302 + Edelbrock 1406 Jetting

[deedubaya]

Hi all,

I picked up my EB about a year ago from someone at much lower elevation. He had just put a new motor (http://www.phoenixmusclecar.com/stock.html#PowerFord Power1) in it and hadn't driven it much. It has 35" tires and 5.5" of total lift. I'm under no delusions of this thing being a commuter vehicle.

The thing runs like a top, but it is definitely running rich. I'm getting about 6MPG on the 55mph highways (maybe this is normal, but I'm hoping not) and there is a strong odor of fuel when I come to a stop while driving.

I'm not sure where to go for jetting and rods though. I live at 5,500' feet and elevation and mostly drive to higher elevations.

Currently
Rods: .074 X .047
Main Jets: 0.95

Looking at the Edelbrock owners manual, it looks like setting 11 is the next (and last!) leaner option with .071 X 0.47 rods and 0.92 jets. I'm unsure if this is the right choice for me.

Does anyone have any relevant advice on what I should try for jetting? I'd appreciate any advice anyone can give!

 

[broncnaz]

Thats pretty crapy mileage I'd say its probably jetted wrong. You didnt mention what gearing your running tho.
In any case are you sure about your rod numbers? I dont see them listed in the chart. I'd also reverify your main jets.
You also need to know what your vacuum readings are when running down the road you could be in the power mode due to low vacuum you may need a different step up spring to keep you in the cruise mode. You only need the power mode when you go up hills or are stepping on the gas.
The best thing to do is look at your spark plugs they will tell you if you need to rejet.
I know I had to lean out the 1406 I was testing on my 302 but Im also a bit lower in elevation so my settings wont work for you plus my engine is probably a little more built.

 

[cs_88]

Sounds like you're running the #7 setting right now. I don't think I'd go to setting #11 that's pretty lean.
According to Edelbrock you want to be 2% lean for every 1500ft.
#11 would put you around 9000ft.
My rig runs well with setting #7, but I'm at about 4500ft.

 

[deedubaya]

Whoops, typo. Running #7 1426 (.095") 1456 (.073" x .047"), cs_88 is right.

So, maybe something more along the lines of #8 or #9 might be a better fit for me? Richer in power mode but leaner in cruise mode?

I will check my vacuum readings as well.

 

[broncnaz]

Still need to check the spark plugs see what they tell you. Im not so sure you need to go richer in the power mode I have a feeling you may be running in the power mode most of the time and that may be your issue. Thats why you need to check your vacuum readings especailly at cruise RPM. If you can go with stiffer step up springs you may be back into the leaner cruise mode without jetting changes.

 

[73azbronco]

a vacuum gage is more valuable to me than a gas gage. Sometimes.

 

[blubuckaroo]

I'd make sure to start with the carb jetted as stock and work from there. The manual will tell you what to start with. Then before rejetting, make sure you're using the correct step up springs. The springs are rated in inches of vacuum. I use my vacuum gauge with a hose long enough to get it into the cab while driving since you need to know the vacuum while driving.

 

[deedubaya]

Thanks for the advice guys!

I checked my plugs, and they are wet, but I've seen worse.

I'll get my hands on a vacuum gauge and see what readings I get.

Once I have firmer footing, I'll go from there.

You guys kick ass!

 

[John Marinan]

I have quite a bit of experience with Edelbrocks at high altitude. I live at 8700ft.
I don't want to bore with you too many details, but I have finally solved my problems.
I replaced the Ebrocks on a Chevy truck, and Bronco with Qjets, problems solved.
I replaced the Ebrock on my Tiger with a 500 Ebrock with 1 jet change. Incredible difference.
I do believe the higher CFM Ebrocks are almost impossible to tune on a high altitude small block. The 500 hundred would do a much better job for you.
My experience only

 

[jim3326]

The problem is it's too much carb for the 302 at that altitude. I had a 1406 on my 289 (at 5000') and had the same problem. I was down to the second to the leanest arrangement (don't re-call numbers) and it was still just a tad rich but it ran great. I was going to get the next set but opted for a 5.0 EFI instead

Jim W.

 

[BRONCOBERT]

Just wonder why it smells of gasoline when you come to a stop, I had the same experience smell of gas when I come to a stop so opened the hood and gas was coming out the top of the Edelbrock carb. Not sure why it would do this but discovered my gas tank was not vented so changed that also my fuel lines were to close to the exhaust and I am in the middle of changing that, hopefully this solves the issue.

 

[rguest3]

Start by tuning with a vacuum gauge and see what you can get. May need a couple sets of plugs to test after running each setting for awhile.

As stated before, you may need to go down to a 500cfm carb. If the 302 is Mildly Modified the 500cfm is pretty good at any altitude. You would get much better throttle response as well.

 

[broncnaz]

Wet plugs(if they are wet from gas) points to floats to high or needle seats leaking.
While I wont disagree with the smaller carbs 600 cfm is not to much its a 4v carb your not running on all 4 barrels your only running on half actually less than half with a edelbrock. Eitherway I've run 600 cfm carbs for years on my 302 and regularly run up to 10,000 ft with no issues yes it runs a little richer yes power is down a little but its not that bad. Smaller carbs do respond better tho but the 600 will work fine.

 

[blubuckaroo]

Just wonder why it smells of gasoline when you come to a stop, I had the same experience smell of gas when I come to a stop so opened the hood and gas was coming out the top of the Edelbrock carb. Not sure why it would do this but discovered my gas tank was not vented so changed that also my fuel lines were to close to the exhaust and I am in the middle of changing that, hopefully this solves the issue.

Gas out the top of the carb? Sounds like too much fuel pressure. Edelbrock is a good carb but it's pretty sensitive to high fuel pressure.

 

[BRONCOBERT]

I was wondering the same thing about high fuel pressure but the problem never happened again after I vented the main tank, although I have low test miles since the restoration. I have a Carter made in the USA pump that works off the engine, is it possible to get too much fuel pressure out of one of these pumps?

 

[blubuckaroo]

I was wondering the same thing about high fuel pressure but the problem never happened again after I vented the main tank, although I have low test miles since the restoration. I have a Carter made in the USA pump that works off the engine, is it possible to get too much fuel pressure out of one of these pumps?

4 psi is enough for an Edelbrock. The reason is, Edelbrock floats put less pressure on their needle valves than some of the other carbs. It's not a problem unless the pressure is high. I ran into that when I tried to run a Carter 4070 electric pump. I finally went back to a mechanical with a regulator.