?s for those running Edelbrock 1405/1406 at altitude

[Dive 30]

OK, so I'm finally getting around to re-jetting my 1405. I haven't ever bumped it from stock until now (1yr after install, see how right on top of things I am?). I re-jetted to .089 primary, .086 secondary (12% leaner than stock) with stock rods. I am thinking of stepping leaner (as the motor no longer seems to be drowning in fuel) is .086 primary and .083 secondary a good place to go? Should I swap rods?

I live in Ft Collins, CO (4600 ft)
AMC 360 with Edelbrock Performer Carb, Intake, Cam
Hedman Headers (leaky)
MSD 6 ignition, Blaster 2 Coil, 8.5mm Heli-Coil wires

Anybody that is running the same or similar set-ups?

Any tips for sealing my leaky headers? I have copper gaskets, hasn't seemed to help.

Thanks in Advance

Phil

[Stuka]

I have run my stock 1406 to 7k ft with no problems of flooding. I drive mostly between 3k and 5k (to and from work) Are you running a 360 dgeree air cleaner? My engine ran rich with the stock air cleaner setup, because it breaths through like a 1" hole. I switched a edelbrock 14x2.5 aircleaner and bam...runs perfect stoich. Plugs are all perfectly tan.

[Ralph]

I think you went too lean, particularly for the secondaries. I believe your original setup had 0.098" jets, and was intended to operate properly up to 4,000' above sea level. The rule that Edelbrock/Carter apply for altitude tuning is to reduce jet size 0.001" for every 1,000' of altitude ABOVE 4000'.

For example, I changed my secondaries to 0.095" because I live at 7700'.

Also -- and I've just learned how important this is -- Jeep/AMC recommended setting the timing at 19 degrees BTDC due to the reduction in atmospheric pressure (normal setting up to 4,000 feet is 12 degrees BTDC). Last weekend at grimgaunt's house I set my timing and had a much easier time driving over the passes to get home.

I regularly drive at altitudes ranging from 5,500 to 11,000' where I live. I just moved here a few months ago, so I've been through the trial and error stuff so far as carb tuning is concerned.

It's also important to make sure your choke opens completely. And if you have an air cleaner assembly with the two vacuum operated flaps, make sure they open when they're supposed to to get good flow through the cold air hose. Cold air is denser than warm air, so this little bit helps driveability at altitude.

[Dive 30]

I am running a 360 deg air cleaner, the cool go-fast Edelbrock chrome one even! The choke is opening fully. I haven't even set it for the colder weather yet. I have an air/fuel meter, but it is useless to me until I can get my exhaust leaks fixed. I don't have any emissions equipment either, no egr or smog pump.

My problem is an off-idle flat spot (tries to die when you romp on it) and it kind of sputters at low to mid throttle.

Is that concurrent with going too lean?

The reason I was thinking of going leaner is that my acceleration and cruise have really improved (even with the hesitaion). It just feels like Gwen is breathing better and not drowning in gas. But she felt like she was drowning even when we were in Iowa, that's why I went so lean. Any thoughts?

Thanks,

Phil

[ December 08, 2002, 03:55 PM: Message edited by: Dive 30 ]

[Stuka]

what color are your plugs?

[Dive 30]

the plugs were a little black in IA, I haven't pulled them since we've been back, but I'm sure that they need to be replaced due to fouling. Even with my exhaust leaks, my air/fuel meter was pegging out on the rich side during cruise and on-throttle driving.

Thanks,

Phil

[Michael]

Dive30- I agree with Ralph as far as the jets are concerned. He is the carter man if you ask me. Now in my experience with mine. The stumble is from lack of fuel on the accelerator pump stroke. If you have never adjusted this then I am pretty sure you will need to. On the acc pump rod there is an adjustment. Pull the clip and adjust the rod one whole down I believe. One way or the other I cannot remember off the top of my head now. I am pretty sure there are three holes....I put mine in the middle and my stumble went away. Hope this helps.

[oddfire]

how bout your accelerator pump. still om the middle setting? remove and replace the linkage on the accelerator pump to the bottom setting. This will give you a bigger'shot' of gas to avoid stumble at take off...also for what its worth before I left for the Ouray trip I slapped on a new 1407. thats 750 cfm. It did perfect on all the trails I tackled [up to 13,000'} wihout even the offroad needles and seats. Only the very slightest loading up on off camber situations wich only needed a little more RPM to cure . I was sold. Also I live at 7300' and yes my timing is set around 19*.......phil

[ December 08, 2002, 09:34 PM: Message edited by: oddfire ]

[Dive 30]

Yeah, initially I had that rod in the uppermost position (most fuel) when I re-jetted I set it back to the lowest hole (least fuel) and in the manual it says that adjustment would help, I just haven't got back out to pull the little pin and move it up a notch.

I think what I am going to do is to switch the secondary jets to the .089, which is what the manual says is 12% lean on the secondarys and then do the jet and rod swap to 12% lean (from stock that is), .095 primarys and see if that doesn't solve my problem. I make regular trips up over the I-70 through the tunnel and vail passes to get to Grand Junction (Collbran, actually), so I should see some good things.

There's also a set of High flow manifolds on e-bay I'm thinking will solve my header leaks nicely.

After that I will replace the plugs and check the timing.

Thanks for all the help guys, I really appreciate it.

Thanks

Phil

[ December 08, 2002, 09:44 PM: Message edited by: Dive 30 ]