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Carb Swap Questions: Edelbrock to Summit

2661 Views 84 Replies 19 Participants Last post by  swooshdave
When going from an Edelbrock 1406 to a Summit 600 will the Summit bolt right on? Are the bolt patterns and such all the same? Hoping to place one order and not several. Thanks!

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Discussion Starter · #41 ·
My buddy said the same thing about the fast idle being particularly difficult to adjust on this carburetor. I guess maybe the base gasket could be leaking, but don't think he had any issue with that. Edelbrock makes a similar one that I have under my Edelbrock carb that would probably also work. Did you have that on your previous carb, maybe try it. I would not put any sealant on the carb base. Maybe it just wasn't snugged down enough.
I’m going to put some RTV on one face and let it dry. Then assemble.
 

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Discussion Starter · #42 ·
Let the RTV dry so it provides a better surface to seal against.

It starts and runs but I need to wait for a nice day to take it outside and tune it up. On a cold start (choke closed, no air cleaner) the AFR meter was showing 14. I would expect it to be a bit richer but maybe with the air cleaner on it will be.

Motor vehicle Hood Gas Automotive tire Car
 

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What did you do? Return it?
I returned the first one I got as it had this problem out of the box. The one I have now is 1.5 years old and has maybe 1200 miles on it. Had been running great until the last couple of weeks. I identified the leak this weekend. Haven’t talked to Summit yet. Warranty is one year. 🙁
 

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I returned the first one I got as it had this problem out of the box. The one I have now is 1.5 years old and has maybe 1200 miles on it. Had been running great until the last couple of weeks. I identified the leak this weekend. Haven’t talked to Summit yet. Warranty is one year. 🙁
I suspect that since you say it's "been running great" that leaky throttle shafts aren't the cause of it suddenly not... my Holley whistles like a pig sometimes but it doesn't affect how it runs one bit.
 

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Discussion Starter · #47 ·

As you can see the idle screw is loose and isn’t affecting the idle. With the screw out the engine shouldn’t run. Won’t idle under 1100. Shafts seem snug. I saw another post and the guy said he took the carb off and put it back on and it worked.
 

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Discussion Starter · #48 ·
Ok, what I discovered is that unplugging the PCV and blocking the port will bring the idle down to 750 (no lower).

Spraying the shafts will affect the idle.

Throttle response is crazy better than the Edelbrock. No waiting for rods and springs and crap. Just now! You don’t feel the secondaries so the transfer must be spot on.

It’s drivable but I’m still not happy that it won’t idle down and there’s enough air getting by that it can’t handle the PCV.

I don’t mind the fettling. Keeps me busy.
 

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As you can see the idle screw is loose and isn’t affecting the idle. With the screw out the engine shouldn’t run. Won’t idle under 1100. Shafts seem snug. I saw another post and the guy said he took the carb off and put it back on and it worked.
This is exactly what the one I had did. I never did figure it out.
 

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You saw my note about the PCV?
Not until after I replied. I tried that with the one I had as well as several different spacers and gasket combos with no effect.
 

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Discussion Starter · #52 ·
Not until after I replied. I tried that with the one I had as well as several different spacers and gasket combos with no effect.
Did you happen to check the fit of the butterflies?
 

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Hey Dave, I have no experiance with a Summit carb. Do they have a transition slot in the venturi like an Edelbrock, that needs to be adjusted to just a small square? I know too much of the slot being open will keep the idle too high. kip
 

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Discussion Starter · #55 ·
Hey Dave, I have no experiance with a Summit carb. Do they have a transition slot in the venturi like an Edelbrock, that needs to be adjusted to just a small square? I know too much of the slot being open will keep the idle too high. kip
They do. And I suspect I’m going to take the carb off again to check things over.
 

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Discussion Starter · #57 ·
@swooshdave Do you have gaskets installed on the manifold and on top of your spacer? Felpro 60059's?
I have the thick spacer/gasket that is provided with the carb. It's what people with a similar issue claim is the best thing to use. But I have a 1/2 spacer with gaskets on the way as I'm willing to try other things.
 

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I had the ridiculously high idle problem also and it's a bit of a bear to get a wrench on that screw, but that fixed that. I retorqued the nuts on the studs to a high value and got it to seal. Check to make sure your throttle arm from the pedal isn't hitting the back of the intake at idle. Mine was because I had the throttle linkage maladjusted. I screwed it out a couple of turns and that got it. I am happy with the Summit but I'm hanging on to my 1406, just in case.
 

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Discussion Starter · #60 · (Edited)
I had the ridiculously high idle problem also and it's a bit of a bear to get a wrench on that screw, but that fixed that. I retorqued the nuts on the studs to a high value and got it to seal. Check to make sure your throttle arm from the pedal isn't hitting the back of the intake at idle. Mine was because I had the throttle linkage maladjusted. I screwed it out a couple of turns and that got it. I am happy with the Summit but I'm hanging on to my 1406, just in case.
They say to only tighten to 50-60in/lbs which isn't much. I do want to crank down more. I don't think I'll warp the flange unless I get ugly on it. But since the spacer is so squishy I think it can take more.
 
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