Custom 454 won’t idle.

[Cookscustoms]

E-brocks are notorious for flooding above 5psi. Agree cam looks big on paper, what you trying to set idle at? Agree timing might br way retarded. What's initial set at?

The info on this cam is reliable and very streetable with the max horsepower. The next size cam I felt would be too touchy.

 

[Cookscustoms]

so it dead heads, the pump has some sort of a bypass in it. Have you swapped pumps?

Haven’t swapped the edelbrock out since it’s giving constant pressure.

 

[Cookscustoms]

Also I tried backing the idle mixture screws out to 2-1/2 turns for this cam.

 

[Hipster]

Thank you all for such fast responses. First I will respond to b454rat-I do not have a fuel pressure regulator. The factory pump was 45 psi. I know from past experience all the small blocks I have dealt with I use the Edelbrock 3 to 5 psi electric pumps and they were great. This is an a edelBrock 5 to 7 psi pump and the carburetor is much larger than the typical 550 or 600 that I put on to the Ford motors so I figured the PSI would be about correct based on what I have also read online for this size motor and this size carburetor. Please see picture of plugs. Pulled

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four different ones out they all look identical.

Carb size doean't matter, A 1407 or similar doesn't like 5 psi much less 7. I have messed with a ton of e-brock 750's on Mopars. Pressure and volume are 2 different things. Plugs look loaded up.

 

[Cookscustoms]

Carb size doean't matter, A 1407 or similar doesn't like 5 psi much less 7. I have messed with a ton of e-brock 750's on Mopars. Pressure and volume are 2 different things. Plugs look loaded up.

Thanks for the tip. I can swap it for a 3-5 pump I have here but would that not let it idle.

 

[yevgenievich]

Backfiring through intake when trying to give it throttle somewhat makes me wonder timing. How well does it run when it goes to 3k rpm?

 

[Cookscustoms]

Backfiring through intake when trying to give it throttle somewhat makes me wonder timing. How well does it run when it goes to 3k rpm?

It will slow roll from about 1800-3500 very nicely. But if you try to rap it really quick it’ll backfire through the carb and die.

 

[Hipster]

Thanks for the tip. I can swap it for a 3-5 pump I have here but would that not let it idle.

It should have idled with that, not like it's doing much more than trickling gas out of it at idle. You put the 5-7psi pump on, it still don't idle, and is not far from fouling plugs.

Several have asked what's the timing set at, initial?, total? How were the valves set and is that in accordance with what comp says for those particular lifters?

You have to get the timing on point before going to the carb adjustments.

 

[Road Trip]

Several have asked what's the timing set at, initial?, total? How were the valves set and is that in accordance with what comp says for those particular lifters?

I was thinking the same thing re: the valve lash. Along those lines, I'd be interested in what a compression test
would give us? (ie: lower than expected compression = valve lash too tight = idling issues?

The plugs: They are showing rich / loaded up?

The carb: We have 2 separate concerns going on. First, we have to get the fuel bowl
filled to the correct level, but at the same time we don't want to send more pressure
than the float + needle + seat can maintain positive control over. I know that Quadrajets
don't like more than 5 psi maximum? I have to defer to Hipster on what the edelbrock
carb wants, but I'll bet that his recommendations are on the money. (Carbs like adequate
volume at low pressure, but they can't control high pressure at all given the needle & seat
with only a float to push back against the incoming psi. (!)

You know, pulling together the carb & spark plug reading discussions together, it doesn't
matter if you have a carb with a good float setting and too much PSI being fed to it OR
the right fuel pump pressure being fed to a carb with a too high float setting and/or there's
dirt/grit preventing the needle & seat from closing completely. Either way, if you have fuel
coming out the main venturis while the engine is idling then it will be so rich that the engine
can't idle unless you give it a fair amount of throttle. (To match the excess fuel.)

Q: Is there any way you can temporarily substitute a 'known-good' carb onto the top
of this engine? Doesn't matter what it's dialed in for, just need to be able to verify
that the 454 can idle correctly, get the initial timing set, ensure that it can take a
quick winging without backfiring, etc.

And if you don't have that, then do you have a 'known-good' engine that you can
temporarily run with this new carb on it? I don't care if it's a 302, 351W or 390FE motor,
just need a happy motor that we can verify that it will idle, accept winging the throttle
without backfiring, the float level is correct, etc.

From out here in upstate NY, I think that you are trying to troubleshoot through 2 or
more problems at once. But with a known-good carburetor I'm sure that everything
will quickly fall into line with the rest of your 454.

Good luck, and let us know what you find. Standing by --

 

[Supercharged111]

It will slow roll from about 1800-3500 very nicely. But if you try to rap it really quick it’ll backfire through the carb and die.

Sounds lean to me. Can you give it a bigger pump shot? I'd get a wideband on there too, makes short work of tuning the thing.