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By ianmatt - 8 Years Ago
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Anyone have any experience with this carb. Looks super ideal for a 292 mummert intake and headers and cam. Thoughts? thanks
https://www.summitracing.com/parts/sum-m08500vs/overview/
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By charliemccraney - 8 Years Ago
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The Summit carbs in general seem to be excellent. Very hard to beat for the price.
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By Small block - 8 Years Ago
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charliemccraney (11/5/2016)
The Summit carbs in general seem to be excellent. Very hard to beat for the price.
the Summit Carb is basically the same as a old 4100 series Autolite 4 barrel, With some improvements
Every body I have talked to that used that used it say it is the best they have used! Ford changed from it to the 4300
because the 4300 was supposed to be more adaptable to the emissions that they were using at the time!
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By charliemccraney - 8 Years Ago
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The Summit carb is an improved Holley 4010 / 4011, which had a removable top, rather than removable float bowls. At a glance and to the uninformed, it does look like an Autolite. Look closely, you will see lots of differences and is clearly not a copy of an Autolite.
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By ianmatt - 8 Years Ago
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Awesome thanks for the feedback. I might have to order one.
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By hjh - 8 Years Ago
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Ianmatt I am running a Summit 750 Vac.secondary on my 337 ci.3800 lb. 60 Merc. at 12.40 to 12.70 @ 107+ MPH & I think it is great. Jets and adjustments are Holley & easy to do. Holley makes it for Summit. Any questions call me at 5one 3 86 eight 33 one one Harry
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By PF Arcand - 8 Years Ago
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As CharleyMcC states the Summit carbs are like the (discontinued?) Holley 4010 series. However, references to the Autolite 4100s come from the fact that they had the Annular discharge feature in their venturies as far back as 1957-58, a feature not found on other common American carburetors. Some have referred to that feature being as close as you could get to Fuel injection in a carb. I don't have any personal use experience with either of these carbs, but I do know that many early Mustangs used the Autolite carb. A few years back, John Mummert's shop built a 331 or 337cu in engine for a customer for street use with a C-4 transmission, that used a 600 cfm Summit. They said it performed as well as a bigger carb they tried on it, and were very impressed, with the exception of having a problem with the fuel line that was provided. As I recall, the engine used a Mummert spec cam for median street use & produced a very impressive 420 Lb. Ft. of torque & 393 H.P. at a moderate 5400 RPM... Note however, the people that formerly operated Pony Carburetors in N.Y. state, said that a must with that style of carb is a good fuel filter..no new filter installed on their rebuilts.. there was no warranty!
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By ianmatt - 8 Years Ago
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Ok guys its down to these two carbs. Which one do you think would be better. Keeo in mind I have headers Mummert intake abd isky cam. with the original heavy t98 manual trans. The quickfuel 450 cfm or the Summit racing 500 cfm? heres the links.
https://www.quickfueltechnology.com/carburetors/street/slayer-series/slayer-series-carburetor-450cfm-vs.html
https://www.summitracing.com/parts/sum-m08500vs/overview/
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By ianmatt - 8 Years Ago
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Thoughts on these two carbs you guys? Is one better than the other? They seem almost identical. i am pulling the trigger soon. Leaning towards the summit carb.
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By charliemccraney - 8 Years Ago
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The only way to know which is better is to get both and try them. If that is out of the question, the err on having a carb a little bigger than you think you need, which is the Summit carb.
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By ianmatt - 8 Years Ago
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Charlie you are saying go with the bigger one the summit?
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By charliemccraney - 8 Years Ago
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I'm saying try both if you can. If you can't, then go with the bigger one, which is the Summit carb,
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By ianmatt - 8 Years Ago
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Ok so I have another carb that has caught my interest. I am reading that many people really like having a carb with mechanical secondaries if they have a manual transmission. Any of you guys have thoughts or experience on this topic? I also read that with a manual trans and vacuum secondaries you can get away with a slightly higher cfm carb. Thoughts. Quikfuel have this 450 cfm carb i am highly considering. https://www.quickfueltechnology.com/carburetors/street/hr-series/hr-series-carburetor-450cfm.html
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By Ted - 8 Years Ago
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The problem with double pumper carbs (mechanical secondaries) is that they are perfect sized only in the rarest of instances. The slightest changes in weather conditions will have them too big or too small. Much of the time they are simply too big due to being fully opened while the engine is in an rpm range that’s simply too low to adequately handle all that cfm. When picking a vacuum secondary carb, always err to the large side as the vacuum secondaries are opening based on demand and as such will only open the amount required and be perfect sized. I have very good results with the 750 cfm vacuum secondary carbs on the Y engines as the secondary side of the carb is only opening the amount required by the engine. The primary side of these carbs is still on the order of size of the original two barrel carbs so drivability is expected to be good when driving with a light foot.
Having too small a carb on an engine can potentially have the engine in a lean condition when pushing the rpms outside of normal ranges such as when using the passing gear. This occurs due to the increase in manifold vacuum that takes place at the higher rpms which in turn allows the power valve to close and subsequently lean the fuel mixture.
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By ianmatt - 8 Years Ago
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With the isky cam in my engine only producing about 11-12 inches of vacuum at idle what has been your experience with the holley secondary springs? I have the kit. With low vacuum do you need a light or stiffer spring? thanks
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By Ted - 8 Years Ago
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ianmatt (11/16/2016)
With the isky cam in my engine only producing about 11-12 inches of vacuum at idle what has been your experience with the holley secondary springs? I have the kit. With low vacuum do you need a light or stiffer spring? thanks
The engine can be idling with 1-2” Hg manifold vacuum and the secondaries can still open the same as an engine idling with 15-18” Hg manifold vacuum. The secondary spring tension is not related to an engines’ manifold vacuum. When the vacuum secondaries are opening correctly, you will not be able to feel them as a jolt or hiccup when they open. It should be a very smooth transition and all you should be feeling is the extra pull or acceleration afforded by the increase in horsepower that accompanies the extra cfm being provided by the carburetor.
Manifold vacuum at idle has no effect on the secondary spring selection for a vacuum secondary carburetor. Keep in mind that most engines will have almost no or minimal manifold vacuum when the throttle is in the wide open position. The air flow speed through the primary venturi of the carburetor is the controlling factor of permitting the vacuum secondary side of the carb to open. It’s the secondary diaphragm spring tension in this case that dictates at what rpm the secondaries actually start to open. Everything being equal, smaller sized carbs will prefer a stiffer spring while larger carburetors will sometimes like a secondary spring with reduced tension. Always start with the secondary spring that comes with a carburetor and never try to second guess the spring rate without first testing the original.
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By ianmatt - 8 Years Ago
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Right on Ted thank you so much. I got my holley 600 vac secondary carb really dial now and can feel the additional performance over the 500 cfm eddy I was running. I drove the truck to work today and felt some funnyness in the gas pedal of sorts around low rpm cruising. I checked the engine at lunch while idling and my fuel pressure gauge is all over the place. Its a carter mechanical fuel pump thats been on for about 6 months. I think its going out. I thought these things lasted for years. Maybe it is susceptible to the engine mods and a bit higher revs that a stock 292. The question is now do i go electrical fuel pump? LOVing the holley now with the 5.5 power valve and 64 jets. If anything I might go to 62 jets. Thanks a ton for all the help. I hope to drive my truck for the rest of my life. if no one buys it for lots and lots of $
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By charliemccraney - 8 Years Ago
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I don't know, but given that a mechanical pump's function is dependent, to a degree, on engine RPM, some fluctuation at idle may be expected, particularly if it has a bigger cam which produces a rougher idle. I'd rev it slightly to see if it stabilizes.
Lots of people still run mechanical pumps on pretty high performance motors, so that should not be an issue. Gary, speedpro56 here has a ~500hp tbird with a mechanical pump.
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By ianmatt - 8 Years Ago
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HMMMM interesting. thats what I thought tooo i thought they were supposed to be very rugged. Mine was going from 1 to 6 psi about 50 times a second. Can the arm jump off the internal bar somehow? I will look when I get home and update.
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By speedpro56 - 8 Years Ago
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Charlie is right, I had too many problems with an electric pump on a every day driver having no lasting ability as compared to a mechanical pump for longevity, dependability is what I needed.
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