Super Six Fail

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rippedvinyl

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Set it up on my 72, 225. New manifold, Carter BBD, Correct linkge (not a kit) and air cleaner (not stock) but it works.


I'm getting worse gas mileage than I had before. I set it up correctly, but I'm wondering if I missed anything???

4 1/4 turns off the air mix on the carb
Linkage is moving correctly
No rats nests in the manifold.
 
Well what mileage were you getting before and what are you getting now?

4 1/2 turns out seems like a lot. Do you have a vacuum leak? Carter BBD's are known for having throttle shaft leaks.
 
ESP47 said:
Well what mileage were you getting before and what are you getting now?

4 1/2 turns out seems like a lot. Do you have a vacuum leak? Carter BBD's are known for having throttle shaft leaks.
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I was getting around 18, now I would say it's closer to 15. I haven't noticed a leak. everything is pretty solid and tight.
 
DarTT said:
you need to step up the exhaust to really reap the benefits.
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What kind of difference did it make for you? I'm reluctant to keep throwing $$$ into a commuter with less than desireable results. If it made a difference for you or anyone else I would consider it.
 
A better exhaust system is better, of course, but messing with the exhaust will not solve your low-mileage problem. Carburetor operation and repair manuals and links to training movies and carb repair/modification threads are posted here for free download.
 
I had my bbd set at 2 1/2 turns out and got 24-26 mpg in a 70 dart with a 225 and auto. Sounds like you might have a vacuum leak, or your carb is in bad shape. Is it a reman carb?
 
Yup, Reman. I should have known better, but my 1920 reman worked fine. I guess I know what I'm doing this weekend.

Are the remans worth rebuilding? Any links to a reputable carb website? Webber fans?
 
You have a bad vacuum leak on your set up.
As far as rebuilding the Holly in my opinon they work great in a stock ride.

I have a stock Holly off a 70 dart that I pulled of a junk car but could not get the throttle plates to to move. if you need parts PM me.
 
rippedvinyl said:
Are the remans worth rebuilding?
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It was in my case. Mine was jetted way too rich for the /6 and a circlip was missing from the float.

rippedvinyl said:
Any links to a reputable carb website?
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SlantSixDan gave you a link to some good sources for DITY work.

Just for grins, is the exhaust manifold heat riser working properly? The fuel mixture needs some heat to remain a vapor. If the heat riser isn't working, it's taking longer for the engine to warm up which can impact fuel economy.

While on the grins line, are you enjoying the extra power from the 2 bbl? If your driving style has changed as a result, expect lower fuel mileage.
 
did you pull the exhaust manifold off when you swaped intakes? if not they may not be mated correctly, causing a vac leak. read this:http://slantsix.org/articles/manifold-install/types-mounting.htm

on the carb, if the shaft bushings are in good shape, you should be able to get it to work. first read and study that carb link SlantSixDan gave you.:read2: (if your unsure about a carbs basic function, goto holleys website, a great start) then go get yourself a good carb kit. as you take your carb apart, compare gaskets to castings to make sure no passages are blocked by the wrong gasket. when you have it apart you can inspect all the passages for blockage, blow them out with carb cleaner (have a couple cans, you dont wanna run to autozone in the middle of this). if you need to run a wire thru any passages use only brass wire to clean them out. as you put it back together, take your time, study all the info you have, obsses on the details, and it should turn out ok. thats how i did mine. pulled it from the boneyard, rebuilt it myself, it runs great and it even passes smog.
 
rippedvinyl said:
What kind of difference did it make for you? I'm reluctant to keep throwing $$$ into a commuter with less than desireable results. If it made a difference for you or anyone else I would consider it.
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Indeed. I'm interested in his response as well. lol
 
powerwagonpaul said:
did you pull the exhaust manifold off when you swaped intakes? if not they may not be mated correctly, causing a vac leak. read this:http://slantsix.org/articles/manifold-install/types-mounting.htm

I pulled the exhaust off. It's funny, I had no broken bolts, and the entire swap took less than a day. I thought I was in the clear. I should have known better.

Thanks everyone for all your help! I will probably start with a rebuild kit before throwing down more $$$$.
Click to expand...
 
rippedvinyl said:
powerwagonpaul said:
did you pull the exhaust manifold off when you swaped intakes? if not they may not be mated correctly, causing a vac leak. read this:http://slantsix.org/articles/manifold-install/types-mounting.htm

I pulled the exhaust off. It's funny, I had no broken bolts, and the entire swap took less than a day. I thought I was in the clear. I should have known better.

Thanks everyone for all your help! I will probably start with a rebuild kit before throwing down more $$$$.
Click to expand...

Start with spraying some starting fluid around the throttle shafts to see if they are leaking,that is the number one failure with the bbd.
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Please don't use starting fluid. That's like spraying gas in the fire....cause it is. I've seen people burn their hair and face like that. Just use water in a spray bottle. You'll know if you hit a vacuum leak.
 
StrokerScamp said:
Indeed. I'm interested in his response as well. lol
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I knew that would be the first response. "Switch to the 2 /14 exhaust".

Maybe I will keep starter fluid around & a spray bottle. If my face catches on fire and start to melt, I'll have water on hand to put the fire out.

I'm thinking about just getting a carb that needs to be rebuilt (either on here or ebay) and just brining it to the carb shop to be rebuilt. As much as I like working on my own car, sometimes I just assume have someone else do it.
 
rippedvinyl said:
I'm thinking about just getting a carb that needs to be rebuilt (either on here or ebay) and just brining it to the carb shop to be rebuilt. As much as I like working on my own car, sometimes I just assume have someone else do it.
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Yes. "Remanufactured" carburetors are junk. Good rebuilders are still out there; see here and here and here.
 
i learned how to do my own because i coulndt find an honest carb shop. the first guy i took my truck to turn the base gasket over and create a vaucme leak to pass smog...for $140. now i do my own and get better results, i pulled my BBD from the bone yard, rebuilt it, and it runs great and passes smog, with the same tune up.
 
Another thing you will want to do is recurve your Distributor. This is one of the best low cost bangs for the buck you can do on your slant.
Frank
 
rippedvinyl said:
I knew that would be the first response. "Switch to the 2 /14 exhaust".

Maybe I will keep starter fluid around & a spray bottle. If my face catches on fire and start to melt, I'll have water on hand to put the fire out.

I'm thinking about just getting a carb that needs to be rebuilt (either on here or ebay) and just brining it to the carb shop to be rebuilt. As much as I like working on my own car, sometimes I just assume have someone else do it.
Click to expand...

Open it up and do it yourself. They are REAL easy to build. Or if you don't want to try it, send it to me, I'll do it for you. Been doin it for better than twenty five years. Just send me the carb with a kit and I'll send it back just like new.
 
I would use the bbd 2 barrel. Like what's on the 318.
 
StrokerScamp said:
Open it up and do it yourself. They are REAL easy to build. Or if you don't want to try it, send it to me, I'll do it for you. Been doin it for better than twenty five years. Just send me the carb with a kit and I'll send it back just like new.
Click to expand...


Thanks man, I really appreciate the offer. My problem is time. Everytime I start a project on the car, namely disc brake conversion. I need to borrow a car to get to work. I've worn out my welcome borrowing friends vehicles. I don't think they ever want to hear the phrase "I'm thinking about doing this to the dart."

I will probably rebuild it this weekend. The throttle shaft is tight, so that's good. If Things don't get better after the rebuild I'll buy a cheap one and take you up on your offer.

Thanks again.
 
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