who is the Edelbrock carb guru on FABO

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trudysduster

trudysduster

FABO Gold Member
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would like to find out who on FABO would be the Edelbrock guru to help with calibrating my Thunder Series 650 carb. Thanks,Bill
 
Try asking RustyRatRod (Rob). He's good with carburetors and rebuilds them on the side.
 
What´s the problem with the carb? I´m by far no carb guru, but if you have a A/F gauge these carbs are pretty easy to calibrate. I´d suggest getting one or borrow one from a friend.

Michael
 
The innovate A/F guages have an adapter that you can buy pretty cheap that allows you to hook it up to the exhaust pipe end.
This way you can use it as a temporary tuning aid and pull it off after the tuning.
It will make is possible to tune the carb to near perfect A/F ratio throughout the throttle range from idle to wide open.

Calibrating by suggestion, or even by the manual takes a long *** time.
 
Oh man these are about as easy as it gets. You don't need an A/F gauge unless your really wanting to tune it precisely ie- race motor, optimum performance etc....and if your doing that your not using any Eddy carb! But if it's your thing then by all means it's the best tool.

That being said, 1st adjust the floats. Easy to do with the top off per instruction DVD
2nd adjust the two idle feed screws with a vac Gauge for highest vacuum and idle till their optimum. The 2ndary is probably real close on a old small block as is.

That's about it on em! You can get into step up springs and metering rods with the tuning kit but again, if your gonna go that far with a carb then start with a Holley, Quick Fuel or Demon
 
Me too! Glad someone posted this as I should have by now. Havent had time yet to dial in my 650 thunder. I have the dreaded low speed hesitation and off idle bog. Other than moving the squirter linkage to the top hole, Ive done nothing. I bought the calibration kit but want to make sure of my timing before doing anything with the carb.
 
i have can up with some hints on jetting an AFB or Edelbrock carb.
Title: AFB and edelbrock carb / the short verson.

setting an AFB carb takes time. make only small changes. and give it time, dont make changes in an hour or two. drive it in different ways over a day or two. on AFBs or AVSs change only the jet OR rod at one time. and start with the jets. a .003" change can be felt if you try. dont forget .003" on a .060" jet is less change than .003" on a.100" jet. Then start changing the rod. A little is a LOT. i do have a computer program to cal any combo of changes. but it is lost in some main frame of my sons. Sometimes you can set the float level to 5/16”. the stock setting is 7/32. if at 5/16” at idle the fuel runs out of the main discharge nozzle reset to the stock setting. NOTE: do NOT change jets AND rods at the same time. Do not put the jets in tight, just snug is fine
 
Yes timing then carb or chase your tail....AF would be best ...after
 
ok, thanks. I have changed the step up spring to the pink instead of the silver because of the big cam I have.
 
^ You could probably step down even further, play around with it, I've got a 226 @ .050 cam and it runs best with the gold 5in springs, pulls 14". Whatever responds the best. Bigger springs feel 'stiff'.

Same goes for distributor springs, mild performance cams like those light springs!
 
I broke down and bought a vacuum guage today. being old school I have never used any gauges or timing lights or anything like that. I never used anything on Tylers 360 and it runs great. But this damn 440 with this cam in it is making me old. I set the timing with it and it doesn't like it where it says it is supposed to be. I advanced it where it ran the fastest and backed it off I inch. took it out for a drive and it pinged like hell. brought it back and put it back where it was at. runs and starts good. I changed the setup springs down to orange and it surged a little when it was at a constant rpm. so I brought it back and put the pink back in. I read in the Edelbrock manual where if you have a bigger cam and low vacuum that you may have to run the pink or silver spring. This car for some reason likes the pink spring. Have a 509/292 purple cam in it. I have between 5-6 hg of vacuum at idle according to the guage. I set the idle up a little. I adjusted both A/F screws and it likes them about 1 1/2 turns out. That is just about where the guage peaks. The problem I am having now is when I drive down the road and slow down to make a turn into a parking lot, it seems like the engine wants to stall. I didn't mess with any jets or metering rods. I did move the accelerator pump linkage to the top hole. It came from the factory in the middle hole.
what would cause the engine to act like it wants to stall when making a turn into a driveway or parking lot. This is a Thunder Series 650 CFM AVS carb. Practically new carb. Other than acting like it wants to stall, this thing runs great. any suggestions. Before you suggest fuel pumps, filters and all the other stuff, it didn't act like it would stall till I started messing with the running rich problem here. Would moving the accelerator pump linkage do this. suggestions appreciated. Bill
 
before fixing the carb.....you need to recurve the distributor...you need to get the intial timing up to 18-22 degree...and limit the mechanical advance to get your total timing of 35 to 38 degrees..
 
trudysduster said:
I broke down and bought a vacuum guage today. being old school I have never used any gauges or timing lights or anything like that. I never used anything on Tylers 360 and it runs great. But this damn 440 with this cam in it is making me old. I set the timing with it and it doesn't like it where it says it is supposed to be. I advanced it where it ran the fastest and backed it off I inch. took it out for a drive and it pinged like hell. brought it back and put it back where it was at. runs and starts good. I changed the setup springs down to orange and it surged a little when it was at a constant rpm. so I brought it back and put the pink back in. I read in the Edelbrock manual where if you have a bigger cam and low vacuum that you may have to run the pink or silver spring. This car for some reason likes the pink spring. Have a 509/292 purple cam in it. I have between 5-6 hg of vacuum at idle according to the guage. I set the idle up a little. I adjusted both A/F screws and it likes them about 1 1/2 turns out. That is just about where the guage peaks. The problem I am having now is when I drive down the road and slow down to make a turn into a parking lot, it seems like the engine wants to stall. I didn't mess with any jets or metering rods. I did move the accelerator pump linkage to the top hole. It came from the factory in the middle hole.
what would cause the engine to act like it wants to stall when making a turn into a driveway or parking lot. This is a Thunder Series 650 CFM AVS carb. Practically new carb. Other than acting like it wants to stall, this thing runs great. any suggestions. Before you suggest fuel pumps, filters and all the other stuff, it didn't act like it would stall till I started messing with the running rich problem here. Would moving the accelerator pump linkage do this. suggestions appreciated. Bill
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Not a chance.
Have you verified the float levels?
Low fuel level can make it where the fuel goes to one side of the carb.
 
Read my post on a new 650 Thunder filled with shavings that had to be disassembled and cleaned out. Slim chance but you never know. It doesnt sound like it wants to stall anymore! What RPMs are you at for idle?
 
I moved the linkage back to the center hole. I have not verified the float levels because the top has never been off yet and it didn't do this before I started changing things so I didn't see any reason that the floats would have changed. But I guess I will have to check this. I think Edelbrock says that there should be 7/16 " on the float. How accurate should that be. should I set them higher to allow more fuel in the bowl , maybe 3/8 or so or just the 7/16.
 
trudysduster said:
I moved the linkage back to the center hole. I have not verified the float levels because the top has never been off yet and it didn't do this before I started changing things so I didn't see any reason that the floats would have changed. But I guess I will have to check this. I think Edelbrock says that there should be 7/16 " on the float. How accurate should that be. should I set them higher to allow more fuel in the bowl , maybe 3/8 or so or just the 7/16.
Click to expand...

Use the 7/16 setting or we will just get farther from right.
You may want to open that thing and blow out all the passages just in case.
Did you happen to take a look at a plug yet?
 
fratzog, That couldn't be my problem here. I ran this carb all last summer to shows. It didn't do it then. Fuel tank, lines, fuel pump, filter all was new. Car is garage kept and anytime it is out, it is RARELY out of my sight when parked. so the chance of it getting something in it is slim BUT.... I will check this out. is it possible that it is running so rich that it is flooding out and when it idles down to make a turn it wants to quit. It still has the same rods and jets that came in it. I think I am going to swap the 750 off of Tylers 360 tomorrow and put it back on here and see what that does. That may tell me something. I will see how his runs with this 650 on his again. I have never played musical carbs before. I will update you guys when that is done. thanks,Bill
 
I am going to swap these carb tomorrow and while I have it off, I will pull the top and check the float levels on it. I did that on the 750 when I was having trouble getting Tylers car running right. They were right on the 7/16 mark so I know they are correct. I set it back up with stock rods and jets and moved the accelerator pump linkage to the top hole and his runs great. He had a slight surge when cruising.
 
reading back over some of the posts. The 5" spring is the stock orange spring. I had that one in there. That is the stock one that came in it. I had the vacuum at 14" when it was running at its fastest but pinged like hell when I drove it. That is why I moved it back down. About recurving the dist. That was done when the car was put together. I know nothing about how to do that. My son done that years ago. Is that something you have to do often. Is there a way around that like a different dist.
 
Your problem is a sloppy needle and seat assembly. Just enough seepage to raise the fuel level to where it sloshes over into the booster when you make a turn...otherwise it just runs a tad fat all the time. Had this exact thing happen many times with these carbs. Last time it was on my 73 Roadrunner. Pulled it apart and found the tiniest bit of fuel line rubber stuck to the pointy end of the needle.
 
Distributor curve is easy to dick with, pull the disto and take it apart; tap the roll pin out of the bottom, springs are inside. You can get the springs in the 'HEI re-curve kit' for under $10 at your local yocal parts store. Takes like 10 mins. In my expierence, performance cams like light springs and a quick curve. Experimentation is key.
 
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