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Can you give us an update on the summit carb grtskydog, and anybody else that is using this carb? I'm finishing up a street/strip 306 for a 1969 Mustang, and I'm looking at which carb to go with. I'm debating on a Holley 650 DP, 600 vacuum secondary, the Summit 600 cfm, or an Autolite 4100 from Carbontooters/KP Carbs. Was this Summit carb pretty much a "set it and forget it" like the Autolite is reputed to be, or due you have to adjust it fairly often?

I already have the two Holley carbs, but could easily make a profit on the on ebay compated to what I bought them for along with rebuild kits if I go with a different carb.
 

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I bought a 600 c.f.m. summit carb back in may. After the car is running, it runs good. But getting the car to start is the hard part. For some reason the check ball for the accelerator pump gets stuck and won't work. So when you pump the throttle it don't get that first squirt of gas. Any ideas to remedy this problem?
 

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I recently bought this carb to replace a Carter 600 cfm. The main reason I switched is because I was looking to get more low end torque. But I was also hoping with the annular discharge nozzles that fuel would be atomized better, resulting in cleaner exhaust. My car has never been able to pass the emissions exhaust test we have.

My motor is a 306 with XE262H camshaft, headers, and RPM Airgap intake. This is mated to a T5 transmission and 3.00 open rear gears (for now).

I've had driven the car for only one day but the difference is unmistakable. Low end torque / throttle response is definitely better. With the Carter, if I was rolling in 1st gear and punched the throttle, the tires would not break loose. Now they will break loose. Also, the car pulls hard to 5500-6000 rpm. So I really don't think I've lost anything at higher rpms.

I don't know yet if I will be able to get through the emissions exhaust test as-is. I adjusted the idle mixture to try clean it up the exhaust as much as possible. The exhaust still has the odor of a car with no catalytic converters, but it doesn't seem as bad. I did notice that I now get about 17" vacuum at idle. I never got better than 15" with the Carter. So I assume that means the engine is burning fuel more efficiently, at idle anyways.

The carb needed minimal adjustment out of the box, mainly just the primary float being too high. Cold idle RPM is about 1200 rpm on my motor, which seems to be fine. The choke comes off after only a minute or two. With my Airgap intake though, choke needs to stay on for a few minutes longer or the engine stalls. So I will see how much I can adjust this.

So far I'm very happy with this carburetor.:tup:
 

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Discussion Starter #44
Cobra, Glad it worked out for you. You can adjust the choke to stay on longer just by tightening up the choke coil (twist the housing)...it's adjustable on the Summit carb.

jholmes, no I'm not running it anymore. I'm building a 351W for my Fox, so I'll probably use the Eddy 650 I have and see how it goes. I would certainly consider running the Summit 750, but I don't wanna put out the cash for it right now.

chornak, If you're relying on the pump shot to start the car, then something else is wrong. That said, if you pump the gas and the check ball is screwing up the pump shot then try to clean out the passage and/or try a different ball...or just send it back. There could be a machining/casting defect.

Thanks all for the feedback.
 

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Hey,
nice review.

i have one question about this carb, does it have a ported vacuum takeoff for a vacuum advance dizzy? the 4100 i`m running presently doesnt, only full time vac.

how is your advance set up with this carb if youre running a vac dizzy?

cheers,

Mark
 

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nice, thanks!

i ordered one of these and its waiting for me at the post office.. should be fititng it this weekend.

apparently the 600cfm vac secondary version doesnt have annular boosters? i`ll see when i open mine, but this is what summit told me.

it didnt bother me though as i have two 4100s and a 2100 i can scrounge them from.

cheers,

Mark
 

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so it does, picked mine up today.. i wonder why they told me it doesnt.
the ones in my autolite are smoother though. i`ll probably just deburr these though.
 

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this is an update to my earlier posts wondering if the booster clusters would fit in the autolite 4100. i bought an old junk holley 4010 on ebay and robbed the boosters out of it and transplanted them into an old autolite 2100 2 barrell i have and in stock form they are some mods that need to be made to either the carb or the boosters clusters themselves, i chose to modify the carb as it was the easier of the 2 options and it only involved a little drilling to the emulsion wells.

the emulsion tubes on the 4010 are slightly bigger than the autolites and won't fit in the autolites emulsion wells as is, what i did was to drill the emuslion wells on the autolite out to the same size as the holley emulsion wells and then removed any burrs and test fit the holley boosters in and they worked great though you will need to use the booster hold down screw from the holley (or summmit carb) as it is a slightly different size than the autolite screw, otherwise this is basically a direct bolt on for anyone wanting to get a little more tuneability out of their autolite 2100/4100 using the summit carb booster clusters with their changeable air bleeds.

just as an FYI here, the holley boosters DO NOT have the changeable air bleeds that the summit carb has i just used the $20 holley 4010 i bought to test the theory that they would work in the autolite 2100/4100. also I have not run the carburetor on an engine yet as i don't have a car, running, that uses a 2 barrell carb and my other car with the 4 barrell is still in winter hibernation. i also don't have an extra 4100 built up yet to test theory on a running engine. i do have a couple of 4100's that i can build and will do so later on this spring to have a quantifiable test on a running engine but again this will be using the holley boosters and not the summit boosters with the changeable bleeds i haven't run across a cheap used summit version of this carb yet to buy and rob the boosters out of and last i checked summit won't sell them seperately
 
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