i made the conversion to a super six this summer and my Mpg is in the garbage at the most im getting 8mpg she idles rough when warm and in gear the heat riser was snapped off so i have left it open all the time and i changed the vacuum advance but i have no idea if its working its new but when i disconnect it, while parked the engine stays the same no change in idling or anything.--ps i am in the Los angeles region and not many mechanics know about the good old slant any recommendations?

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1970 Dart Swinger Matching Numbers..

Check the operation of your choke. Are you using a 318 or slant six BBD?

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Casually looking for a Clifford hyperpak intake for cheap.

slant 6 bbd..but i don't have the choke connected i thought as long as i would warm up the car it would suffice..ps i dont have one..i just have the one bbl choke in the exhaust manifold since i never found one for the 2bbl

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1970 Dart Swinger Matching Numbers..

Do you have a photo of the top of the carb with the pie tin removed?

What is the condition of the carb? Tested for vacuum leaks?

Is the carburetor and intake all you changed? How about the kickdown linkage and transmission lever for the TV?

CJ

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Part of Tyrde-Browne Racing

the carb was rebuilt twice! the first time the place did not replace the bushings and huge vacum leak through there i still think the carb is acting up, the kick down linkage is from the original 1bbl i just elongated it by straightening out here and there.. also it acts up alot when its warmed up at the stop lights it shakes and turns off when i get off the highway but when i drive it cold its nice and smooth..

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1970 Dart Swinger Matching Numbers..

Have you visited the carburetor information in the FAQ? A rebuilt carb is not a tuned carb. Sounds like your running rich. A rebuilt 40 something year old carb still may be a useless POS.

Have you adjusted the valves recently?

Do you get full operation of the TV at WOT with your modified kick-down?

CJ

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Part of Tyrde-Browne Racing

i do get full response i beleive if i read the article correctly there is no slack at WOT and the rod goes alll the way back at WOT i will have pictures later this evening up because i know theres something is up..and yes i had the valve adjusted the engine was rebuilt 1 month ago

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1970 Dart Swinger Matching Numbers..

Looking forward to seeing the photo.

Double check your float level, and verify the adjustment for the metering system. Verify passages are clear. Verify the enrichment circuits are working correctly.

I feel for you. Finding a re-buildable BBD is getting to be slightly harder than locating the Holy Grail.

CJ

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Part of Tyrde-Browne Racing

What was your mileage before the change to 2 bl.

Sam

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unfortunately when i bought her she had a bad piston later found out it had holes on the piston head so i was getting bad millage from the get go..but according to the ex owner he was getting 19-22 highway.. how would i check the float levels?

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1970 Dart Swinger Matching Numbers..

Go to the FAQ near the top of the Engine index.

find the link to Carburetor operation & repair information. Select the Carter BBD link.

You will find what you need to know there.

CJ

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Part of Tyrde-Browne Racing

Jose, I'm in the los angeles area, pm me your info and maybe we can get together.

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70 Plymouth Valiant 4dr

How far are you driving, and at what speeds?

The reason I ask is we had a member that was driving less than two miles on surface roads for his commute. That sort of thing needs to be considered.


CJ

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Part of Tyrde-Browne Racing

Bad mileage can be ignition, or fuel. Usually is it is a little of both. If it got good mileage before, (18-22 is fine for an automatic), then focus on fuel as the culprit. I would check your power rods and see if they are adjusted properly. If they are riding too high, you are operating rich all the time. Various BBD's had various setups there. Some power rods were adjusted with an easily accessible cam. If this is your type, then you can check that out. In any event check out the rebuild instructions and see how this was supposed to be set up.

Also check your electrical. With the car running, check the votlage at the red wire on the alt, and also check the high side of the ballast resister. They should be nearly the same. If there is a V drop there, you will see it in your mileage. This is true especially if you have and electronic ignition. Points ignitions were not was voltage sensitive. Accept no less than .5 volts drop or less.

Sam

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1970 Dart Swinger Matching Numbers..