Slant Six Forum :: Edelbrock tuning

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Edelbrock tuning https://slantsix.org/forum/viewtopic.php?t=58194	Page 1 of 2

Author:	225kid [ Thu Aug 06, 2015 9:05 pm ]
Post subject:	Edelbrock tuning
Hey, I have a 500 cfm edelbrock carb on my car, I've done a couple jet changes and rod changes and I can't seem to get it tuned right, when I take off if I give it too much gas it sputters and at wide open throttle it bogs. I have the carb on so both the primarys are forward. Any advice is welcome

Author:	ceej [ Thu Aug 06, 2015 10:06 pm ]
Post subject:
Do you have a performer or a thunder AVS? Is this a new carb, or used? Basically, the jetting will be very close to base. The pump shot may need a little adjustment. I'm running a Carter AFB set up as a 500. I'm running the base calibration, the highest rate springs available for the primary needles, and slightly less pump shot. This is on a 250 Cubic Inch slant, across many iterations of cams. Mild to wild. Just shy of 11:1 compression. I've also swapped out the primary boosters and re-jetted to base as a 600cfm in the same carb. Runs well. The Carter and Edelbrock are virtually identical. I ran an Edelbrock 525 AFB on a mild 318 some years ago. Chased my tail in a big circle on that one too. Right back to the base calibration. The difference between the 525 and 500 is the name. Nothing else. Marketing. The AVS secondary spring adjustment for the air door should be very carefully checked. It should be set to match "Out of the box" factory. Any more aggressive than the factory setting, and it's going to open the air valve too soon. If you have the Performer AFB version, check the air door weight. If somebody got in there and lightened it up by drilling holes, see if you can get a new one. Putting weight back on just invites something to come loose and go through the engine. Any lighter than stock, and our small displacement engine will open the secondary too soon, and bog. The primary springs lift the needles up to richen the mixture. You want those to tip in as soon as possible when your vacuum drops out. That is your "power valve" if your used to Holley's. I think I'm running 10" springs. Haven't had to futz with the Carter since I put it on, so I can't remember. If you have less than 12" vacuum at cruise or idle, you may need to adjust for that. Hope that helps. CJ

Author:	Nicademas [ Fri Aug 07, 2015 6:39 am ]
Post subject:
I got a thunder series 500 on mine. AKA (1801) It is set at 2 stages lean (8%). Primary lets are 1422 and the metering rods are 1460. The pump shot is in the middle hole but that is a little lean for fast WOT.

Author:	225kid [ Fri Aug 07, 2015 8:23 am ]
Post subject:
Its a new thunder avs

Author:	225kid [ Fri Aug 07, 2015 10:30 am ]
Post subject:
Would it help if I turned my carb sideways so the primary's are facing the head?

Author:	kesteb [ Fri Aug 07, 2015 7:13 pm ]
Post subject:
No. What else has been done to the engine? What has been done to the car? This carb with factory settings should work fine.

Author:	225kid [ Fri Aug 07, 2015 7:27 pm ]
Post subject:
Its a stock 225, I milled the head a little so it has like 9:1 compression and and iffy intake and old long tube header.

Author:	ceej [ Fri Aug 07, 2015 11:18 pm ]
Post subject:
What was the final chamber CC? How far down the hole was the piston? What gasket did you use? How much did you mill off the head? CJ

Author:	225kid [ Fri Aug 07, 2015 11:28 pm ]
Post subject:
I don't recall the cc. Its a stock head gasket.

Author:	Nicademas [ Sat Aug 08, 2015 8:18 am ]
Post subject:
make sure the IMS are not sticking. Check your timing. (mine is at 10DEG) and check your idle speed. (mine is at 500RPM) Also check for vacuum leaks.

Author:	kesteb [ Sun Aug 09, 2015 7:52 am ]
Post subject:
What transmission and rear axle gear ratio? \

Author:	matv91 [ Sun Aug 09, 2015 8:13 am ]
Post subject:
Intake manifold heat,water? Is the bottom of manjfold cold under the carb?

Author:	225kid [ Sun Aug 09, 2015 12:29 pm ]
Post subject:
7 1/4. 2:76 gear... No heat in the intake.

Author:	kesteb [ Sun Aug 09, 2015 5:33 pm ]
Post subject:
Ok I'll assume automatic. Return the carb to stock cofiguration. Adjust timing to 15* btdc. Now try it. Some caveats, you can't mash the throttle pedal at 25mph and expect miracules. It won't happen. This is not a modern computer controlled engine, but a 40 or so year collection of worn parts. Slapping a manifold on and shaving the head will not get you a Mustang killer let alone a Civic muncher. The 500 avs is a great carb, but by itself it will not make your car a holy street tear. You need a plan, you can follow several builds that have been documented on this site. Any one of them are a proven combination.

Author:	Reed [ Sun Aug 09, 2015 6:07 pm ]
Post subject:
Quote: Ok I'll assume automatic. Return the carb to stock cofiguration. Adjust timing to 15* btdc. Now try it. Some caveats, you can't mash the throttle pedal at 25mph and expect miracules. It won't happen. This is not a modern computer controlled engine, but a 40 or so year collection of worn parts. Slapping a manifold on and shaving the head will not get you a Mustang killer let alone a Civic muncher. The 500 avs is a great carb, but by itself it will not make your car a holy street tear. You need a plan, you can follow several builds that have been documented on this site. Any one of them are a proven combination. This is all true. A stock slant six with nothing more than 9:1 static compression ratio probably is too small of an engine to even use a 500 CFM carb. What cam are you running? What size valves? A 2.76 rear axle gear ratio pretty much guarantees that your engine won't turn enough RPMs to use 500 CFM effectively and an unheated intake is also a poor idea for the street. It will lead to poor fuel distribution and drive-ability problems. I recommend you make a plate to mount the stock carb on whatever intake you are running and rig up some way to heat the intake (exhaust or water).

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