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Author
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Topic: Cam, Gear, MPG Comparo
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MidLifCrisis
Gearhead Posts: 673
From: Frederick County, MD
Registered: Oct 2001
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posted 10-07-2006 02:43 PM
 
After having a trouble free summer of driving my '67 vert. I have a yearning to tinker with the motor. My current set-up is a 289 with Holley 600 VS, Performer intake, CompCam XE262, ported stock heads, Hi-Po exhaust manifolds into 2 1/4" duals, 2.79 rear gear.The power doesn't really start ripping until about 3K and then by 4500 it drops off. I understand the heads and lack of headers are a hinderance to more power at higher RPM, but I wish to stay stock for appearance purposes.
Mileage wise I can get 15mpg on a good day, but there aren't enough good days, mostly 12mpg around town.
Looking for a cam, gear combo that offers better mileage so that a rear gear change wouldn't cause a terrible drop in mileage, OR possibly only a cam change that offers better milaage and comes on stronger at lower RPM. Any body running the Edelbrock Perf Cam? What are the combos you guys are running and your MPG? Charlie
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Fastymz
Moderator Posts: 22791
From: Reno Nv M&M #1240
Registered: Apr 2001
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posted 10-07-2006 03:25 PM
Charlie, in my opinion rear gears would give the best all around RPM pick up for the money. 
Something in the 3.55 range would work great. With my set up now if I can stay out of it I can get 12mpg. Thats with 3.91 gears,the great thing about the gears is they get you to your power range and keep in your power range longer.
I don't think you need more cam. just my .02------------------
oddly obsessed with big scoops on little Mustangs HOOD HACKERS DELIGHT!
My Pics 13.563 @ 108.64 [This message has been edited by Fastymz (edited 10-07-2006).]
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mustangboy
Gearhead Posts: 1343
From: Ont, Canada
Registered: Mar 2002
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posted 10-07-2006 09:59 PM
Before trying a different cam or gears I would try playing with the carb. Maybe even a different carb if mileage is a big issue.My totally stock 68 J code motor used to get in the low 20mpg range on the highway with a set of 3:00 gears....A set of headers would wake up the performance and probably give you better mileage as well.A set of tri-ys looks nearly stock to me.You could say they were a shelby option ------------------
68 J-Code,Sprint,306 4 speed,4.11s 13.69@101...............
66 coupe 289 4 speed, 3.20 cruiser http://mustangsandmore.50megs.com/MembersPics/mustangboy.html http://mustangsandmore.50megs.com/MembersPics/mustangboy2.html
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MidLifCrisis
Gearhead Posts: 673
From: Frederick County, MD
Registered: Oct 2001
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posted 10-08-2006 05:22 PM
Yeah, I want it all- blinding speed and 40MPG, but that's just the way I am.  Ron, the gears would give me the seat of the pants increase in accellaration that I am looking for, but I don't want a drop in MPG. Mustangboy, the Holley carb has been tuned pretty close for my application. I am sure there is room for marginal improvement, but the jets were dropped 3 sizes and the squiter sized up to compensate at WOT. I am thinking mostly a milder cam or one that will work better with what I have to increase the mileage, before I drop it by adding more aggressive gearing. Any suggestions? Thanks, Charlie
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buening
Gearhead Posts: 317
From: Decatur, IL
Registered: Mar 2005
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posted 10-10-2006 05:35 PM
I have a 351w, stock heads, hooker comp headers with 2.5" stainless magnaflow exhaust, CompCams XE262H cam, performer rpm intake, edelbrock 1405 (600cfm manual choke), and 3.00 open 9" rear and i just got 18mpg on the highway with some spirited city driving. I get 10mpg purely city driving though  Just a reference point with a larger motor.------------------
1970 Grabber Blue Mach 1 H-code
1970 Fastback
2003 Torch Red Mustang
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MidLifCrisis
Gearhead Posts: 673
From: Frederick County, MD
Registered: Oct 2001
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posted 10-10-2006 09:35 PM
quote:
Originally posted by buening:
I have a 351w, stock heads, hooker comp headers with 2.5" stainless magnaflow exhaust, CompCams XE262H cam, performer rpm intake, edelbrock 1405 (600cfm manual choke), and 3.00 open 9" rear and i just got 18mpg on the highway with some spirited city driving. I get 10mpg purely city driving though Just a reference point with a larger motor.
buening, seems like you've got close to what I have. I am running a 2.80 open 8" rear, and you still get 3mpg better than I do. Maybe it is better fastback aerodynamics over a vert. Where do you feel your power come on? I suspect my cam isn't degreed properly. If I yank the water pump off the front of the motor, I just need to know that if the cam IS set-up properly that there is a better cam selection that I can put back in. Thanks for the feedback. Charlie
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mustangboy
Gearhead Posts: 1343
From: Ont, Canada
Registered: Mar 2002
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posted 10-10-2006 09:40 PM
quote:
Originally posted by MidLifCrisis:
buening, seems like you've got close to what I have. I am running a 2.80 open 8" rear, and you still get 3mpg better than I do. Maybe it is better fastback aerodynamics over a vert.I
I bet its the headers 
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68 J-Code,Sprint,306 4 speed,4.11s 13.69@101...............
66 coupe 289 4 speed, 3.20 cruiser http://mustangsandmore.50megs.com/MembersPics/mustangboy.html http://mustangsandmore.50megs.com/MembersPics/mustangboy2.html
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MidLifCrisis
Gearhead Posts: 673
From: Frederick County, MD
Registered: Oct 2001
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posted 10-12-2006 10:04 PM
mustangboy, I would bet you're right. I am sure I am giving up a couple MPG and a bit of HP by not using hearders.
BTW, what cam are you using in your 66 & 68? Charlie
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buening
Gearhead Posts: 317
From: Decatur, IL
Registered: Mar 2005
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posted 10-13-2006 11:30 AM
I feel the most power between 3000 and 4000rpms. The cam pretty much done that for me. In my opinion the car is a dog off the line, with that cam and those rear gears. It'll sure pass a car on the interstate in a hurry lol. My edelbrock carb is sucking air through the throttle shafts so it is running a bit lean. This may give me a little bit better fuel economy, but the longtube headers and exhaust probably contributed most of it. I made the mistake of reusing the stock pistons when i rebuilt the motor. They were perfect and low miles, plus i was on a budget at the time. This pretty much shot myself in the foot for adding AFR heads. Oh well, it'll be a 408 stroker eventually ------------------
1970 Grabber Blue Mach 1 H-code
1970 Fastback
2003 Torch Red Mustang
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mustangboy
Gearhead Posts: 1343
From: Ont, Canada
Registered: Mar 2002
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posted 10-13-2006 12:07 PM
quote:
Originally posted by MidLifCrisis:
mustangboy, I would bet you're right. I am sure I am giving up a couple MPG and a bit of HP by not using hearders.
BTW, what cam are you using in your 66 & 68? Charlie
I was running a comp cams magnum 292 in my 68 which isn't a cam thats good for mileage.It was likely way to big for my engine but I built the engine following a magazine recipe for a 300hp 302 way back in the mid 80s....The cam that I put in the 66 coupe is much more street friendly.It came as part of a rebuild kit so I'm not sure who actually made it.The specs were 212@.050 with .448 lift so it was very mild.The engine did pull very well though with ported heads, tri-y headers and dual 2 1/4 exhaust,a shelby style aluminium hi rise intake and a 600 holley.It pulled good on the bottom with very strong mid range right up to my self imposed 5500rpm redline(I didn't put screw in studs in )..I'm not sure on the gas mileage since I shipped the car to my sister out west shortly after it was completed.
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68 J-Code,Sprint,306 4 speed,4.11s 13.69@101...............
66 coupe 289 4 speed, 3.20 cruiser http://mustangsandmore.50megs.com/MembersPics/mustangboy.html http://mustangsandmore.50megs.com/MembersPics/mustangboy2.html
[This message has been edited by mustangboy (edited 10-13-2006).]
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mustangboy
Gearhead Posts: 1343
From: Ont, Canada
Registered: Mar 2002
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posted 10-13-2006 12:31 PM
Here are some pics of the port work,headers and exhaust on the 66 coupe.These headers fit very well and were very easy to install.They did cause me some grief with the clutch linkage and the drivers side did contact the bellhousing a little but they would be probem free with an automatic.. 
[This message has been edited by mustangboy (edited 10-13-2006).]
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Tom G
Gearhead Posts: 1069
From: Bethlehem, Pa USA
Registered: Nov 2001
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posted 10-14-2006 07:58 PM
Move up to a 3.25 gear, get a decent set of headers. Your restriction seems to be the performer intake I would move up to the Performer Rpm and have the engine dyno tuned with some O2 sensors welded into the head pipes. This will get you real close on optimum fuel and performance. I can still get 15-16mpg with a 650DP headers 2.5 exhaust 3.89 gears and a T5 (which is probably the best for MPG. You could even go to an AOD instead of a T5. If your goal is performance and MPG go 3.55 and some type of Overdrive. BTW my 302 puts down 310 RWHp and 300 torque and still gets 15MPG------------------
67 Mustang F/B 302 GT-40X FMS engine RPM Air Gap 650 Holley DP Crane 1.7 roller rockers, Performer Nitrous, ceramic headers WC T5, cable clutch MagnaFlow SS kit W/X Pipe 3.89 9". SSBC 4 piston frdisc Clearwater Aqua, Vintage 40 series 16X8 215 front 255/50 drag radials 308 RWHP@5800rpm 300 tq NA 385rwhp 380 w 75 shot 13.11 @111mph 88 GT (FiveOfastback's ride)
347 Twisted wedge custom HYD roller 565 lift 282 duration Street Heat, BBK headers X pipe
G Force 353 RWHP 393 RWTQ Red/Silver Newest Project!
69 Boss 302 Acapulco Blue
65k original miles Matching number motor and trans
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MidLifCrisis
Gearhead Posts: 673
From: Frederick County, MD
Registered: Oct 2001
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posted 10-14-2006 09:07 PM
Thanks for all the info.buening- your performance matches mine to a T. The 3-4K power band and soft off the line. mustangboy- thanks for the info on the duals. What type of mufflers did you use? I do have duals. I used the 2 1/4" Boss302 kit from one of the Mustang parts suppliers. I believe it flows well, because the exhaust is low and loud. Tom G- I had the car out today, and I am seriously considering rear gears, mileage be damned. As for the RPM manifold, I believe I will have clearance issues. The motor sits up higher limiting under hood space. I would have to make some major motor mount changes. Keeping the car an automatic, other than an AOD, what other overdrive options are there? Thanks, Charlie
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mustangboy
Gearhead Posts: 1343
From: Ont, Canada
Registered: Mar 2002
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posted 10-14-2006 09:21 PM
The mufflers are called "stormers" but I'm not sure who makes them.They have a nice rumble to them.------------------
68 J-Code,Sprint,306 4 speed,4.11s 13.69@101...............
66 coupe 289 4 speed, 3.20 cruiser http://mustangsandmore.50megs.com/MembersPics/mustangboy.html http://mustangsandmore.50megs.com/MembersPics/mustangboy2.html
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