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Discussion Starter #1
I am restoring a 66 mustang coupe 302-4speed for my sister.The engine is a 74 2 barrel motor cast exhaust manifolds,totally stock.The car will be a Sunday driver and taken to the odd show but I was wondering if I could increase the power a little and maybe pick up some mileage as well.Does anybody have a combo that might do both.The engine needs a total rebuild and I may even stay with the 2 barrel.I was thinking of getting one of those mass produced engine builders to do it with a few of my mods such as cam etc.Any ideas?

 

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How about a spreadbore carb and intake? I've never used one but by principle I'd think you could get the best of both mpg/power (granted you keep your foot of the gas).

I'd look into an electronic ignition upgrade too, a duraspark setup is cheap and will help alot.

I'd call your favorite cam company and see what they recommmend as far as a cam for your setup.
 

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From a fuel economy standpoint it's hard to beat the combination of a mild cam, small 4 barrel carb, higher compression and low restriction exhaust. Spread bore carbs such as Thermoquads and Quadrajets are excellent but it's hard to find a manifold that they would fit without using adaptors. Another excellent combination for your engine would be to find a stock intake manifold and carb from an 83 to 85 5.0 litre HO Mustang engine. These cars made good power but were capable of getting 25 - 30 MPG during highway cruise conditions because they have annular boosters in the primaries and the carb calibration at part throttle was quite lean. As cams go, it depends a lot on what rear end gear ratio and tire size you're running. The cam that's best for fuel economy with 2.79 gears and overdrive is far different than the ideal cam for a car with 4.11 gears and a C4. Crane lists a best cruise RPM for each cam and they will tend to get the best mileage if you're cruising in that RPM range. I will say though that cams with wide centerline angles (114 degree or wider) tend to be much more efficient at part throttle than cams with under 112 degrees of lobe seperation.

<font size=-1>[ This Message was edited by: mach1morgan on 4/17/02 8:25am ]</font>
 

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I would not recommend the Quadrajet. They guzzle gas like you wouldn't belive. It seems like those tiny primaries would give you excellent gas milage, but they don't. I think it has to do with their funky main metering system. Also, that two barrel will guzzle gas too. I'd get a cheap low rise dual plane intake and throw a Holley 4160 on it. You should get around 18-20 mpg. Plus, it'll have some balls when you get on it.
 

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4 speed and 3.25 gears, youd be lucky to get 18mpg. i have a 68 coupe with a stock 289, stock 4bbl intake and 600 vaccum secondary holley with a C4 and 2.79 gears, stock manifolds and 2" dual exhaust with turbo mufflers. when i was driving it to school regularly i got about 14-15mpg average with about 1/2 city 1/2 freeway driving. The best i ever got was about 18 or 19 on a 2 hour freeway trip with barely any traffic at all. put some 3.25 gears in that and expect to drive about 50-55 mph on the freeway to acheive the same mileage. for the best mileage i would recommend a good rebuild with a very mild cam, aluminum intake, holley 4160 (maybe the 450cfm version if you want to spend the extra money over the 600) a set of small tube headers and a good 2.25" dual exhaust with some turbo mufflers. And most importantly make sure everything is tuned without that you could forget everything. save yourself the headache and buy a new carb or one rebuilt by a competant shop. then if you really want to see an improvement on the highway, throw in a 5 speed
 

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Discussion Starter #7
I know the 3.25s will hurt mileage a little but I thought they would help give it a little more jump.The 4-speed will give a little better mileage than an automatic as there is no slippage and less power loss.Anyone have experience with a cam that worked well and gave better mileage or should I just get a stock cam.I'm shooting for around 200hp and 20ish mpg.
 

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Have you considered a retro fit fuel injection? I did one on a 460 motorhome(20') that was getting 6, now it gets 10. As for the cams, I have done a couple in big blocks, big Olds, & a couple of FE's with good results. Even the 460's got inproved mileage, up to 4 + with tuning.
 

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I'd recommend an Edelbrock 600 carb on a dual plane intake, along with a cam measuring around 214I/220E @ 0.050 with a 110-112 lobe seperation, with long tube headers (tri-y's are fine) and a free flowing exhaust.

Build the engine to be efficient at whatever rpm it's going to be running. If it sees much highway use with the 3.25 gears, the above cam will be about perfect for mileage and power.

You can't beat an Edelbrock carb for street power and mileage. They are totally superior to the Holley 600 vacuum secondary (#1850) unit.

Good Luck!
 

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Discussion Starter #10
The retro-fit fuelie is a great idea but its just not in the budget,nor is the 5-speed.What kind of intake would be good.The stock 5 litre aluminium 4 barrel has already been mentioned.
 

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I'd use a dual-plane intake for low-end & economy. Performer 302 is a good intake. A smaller(600 cfm) carb is a good choice as well. Small tube headers & a 2"-2 1/4" exhaust will help as well. Choose your cam wisely & ask questions from all the manufacturers. I have not used Edelbrock's cams but have heard good things. There's no reason you can't get 18-20 highway. My 460 F-100's always do.
 

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About 10-12 years ago I had a 75 F100 with a 428 SCJ and a 69 Mach 1 with a mild 4V Cleveland. For about 4 or 5 years I had a 30 mile highway commute to work, so over that time I experimented with both of them trying to find what would give me the best combination for fuel economy. I recorded all my results and always used the results of more than one tank of fuel so that the results would be more consistent. Out of the literally dozens of carbs I tried 3 of them always provided fuel economy that were a big step ahead of everything else. Carter Thermoquads, Quadrajets, and the OEM Holleys that came on 83 to 85 5.0 litre Mustangs. These carbs always seemed to get 2 or 3 MPG better than I could get with my best AFB setup and literally 4 to 6 MPG better than I could ever get with even leaned out squarebore Holley's whether they were 1850's, 3310's, 7010's, 6919's or any of the double pumpers. To get the best fuel economy with the Thermquads and Quadrajets, I had to adjust the plungers for the primary calibration needles so that during high vacuum cruise condition the needles would be at the lowest position that still allowed the engine to respond well to just slight increases in throttle opening. I also ran a few different cams on both engines. The best cam with the Cleveland which was a 3.00 geared, 25 inch tired, C4 car was with an Erson 208-214 cam that had a 114 degree lobe seperation. With my 3.73 geared 27 inch tired, 428 SCJ powered, C6 truck, I got the best mileage with a Crane 222-234 114 lobe seperation cam. I tried some small 108 and 110 degree l/s cams and they weren't great from a mileage standpoint. Low restriction exhaust and headers also seemed to make a huge difference, but on the other hand big ignition systems didn't make a measurable difference over a stock Duraspark ignition. In the end though I was able to consistently get 17 to 19 MPG with my F100 and 22 - 25 MPG with the Mach 1 and I did learn a lot. I hope this info can help a bit.
 

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Discussion Starter #13
Mach1Morgan how did the carbs compare performance wise.I like the sound of the 83-85 mustang setup as I might be able to find the whole setup at a swapmeet.The only problem is that carb is pushin 20 years old,might be hard to find one thats not worn out.
 

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Discussion Starter #14
A question for N2O Mike do you agree with the power combos and the hydraulic cam selections on the HTTP://www.jason.fletcher.net site? I picked a cam with specs close to what you suggested(XE-256H-10)but this seems a little radical for a very mild streeter.Opinions please.
 

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On 2002-04-19 02:07, frdnut wrote:
Mach1Morgan how did the carbs compare performance wise.I like the sound of the 83-85 mustang setup as I might be able to find the whole setup at a swapmeet.The only problem is that carb is pushin 20 years old,might be hard to find one thats not worn out.
Since I was running a 4V Cleveland and a 428 SCJ it makes sense that the 800 cfm Thermoquad and the 750 cfm Quadrajet performed better than the smaller Holley in those applications. I would give the Thermoquad the edge as it seemed to make the most power. I have run Thermoquads, Quadrajets and those OEM 590 Holley's on mild 302's though and found out that the Thermoquad was too big for good of the line power, the Quadrajet was marginal but worked and that the 590 Holley was the best. Of course if you had a 2500 stall the Thermoquad would probably work excellent.
Yes, I've seen the 5.0 Liter carb and manifold setup at swap meets before. I've seen kits for drilling and rebushing throttle shafts before as well although I can't recall where.
 

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On 2002-04-19 02:55, frdnut wrote:
A question for N2O Mike do you agree with the power combos and the hydraulic cam selections on the HTTP://www.jason.fletcher.net site? I picked a cam with specs close to what you suggested(XE-256H-10)but this seems a little radical for a very mild streeter.Opinions please.
You won't really pick up any significant power or mileage by 'just' swapping cams. If you follow my whole recipe (listed above) the car should pick up a significant amount of both. Your cam choice (if you follow the above recipe) should be perfect.

Good Luck!
 
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