sarguy01
Well-Known Member
It dies instantly with a towl over the choke.
1987 318 Tuning with Summit Carb
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I tend to agree. You sound sharp enough that I think you'd have found a vacuum leak by now. Keep in mind my advice on that carburetor. You can still send it back.
I think that tells us no vacuum leak.
Is it hanging up on the choke fast idle cam?
If you messed with opening up the secondaries via set screw, take that back out. Can't kill it taking out all the primary idle speed screw, something is making a mess of this thing.
If you have the throttle cable hooked up, disconnect it.
If you messed with opening up the secondaries via set screw, take that back out. Can't kill it taking out all the primary idle speed screw, something is making a mess of this thing.
If you have the throttle cable hooked up, disconnect it.
sarguy01
Well-Known Member
I'm calling tomorrow. I should not be having this much trouble with an out of the box 600 cfm carb. I know I'm not the greatest carb tuner, but I also know that this carb should be letting me adjust the idle somewhat with the idle speed screw. It's frustrating. I can't set the timing properly without setting the idle low, I can't adjust the idle any lower. Okay, time for a beer. Thanks for the help.
You sound like me. You ain't the sharpest knife in the drawer, but you ain't the dullest one, either. lol
sarguy01
Well-Known Member
I just checked. No fast idle cam interference. Cable removed, same thing
I popped the carb off and going against the directions, closed the secondary all the way. The directions say to close the screw until the butterflies are closed, then add 1/4 turn. I started the engine, now it needs the speed screw to run. But the idle mix screws can be shut and it will still run off just 1/4 of a turn on the speed screw at 750 RPM.
Looking at this pic, with the screw all the way out I feel like this is way too much transfer slot showing. I just looked at my Eddy, with the idle screw out you can't see the transfer slot in the primary at all. I wonder if this is normal. I can't see any adjustment or way to fix it. Anyone with a Holley, is it normal for Holley's to show some transfer slot when the speed screw is out??
As the beer flows through my system, I'm starting to think it's running off the transfer slot and not the idle circuit.
sarguy01
Well-Known Member
That's the nicest complement I've heard all weekend. Thanks!
Any shiny spots in the bores where throttle blades may be hitting.
sarguy01
Well-Known Member
Not that I see. Just some dirt marks.
Newbomb Turk
Well-Known Member
Ok, let’s clear up some **** before you go down a rabbit hole you don’t want to.
Unless you have way more T slot showing than what you showed, quit worrying about T slot exposure.
Just stop. If not, you’ll go bat **** crazy trying to do something that isn’t THAT critical.
How much is too much? When they aren’t working that is too much T slot exposure.
If it takes a .060 or .080 wide window who cares?
Does it idle? Good!
Do the idle mixture screws work? Yes. Then who cares?
What if it idles but the screws don’t work?
Well, you can jack a bunch of initial timing into it, but I’m not a fan of that but I use IF I have no other options.
So it idles but the screws don’t work. Then you drill a 3/32 hole in each butterfly and see if you can shut the throttle down and get the screws to work.
If they work then you’re golden. If not make the holes .125 and check it again. If it idles and the mixture screws work you’re good. If not, repeat the steps in very small increments. Once you get to .125 any increase in hole size should be about .010 at a time.
If you get greedy and try to cut a corner and make another 1/16 after the 1/8 inch holes (so going right to 3/16 from 1/8 is a BIG move.
And what happens if the holes are too big? Then you can shut the throttle and the idle speed would stil be too high.
Then you need to buy a new set of throttle blades and start over.
Take your time and don’t cut corners.
If you really want to do the super zoot drilling, line the holes in the throttle blades with the curb idle discharge port. And keep the hole close to the edge of the blade but stay far enough back so you can increase the size to At least 3/16 and still keep the hole far enough from the edge of the throttle blade.
Some guys hate drilling holes. So what? It’s an acceptable practice solution to a small problem. Do it if you have to.
And so I’m clear, a .020-.040 T slot exposure is great, but if it won’t idle correctly and you have to open the throttle and make the exposure .080 who cares?
It won’t idle any better if you screw around and get the T slot to have less exposure. It won’t make 1 hp more.
I see guys going bonkers fight T slot showing. It’s insanity.
Of course, you’ll have guys tell you my way is cutting corners and their **** idles blah blah blah, blah blah, blah blah blah.
Don’t die on the “if the T slot is exposed more than square the world will end” hill.
You could put those efforts into tuning that makes power.
He has the idle screw backed ALL the way out now and it's idling at 1000. He clearly said his mixture screws work. If he drills holes in the throttle plates, that will make his problem with the high idle WORSE. You need to read what he's posting. Do I need to call your wife and tell her to slap you?
sarguy01
Well-Known Member
Totally understand what your saying, but I think it's getting too much air, not too little. That's why I asked about t slot exposure. I'm not completely stuck on them, but really looking for reference.
sarguy01
Well-Known Member
I'm staying out of the wife and slapping thing, but I agree. I think I'm getting too much air. Calling Summit tomorrow.
He needs it every now and then. Even he admits it. lol
Newbomb Turk
Well-Known Member
No, I got that. He’s getting air from somewhere and when he stops that he may have to drill holes.
It must be a pretty good leak.
Newbomb Turk
Well-Known Member
Like I said to Rusty I get your issues. That was a left of bang type thing.
Google it if you want to know what that means.
Maybe Summit will exchange it and he can start over.
Yeah, you need to be before the bang. lol
Newbomb Turk
Well-Known Member
Probably the best plan because where ever the leak is, he should be able to spot it pretty quick.
The fact that he can’t find a leak means something internally is cracked or a hole or two got drilled too deep and broke through.
If they will swap it out I’d be doing it.
Does the OP know someone with a known good carb they could try, already running on something. Don't jack with it, just install it, fire it off and see if it acts the same way.
I thought that was a 4150-4160 carb. Doh! It's one of those motorcraft copy carbs, friend had one many years ago when summit first started selling them, a trash can would have been a better carb.
Run the float level down half a turn, see if that helps. That cam is so small, you shouldn't have to dick with anything on the carb to get it running. 12-14 initial and it should idle smoothly around 700-800 easily.
Something, somewhere is royally F'd up.
Trigger wires from distributor reversed?
I tried... good luck.
I thought that was a 4150-4160 carb. Doh! It's one of those motorcraft copy carbs, friend had one many years ago when summit first started selling them, a trash can would have been a better carb.
Run the float level down half a turn, see if that helps. That cam is so small, you shouldn't have to dick with anything on the carb to get it running. 12-14 initial and it should idle smoothly around 700-800 easily.
Something, somewhere is royally F'd up.
Trigger wires from distributor reversed?
I tried... good luck.
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Something very odd about this carb. Post #67, idle tubes measure 0.053" ??? Surprised more folks have not commented on it. Or, is the restriction in the top of that thin tube? Check with drill bits or thin wire if drill bits are not long enough.
A general purpose over the counter 600 cfm carb, no matter what brand, you would expect to see an idle jet in the 0.028-0.035" range. Using 033 as datum, 053 represents a 158% increase in area, more than 1.5 times. Something is not right.
The idle jets in the spec sheet showing as 0.046". I wondered why that size would be given because they are not replaceable; the idle feed is the brass tube, but the restriction may be at the top of the tube, as discussed.
I believe the 046 refers to the Economizer jets & I believe they are two replaceable jets shown in the red circles. They are also part of the idle cct. Econo jets are always above the fuel level, as these are. The Econ jet in the 6000 series TQs are in the 046-048 range & also in some AFB carbs. The econ jet supplies mixed air + fuel to the t slot & idle mixture screw port, for idle & low speed cruise. It is a jet that might need to be changed so it's position in the cluster makes sense [ to me ].
Pic in post #53 of the booster assy. I see holes in the casting that are probably air bleeds. Not sure about the brass jets.
A general purpose over the counter 600 cfm carb, no matter what brand, you would expect to see an idle jet in the 0.028-0.035" range. Using 033 as datum, 053 represents a 158% increase in area, more than 1.5 times. Something is not right.
The idle jets in the spec sheet showing as 0.046". I wondered why that size would be given because they are not replaceable; the idle feed is the brass tube, but the restriction may be at the top of the tube, as discussed.
I believe the 046 refers to the Economizer jets & I believe they are two replaceable jets shown in the red circles. They are also part of the idle cct. Econo jets are always above the fuel level, as these are. The Econ jet in the 6000 series TQs are in the 046-048 range & also in some AFB carbs. The econ jet supplies mixed air + fuel to the t slot & idle mixture screw port, for idle & low speed cruise. It is a jet that might need to be changed so it's position in the cluster makes sense [ to me ].
Pic in post #53 of the booster assy. I see holes in the casting that are probably air bleeds. Not sure about the brass jets.
I agree totally and 100% about the early ones. I remember well. But it seems like most everything they got the bugs worked out. I know a few people locally who have them and they work well. Also, the Autolite 4100 they were designed off of are literal legends in the Ford world. They were among the best carburetors Ford ever offered. They powered some of the more hot FE engines. .......man that's gettin to be a LONG time ago now, ain't it? lol
That right there is what I was thinking, too. He's having to do everything you'd have to do with a cam MUCH bigger than what he has. That's why I originally jumped on the defective carburetor bandwagon.
sarguy01
Well-Known Member
I have the 600 Eddy that was replaced with the Summit carb. I decided to replace it because the throttle shafts are pretty worn and I wanted to take a crack at tuning a Holley style. I had the Eddy on two days ago after I fixed the ignition and was able to fully adjust the mix and speed screw as normal. So when I turned in the mix screws on the Eddy, it died. With the Summit carb, it won't die with the mixes all the way in and the speed screw in just 1/4 turn. I don't get it.
I actually have the floats lower then what the manual says. Spec is supposed to be middle of the sight glass, I have them set at the bottom.
Just redid the ignition and double checked the wires from the dizzy before splicing them to the MSD harness.
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