Hi guys,
Finally got the 455 in and running.
Problem now is when the car is hot she won't idle.
I have a clear fuel filter that looks empty when hot (I can't believe the car even runs like that).
Checked all the rubber line from tank to engine...none if it is collaped when running.
The car purred like a kitten before the engine swap.
I changed out the fuel pump and carb (now a fresh 750cfm q-jet)....same problem.
zero vacume leaks.
If I maually choke (when hot) it it will idle,but not in gear when hot.
Runs fine with plenty of power under full trottle...just won't idle ????

The setup is :
fresh 455 ,edlebrook performer intake,750 cfm freshly rebuilt by holly q-jet (correctly adjusted by a pro).
choppy cam (don't know specs but power brakes still work ok) stock exaust manifolds

 

A couple of thoughts. You say starving for fuel, but it runs fine with plenty of power under full throttle suggests to me that it isn't starved for fuel. What is the carb number? Q-jets are famous for well plugs leaking, which could definitely effect the idle. Earlier carbs were the worst for that, and later models better, but I always drill out, tap and install screw-in plugs sealed with Marine Tex to eliminate any possible leaks. Just applying some sealer on the outside of the plugs will do little or nothing for long term sealing.

 

Thing that worries me most, is the Q-Jet rebuilt by Holley. Holley makes some pretty decent carbs for sure, but has no business messing with a Q-Jet. Q-Jets are very sophisticated carbs, that should only be worked on by people who know them. Also betting the jetting is way off for your application. Where I'd start.

 

Sorry guys,
I failed to mention that I had this carb on the old engine only 3 weeks ago ( for 2 yrs) and it idled fine.
The app for the carb is Pont 400-455 ...750 cfm
I also had the exact same idle problem with the edlebrook carb on it that's why I switched to the q-jet,
so I personally don't think it's the carb.
I also have a new filter in the q-jet and new in line filter.

Again...I switched carbs and fuel pump with no change in the problem

 

I would check 1st to make sure you
are getting suffcient pressure from
the fuel pump. I would ditch the in-line filter
and stay with the original steel line, pump to the carb
and it's filter.

Did you have problems before with a dirty tank?

 

What is your idle RPM? I have to ask, what method did you use to set your A/F mixture? What torque converter? Sometimes ignition systems manifest themselves as carb problems. What igniton are you running and what are the setting?

 

I have a Clear fuel filter on my Dodge 496 in my 65 Coronet,( I know,I know) and when running it looks like there is no fuel in the filter. I couldnt believe it and thought something must be wrong but it runs just fine. I never could explain it. The fuel bowls has gas in it... Maybe the gas sort of vaporizes but is under pressure so it's OK? I don't know but just to let you know that maybe that empty look is normal with a clear filter???

 

Definitely start with checking fuel pressure or maybe throw your old fuel pump back in.

 

How much vacuum do you have at idle with this engine, and how much did you have with the "old" engine 3 weeks ago?
And what RPM, exactly, do you have that vacuum at?

- Eric

 

I'm gonna say vacuum leak, with the same problem and 2 carbs-squirt starting fluid around the carb base and manifold - you'll find it!
Check all your hoses, too!

 

Did find a leak in the cheap Q-jet gasket last night.
Much better but still not right,at least it was drivable...that is until the starter wires burnt up and had to get towed home
Thank God for Hagerty free road service !

Will keep you posted after I get the wiring problem fix and running again.
I guess my 38,000 orig mile virgin isn't happy I "messed" with her

 

And No major dirty tank problems before , fiter is brand new and clean.
Also went with a Crane electronic ign conversion.
When it was running last night...she was starving for fuel on WOT upper rpm's and no I wasn't bouncing off the rev limiter.
After the WOT shift to the next gear...she still bogged for a few seconds before "catching her breath"

I am having a buddy come over with gauges and check fuel and vac pressure after I get it running again.

Thanx for all the advise guys..it really helps