66 L-36 carburation.

[Richard S.]

My 66 427/390 4spd., 3:36 rear, is currently running with the correct 585 CFM Holley. If I wanted to pep up the performance a bit without making any other changes, is there another carburator I could bolt on that might provide some performance improvement? I'd be interested to know what's been tried before by others and the results. By "performance improvement", I mean low end....off the line improvement. Thanks for the help.

[Clem Z.]

Re: 66 L-36 carburation.

change the rear gear to a 3.70 or a 4.11 if you want more bottom end performance
both of my BB corvette were ordered with 4.11 gears and i was never sorry as i even drove them from PA to FLA and SC on vacation and i know you guys do not do that.

[G B.]

Around town difference

Clem has an excellent point.

I might add that installation of a multiple spark, high voltage ignition system will make a difference you can feel. So will using a GM lightweight (16 pound) iron flywheel.

Personally, I haven't noticed any good differences by installing a different carburetor on this engine. If you're suspicious that your accelerator pump is dumping enough gas off the line, try a different pump cam and a larger shooter nozzle before changing carbs. Just don't expect much from this approach. Ten million teenagers CAN be wrong; a Holley double-pumper is not the way to go on the street.

If your current stock Holley isn't working right, try fixing it properly including re-surfacing the main body.

[Richard S.]

Re: 66 L-36 carburation.

Thanks Clem. I have 4:11's on the 67 and I know what you mean. I'm just hoping a larger or different carb might help a little.....I don't need or want much....just a little improvement. Thanks for the reply.

[Werner R.]

Re: Around town difference

jerry you raise a good point about the lighter flywheel. this was discussed on a post some time ago. i always thought that a lighter flywheel allowed better acceleration because it was easier to change the rotational speed of the lighter wheel ie less torque was needed to change the rotational speed [less inertia]. however, on a past post someone argued the opposite, although i can't remember the reason. i thought speed shops will "butch" the flywheel by drilling big holes into it to reduce the weight and therefore the inertia and therefore allow better acceleration with the same torque. does this sound right to you?? werner

[Duke W.]

Re: 66 L-36 carburation.

Another carburetor will have very little effect on the torque curve. Also, a light flywheel will make the car harder to launch, and won't make that much difference in performance.

The best way to improve low end torque is to quicken the centrifugal advance curve by installing lighter springs. The OE curve is conservative - i.e. slow - to keep the engine out of detonation.

Chances are you can quicken it, even with today's lower octane fuels. Spring kits are available from various Corvette vendors and aftermarket sources. Buy one and try the lightest springs. A dial back timing light is also a good investment so you can quickly characterize the curve on the car.

Low end torque will be improved by getting all the advance in as quickly as possible, but the limit on how fast it can be brought in is detonation.

Duke

[G B.]

Light flywheels

This is something I know about from driving experience. Once again I must apologize for not having controlled lab experiments and calculations to document my opinions.

Back in the sixties, the aftermarket light flywheels were made of aluminum with steel starter teeth and clutch facing. The problem wasn't that they took more power to launch (actually they required less to accelerate), the problem was warpage/flex when they got hot.

The modern GM 16 pound iron flywheel is a super nice piece. It is good for high rpm and temps. You can definitely feel the difference accelerating at aggressive street speeds. This flywheel is available from non-GM retailers for about $130. I think that's a bargain. Yes, track racers will even lighten this flywheel more by drilling holes, but I don't recommend that approach for safety reasons. I'm down to my last pair of feet.

Now if you are drag racing an 8,000 pound Humvee and need all the momentum energy of a 25 pound flywheel to launch without a stumble, then that's a different situation.

[Joe L.]

Re: 66 L-36 carburation.

Rick-----

As the others have mentioned, installing a larger or different carburetor is NOT an effective means of gaining a performance improvement. Anything you gain this way will have, at best, negligible performance benefits. As a matter of fact, installing a larger CFM carburetor will likely have a NEGATIVE effect on street performance.

[Clem Z.]

Re: Light flywheels

we used 40+ pound flywheels in our drag cars to help launch the car because of the traction afforded by the slicks. even 6000+ rpm would bog the engine if you did not have the 40+ pound wheel. you can not beat a light fly wheel for street and road racing.