Dumb carb questions

[Dino]

I know nothing, please forgive my ignorance.

After the winter I want to do something with my current carb setup.  I need to install a valley pan with crossover block and have a few more options to choose from.  This is where I need some help.

69 Charger with a '71 440HP, headers, 727, 2.96 open gears and 215-70-14 tires.

I currently have an Edelbrock Performer (non RPM) intake manifold with an Eddy 1407 carb with electric choke.  It is a very reliable setups but it runs really rich at idle, and maybe a bit lean under load.  I get the occasional bog from a stop.  Mpg is pretty bad, around 11mpg on the highway, I don't even want to know what it does in town.

I also have the '71 only cast iron intake #3512501 which I was told here by the pros is a better unit than the eddy so I can either swap the intakes and get the tune up kit for the carb and hope for the best or go with something else.

I have a Carter thermoquad 6545S, probably off a truck or motorhome, and I hear that if properly tuned they will give better fuel mileage and will run pretty good.  Can I fit one of those on the 71 intake or do I need another one?  My primary use for the car is cruising so getting the best possible mileage is high on the list.  It has plenty power right now so as long as I don't lose too much I won't complain.  The carb needs a good cleaning but I think it looks pretty good.  Where would I go for a rebuild kit?

Once I have this thing rebuilt and tuned, how reliable is it?

Thoughts?

[Chryco Psycho]

you need the spread bore intake for the TQ carb , any local parts supplier should be able to get a generic rebuild kit for the TQ , IMO the TQ is far better than the 1407

[Dino]

you need the spread bore intake for the TQ carb , any local parts supplier should be able to get a generic rebuild kit for the TQ , IMO the TQ is far better than the 1407

I guess there's no pint in cleaning up the '71 intake then unless I can use a square to spread adapter on it.  Now the stock spreadbores are '74 and later correct?  So they are considered smoggers.  I know the performer takes both square and spread so should I just stick with that one since it's just a cruiser?

Thanks CP

[elacruze]

Being close to stock with that high gear, I'd not worry much about the intake manifold-they're all pretty much the same below 3500 rpm (talking dual-planes) Keep what you have, save the cash. Rebuild the carb and get a good tuning manual, you'll be happy with it. I never forget that there are an enormous number of hours in engineering and testing those old 'stock' carbs-they aren't just some crap whipped together by amateurs. Just because they came stock doesn't mean they suck.

[Dino]

Being close to stock with that high gear, I'd not worry much about the intake manifold-they're all pretty much the same below 3500 rpm (talking dual-planes) Keep what you have, save the cash. Rebuild the carb and get a good tuning manual, you'll be happy with it. I never forget that there are an enormous number of hours in engineering and testing those old 'stock' carbs-they aren't just some crap whipped together by amateurs. Just because they came stock doesn't mean they suck.

Ok I'll stick with the performer, it sure doesn't hurt to try.  I don't know how succesful I'll be in getting the thermoquad to run as it should, I hear they are tricky, but it's certainly worth a shot.  Realistically, how much gain in fuel mileage am I looking at?  I don't expect it to be too much but every bit helps.  If I can get it dialed in so I'm not throwing raw fuel out the tail ends and running lean at wot, I'll be a happy camper, everything else is a bonus.

[elacruze]

I'd guess that the stock TQ will be close enough on yours to satisfy, but of course anything can be optimized over time with some good reference manuals and effort.

[Dino]

I'd guess that the stock TQ will be close enough on yours to satisfy, but of course anything can be optimized over time with some good reference manuals and effort.

Meaning I can get a tuning kit with jets and metering rods for this one and tune it optimally?  I would actually like to give that a go.  I want this engine running as efficient as possible.  I can only assume that right now it is tuned for economy seeing it came off a smogger truck so it may indeed be ok for my use but I wouldn't mind tinkering with it a bit more passed a rebuild.  From what I hear, I shoujld be able to get it to cruise nicely with better mpg and even increase the bottom end a bit.  I also hear that it may give me better throttle response.  Since cruising and driving it to work is what I do most of the time this will be great.  If I can now tune it so that it still roars and roasts the tires when I drop the hammer, now we're cooking!  I know, high gears, but my skinny tires roast quite a bit right now.

[71bee]

The Eddy Performer is a "decent" streetable carb, but its not a perfect fit for a 440 HP engine. the Thermo-quad is an excellent carb, as long as you take the time to get familiar with it's functionality. the Eddy Thunder Series AVS is also a great carb, as they have the tuneable secondary air valve (like the T-Q) to eliminate bogging &  produce more CFM's than the AFB models.

[elacruze]

Sounds like you're on the road to happiness with the TQ. Don't forget, once the carb is on and running, optimize the ignition timing before trying to dial the last bits on the carb.

[Dino]

Didn't know that about the thunder series carb, it's good to have options.   Thanks!

I'll be sure to do the timing before final tweaking.

I was looking at the rebuild kits and see there's a few different ones.  I wanted to go with the hygrade 657c kit.  Is that one okay or should I go for one like this?  http://www.carbkitsource.com/carbs/kits/CK109.htm

[71bee]

Didn't know that about the thunder series carb, it's good to have options.   Thanks!

I'll be sure to do the timing before final tweaking.

I was looking at the rebuild kits and see there's a few different ones.  I wanted to go with the hygrade 657c kit.  Is that one okay or should I go for one like this?  http://www.carbkitsource.com/carbs/kits/CK109.htm

Auto Zone sells the choke pull-off for only 12.+ (part # CP47). their Sorenson re-build kit is just as good as any i've come across & will run you $28.00 (part # 96-256C '72-'74 models) or $19.00 (part # 96-570 '75-'85)


If you want a good set of brass floats, I have plenty of extras I could clean up & send you for $10 pair + shipping.

[Dino]

Didn't know that about the thunder series carb, it's good to have options.   Thanks!

I'll be sure to do the timing before final tweaking.

I was looking at the rebuild kits and see there's a few different ones.  I wanted to go with the hygrade 657c kit.  Is that one okay or should I go for one like this?  http://www.carbkitsource.com/carbs/kits/CK109.htm

Auto Zone sells the choke pull-off for only 12.+ (part # CP47). their Sorenson re-build kit is just as good as any i've come across & will run you $28.00 (part # 96-256C '72-'74 models) or $19.00 (part # 96-570 '75-'85)


If you want a good set of brass floats, I have plenty of extras I could clean up & send you for $10 pair + shipping.

Thanks!  I have no idea if I need the floats or not, guess I'll have to open up the carb and see what the story is so I'll get back to you on that.  Is the choke pull off commonly renewed or can I use the one I have?  Any way to test it? 

[ACUDANUT]

I disagree.  I love the Holley 750's on big blocks.
If you want good and efficient fuel milage, your in the wrong hobby.

[Dino]

I disagree.  I love the Holley 750's on big blocks.
If you want good and efficient fuel milage, your in the wrong hobby.

Many seem to like a Holley 750, but I have an Eddy 750.   

Oh not to worry, I'm not looking for 20 mpg, I know that's out of reach.  Not really looking for good fuel milegage, just better.  I hate throwing fuel out the back, that's just waste, hence the engine is not running efficiently as it should.  If all it can do is 14 mpg at it's most efficient state then that's how it is, but I'm not there yet.  This also goes beyond simple fuel use.  An efficient engine is a reliable engine, meaning less surprises down the road, that's all I'm going for.  The Honda sets off the lousy mileage so if I only gain a few mpg in the process I won't complain.

[elacruze]

I made one tankful @ 14.6mpg with my 505" motor with 3.20 rear axle (4.10:1 x .8 GearVendors OD) so 20mpg isn't out of the question, in fact I expect to achieve that goal with this motor dialed in better and a 3.55 gear + the OD.

[71bee]

Thanks!  I have no idea if I need the floats or not, guess I'll have to open up the carb and see what the story is so I'll get back to you on that.  Is the choke pull off commonly renewed or can I use the one I have?  Any way to test it? 

The pull-off is comon to failure on all carbs. after 30 some odd years, I would definitely snag a new one, as they are relatively cheap & difficult to change without tearing the carb apart.

To test your pull-off, simply pull the vacuum line from the carb, push in the linkage diaghram on the pull-off & hold your thumb over the vacuum tube. if the link stays pushed in against the back of the housing, try pulling the link back out. if it won't budge, your pull-off is still working correctly. if the pull-off pops back out to it's original starting point after capping the vacuum line, then your pull-off is leaking, toss it.

[Dino]

I made one tankful @ 14.6mpg with my 505" motor with 3.20 rear axle (4.10:1 x .8 GearVendors OD) so 20mpg isn't out of the question, in fact I expect to achieve that goal with this motor dialed in better and a 3.55 gear + the OD.

Be prepared to have your brain picked a bit more in the future. 

[Dino]

Thanks!  I have no idea if I need the floats or not, guess I'll have to open up the carb and see what the story is so I'll get back to you on that.  Is the choke pull off commonly renewed or can I use the one I have?  Any way to test it? 

The pull-off is comon to failure on all carbs. after 30 some odd years, I would definitely snag a new one, as they are relatively cheap & difficult to change without tearing the carb apart.

To test your pull-off, simply pull the vacuum line from the carb, push in the linkage diaghram on the pull-off & hold your thumb over the vacuum tube. if the link stays pushed in against the back of the housing, try pulling the link back out. if it won't budge, your pull-off is still working correctly. if the pull-off pops back out to it's original starting point after capping the vacuum line, then your pull-off is leaking, toss it.

I'll give that a try later on just to see how it works but I'll definitely get a new one.  I don't want to put all this effort in making my car run as best as possible and skimp on a $12 part.