Edelbrock 1410 750 CFM carb

[saluscon]

I have an omc 5.7 with an edelbrock 1410 750 cfm carb. i have read that it is to large for my GM 350 and i should have a 600 or 650 cfm carb. I am also have trouble reach WOT and have noticed that the mechanical secondaries will not open. I only get about 3000 rpm at full throttle. Any suggestions?

 

[John_S]

Re: Edelbrock 1411 750 CFM carb

Re: Edelbrock 1411 750 CFM carb

The 1411 is an auto carb. That needs to be removed. The 1409 is a marine 600cfm and would be enough for your engine. It will need little or no tuning for most 350's. A 750 (1410) can work fine, but will need considerably more tuning.

 

[saluscon]

Re: Edelbrock 1411 750 CFM carb

Re: Edelbrock 1411 750 CFM carb

thanks, but my apologies, it is a 1410. If not tuned properly would the 750 cause the low rpm at wot?

 

[John_S]

Re: Edelbrock 1411 750 CFM carb

Re: Edelbrock 1411 750 CFM carb

thanks, but my apologies, it is a 1410. If not tuned properly would the 750 cause the low rpm at wot?

It sounds like the 2ndary air valve is not opening. The 350 should easily open them, but might not fully open at 5Krpms. See if they move freely.

 

[saluscon]

Re: Edelbrock 1410 750 CFM carb

Yes, the flaps do move freely. If i can't go over 3K rpm will the mechanical secondaries open?

 

[John_S]

Re: Edelbrock 1410 750 CFM carb

Yes, the flaps do move freely. If i can't go over 3K rpm will the mechanical secondaries open?

The secondaries are mechanically linked to primaries. With engine off moving the throttle to wot, the secondaries should be wide open, Push the air valve open to see them. The secondaries start to open at a certain throttle position (around 50%), not rpm or vacuum. A 350 that is on cruise, the air valve should open shortly after the 2nd butterflies open. On mine (1409), it is about 3500 rpms.

What is the history of carb, used? was on boat? new out box? refurb?

 

[saluscon]

Re: Edelbrock 1410 750 CFM carb

The carb was on the boat. But if your saying that the secondaries kick in about 3500 rpm, then my problem may be that the engine won't go beyond 3000 rpm. I have checked the anti siphon valve, the vent tubes, fill tube, fuel separator, fuel lines, distributor, electronic ignition. The only thing i haven't checked is the exhaust flaps (cause i have to pull the boat out the water) and the fuel pump.

 

[John_S]

Re: Edelbrock 1410 750 CFM carb

I see in an different thread, you have rebuilt the carb. Did you record the primary and secondary jets and what rods were in it? Spring color?

If this is a new to you boat, and you have never been over 3K, there are many a things other than fuel that may cause that. PS; see you are working on Don's list - good.

Have you done basic mechanical check-out of a full compression test and read idle vacuum? You should have a steady reading of 16-19" range. The vacuum gauge can find many things a compression test can not.

 

[saluscon]

Re: Edelbrock 1410 750 CFM carb

my carb doesn't have vacuum lines. Is there another vacuum location?

 

[John_S]

Re: Edelbrock 1410 750 CFM carb

There is a pipe plug on the intake, behind the carb. Remove it, and buy a vacuum tap plug at the auto store. The rubber cap and a small wire tie keep it sealed, when not using the gauge.

 

[saluscon]

Re: Edelbrock 1410 750 CFM carb

Thanks will try that next week. I did do a vacuum test on the fuel pump and according to the seloc manual i should have 9-10 in Hg. when i replace the fuel line with the vacuum meter and crank the engine i only get 5-6 in Hg. could this mean bad fuel pump?

 

[John_S]

Re: Edelbrock 1410 750 CFM carb

The fuel pressure to the carb should be fine at 5-6psi. More than that, and the float needle/seat will start to leak fuel on many carbs.