i’m looking for a holley 4 barrel 650 cfm double pumper. its for a 350 sbc thats mildly built. i’m not looking to spend alot of money, i’d like something cheap that i can rebuild for myself, unless someone has a good deal on something they have already done. i’m also up for a little trading cuz i have alot of chevy parts around. thanks
ADAM
dbl pumper is to much fuel for a mildly built sbc.
[quote=“dirtye30,post:2,topic:39072"”]
dbl pumper is to much fuel for a mildly built sbc.
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i think so to
Edelbrock 600 cfm
#1405 manual choke
#1406 electric choke
Holley 670 cfm Street Avenger #0-80670
double pumper is too much for mild street
hey what do you kow im selling one of thoseedelbrock cars with a brad new rebuild kit for one low low price of 170 bucks obo
Since when is a 650 cfm double pumper too much for a mild built 350? And I dont like Edelbrock carbs personally. Get a holley.
[quote=“Maximus33,post:6,topic:39072"”]
Since when is a 650 cfm double pumper too much for a mild built 350? And I dont like Edelbrock carbs personally. Get a holley.
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since its always too much fuel?
[quote=“dirtye30,post:7,topic:39072"”]
since its always too much fuel?
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Always? I guess everybody out there with a mild 350 and a double pumper are really screwin’ themselves!
i disagree my cousin has a mild 350 roller motor and he has a 750 holly dp the 650 was too small, also i agree the edelbrock carbs suck performance deffinately suffers compared to a holly, i reccomend a 670 street avenger those carbs are really nice perform good and are easily adjusted
A double pumper IS too much for a mild SBC. You need some serious mods to be able to burn all that fuel all at once.
A 350 cubic inch engine at 6500 RPM and 80% volumetric efficiency can only use 526 CFM. Anything bigger than that and you’ve overcarbed it, plain and simple, end of story. Everybody thinks that they need more carb than they really do. Yes, the engine still runs fine with a huge carb, but you do lose some low end torque and throttle response because the venturis are too big and you have a low velocity resulting in a poor mixture. Fuel economy also suffers. A 500 CFM carb would be more than fine for a street driven car. It’s 26 CFM undersize, but you’ll have better throttle response and better low RPM behavior for cruising. A 600 CFM is 74 CFM oversize so low end will suffer a bit, but the carb outflows the engine so it can reach it’s full potential. No matter what you get, you’ll still have to tune and retune it to your specific application.
it depends define what you consider mild
Whats done to the motor? Whats the rest of the combo look like?
[quote=“Southtowns27,post:10,topic:39072"”]
A double pumper IS too much for a mild SBC. You need some serious mods to be able to burn all that fuel all at once.
A 350 cubic inch engine at 6500 RPM and 80% volumetric efficiency can only use 526 CFM. Anything bigger than that and you’ve overcarbed it, plain and simple, end of story. Everybody thinks that they need more carb than they really do. Yes, the engine still runs fine with a huge carb, but you do lose some low end torque and throttle response because the venturis are too big and you have a low velocity resulting in a poor mixture. Fuel economy also suffers. A 500 CFM carb would be more than fine for a street driven car. It’s 26 CFM undersize, but you’ll have better throttle response and better low RPM behavior for cruising. A 600 CFM is 74 CFM oversize so low end will suffer a bit, but the carb outflows the engine so it can reach it’s full potential. No matter what you get, you’ll still have to tune and retune it to your specific application.
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:word: someone in the know
[quote=“J&J,post:13,topic:39072"”]
:word: someone in the know
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thats just the amount of air needed for a specific cubic inch engine to run efficently, not counting performance items such an exhaust , cam, or heads that all would allow a specific engine to need or be capable of useing to produce more power. but to get the extra air you need a higher flowing carb and intake to get the air into the motor, yes his motor might get more mpg with a smaller carb but the smaller carb isnt going to give it the extra air that its capable of supporting thats why i asked the specifics of his engine setup to see what combo he has, but id go with the 670 street avenger it gives alot better mpg than a double pumper because its not constantly giving lots of fuel,
i ussually ran a 750 double pumper on my mild built 302 no problems at all whatever you do dont put an edelbrock on it !!!
[quote=“speedped79,post:14,topic:39072"”]
thats just the amount of air needed for a specific cubic inch engine to run efficently, not counting performance items such an exhaust , cam, or heads that all would allow a specific engine to need or be capable of useing to produce more power. but to get the extra air you need a higher flowing carb and intake to get the air into the motor, yes his motor might get more mpg with a smaller carb but the smaller carb isnt going to give it the extra air that its capable of supporting thats why i asked the specifics of his engine setup to see what combo he has, but id go with the 670 street avenger it gives alot better mpg than a double pumper because its not constantly giving lots of fuel,
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air volume /= air velocity. im not pretending to know much about carbs because my knowledge is far from vast. but just by reading what you wrote… it seems like you are overlooking, or just straight up don’t know what makes up cfm, and the interactions between velocity and volume
I am a big fan of the Q-Jet.
My old mild 350 ran 10x better with a Quad than a holley.I picked up 3 tenths,gained 5-6MPG and my idle sounded amazing compared to the holley.
its never been run, i’m working on an old Camaro to put it in. its an early 70 ‘010’ 350. bored 30 over. new flat top pistons, new cam (speed pro sealed power CS-179R)-valve lift .447, .050 dur:222. hydrolic lifters(flat tappet), right now i have factory rocker arms, but i have a set(s) of stamped steel roller tips, 1.5 or 1.6 if i want to put them in. the heads that are currently bolted on are 3998993 heads, but i have access to a pair of 462’s or 896’s. i have an edelbrock performer intake-i paid $20 at a garage sale for it. it will have long tube headers and dual exhaust when installed, it will be a 4 spd manual car if that matters. i have several old q-jets around, but i’m not familiar with carbs and i heard Holleys are easy to tune and run fairly well. thanks for all the info i’m learning alot here!
for that combo with the parts that are on it now id go with something along the lines of 600cfm and see how that works out
I have a holley avenger 670 along with a bunch of jets,sec. springs, and extra gaskets i’d be willing to sell. I used it for about a year then switched to a 750. i’d let it all go for 250.