Drive On.
Gas prices are sky high. Makes it tough driving an early model Vette with no overdrive. More so if you have gears and a Big block.
Several options are available to address the fuel costs involved in operating a vehicle built when gas prices were ¼ the price of today. The easiest is to park it and hope prices go back down. Looks good up front but then what are the chances of the prices falling to more normal (whatever normal is) levels. Besides, we all know that extended parking of a vehicle without driving is not good, let alone the issue of enjoying the car. My philosophy is a car is built to be driven, not parked.
Another option……..install a Honda motor. In fact, you may be able to install an entire Honda Fit into a C3 engine bay.
You could plug the Energizer Bunny into the cigarette lighter and have the first “hare-brid” car. Sorry, couldn’t resist.
Aside from making the engine in your Vette more fuel efficient, which is a possibility, changing the speed at which your engine spins is a real alternative. This is where the transmission and rear end gearing are involved (you could include tire/wheel diameter).
Although changing out 4.10s for 3.07s will lower the engine rpm for any given vehicle speed, the amount of rpm reduction at cruise is noticeable. However, the perceived loss of acceleration may be greater than any benefit realized. Sure, reducing rear-end ratio from 4.11 to 3.07 is essentially reducing overall gearing by 25%. But this reduction is occurring in all gears. Therefore, lower gear acceleration is negatively impacted.
This leaves us with the transmission and, whether you have a ‘2 pedal’ or ‘3 pedal’, there is an overdrive for you.
Since 1982, all Corvettes have had overdrive transmissions. In fact, all ‘82s had overdrives, since all ‘82s had automatics (700R4). In ’84 the manual tranny (MM4) was ‘re’-introduced. Unlike the automatics with an integrated overdrive, making it a 4 speed, the manual transmission was a 4 speed Super T-10 with a 2 speed overdrive slapped on the back. When disengaged the overdrive had a ‘pass thru’ ratio of 1:1 & when engaged it provided a .68 (there were actually 2 overdrive ratios available) reduction gear. Additionally, unlike the automatic with overdrive available only in top gear, the manual could apply the overdrive in 2nd, 3rd & 4th gears, hence the badge “4+3”.
My point? Overdrive transmissions are an essential element in modern Corvettes, and there is no reason this technology, although some of it is 25+ years old, can not be applied to older Vettes.
Both autos and stick shifts are candidates for this retrofit. One of the beautiful things about Chevys is their interchangeability. The 700R4 from a 96 Impala SS will bolt up to a 67 BB Vette (DO NOT use a C4 700R4 since the tailshaft housing utilizes the torque beam mount). Sure there are some components that need to be addressed; shifter, flywheel, torque converter, trans mount, etc. But when you get right down to it, it is essentially a “bolt-on” upgrade. This means you can always return to the stock configuration.
The manual transmission swap is more involved than the auto upgrade (DO Not use a C4 ZF in a non-C4 since this transmission utilizes the torque beam mount) since the shifter location on the ZF requires cutting the trans tunnel for clearance.
So what is the real benefit of this upgrade?
Certainly fuel economy would be greatly increased. As an example, my ’85 has a 4+3 transmission and a 400+HP engine. Driving at 70 MPH my tach was somewhere in the 2900 rpm range. With the overdrive engaged it drops to 2000 rpm. This is a 900 rpm drop in engine speed. Now, imagine driving from California to Maryland with a 6.3L engine turning 2900 rpm for 3,000 miles. By my estimate, driving easy, my MPG would have been around 17-18. I made this trip, with overdrive luckily, and based on my gas station receipts and fuel log, I averaged 31 MPG. So, if I were to make that same trip today, my fuel expense would have been about $685 without an overdrive (3000miles/17.5 x $4 gal). That same expense drops to $387 with an overdrive. This equates to a $300 savings for that one 3000 mile trip. This does not take into account the reduced wear and tear on the motor, and your ears.
Corvettes were made to be driven. Do not let fuel prices force you to mothball your Vette. Let modern technology take the ‘pain at the pump’ out of enjoying your Vette.
Drive On!!!!
[If you have any questions or you are interested in learning about the Complete Transmission Upgrade Kits we are putting together, drop us a line at USMracer.com]
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