Street carburetor
- Thread starter WVRigrat05
- Start date
TBH, unless your pulling extreme rpms your better off with an edelbrock 500cfm. I know it seems small but your really not built for anything bigger. 700cfm carbs are hard to lean out for smaller cubic low rpm motors. The carb running rich is why it fires easily. Through a wide band on it and see what mixture its running.
Shit I run a 650 Edelbrock on my 468bbc the vacuum secondary don't open until 2500rpm..
Feed it with a 80gph mechanical summit lift pump
Dead reliable and pulled 16mpg running 75-80mph out to Colorado in a 79 Malibu hauling a LMM long block
Had a 650 Edelbrock on a 305 sbc with intake cam heads secondaries opened around 5000rpm
So either go mechanical or spin faster:thumb:
Feed it with a 80gph mechanical summit lift pump
Dead reliable and pulled 16mpg running 75-80mph out to Colorado in a 79 Malibu hauling a LMM long block
Had a 650 Edelbrock on a 305 sbc with intake cam heads secondaries opened around 5000rpm
So either go mechanical or spin faster:thumb:
Vortec heads, this was a odd spec motor, I remember my friend Dave saying what the **** when he looked at the sheet years ago.
I wanted to go flat tops but Dave said I couldn't with the small chamber heads as the compression would be way too high and I'd have to recess the valves to keep from hitting the pistons.
The edelbrock that's on it now is a 650. The quadrajet that was on it to start with pulled a lot harder and you could hear it sucking air, it did have a lag when the 4bbl opened up but it would actually pull. It just falls on its face below 2500 RPM's with the carb on it now.
Reger, your a stubborn bastard, we all know this :hug: 
but i wouldnt go a bigger carb. bigger carb means your engine needs the CFM flow. with what you are posting about, you dont have that flow to go bigger and all you are doing is creating a setup that will be harder to tune in. running that cam means less rpm which means less CFM flow through the engine. those heads do flow better than old carb heads but not by a huge amount and they really work best when joined with the right intake for FI (thats what they were designed around).
Really i think you are feeling the affect of a combo of parts not matched well to each other OR the fact the carb just is not tuned correctly for what you have.
i can bet you adding that bigger crab is going to put MPG down the crap hole and its going to feel lazy. not to mention it will have to have the crap leaned out on it and more than likely have to put some tiny pilot jets and so on inside to keep it from running rich.
put it like this, my dads 427 small block with AFR heads and block with eldlebrock high rise intake, speced cam for 3000-7000rpm, and all the goodies to go with, runs a 850 holley double pumper and its no where near its max on that carb but its not too big for the engine either. this is an engine that makes 650hp at the crank. ill bet yours is lucky to make 350ish at the crank but have a nice torque curve with that cam. So your trying to add another 100cfm larger carb on an engine that will never move the amount of air it needs to to actually see the use of it. that make sense? there should be some pretty simple calcs out there to tell you what size carb to run for your setup. its all based off math.
but i wouldnt go a bigger carb. bigger carb means your engine needs the CFM flow. with what you are posting about, you dont have that flow to go bigger and all you are doing is creating a setup that will be harder to tune in. running that cam means less rpm which means less CFM flow through the engine. those heads do flow better than old carb heads but not by a huge amount and they really work best when joined with the right intake for FI (thats what they were designed around). Really i think you are feeling the affect of a combo of parts not matched well to each other OR the fact the carb just is not tuned correctly for what you have.
i can bet you adding that bigger crab is going to put MPG down the crap hole and its going to feel lazy. not to mention it will have to have the crap leaned out on it and more than likely have to put some tiny pilot jets and so on inside to keep it from running rich.
put it like this, my dads 427 small block with AFR heads and block with eldlebrock high rise intake, speced cam for 3000-7000rpm, and all the goodies to go with, runs a 850 holley double pumper and its no where near its max on that carb but its not too big for the engine either. this is an engine that makes 650hp at the crank. ill bet yours is lucky to make 350ish at the crank but have a nice torque curve with that cam. So your trying to add another 100cfm larger carb on an engine that will never move the amount of air it needs to to actually see the use of it. that make sense? there should be some pretty simple calcs out there to tell you what size carb to run for your setup. its all based off math.
LOL, I see what your saying now James, probly why it always loaded up before and got 8 mpg and doesn't now with the carb that's on it( truck was originally an auto and I kept it to the floor). Trust me I'd love to put a TB on it but it's not mine and I know it's a matter of time before this ones trashed like my first 86'.
I'll play with this carb some more and live with it, I'll only be driving it once and a while on my days off anyhow.
I'll play with this carb some more and live with it, I'll only be driving it once and a while on my days off anyhow.
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yeah then id stay carb. if you can, find a shop that can rebuild/setup the carb based on your specs. there are still quite a few shops around that will do this and they usually get you within 80-90% of a perfect setup. rest will need to be done with the truck in the shop for the tech to see just what needs tweaking.
Reger read the tuning basics on Edelbrock carb book it's online and downloadable
http://www.edelbrock.com/automotive/misc/tech-center/carb-faq.shtml
They are pretty simple things once you understand the basic principles in how it operates:thumb:
http://www.edelbrock.com/automotive/misc/tech-center/carb-faq.shtml
They are pretty simple things once you understand the basic principles in how it operates:thumb:
That was fixed before we put it in, it was rebuilt and was in a 700 hp mud truck. I know the ol boy that had it put a upgraded nut in and welded it.
Hard to beat a good Q-jet... I tried them all on my 396 in my 84' always ended back up with the q-jet... It just flat worked in all conditions.
https://www.summitracing.com/parts/sum-210216/applications
https://www.summitracing.com/parts/sum-210216/applications
oh ill bet she last a good while then
Yeah, I know it's not the cure all. My friend put a new nut on this 12 valve and three weeks later was in 4th all the way home, the welded it and it lasted 6 months, weld cracked and nut backed off. He ended up getting a whole other trans, he said that one had a voodoo curse lol. He's had the new one in for 3 years now and it's been flawless. I'll let you know how many miles this one make it with me.
If it makes it 6 months under you, that's like 20years and 150k miles under anyone else so you would have done good!
.Really being a smart ass with you today for some reason. :hug: