Tuning an EB 1405 for use @ 5500 feet???

B

brad bedell

New member
Could anyone provide some good baseline tuning for the above scenario? Newly rebuilt 392 with rpt aluminum square bore manifold, .5" phenolic spacer, rv cam, 14"x3" open air cleaner, 32" tires & 3.54 gears. Also has dui distributor. Edelbrock says to change from the original metering rod, #1451 (.070"x.047) to a #1459 (.075"x.047"), rod only change. This would supposedly change the cruise mode 8% leaner.?. Wouldn't the power mode need to be leaner as well? Additionally how does changing the "pump drive link location" affect tuning? Currently set too the "out of box" middle location? Lastly, in denver with most trips only going up in altitude.

Thanks in advance, you guys have been much more helpful than I've experienced on the "old" bulletin board. With out all the extra opinions....

Happy memorial day!!!,
brad
 
Robert needs to address this one for ya brad, he's got the experience in dealing with these mixers at altitude. But...he'll need to know the numbers on the camshaft installed.

When you say..."rv cam", do you know the brand/part number and have the timing sheet for it? If you just have the manufacturer's part number, we can look up the cam card for it.
 
Thanks for the quick response michael. Unfortunately when you come across a deal, like when you buy an engine someone else had rebuilt but couldn't afford to pay, then you don't get all the specs. I have receipts and specs for everything but the cam. They said it was an "rv cam". Which is like saying "its hot today". In who's opinion??? Its no thumper, and she still runs out of juice around 4600-4800 hundred rpm. Helpful I know.... Hopefully Robert will catch this post, as I have read most of his on eb stuff...

Brad
 
Hi brad,
I am in denver also and I run a eb 1400, I dont know the jets or the rods I have as I bought the carb used, however it runs very good here in denver. Passes emissions easy.
I do know the accelerator pump lever with the 3 settings. The bottom setting gives the largest accel pump discharge, because it moves the diaphragm on the pump the most. I use the top setting, which is the leanest. I find it works the best between daily driving and 4 wheeling at higher altitude.
 
Thank you for the response. I need to have this truck put back together by this weekend so I can get out and drive it with the new carb. I figure I'll need a day to get a baseline idea as to how it runs out of the box.

Brad
 
brad bedell said:
could anyone provide some good baseline tuning for the above scenario? Newly rebuilt 392 with rpt aluminum square bore manifold, .5" phenolic spacer, rv cam, 14"x3" open air cleaner, 32" tires & 3.54 gears. Also has dui distributor. Edelbrock says to change from the original metering rod, #1451 (.070"x.047) to a #1459 (.075"x.047"), rod only change. This would supposedly change the cruise mode 8% leaner.?. Wouldn't the power mode need to be leaner as well? Additionally how does changing the "pump drive link location" affect tuning? Currently set too the "out of box" middle location? Lastly, in denver with most trips only going up in altitude.

Thanks in advance, you guys have been much more helpful than I've experienced on the "old" bulletin board. With out all the extra opinions....

Happy memorial day!!!,
brad
Click to expand...

Hey brad, I was sleeping and missed your post till michael alerted me.. Sorry!!

After a quick look at your 1405 oob jetting pmj= 100, smj .095 I would leave the jets alone till you get some seat time on it. Believe it or not those jets are already lean for sea level in my experience.

The last sea level hot 392 I jetted for a guy whos engine I rebuilt was pmj= 98, smj =101 needles 68-47 and the orange springs on a 600 cfm performer. Run great, pulls hard to 4800 and takes spot on matting the throttle.

Leaning the cruise mode with the needles is a safe change since you can't hurt it under low power settings.

I do however suspect it will transition to power mode early at your altitude on the orange 5" spring. I would see if it rattles/roughens when going from high power settings under load to reducing throttle when it goes from power to cruise mode. If it does install the yellow 4" power piston springs. It will go to power later. This is a common mod I make to the performer at altitude.

The accel. Pump link should actually be as close to the arm pivot as you can get it at high altitude since fuel signals are weak and lazy. The extra pump shot will prevent the flat spot. Try that at first and after getting the jetting right then play with the pump shot. If it takes rapid throttle advance smoothly try the next hole away from the pivot.

Lean idle settings will exaggerate tip-in flat spots so set best idle at full temp after a long drive then 1/4 -1/2 further out.

Hope this helps.
 
I sure do appreciate you guys helping me out. I took the 'ol 800 apart a few months ago to finally finish up some lingering details I've been overlooking for awhile. It'll be ready for a drive this weekend if I stick to it. I am very curious as to how it will perform as I have added a phenolic spacer and a much larger air cleaner. I suspect my archaic "edelbrock triangle foam air cleaner" was what led to my previous carbs failer. Additionally, I had a serious hot start problem which I believe to be the carb being mounted to the manifold with no heat barrier. Anyway, I do appreciate the your educated baseline starting point. I am no carb tuning guru, but I can lay down one serious paint job.... Lastly, do you feel I am better off purchasing the edelbrock tuning kit, or just the individual needles, springs etc.?

I'll be sure and post results.

Brad
 
I think the tuning kit is a good buy if you plan on getting it perfect. If you are only interested in making it run well but not necessarily the best possible mileage you can do it with one set of needles and maybe a couple of pairs of jets. Kinda your situation weather or not it is cost effective.

The kit is a nice thing to have around for sure either way. I have one but have added probably 10 sets of jets/needles.
 
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