Inliners International Forums General Discussion Engines Edelbrock afb

Hi all, Ive been running a new Edelbrock 500 for a couple of months now. From day one fuel has been collecting in bowls where the air valve weights are. The carb otherwise runs beautifully, I havent had flooding problems nor does fuel drip from the throttle shaft. My mechanical fuel pump delivers between 5.5-3.5psi.Float level and drop are set to factory specs. Could this be a percolation problem?
Any ideas?

A rare but consistent problem I found in 2 600 cfm Edelbrocks was the secondary booster nozzles were not sealiing tight to the carb body. Take the top off the carb and check the 2 screws that hold each of the secondary boosters in place. It seems one or more of the carb body holes aren't drilled and tapped deep enough so one or more of the screws bottoms out before making the booster tight against the gasket and carb body. The screws feel tight but no seal is made. Loosen one screw at a time and try wiggling the booster gently. If it moves, the screw remaining in place is bottomed. If it doesn't move replace the screw and remove the other one and try again.
The fix is very simple. Just put a small flat washer or two under the head of the screw. No need to drill and retap the hole deeper. As further evidence the booster isn't tight you can remove it and study the gasket carefully. A properly seated booster will leave an impression evenly across the gasket. You can reuse both the booster gaskets and the main body to air horn gasket if they didn't tear. I always put a tiny dab of anti seize on all the screws of these carbs.

On one carb all it did was fill the cavities the counter weights swing in. On the other it was loose enough to cause a very serious spillage and over rich running condition as fuel trickled down the secondaries past the closed throttle plates. The 500 and 600 use the same housing and the difference in airflow is due to the 500 having much beefier boosters which restrict airflow.
( see an easy upgrade trick here?? ) Although this is a rare problem it might be a production flaw since the 500 and 600 are the same until assembly.

Just for your info the 2 carbs with the leakage were both purchased brand new around June of last year and from 2 different sources.

Hope this works for you.
Mike

Thanks Mike,
Your explanation makes perfect sense!
I will investigate further today. The Edelbrock tech tried to tell me it was a fuel pressure problem which didnt make any sense to me. For what its worth the carb was purchased late last year over here in NZ.

Thanks again
Jeremy

Well Mike you definitely hit the nail on the head. The problem is now fixed. It must have been leaking more than I thought as she now seems to be a bit down on power and has a slight bog. It looks like I'll have go bit richer with the jetting, as it seems that I've inadvertantly leaned out the carb compensating for the fuel leakage :rolleyes:

Cheers Jeremy

I'm glad it is solved Jeremy. In all the Edelbrock carbs I've instaled or worked with I've never had a quality control problem until those 2 I mentioned. Ever since then I now take the time to check the boosters while I have the top off to check / adjust the floats. I'm sure both you and I will never have that problem surprise us again.

Hope you are enjoying your Summer down there. We are freezing and snowbound up here in Boston, Mass, USA.

Mike

Well Mike the bad news is that the leakage is back, although on a lesser scale. I just re-read your post and noticed you used flat washers. I used spring type washers. I am wondering if this could be cause.
The gaskets appear to be in good nick however I would prefer to use new ones just for some peice of mind. I think these are only available in the full rebuild kit. Are Carter afb ones the same?
I am cautious about doing the screws up any tighter
as I dont want to strip what little thread is there. Hopefully I don't have to re-tap the thread..

Cheers Jeremy

I've never swapped any Carter gaskets with the newer Edelbrock so I cannot give you a true answer. The wahsers shouldn't matter much. Did you just barely snug the screws or give them a fair amount of tightening? The holes won't strip easily but you can't be a gorilla either. I'd go a little more on the screws and see what happens.

Mike G

Since Carter is out of the Carb business, whenever I go into the hot rod shop to get a part for my 600 CFM Carter AFB, they give me an Edelbrock part. Late production Carter AFBs are compatible with their Edelbrock clones. The gaskets are definately the same.
Edelbrock has done some "tampering" with the needle/jets; instead of Carter's small, medium & large approach, Edelbrock has introduced a whole rainbow of intermediate sizes and spring weights, just to complicate matters. Or so I gather from comparing the Edelbrock Tuning Manual [War & Peace] with the Carter instruction sheet [telegram].
I just ordered a EDL-1404 500 CFM today for my '68 292 w/ Offy intake & Clifford headers. They [Carter] don't make an AFB 400 CFM anymore, and I've had it with my 27 -year -old Holley 390 CFM.