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First 500 mile trip in my Track-T

deckofficer

deckofficer

Banned
Hi all,

First post and first long trip in my '23 Track-T. A little disappointed in the fuel mileage but with the cam profile and duration I guess it is OK. Running a 355 Chevy, Holley double pumper mechanical secondaries 600 cfm with a m20 4 speed. 3.54 Jag IRS. Driving at 60 mph up highway 395 to Tahoe got 13 to 14 mpg running 2250 rpms. Comp cam XE274 H-10 110 degrees cam lobe seperation, lift .327 to a 1.52 ratio roller rocker and 286 degrees duration. Car is 1790 lbs. Can any kind soul shed some light as to this mileage with this setup? I'm considering going to a Rochchester Q-Jet carb for better mileage.
 
Show us pics of your car if you have large rear tires there is alot of rolling resistance. :hijacked:
 
Welcome to the forum deckofficer, I run a similar setup with a Demon carb and Crane cam and get about the same mileage you're getting.
 
The double pumper would be the first thing I swapped. I had one of those on my 327, 4mpg in the city...ouch.

Changed to a vacuum secondary and it improved quite a bit. Of course the cam you are running does not help mpg in anyway...lol
 
Thanks to the senior members Telman2, LumenAl, Keeper, and Putz for taking the time to respond. I'm just getting back into hot rods after a 20 year break and this is my first with this kind of power to weight ratio. Needless to say I am impressed with our lite car's abilities to "hook and book", as I thought traction would be a problem but it isn't. When I built a couple engines in the 1960's I was keenly aware of certain trade offs, such as going for max hp from a small block would be pushing the hp and torque curves much higher in the rpm range and losing a fair amount down in the lower revs. I have always used manual transmissions but my friends from that time used automatics with 3000+ rpm stall speeds on their torque converters. I still use a manual today as an old fart but would like to know if anyone here is using either a 700r for chevy or an AOD for a Ford with a high stall speed AND lock up torque converter. I would think that might offer the best of both worlds, fast off the line and good cruising economy.
 
First things first :welcome:and of course you need to post pictures 'cause it's somewhere in the rules.:flip::hijacked:

I have a 700R4 with lockup. Converter was supposed to be 2200-2400 stall. On my recent trip to Mountain Home (1300 miles altogether) I got 18 MPG pulling a Mullins style trailer. 20-22 without the trailer. I don't use the lockup in town because the cam doesn't like it. The engine bucks at low speed like a manual in too high of a gear. I'm running 3.42 gears and I'm thinking about bumping them up to 4.10.

I'm cruizing at about 2000 RPM at 70. My engine is a Vortec bottom end, Ramjet 350 roller cam and ported 461 camel hump heads. Intake is 3x2 Rochesters.

Are you running vacuum advance on your distributor? Hard to get good mileage without it. There is a very good article in the tech section on this board about it.

The Q-jet is a very good STREET carb IF you can get one that's not worn out. They're just plenty ugly!:eek:

Hook up a vacuum gauge where you can monitor it while you drive. See what your vacuum is when you're cruizing. Then check the power valve in your Holley. You need a valve that is closed at least 4 inches below your reading. Check the float levels and then read the plugs. Most double pumpers come jetted for all out performance. You may be able to lean it out a little.

Mike
 
Welcome to the forum, like they say, we love pics :hijacked: Funny that people build an engine for power then wonder why they are not getting great mileage, a completely stock engine is all that any T Bucket really needs and will still tare the pants off any stock car on the street, from 4 cyls to V8s... and Yes a Vacuum guage is what I call the most important guage, besides the temp guage:) Drive safe :flip:
 
deckofficer

I was at work when I posted my previous answer and pretty rushed.

I should have added that (IMO) the mileage you're getting with your setup is probably about right. You could fine tune it and maybe pick up a little more MPG, but I doubt more than 10 - 20%. If you're not running vacuum advance, adding it would get you little more.

I also doubt that overdrive would get enough of a mileage boost to be worth the expense. It might even lower your mileage. Your 3.54 gears are at the low side of what that cam really wants. Overdrive MIGHT lower the RPM's to point that the engine is in effect "lugging".

Your cam has a duration of 230 @ .050. You can see from this dyno sheet that the torque curve doesn't start to flatten out until about 3000 RPM. Comp doesn't even show the curve below 2500. Probably because it's pretty steep and they consider anything below that insignificant.

XE274H-10, Camshaft Part#12-246-3 Dyno Sheet

I know that with the old 274 DE cam (which was about .224 @ .050), Comp recommended 3.90 to 4.11 gears. Looks like they were wanting a cruise RPM in the 3000 range.

Without going to closed-loop EFI, it's really hard to get high performance AND high fuel mileage. Also, most of the modern factory "performance" engines are setup to give buckets of low end and midrange torgue. This is what really works well with overdrive.

Just my .02.

Mike
 
Mike,

Thanks a lot and I agree with everything thing you mentioned. I bought it set this way, the original builder was the previous owner and he just went to a race engine builder and gave them cart'e blanch saying "you guys know how to build engines". Had it been me I would have asked for a build that only empasized low rpm torque and hp even if it meant losing 100 hp from the top end. The engine builder used a dyno on the engine for break in and final tuning. It produced 384.7 hp @ 6100 rpm but the technician reported at 5800 rpms the points were an issue. The builder agreed saying that it should be around 430 hp at 6400. They stopped the test at 6200 because the points were floating bad and power had dropped to 368.6 hp. Peak torque occured at 2 locations, 391.1 lb-ft @ 4000 and 391.2 @ 4300. The test was not started till 3800. Yes, this is a high strung engine that would not be my choice but that is why I'm hat in hand coming to you guys to figure some choices short of re-camming. I just put in a breakerless solid state point replacement that should handle the early drop off of power. At this time it does not have vacuum advance, that is my next project. The Q-Jet carb I would like to replace the Holley with needs a large spacer because those carbs have a fuel percalation issue if too much heat it reaching it from the manifold. I know there is a second reason for the spacer but I forgotten it. The hood is a close fit and I would need to find a lower profile air filter. I have seen one that was low restriction and even had pleats on the top. Can't find it on the internet. That is why I'm asking for input to see if enough of you guys feel the carb swap will be worth it. I know a lot of people do not like the Q-Jet but I don't know why? It gives the best of both worlds, responsive at low speed with plenty of velocity and less than 200 cfm on the primaries and the 550+ cfm on the secondaries, total being rated at a 750 cfm carb.

Thanks again for the help,

Bob

Also I load some pictures tommorrow.
 
Definately get your vacuum advance hooked up I haven't had a quadrajet in a while but the ones I had where very dependable.
 
If you decide to go with the Q-Jet, you can run the heat insulator gasket instead of the spacer. They're only about 3/8" thick.

I would try to tune the Holley before swapping. I'm not a Holley guy, but they are good carbs. Set up right, there is no reason why it shouldn't give decent mileage.

You might be surprised when you get the vacuum advance hooked up. Also, you may have to go with an adjustable vacuum canister if you have trouble with "pinging". I like to set mine up to start retarding just below cruise vacuum levels.

I know you said you didn't want to recam, but an XE262 (or smaller) would give you a nice boost in low end torgue and probably mileage.

BTW here's a link to the advance tech article.

http://www.tbucketeers.com/forum/f46/timing-vacuum-advance-101-a-4350/#post45134

Hope you get it sorted out.

Mike
 
Mike,

I read the article on timing, well written and informative. On the carb, I will tune the Holley but if money wasn't an issue, I'd go with your setup of 3X2. The look is right and quite functional. Hell, I like everything you have done, 700r, etc.
 
As per request, I have posted some pictures I took today. Had to resize them all because I didn't know about the 200K size restriction. Test drove the car today with the electronic point replacement and found the lost 45hp due to point float. Also found out with the added power that approaching 6000 rpms in second gear, both tires start to lose traction. Unlike my blown 427 '55 Ford or the Corvette, this car does not get sideways unless you lose traction in a turn and as soon as you let up on it, it straightens right out. I have never driven a car as forgiving as this Track-T. You guys have really been on to something very fun with these cars that have such a high power to weight ratio. This is new to me, but it is nice not fighting the Laws of Physics by trying to propel heavy cars.
 
Thanks for the kind words, but I gotta return the compliment! I love your car. Looks sharp. Sits right.

I've had a lot of different kinds of cars, but I'm enjoying my T more than any other. The only other thing I've driven with this kind of power-to-weight is a motorcycle.

You'll also find that they seem to be universally enjoyed by most everyone that you encounter. My T is the only car I've had that people actually chased me down to look at!

You have a nice car, drive the wheels off of it!!

Mike
 
Hotrod46; Thanks for the kind words, but I gotta return the compliment! I love your car. Looks sharp. Sits right.

I've had a lot of different kinds of cars, but I'm enjoying my T more than any other. The .

My T is the only car I've had that people actually chased me down to look at!

Mike

Mike,

After looking your car over at the Bucket Bash last month I have to tell you that's a slick piece. You need to post pictures of that frontend. If not then maybe I will. Good meeting you and look forward to seeing you in the future.

George
 
George

Good to hear from you! I enjoyed meeting and talking with you at the Bash.

I'm flattered that you liked my work. I hope our path's cross again.

Mike
 
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