C3...LT1 with 3:36 gears

[bruce11495]

Would there be a problem with changing gears down to 3:36 or lower from 3:73 for mileage in an LT1? With the price of gas going through the roof, it may be the only way get out of sight from the gas station this year..........

[Duke W.]

Re: C3...LT1 with 3:36 gears

At best your mileage might improve five percent on the highway, little if any around town.

Better fuel efficiency could be had by remapping the ignition curve to something on the order of the 327/365.

The early seventies ignition and fuel maps significantly reduced idle and light to medium load fuel efficiency in order to pass the EPA emission test - TCS, slow centrifugal curves, ported vacuum advance, etc.

If it's a post '70 model it was designed to run on our current 87 PON fuel.

Duke

[Joe L.]

Re: C3...LT1 with 3:36 gears

bruce-----

....plus, the cost of the conversion would take you years to recoup in terms of fuel savings. If you drive the car modestly as most folks with classic Corvettes do, you'd probably never recoup the cost in your lifetime, even if gas goes a LOT higher (which, incidentally, I believe it will).

[Michael W.]

Maybe it's time

to repatriate all those Corvettes sold to the US over the last decade back to Canada- where we're used to paying high gas prices. We'll take them off your hands real cheap.

[Tom S.]

Re: Maybe it's time

Bruce
I just put a 3:36 in my L-46,69 with a M-21 tranny. The improved drivability over the 4:11 that I had in the car is unbleiveable.I was not so much concerened about the milage as the rpms I was turning on short road trips .It drives like a totaly different car.I kept the original 4:11 IN CASE i EVER SELL THE CAR.I am very happy with the change.

Tom

[bruce11495]

Re: C3...LT1 with 3:36 gears

Duke....the car has had the distributor recurved for 15 years. The vacuum was changed from ported to manifold vacuum 20+ years ago because of run on, poor performance and poor Canadian gas. We have not had good gas for 20+ years and it has got worse in the last few years becuase of the banning of leaded fuels even in aircraft.

[bruce11495]

Re: C3...LT1 with 3:36 gears

Joe....The gas has been HIGHER here for years. Did I see a post here today of $3.00/gal in California? Sunoco 94 has been over $3.00 (75-80cents/litre) for 10 years!!! Racing gas has been $4.00 for at least that long. Dropping the revs from 3300 at 70 mph to say 25-2600 has to be a marked improvement.

[Patrick H.]

Re: C3...LT1 with 3:36 gears

I'll side with Joe on this one. We're working on putting together a correct rear for my friend's 66 to replace the non-posi small block one that is now in his big block car. It will be at least $600 and likely more by the time it's done, using used parts. I've seen $1200 for a fully rebuilt unit with correct dates and certain geared internals.

Even at $4 a gallon, if you mileage improves from 15 to 17 on the highway, it will take years to make up $600, much less $1200.

If gas is the ONLY reason you are contemplating the switch, it is not cost effective. If driveability is the reason, then that is a personal choice.

Patrick

[bruce11495]

Re: C3...LT1 with 3:36 gears

Hi Pat...I understand your mindset and I guess if we sat and did ALL the math it may not be financially that much of a savings. But I have 2 complete rearends already, total outlay of $300. So I don't think it will take that long to pay for itself

[Mike McKown]

Re: C3...LT1 with 3:36 gears

If your gear is good, I'll just take the the hit on milage and trade you a good '76 3.36 posi for your GOOD gear. I don't remember a 3.73 ratio but what the heck. You pay shipping for both. How's that for a deal?

[Patrick H.]

Re: C3...LT1 with 3:36 gears

Don't forget to change the speedo gear too.

Still a waste of time in my mind, but not my car.
Have fun with it!

Patrick