Edelbrock 1410 stalls unless kept at 1/4 throttle
 

Hi , so I swapped out a dead efi for an edelbrock 1410. I kept the electric fuel pump and added a regulator with bypass. So I've got 5.3psi at the carb. Problem is, the engine starts but to keep it running I need to give and hold it at about 25% throttle. If I bring it back to neutral it stalls. What do I need to adjust here to have it idle at neutral without throttle? Thanks

Engine specs ?
ignition and verified timing specs ?

It's a Gen V mercruiser 7.4l 330hp / bravo 1. Since it's not currently running right I didn't think I could check or adjust the timing unless I could first get it to idle in neutral. Currently I can only run the engine under some throttle . Nevertheless until my Fitech died 3 weeks ago the engine was running fine at whatever timing it's currently set at. Edelbrock told me the solution is to do with adjusting the mixture screws and the idle screw on the carb. But as for the mixture screws I'm not sure if my situation is a too lean or too rich deal... I was hoping to figure which direction to start with on that.

Okay, well, we need that verified. Ignition must be working correctly and set correctly before moving on to possible carb issues.

Also, what spacer or adapter did you use to seal the carb to the OE Quadrajet intake ? Or is it another intake ? Asking, because you could have a vacuum leak.

I used the edelbrock 2696 spacer with all their gaskets. The engine runs very well, only I need to give throttle . No missing or weirdness.

You said you swapped out for the edelbrock carb but is it new or used. Is tge choke working properly? Maybe zip tie it open and adjust your mixture screws. Start with backing them out a half turn at a time and fine tune from there. If you can’t figure it out within minutes something’s gotta be screwed up the the circuitry. Find another carb of any sort just to try.

Brand new 1410 out of the box . Yes electric choke works properly, I looked at that to be sure.

did your fitech control ignition?

No ignition is original. I only kept the electric fuel pump and added a bypass regulator and pressure guage after it.

Are the ignitions the same or compatible with one another. I didn’t think about that.

All ignition components are original mercruiser as when the engine originally had a Quadrajet carb. Zéro fitech stuff only the throttle body was fitech

Doesn't your fuel presser seem low ? I thought carbs needed 7,8 lbs........I also was thinking vacuum leak as SB stated

Edelbrock was very specific that this carb cannot handle more than 6 5 psi so I started at 4 and upped it to 5.3. This did not have any effect and the pressure stays steady even on revs so I think the bowls are maintaining fuel levels. As far as vacuum, I can't see where there could be a leak I even smeared a thin coat of permatex rtv on each side of each gasket to be sure of that possibility upon installation. Edelbrock has said the problem lies with the mixture screws and the idle screw. Only I'm not sure how to go about adjusting them to at least get a start on idle and not on throttle.

Did the carb slide on adapter fine ? Many of these adapters had the stud holes slightly off (too close together) causing too tight for carb too slide on easily. Peep’s had to make carb mounting holes bigger.

Any vacuum ports not plugged ?

5ish fine on edelbrocks.

Spray something around the base while running and see if the revs go up, but be careful of the exhaust

heres a video you can watch.I'd try pulling idle mix screws and blowing air into the carb.

I have an Edelbrock on my 32 Ford coupe w/mild 327 small block. That thing never has idled the same from one start to the next. It is coming off this winter and I am going to put the old Holley (re-built) back on or a Quadrajet.

Good idea. :thumbs

Only thing making any sense at moment. This would drive me nuts. Not sure what production date carb is but since and during Covid era I found many parts to be fked up.

is it possible there’s buggered up cast flashing in and surrounding the adj ports? Fuel pressure definitely not an issue at least idle for certain so if nothing else changed during this swap wtf 😳

Edelbrocks are easy, but you gotta do step by step.

First, we will ASSUME your ignition timing is IN THE BALLPARK for now.

Edelbrock is good w 5 to 8 psi.

If the carb is brand new out of the box, then it will probably be a touch on the rich side, which is safe.

You need a vacuum gauge, and a timing light.
Hook the vacuum gauge to the fulltime vacuum port (not the "ported vacuum"). Count the number of turns required to close the idle mixture screws, and then put them back where they were.

So, for initial settings, do whatever you have to do to get the engine up above 140 degrees or so. THEN adjust the choke fully open for now. Then set idle stop screw to 800 rpm.
Take note of the vacuum reading.
Then turn the idle mixture screws IN 1/4 turn and see of the vacuum drops or rises. If no big change, turn another 1/4 turn. If vacuum is weaker, then go back to the original settings and 1/4 turn OUT and watch vacuum. Keep turning (both in 1/4 increments) until you see MAX vacuum.
If, at any time during this, the idle increases past 1,000 rpm, readjust the idle stop screw back down to 800 rpm. Keep repeating the process until you've found the setting that gives max vacuum at 800 rpm.

NOW look at where you ended up - if you landed at more than 2.5 turns out, then it is likely that your jetting may be too lean on the "needle down" position (you can refer to the jet/needle chart that came with the carb).

Once you get your idle mix set, then move your timing around, also watching the vacuum gauge. Once you find the timing setting that gives you best vacuum at 800 rpm, (again, you may have to adjust the idle stop screw) use the timing light to see where it is. Write it down.
But if you are using the normal V8 Module on your T Bolt ignition you should not run more than 10 BTDC.

Let's say you end up at 10 BTDC and 2.5 turns out on your idle mix screws at max vacuum at 800rpm.

Now you should go drive around at mid-cruise and be sensitive about listening and feeling for rich/lean conditions.

If you're happy with that, then set your choke per normal procedures (it has to be done when fully cold).

Good call - I remember adjusting (positioning) those needles just experimenting back in the 80’s early 90’s. Seems like there was about 5 different settings to hang them on. It would almost seem it’s a lean condition with the needle not coming off the seat soon enough. (Makes sense). I can’t remember how they play a part in the idle position. Definitely confirm NO vacuum leaks as that will kill your idle for sure. Several ports on those carbs for different applications. I have a book on those carbs still somewhere. Yes an actual hard copy. Lol.

I had a very similar issue with a merc carb, and also a holley. The merc carb turned out to be a vacuum leak (still leaked with RTV on both sides of old gasket, new gasket with NO RTV fixed it)

the Holley ended up having the incorrect gasket installed between the bowl and the base.

Just put a new Edelbrock on my boat. The idle set screw, out of the box was about 1-1/2 turns too low to keep the boat running.

you win! That is exactly the issue, found it yesterday.

With "no vacuum" the springs push the needles fully up (rich). Vacuum pulls then down (lean). Spring strength determines the vacuum point where they start lifting.

Generally, at and around idle there is zero concern about needles lifting. WHEN the needles lift is one of the last tuning steps in a car. A boat is a constant load application which does demand that you get at least "in the ballpark" with the springs before fine tuning.

Properly working, the throttle plates will be very nearly shut at idle and the main jets and needles will have a minimal effect on your idle mixing. If things are WAY out of whack, you can come across examples of the throttle plates needing to be open partially into the transition slots to idle but an out-of-box Edelbrock on a near-stock motor won't fall into that category.

Glad you ‘fixed’ it.

Getrdun mentioned it early, post #6.

Reminder to rest/all of us, don’t assume person needing help did the ob
automatic 1st thing.