Carb out of tune? Should be closer now...

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Carb out of tune? Should be closer now...

Postby ColinOpseth » Sat Oct 16, 2010 4:20 am

When I bought my Vega it had an Edelbrock 1406 on it. The owner told me he changed the jets and metering rods to "tune it." I now know that the 327 had a bad cam in it, so obviously the metering rods and jets were a pointless attempt at getting it to run better.

I pulled .070 x .047 rods out of my carb today and put the stock .075 x .047 rods in. Changed the primary .101 jets back to stock .098 and the secondaries were unchanged at .095. What does all that mean?

I'm assuming that the .070 rod (smaller) allowed more fuel to flow, and coupled with the larger jets created a very rich condition? Per the 1406 manual, the .101 jet is 8% (two steps) larger than stock. And having the stock secondaries with the smaller rod continued the rich condition? I do know that the car ran pretty rich, and one time dieseled for about 45 seconds when I shut it off. Would running this rich kill power, too? I know it's pretty hard on the cylinder walls to have that much fuel entering the combustion chamber.

Am I making sense? I don't know a lot about the actual functional parts of a carb. Trying to learn, though. I guess what I'm asking is whether my car should run better now than before? It smoked a bit on acceleration.

Thanks,
Colin
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Re: Carb out of tune? Should be closer now...

Postby cjbiagi » Sat Oct 16, 2010 8:29 am

Yeah, he made two changes to richen it up, larger jets coupled with smaller metering rods. These are 2 step rods so the larger part (.070) sits down in the jet during high vacuum levels. When the vacuum level drops the springs will lift the jet out of the rod and richen it up some more. The point that it happens is determined by the springs in the carb which can also be changed to adjust the tip in point.
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Re: Carb out of tune? Should be closer now...

Postby gerbsinmd » Sat Oct 16, 2010 8:34 am

sounds like you are on the right track Colin. And Yes, running rich will kill the power, if its smoking it will really kill the power. Like a dyno tuner told me, LEAN IS MEAN! Just don't let it ping.
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Re: Carb out of tune? Should be closer now...

Postby marco_1978_spyder » Sat Oct 16, 2010 8:17 pm

When I bought my used 1406 this past summer, the owner told me the same thing, and I believe had the same exact step up (richer) jets in there. (My project journal has all the details I believe) .... In my case the jets were stock, but the step up spring was also changed..(this spring controls how fast the extra fuel for the secondaries kicks in)..

My springs were allowing fuel to start flowing sooner, creating a rich transition, to an already rich carb. (for my 310ci)
Mine had silver springs but was calling for either pink or orange I cant recall. I installed them and reset the idle mixture screws again as per some youtube instructions and the manual.

The difference in crispness and drivability is downight awesome. And every time I start it up, the performance is consistent.

And the floats weren't set right...that made a big difference too.

Oh and then lastly I actually hooked up the electric choke... and got it working right, and I love it!! The car runs great on colder days I can back it out of the garage smoothly right away. This car hasn't had an electric choke since probably 1989...lol
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Re: Carb out of tune? Should be closer now...

Postby ColinOpseth » Sat Oct 16, 2010 10:18 pm

Marco,
I think that my step up springs are stock? They didn't look like they were painted. Per my book the stock ones should be unpainted. Well, they were kinda bronze or whatever but definitely not red or yellow. It's still pretty warm but I'll probably follow your lead and hook up the choke. I want to drive it quite a bit. I've driven cars without a choke and I agree that it isn't a whole lot of fun warming it up. Did you have to adjust yours? Mine is two notches below half way.
'72 Vega with '93 Camaro LT1/M29 T56/12 bolt 3.31. 16" IROCs all around. Sanderson headers into duals with an H-pipe and Flowmasters. It's loud but at least it's faster than your grandma's Buick. pwned.
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Re: Carb out of tune? Should be closer now...

Postby ColinOpseth » Sat Oct 16, 2010 10:24 pm

OK, so I'm going to eat my words here. I quickly checked online and found a post at: http://www.hotrodders.com/forum/edelbro ... 59649.html

As described in the post, the springs are from left to right. I am running the stock.

3" Hg (blue), 4" Hg (yellow), 5" Hg (orange), 7" Hg (pink) and 8" Hg (plain) springs..

The 1406 comes with:
98 primary x 95 2’ndary jets
75 x 47 rods
Yellow (4”) step-up spring

The 1405 (manual choke 600) comes with:
100 x 95 jets
70 x 47 rods
Orange (5”) step-up spring
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'72 Vega with '93 Camaro LT1/M29 T56/12 bolt 3.31. 16" IROCs all around. Sanderson headers into duals with an H-pipe and Flowmasters. It's loud but at least it's faster than your grandma's Buick. pwned.
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