I just got a summit carb, their new invention. The technology is OK as everything is easy to get to and no power valve to blow however I have a slight bog at take off and need to know how to get rid of it. The carb a 750 cfm is on a 400 pontiac motor, edelbrock intake, motor has a high energy cam. I took a 750 holley off. It was tuned perfect however the bowl in the rear kept filling with gas and shooting gas out the air horn. I changed the float and it would do the same thing after a month or so. The new carb is economical I am getting better gas mileage just that bog on take off.
i had no idea that Summit was making carbs , so i checked their website and sure enough they do. looks like they copied Holely....and the use Holley jets , floats , needles and seats, accelerator pump diaphragms and power valves. so there is a power valve info here: http://www.summitracing.com/expertadvice/storydetail.aspx?id=e554f335-4838-4153-97dd-ae393dd2247d
Not really their invention, that carb was marketed by holley as the short lived avenger line in the 90s and it's original life was OEM ford in the late 60s. Summit doesn't really invent anything, they only rebrand existing products. Good luck with your project
No, I did not as I still have Holley's on my mopars. The 55 Chevy I own had a holley I think it was to small. I kept having issues. I went to a Edelbrock carb and I have not been in it in 4 years. I know that with the Holly I could really tune it to the point of burning rubber at will. I had instant success however when my friends where ready to cruz I was pulling metering blocks and cleaning and replacing power valves. The edelbrock is a different story. So you think it's the accelerator pump which way do I want to go. Your right summit does not "invent" these however I have never seen it until I looked in their catalog. It is nice and light, shinny and compact.
Hello Everyone, My name is Mike and I am a technical representative for Summit Racing Equipment. After reading the postings in your forum on our carburetor, I believe I can be of some assistance with the hesitation problem you are experiencing. Typically the hesitation you are experiencing is due to a weak accelerator pump shot which is common on larger cubic inch engines. This can be solved a few different ways: A) Change the accelerator pump cam out for one that has a more aggressive profile. Your carburetor should have come with the "Dark Green" cam install out of the box. Attached is a link to a kit with different cams to tune with: http://www.summitracing.com/parts/HLY-20-12/?image=large The "Orange" cam may be the best one in the kit to install on your application. B) There is also an accelerator pump discharge nozzle tuning kit available that makes it possible to increase the sizing of the nozzle output. This will supply more initial fuel output out of the discharge nozzle. You will want to likely up the sizing to the .040 jet that is included in the kit: http://www.summitracing.com/parts/SUM-M08040/ The above kit makes it possible to tune the accelerator pump circuit more precisely than the pump cam kit. C) The other thing that could be causing the problem is Dependant on the size of camshaft you have in the engine. If your engine does not make very much manifold vacuum, you may need to change out the power valve. These carburetors have a fairly aggressive power valve installed in them (9.5 Hg) and it could be opening too early which will also cause a hesitation problem. If you decide to make a power valve change, a 6.5 Hg valve will likely be the solution: http://www.summitracing.com/parts/HLY-125-65/ The procedures on changing all of these items is in the instructions that were included with the carburetor. We really tried to design these carburetors to fit the needs of most customers but as with any carburetor, tuning will be required for some applications. I hope you find this information helpful and it solves your hesitation problem. Mike
Mike I have a summit carb on a stk 350. About a year secondary pouring fuel over the horn. No matter how it's adjusted it pours. Even at the min. Level it is leaking into the primary side? I just ordered new float and seat kit. What do ya think?
If the thing has the Viton tipped needle and seat assemblies - you may have to get some of the steel ones - built for alcohol. The new junk gas we get locally here hates rubber anything. I had to swap all of the Holley needle and seat assemblies out (that were Viton).
Don't believe everything you are told about steel needles being a long-term solution for use in ethanol: That isn't paint on the needle on the right. Jon.
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