New forum member - questions on Edelbrock 1904 Q-jet

[jarrington]

Hi all-

A couple months ago I picked up a 1960 Nomad to haul the kids around, and I've been working on getting it more roadworthy. In the process I installed a Vintage Air kit, which made the already marginal Rochester 4-Jet on the original 283 no longer viable, since every time I turned a corner with the A/C on it would bog the engine and die. 

So I started looking into my options, even giving Cliff a call to see if I could pick up a rebuilt carb, but with his backlog that wasn't an option for me. In looking around for a suitable manifold I stumbled across an Edelbrock 1904 aftermarket 795 CFM Q-jet on a Performer 2101 manifold - scored the pair for $100! The guy had run it on his 283 Chevy pickup for a while with no issues, so I figured I'd bolt it on and give it a shot. So far so good - it all bolted up fine after a bit of fiddling with the throttle linkage, and it fired right up with no obvious major issues. I do have some fine tuning to do, and I have a few questions...

1. What is the size and thread of the two threaded holes where the idle stop solenoid bolts on? I've tried every combination I had, metric and standard, and they all seem either slightly too big or slightly too small.

2. Will the stock jets and rods work for a stock 283? From what I've found they are: Main Jet: .073; Metering Rods: Primary-50M, Secondary-DR. I haven't opened it up but I doubt they've been messed with, since it doesn't look like the carb has ever been apart. The .073 main seems really big, but since this was supposedly a direct replacement for a 1980s Chevy truck with a 305 or 350 I'd think it would probably be pretty close.

3. Is 795 CFM on a motor more suited for half that going to be a problem? From what I've read it seems that the extra capacity isn't an issue like it would be for a Holly or Carter, just checking to be sure.

4. What's a good starting point for idle mixture screw settings on this model? I seriously suck at setting mixtures, so any idiot proof method for getting the idle mixture close would be appreciated.

That's probably it for now, but I'm sure I'll have plenty of other questions in the future. A pic of the old beast is attached.

Thanks,
Jason

[Cliff Ruggles]

Nice score on the 1903, they are very nice units.  I would still replace all the internals with modern components at some point, and go thru the carburetor and check everything out.  I have numerous problems with every single one of them, so quality control is and always has been an issue with them. 

I've seen miss-matched parts, bent power piston hangers, idle bypass air passages not drilled on one or both sides, POE holes not drilled thru the airhorn, POE well supply holes not drilled on one or both sides, poor seat at the accl pump check-ball, different size idle tubes in them, idle down channel restrictions different sizes, etc.

They also used poor quality accl pumps and seals.  At a minimum I would go completely thru the unit to make sure it is up to par for this new fuel, float set  correctly, etc.

Set the mixture screws for the best idle quality at the leanest settings.  This is done by turning them in slowly one at a time till the engine slows slightly, then back about 1/2 - 3/4 turns or so till it smooths up......Cliff

[429bbf]

jarr .nice ride. did you ever fiqure out the screw size? ive never had an edel 1904 but i thought they copied the q jet  which is 10-24 nf.   if you didnt know that already. dean

[429bbf]

jarr sorry for the bad info had a brain cramp. the screws are 10-32 nf not 10-24  had posted wrong.sorry