Edelbrock carb question

[Sonny]

I have a new Edelbrock avs2 carb on a rpm air gap intake on my ‘78 360. Here is the problem (I believe). My idle vacuum is a strong 21”. When I go from cruise mode to cruise acceleration, my air fuel gauge goes lean and not richer. I am using the stiffest step up spring, but I think it can’t overcome the high engine vacuum and raise the metering rod. Anyone else have this problem?

 

[FrnkNsteen]

I'm not a carb expert, but I had a good conversation with someone on the FABO (ForABodiesOnly) sight. From what he was saying, what you are seeing is normal. I will attach a snippet of our conversation on here for you. I will also post a link to my thread over on FABO. The part we were discussing this information is on the last page (specifically Post#53)

He said,....
"The clue [relationship] here is rich idle, lean cruise, leaner (leanest, actually) part-throttle acceleration and rich WOT. The leanest is at mid-load, half-throttle or so.

http://www.forabodiesonly.com/mopar...g-to-compare-to.395945/page-3#post-1971912549

 

[oldbee]

Smaller diameter rods is probably what you need. Your 21” vacuum will surely drop on any kind of acceleration.

 

[Sonny]

Smaller diameter rods is probably what you need. Your 21” vacuum will surely drop on any kind of acceleration.

I’m using a 7537 with a .104 primary jet. Cruise afr is already rich at 11. If I go smaller than 75, cruise will be more rich. Plus 37 is the smallest tip too. I feel like I’m trapped between the two ends.

 

[Sonny]

Would this air cleaner be restrictive enough to cause a rich cruise?

 

[oldbee]

Probably not, maybe ur going at this wrong; what are the timing specs? Idle,2000rpm, over 3000?

 

[Sonny]

Probably not, maybe ur going at this wrong; what are the timing specs? Idle,2000rpm, over 3000?

Terrible ha ha! I’m putting in a new Mopar electronic ignition conversion kit in it tonight. I’ll let you know tomorrow with the new system what the timing specs are.

 

[coloradodave]

#1 Rule in tuning is to get the timing squared away BEFORE trying to tune the carburetion. Otherwise you'll be chasing your tail for a long time...

 

[Sonny]

Probably not, maybe ur going at this wrong; what are the timing specs? Idle,2000rpm, over 3000?

Ok. Got the mopar electric ignition conversion installed and is working nicely! It said to start with 5 deg initial timing...when I rev it to about 2500 it’s at 25 deg. I haven’t hooked up the vac adv yet. It actually idles nice and the pedal is quite responsive at 5. I expected sluggishness but not so. Anyway, should I use 15 initial to get to 35 total, or let the vac advance do it? Or leave it where it is? By the way, I swapped the snorke air cleaner with an open type and my cruise air fuel ratio went from 11 to 12.5 (on the highway at 75mph) no change around town though- guess the new dizzy and timing could have changed it some too

 

[Don Frelier]

I would suggest setting initial to 15-17 to get 35-37 total advance. It will start better and have more snap.
I think 12.5 AFR is still rich for cruise 13.8 - 14.2 is what I like. Try a smaller primary jet and see how it acts.

 

[rumblefish360]

Sonny;

Did the ignition kit come with instructions?
Do you have the MP engines book?
Do you have the Edelbrock instructional booklet on “How to tune your Edelbrock carb” by chance?

 

[Sonny]

I have the Edelbrock tuning book; however I spoke to their tech support complaining that they haven’t released the tuning charts for the AVS 2 yet. Should be next week they said. We’ll see.

 

[rumblefish360]

You shouldn’t need the new tuning touch. The old way and will suffice just perfect. There is no newfangled way to tune a carburetor.
Please do remember that carburetors about earthquake me to refuel. It is designed to constantly confused and compound the end-user. With an Edelbrock, Jet it, set it, forget about.

Carburetors stay tuned only on the day they were tune on.
Tomorrow, there out of tune.