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Carb Tuning and Engine Timing

handloader90

handloader90

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I'm relocating from Colorado Springs, CO to Fort Campbell, KY in about three weeks and I'm going to have to rejet my carb to accommodate the new elevation change.

The elevation down there is right around 500 feet and wanted to know if you guys had any recommendations for primary and secondary jet size and metering rod size.

I have an Edelbrock 1406, 4 bbl, 600 CFM, Electric Choke up top of a Edelbrock Performer RPM intake sitting on a 350.

I'm going to buy the Edelbrock calibration kit specific to my model carb.

Also, I want to get this thing just right and have been reading up on using a Vac Gauge to get the Air/Fuel mixture just right. Does anyone recommend a good gauge for the job? I was looking on google and found one by Holley, but the layout of the numbers didn't match up to the other gauges that I saw.

Which port on my cart would I hook this gauge up to? I read somewhere that I hook it up to the small port on the passenger side where the vac advance from my dizzy hooks up to, just want to confirm this is the right port.

Also, I was in the process of putting a Canton Billet Aluminum 4 Hole 1" Spacer between my intake and carb (which didn't work out that well) and hit the dizzy and it moved, the clamp was a little loose, so I threw my timing off. Well, I timed it by ear and got it back close, but it idles at around 1000 RPM and I don't really like that. I've adjusted the idle screw on the carb to keep the RPM's a little higher than usual to keep it running while its in gear, also I made sure I was TDC before I messed with anything.

I want to get the Innova 5568 TIming light, has RPM and dial back and all that good stuff, does anybody recommend a better one besides a Snap-On or Mac? I don't have any of the MSD ignition stuff in my truck either.

My trucks already on the car carrier, so I have a few weeks to collect this stuff and plan on timing the engine and tuning the carb as soon as the truck gets off the carrier.

If anyone has any tips or recommendations or suggest any other things i should aquire prior to me doing this please let me know!
 
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Hi n-martin,
The only thing I can help with is ......Remember Edelbrock's don't like more than 5.5 PSI fuel pressure.

Good luck on your move.:D
 
Thanks for the info and the good luck! How do I incorporate that into my tuning, do I need to hook the gauge up to another port to read the fuel pressure or will I get that info while I'm doing the air/ fuel mixture?
 
You want to hook the gauge to manifold vacuum,a port thats on the intake or at least below the throttle butterflies on the carb--one that has suction at idle..

I usually use the one behind the carb thats normally used to supply vacuum to the tranny modulator on older engines...usually there is at least one vacuum port you can hook the gauge too thats not being used and blocked off ..dont use the PCV valve port,that should be left alone & connected while you tune it to acheive the highest vacuum ..the PCV valve is a "controlled" vacuum leak and removing it to hook the gauge to its port will give you false readings,when you hook it back up it'll show a different reading..

You can get a vacuum gauge / fuel pump tester for about 15 bucks at a parts store,K-D makes a decent one..(only good for testing mechanical fuel pumps though,they go up to only 15 PSI--no good for most EFI engines with electric fuel pumps)..you use the fuel pump tester by hooking the hose on the tester to the fuel line,and run the engine on whats left in the carb bowl...be sure the hose cant pop off while its running!..
 
Thanks for that info. I have a mangled vac port right behind my carb that I was going to pull out and plug the hole, but I guess I'll pick up a new fitting and use it to tune this carb in a few weeks.

Also, thanks for the recommendation on the gauge. I order from Summit a lot and found some nice vac gauges. I was looking at an Actron model and an OTC model that I might get when I order my timing light.

Thanks again!
 
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1406 is factory calibrated to sea level so unles it was recalibrated for colorado I wouldn't mess with it. First fix your vacuum leak. Then adjust your idle mixture screws ( close them all the way then turn out 2 1/2 turns) See if it runs. If so ball park your idle speed and set your timing. Go back to the mix screws and one at a time slowly close until the engine stumbles then turn back a 1/4 turn. Set your idle speed for the last time.
 
earnett said:
1406 is factory calibrated to sea level so unles it was recalibrated for colorado I wouldn't mess with it. First fix your vacuum leak. Then adjust your idle mixture screws ( close them all the way then turn out 2 1/2 turns) See if it runs. If so ball park your idle speed and set your timing. Go back to the mix screws and one at a time slowly close until the engine stumbles then turn back a 1/4 turn. Set your idle speed for the last time.
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I bought the 1406 new while in Colorado and installed the correct jets and metering rods for the altitude.

I have the factory ones that were in there when bought new, but I don't remember which jets are which. Are the stamped numbers on the jets readable with a magnifying glass, if so I won't need to pick up the calibration kit.
 
earnett said:
Fact calibration is .098 main jet ,075 x 047 metering rod, .095 secondary jet. Id think at 500ft your close enough.
Click to expand...

Thanks for that info! I'm going to try and see if I can read the numbers on the jets somehow once I get home.

Thanks again!
 
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