Have my car tagged and have put about 500 miles on it. I have a new ford factory crate 302/340 hp with a 670 holley street avenger (vacumm secondaires) and a t-5 with 3.73. I would say 85% of the driving has been street - 15% highway. My foot has not been real heavy - I am averageing 12 miles per gallon....Any comparisons?
Need help finishing your project we can help here or at your shop.
FFR GTM #34 first GTM with working AC. 400 hp LS1 w/G50
FFR coupe 3617CP 331 Stack EFI T-5 IRS Cobra brakes, AC/heat.
Both cars by NRC, we can build (and have built) any FFR product.
We also make and sell a ton of great parts for the FFR community.
Brake kits, AC systems, #1 supplier of Team III wheels.
yes lots of people will probably say your carb is too big.
your number is low compared to what i've read historically.
3.73 is super-fun but higher RPM's across the board. most guys with 302's get about 16mpg. i got 17mpg on the freeway with a 570. i got the same result with the same carb and my new 347.
~1800rpm @ ~75mph cruising
it's less than 15 bucks and 90 seconds a change if you want to experiment with the secondary spring kit:
I get about 20-22mpg highway, and somewhat less than that around town. Only about 5mpg on the track.
Probably too much carb, but do some data logging and check your AFR before making any changes. Also check your timing curve.
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.boB
Dart 427W, Momar 8 Stack EFI, 600'ish hp, TKO, 3.55 TruTrac, Red with Ghost Flames. More fun than should legally be allowed. http://home.comcast.net/~bobcowan035/site/
You ll find at about 1k miles or so it ll feel like a different engine. Mine idled smoother and the idle dropped 200 rpm. Oh, and did I mention more power? Oh Yeah !!
I only get about 16 mpg with my 418/530hp engine.
Sorry for the Hy jack but I am looking are at the same setup. Ford racing 302 with Street Avenger 570, I have 373 rear already. Are you happy with that set up? If you were starting a new build would you do it the same? I have not ordered a kit yet just getting a plan together.
Sorry for the Hy jack but I am looking are at the same setup. Ford racing 302 with Street Avenger 570, I have 373 rear already. Are you happy with that set up? If you were starting a new build would you do it the same? I have not ordered a kit yet just getting a plan together.
I'm very happy with my setup and would do it again, however sometimes I wish I had another 50-75HP. With that said, my car is very streetable and has great manners.
HTH
Mike
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Mike
Mk 3.1 Non-donor, Ford Racing Crate w/GT40X heads & B303 cam, 3:73 3-link, Gas-N pipes, 15" Halibrands
I'm averaging about 30... 30 burnouts or races from one light to the next per tank!
Checked it Friday for the first time and got 17.9 MPG, mix of highway and city.
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Last edited by Epicenter; 09-16-2012 at 02:23 AM..
I have the exact setup as you except I'm running a 570 street avenger and I consistently get 17-19 mpg.
Same setup here but manage 21-23 mixed when driven like a "nornal" car. Spent a lot of time with a wideband modifying the 570 for a near EFI fuel curve.
Just today, I picked up a Holley 650DP and will see if I can massage it to run economically around town and deliver neck snapping response when needed.
OK, I'm bored again. The TR6 is running perfect
Greg
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FFR4373 MK3, nondonor, DIY options/mods/paint, Lexus indigo/Viper silver, Hydroboost PS&PB/discs/ABS, AC/heat, 3-link/Konis, FMS302E, Holley 600DP/Airgap, 4X4 exhaust, Halibrand deep lip chrome CobraIII, TeamIII spinners, rollbars: chrome full & single
I had a 670 avenger but it was too lean in transition, would buck at certain speeds but got 23 on the highway. The 650dp was a big change but was rich on the transition, needed to change air bleeds if it were possible on the carb ( tried the small wire in the metering block trick ). Got like 12mpg running around.
BTW, if you look at bore size and throttle size the 670 is the same as a regular 600. I believe the Avenger is for more mild combo's if not doing a lot of tuning.
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331, RPM intake, TW heads, TF STG II cam, 3:55, powerjection III, 3550 trans, NT-03M Enkei 18x8.5 & 9.5, Kumho XS 245-40 \ 275-35, 3-link, Fast Freddies PS, ABS
I have a Levy 347 FI, Tremec TKOII (0.80) and a 3.27 IRS rear. City is 12 to 15, Best highway at 65MPH is 20.9.
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Build started 15 Dec. 2002
Registered June 2009, kit delivered December 2002. Levy Stage 4,347,EFI TKOII, IRS, FFR 4 into 4 pipes, Roh 17 inch wheels, Nitto 555's, 275/40/17, 245/45/17. Power steering, C&R Water to oil heat exchanger. Levy / Ron Davis big radiator. Tweeker RT, WB O2 system. Street performer seats, tracks both sides, Levy pro bump steer, SN95 front spindles, FFR LCA's, Levy / Willwood brakes.
Lomborghini titanium silver, painted by Gordon Levy.
I have about the same set up as you but with a Demon 575. With GT40P heads I consistently got 20 - 22 mpg and when I switched to AFR heads the mileage took a significant downturn. (17 mpg.) Then it magically dropped to 8. Then I knew there was something that needed attention and found 3 fuel leaks. Fixed those issues and the last two tanks were 20 mpg.
Lesson learned: DON"T put 3/8 hose directly on to 3/8 tubing - even with two clamps per connection. Bead the tubing first and sleep easy.
BTW - I agree with some of those that weighed in earlier - if you are driving fairly easy, I wouldn't suspect the size of the carb to be the issue (as my first guess). Check for leaks and then your A/F levels.
Good luck, Darrel
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I've only got about 600 miles on my FR347 with the Holley 670, TKO 600, and 331 rear end, but I'm pretty sure I'm getting 11 around town and 15 on the freeway. It smells "fat", and the plugs look a little black. Would a step down in jet size help?
Hi PJ,
Give me a call on Monday and we need to go over some questions and make a few changes to make it run cleaner.
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Forte's Parts Connection
40 Pearl Street
Framingham, Mass. 01702 mikeforte302@gmail.com
508 875 0016 www.fortesparts.com http://www.facebook.com/home.php?#!/...?v=info&ref=ts
The Early Ford & FE Tremec were also originals from Mike. The Mustang firewall adjustable quadrant kit also is an original from Mike. His latest developments are external slave clutch release conversions & cable release conversions too.
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I have the same setup and get 22mpg all day long at 65mph.
FWIW, I have an Edelbrock Air-Gap dual plane intake and I'm using an 85 Mustang GT distributor with the vacuum advance connected.
My mileage was never as bad as yours.
Two things that really helped mine was adding a four hole phenolic spacer under the carb and dropping the power valve to a four.
~12 mpg with QFT DP 650, 347 stroker, 3.73 rear, and T5 with 0.80 final drive. Wish I had a longer gear setup, but the engine does not like running less than 2500 rpm. So this combination of ratios keeps it in the happy range.
I have the levy 347 with 670 street avenger/vacume secondaries on a single plane manifold /3:27 rear and get smooth running in 5th down to 1,200 rpm though I'm still slightly rich (I'd change the manifold to dual plane but I don't wanna go through the tuning yet agan after the DP)-highway is 24MPG and maybe 15 in the lower fun gears-my buddy's spec racer gets 24 with a 250,000 miles engine running 2:73 rear. the only time I got bad mileage was with the Holley 650 DP-that thing always ran rich even with all the jet changes, something like 12 MPG.
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