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Discussion Starter · #1 ·
Long time lurker, first time poster.

I got to know my Edelbrock 1806 650 AVS carb recently, and found a lot of useful, but scattered, information on this site to help me tune the carb.
I would like to start a tech/setting list for edelbrock carbs. If there already is one, my apologies...
Please list motor,carb,intake,climate with changes you made to carb and results. Maybe a little story too.
I'll start.

Motor - 350ho. (vortec heads)
Intake- Rpm Air Gap
Carb- Edelbrock 650 1806 thunder avs
Climate- Sea level, winter, dry and cold 25-35d. January western wa state.

Ran okay with performer intake 1806 650 edelbrock carb, but I expected more from a "HO" motor. Switched to RPM Air Gap intake and there was a noticeable power increase, but the engine would bog so bad that it would pretty much die when it was floored. I was also having some pinging with heavier accel. Suspected lean condition due to better flowing intake or fuel pump not up to the task. It also had extended cranking time when the motor was hot (20 min or so after shut down). I know, I know, buy a 750 Holley. I wanted to give the new Edelbrock that came with the car a try before losing $500. Cruise and light-mid throttle excellent. Idles smooth, 16" vacuum.

Step 1- Adjust floats (way off). Build fuel system with high flow pump and pressure regulator (set to 5.5psi). Check base timing, back way off timing advance until pinging stops. Severe WOT bog unchanged

Step 2- Tried several combinations of rods/jets/step up springs. AVS settings.

Best results
#2 on tuning chart (1 1/2 richer power mode only)
Silver 8" step up spring (strongest)
Top accel pump hole, rod straightened/lengthened slightly
3 stages rich secondary jets (tried stage 2 first and bog was much improved but still there).
2 1/2 turns on AVS Valve. (AVS also helped to tame the bog)
.30" Edelbrock insulator spacer/gasket (helped with hot extended cranking time)

The step up springs were the only thing I ultimately used from the "tuning kit" wasted $50. It did however show what didnt work.

The bog is still there slightly, for a second, if I stab wot. Non existent when I roll the throttle to WOT and I was able to add the timing back in without pinging. Runs like a raped ape. Feels like an honest 375hp. The larger secondary jets and avs adjustment had the biggest effect. I suspect there will not be any bog when the weather warms up, and it will lose some power as well. These cold and dry days seem almost optimum for performance.
Still wonder if I am leaving anything on the table not buying a double pumper...It would have been helpful if the hotrod magazine that published the significant power gains with the rpm/holley swap showed the gains separately.
 

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Welcome out of the shadows...
Motor - 350ho. (vortec heads)
Intake- Rpm Air Gap
Carb- Edelbrock 650 1806 thunder avs
Climate- Sea level, winter, dry and cold 25-35d. January western wa state.

Ran okay with performer intake 1806 650 edelbrock carb, but I expected more from a "HO" motor. Switched to RPM Air Gap intake and there was a noticeable power increase, but the engine would bog so bad that it would pretty much die when it was floored. ...

I was also having some pinging with heavier accel. Suspected lean condition due to better flowing intake or fuel pump not up to the task. It also had extended cranking time when the motor was hot (20 min or so after shut down).


I know, I know, buy a 750 Holley. I wanted to give the new Edelbrock that came with the car a try before losing $500. Cruise and light-mid throttle excellent. Idles smooth, 16" vacuum.

Step 1- Adjust floats (way off). Build fuel system with high flow pump and pressure regulator (set to 5.5psi). Check base timing, back way off timing advance until pinging stops. Severe WOT bog unchanged

Step 2- Tried several combinations of rods/jets/step up springs. AVS settings.

Best results
#2 on tuning chart (1 1/2 richer power mode only)
Silver 8" step up spring (strongest)
Top accel pump hole, rod straightened/lengthened slightly
3 stages rich secondary jets (tried stage 2 first and bog was much improved but still there).
2 1/2 turns on AVS Valve. (AVS also helped to tame the bog)
.30" Edelbrock insulator spacer/gasket (helped with hot extended cranking time)

The step up springs were the only thing I ultimately used from the "tuning kit" wasted $50. It did however show what didnt work.

The bog is still there slightly, for a second, if I stab wot. Non existent when I roll the throttle to WOT and I was able to add the timing back in without pinging. Runs like a raped ape. Feels like an honest 375hp. The larger secondary jets and avs adjustment had the biggest effect. I suspect there will not be any bog when the weather warms up, and it will lose some power as well. These cold and dry days seem almost optimum for performance.
Still wonder if I am leaving anything on the table not buying a double pumper...It would have been helpful if the hotrod magazine that published the significant power gains with the rpm/holley swap showed the gains separately.
As for your bog, have you checked the distributor and timing? I did have a similar bog a few years ago, and I was thinking it was the carb, but it turned out to be the "cheap" $89 Summit HEI. One of the spring/weight pins pulled out, jamming the mechanical advance. Like yours, it had a bog and hard starting... Swapped in another distributor (actually, another $89 Summit HEI), and it ran great again...

I recall a saying, something like "90% of all carb problems are ignition related."


My experiences are quite different... I used to always run a Holley, because thats what everyone thought was best... Years ago, after running a 750 DP and then switching to a 750 DP (1966 396/TH400 in my El Camino), I found that while the car felt (butt meter) slower with the vacuum secondary, it was nearly identical at the racetrack (low 13 second range). But milegae and overall driveability improved... IMO and experience, the DP is usually overrated for a street car... If you can launch/use WOT in the lower rpms, then the DP starts to shine...

I find that of the people that automatically say "Holley", very few have actual experience with the Edelbrock, typically none, or one like yours that may or may not actually be the carb. Not saying Holley isn't a better choice when the car/setup is serious enough to surpass the limits of the Edelbrock, but a lot of people seem to think the Holle yis somewhat magical. Some seem toi think "swap on a Holley and magically gain horsepower"... :sad:


around 2000, I decided I wanted to run a Dual Quad intake on my 396 powered Chevelle convertible... I decided to go with the Edelbrock intake and suggested carbs (IIRC, 600cfm for the BB, non-AVS). The intake came with a set of 4 metering rods suggested. I swapped those in, and adjusted (basically just checked) the idle speed and idle mixture screws (watching the vacuum and listening to the engine). The car ran great. Poor traction (4-speed on BFG radials) so I didn't race it much. I had also swapped the heads from Rec port "858" heads to a set of Edelbrock aluminum heads, so I have no comparison...

But basically, the 2X4 setup ran great out of the box. The only other change I made was to further swap the metering rods when I travelled from home (basically sea level) to Reno Nevada (Elev 4500 feet, with mountain pass of 7000+ feet), so I swapped another step leaner on the rods... In about 6-7 years I had the setup, I never needed to touch it. No bogs, no hesitation, no pinging, etc...

Since the mid-80's, I tuned carbs for most of my friends. We always went with Holleys... In the late 90's, a few were having issues, and were told they should try the Edelbrocks (performance oriented cars, but mostly cruising around). I helped install and tune the carbs, and EVERY one of the cars ran great, with no discernible loss in performance.



Fast forward to 2009, and I decided I was tired of the Demon DP on my latest project. It was VERY fun, and would light the tires from a 25-20 MPH roll. Trouble with traction, but managed mid-to-high 12's at 108 MPH (lowered with 17" tires)... Previous owner said he pulled an 11.99 with 15" drag radials and bumped timing (no vac advance)... But mileage was horrible (DP, 3.70's and locked out timing)...


1970 Chevelle, all steel, factory air conditioning, buckets, console.
427 stroker small block,
True Pump gas, 91 octane (highest generally available around here), but can run 87 octane without discernible pinging (in a pinch). Usually buy Costco or Chevron gas.
AFR Eliminator 195 heads
Comp flat tappet hydraulic (274 degrees duration)
RPM air gap intake
Elelbrock 800 cfm, Thunder Series" AVS, Choke wired open.
Summit HEI, 16 degree initial, All mechanical in by 2900-3000. Summit CD ignition box
TH400
3.70 gears (9-inch)
lowered suspension with 17inch Nitto Drag radials (currently 315/35/17 in back, but 275/40/17 when I last raced it)
about Sea Level, central California (Sacramento Metro area), typically 80-105 degrees in the Summer (when I drive the most)


I swapped to a new Edelbrock 800 cfm Thunder series AVS, and literally right out of the box, turned a 12.34 ET and 110 MPH.. 1.70 60-ft.. NO tuning other than checking the mixture screws and idle speed... I had also swapped in a "cheap" Summit HEI at the time (I wasn't going for back-to-back comparison, but weather conditions were similar). No bog, no hesitation, lower ET, higher MPH... Still lights the tires from a roll, but 20-25 MPH instead of 25-30 MPH... At the track, I still can't launch above 2400 RPM without smoking the tires, but the car is quicker down low. Sure, with slicks of "better" drag tires and a more drag-dedicated suspension, then the DP would probably start being dominant...

Since then, the carb has been dead-reliable. I did swap on step leaner on the cruise for the trip to Reno, but never bothered to swap back once I returned, and since my last "race" I have been playing with the AVS adjustment, getting it to come in a little sooner... Great manners.


I have seen a few dyno comparisons (carb versus carb), but don't recall any with Edelbrock versus Holley or Vacuum versus DP. The ones I have seen (vac vs DP vs Q-jet, etc) seemed to have very similar power numbers... Now I realize, "you can't drive a dyno", but it seems as though the better choice for a carb is based off the overall car and setup... Can your chassis handle WOT launch with a DP, and effectively keep the tires stuck to the pavement? Or does it need more finesse to avoid blowing the tires off? I have seen a few guys that detuned their DPs just so they could get better driveability and launch, while still being able to say they were running a DP... Real racecars use Holleys, but they are race cars, not street cars with typically compromised traction...
 
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