same troubles as you and this cured it let us know how you make out.
 
Re: Edelbrock GURU\'s needed BADLY

well spacer is installed and it's better but still a little to fat and I've done everything possible so let my ignorance be an example to you guys wanting to put a 750 on a 350 it is just a little to "BIG" maybe if you were running a BIG cam and high rise it would be good for a high revving 350 but mine is built pretty good and it won't take it! /forums/images/graemlins/dunno.gif /forums/images/graemlins/thinking.gif
 
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