DFEV question

[apexwc]

I just put a used DFEV on my '78 1800. It came with a 45 main idle jet and a 50 secondary. It would not idle with the 45 so I replaced it with a 50 and then a 55. I haven't noticed much difference between the 50 and the 55, it idles fine with either and they both idle best with about 2 1/4" turns out on the mixture screw. It only takes about 1 turn or less on the idle speed screw to get 850rpm. The problem is after warming up until the choke is fully open I get a hesitation and sometimes a little backfire from the carb when I quickly bump the throttle. It also happens when starting out in first after stopping for a few seconds. When lightly accelerating through the gears I get hesitation but if I give it enough throttle to open up the secondary it runs fine with plenty of power. The plugs are a nice light brown. The more I drive it the worse it seems to get. If I let it cool off for a little while it runs good until it warms back up again. I'm guessing this is because the choke is partly closed? It's a mostly stock engine with all of the emissions stuff removed and plugged. I have a Crane XR700 ignition and the exhaust is a stock 4 into 1 with a small resonator and a stock muffler. I do not know what size the air correctors and the other jets are but I plan on checking. Any thoughts on what to try/check next? Could the primary main be too small?

[So Cal Mark]

I'd look at the accelerator pump and the discharge nozzle. The accel pump diaphragm may not be working or the nozzle could be loose or plugged

[apexwc]

That's what I first thought of but it seems to put out a good stream. With the spitting back through the carb am I on the right track with thinking somethings too lean?

[baltobernie]

I think you're on the right track. The 32/36 DFEV comes from the factory with a 60 primary idle jet, and that carb is not overkill for 1756 cc. Others say that 2 1/2 turns out is the max for mixture screw, and indicates the jet is too small.

[apexwc]

That's what I was going to try next, I'm just tired of paying over $5.00 shipping for a $5.00 part that could be mailed in an envelope. Anyone have a 60 idle jet they want to trade for a 45?

[lanciahf]

Before buying a idle jet check your primary fuel jet. I had the same problem you did and I increased the primary jet from 125 to 130 and all was well. I have a couple of extra jets if you need one.

[apexwc]

Thanks, I do need to pull the top off and see what's in there. Since it had such a small primary idle the other jetting may be smaller too. The guy said it was off a Lancia Scorpion that he was converting to FI. It should be the same engine as mine so I don't know why the primary idle was so small. Of course, I know even less about Scorpions than I do Spiders! They look cool, though.