Interesting result, Bill. What MPG are you getting now and what did you get before the conversion?

FWIW: My '60 turns in around 18.5 MPG on long trips. That's with manometer calibration performed 10 years ago. My hunch is that I could do better if I re-visited the calibration with my wide band O2 gauge.

Jim

 

Jim
email sent
Bill

 

Part of an LS motors efficiency is the fact that most aren't in cars that have a Cd of .45....

With 3.08 gears on m y SB 427, with pretty high tech Dart Pro-1 CNC heads over dished pistons, I can get about 22-23 MPG on flat road at a steady 55 MPH and 15.6 AFR; at 85 MPH, it is about 16-17, and drops even more rapidly at higher speeds.

Doug

 

Doug
i believe i remember Charles Bernhardt and John McGraw getting mpg #s in the high 20s+ with their LS C1 conversions.

i can easily get into the low 20s with my rolling brick with my ZZ4 (even my LT1) at 70 with 3.36s and .73 OD.

Bill

 

350 Ram Jet crate motor (tuned), 3.08 rear, T-56 transmission with 0.5:1 overdrive, 1400 rpm=75mph, 29-30 mpg at cruise, 14.8-15.0 A/F ratio.

Charles

 

Charles
that must be some kind of torque motor...barely above idle at 70....

and i thought 2400 at 80 was good...
Bill

 

This is a very interesting and timely thread. I too have been considering adding the MSD Atomic to the Edelbrock Performer crate 350 in my '65 Corvette ... or to the stock 350 in my '75 Silverado.

More specifically, the question for me is a full LS engine swap vs. EFI Carb swap.

The truck is currently classic insured (no hauling allowed, baah!) but one day may be returned to regular insurance and hauling around our vintage Airstream. I think when that day arrives, I will put the 350 Edelbrock from the Corvette into the truck, then drop an LS into the Corvette... or maybe put a completely modern LS drivetrain into the truck and just Atomic EFI the Corvette.

Either way, they're both going EFI - the options are gonna get weighed over the next year as hopefully the price of these EFI conversion products fall amidst more popularity and competition. I'll be following all the swap experiences very closely!

For now I still need to get the 260hp Mercruiser (also a 350SBC) in my '80 Baja up to full performance. Oh if only these vintage toys could take gas today at yesteryears' vintage prices. I may start looking at a marine application EFI, or another swap there, too. Hybrid???

 

Those 29 - 30 MPG's are equal to a stock late model LS Corvette. Nice.

 

My 555" went from 12 MPG with the 1050 Dominator....to 16.5 MPG with the Holley EFI. That's with a .774" lft cam with 266@.050 duration....heads big enough to drive a truck through, and no O/D trans.


Road trip story...

http://www.amosauto.com/Articles/Gen...aggie-valley-1


About an hour before this pic was taken it had just knocked off a string of 9 sec ET's..then bolted on street tires and cruised over to the Vette plant in Bowling Green.




JIM

 

Pauluptime,
If I had it to do over I would go with the LS engine. What worried me about the LS is the other mods that have to be made to make it work right. I like the vintage look but by the time I am done I could have had an LS for the same $ or a little more With gas prices on the way up gas mileage is something you have to consider. For power, performance, gas mileage and driveability it is hard to beat an LS.
I am to the point of no return on the 400. It is on the test stand ready to be installed. I am sure I will be happy when it is all said and done.

 

[QUOTE=67-427ci;1580370574]I had read about this system several months ago and when MSD started shipping the I decided to go for it. http://www.atomicefi.com/home.aspx

This is a new system that can be installed by itself or with one of MSD's distributors so it controls timing as well. FYI their 8572 tach drive distributor fits under the shielding and drives the tachometer properly. Right now they are offering a free MSD Digital 6A box with the purchase of the unit.

One of the best features is it fits under our stock Corvette air cleaners and the factory linkage connects perfectly without modification. I mounted the Digital 6A box under the passenger side fender above the battery and the EFI power module is on the firewall. There is plenty of cable and wires to mount this module under the fender too.

I finished the Atomic installation on my 67 Coupe a few days ago. At first I was going just install the Atomic unit and setup the timing later, then I decided to do it all right away. First off MSD has done a terrific job putting this kit together, nothing has been left out of it.

Since I drive my Corvette all around the USA I mounted the pump in the tank to avoid any possibility of heat related issues and setup the returnless fuel system. While I was running the new fuel line I also plumbed in the original steel line to be a return line in case I have a need to change it. To make it a return system all I need to do is add one line and a regulator in the front.

I installed MSD's 8572 tach drive distributor with the Atomic system and the plugs are gaped at .050" for the Digital 6A box.

Once everything was connected and I had fuel in the tank I cycled the key a few times to build pressure and made sure there were no leaks. On the first start I was impressed that it started immediately without hesitation. First off I locked the timing and set it to 15* on the timing mark. Initially it was advanced a bit much at 25* so I brought it back to 15* and locked the distributor. After it was set I ran it at different RPM's and checked the timing against the hand held display and it is right on target. After that I got the idle settled down so the IAC is open less than 20 points.

Once that was done it was time to drive it and I am again impressed. It is much more responsive than a carburator and after driving it about 20 miles it settled in nicely.

This is my third experience with aftermarket EFI, my first was with PowerJection III which I installed on my 66 Impala Big Block Pro Touring car, it was a pain in the a$$ and after two months of trying to get it running properly I returned it. Then I installed a MassFlo EFI system on the Impala which is flawless in the way it runs. Now the Atomic System is equally as good as my MassFlo system. We are driving the Corvette to Tahoe, CA in September and I am already looking forward to how it will run in the mountains.

Update: I now have about 150 miles on it and it is amazing how well it runs. Hot or cold just twist the key and you are ready to go as it runs the same (just like a new car).





I have the same exact story as 67-427, I had the Powerjection III and returned it and have installed the Atomic with timing control on my 65 327 and it is the closest thing to plug and play for aftermarket TBI's, could not be happier. It may not be the cheapest solution but it is one to consider, I just wish my car was as pretty as his.

 

Your mechanic has prepared you for $5k already. For $1k more you can get this system which combines the FAST self learning computer with individual port injection. The dyno numbers were fantastic with lots of torque starting very low in the rpm range. This motor dyno'd at 565hp and 585lbs of tq. The car is not on the road yet, still getting assembled.

 

Very impressive!!