I found out today I need a new flywheel. Is there only 1 flywheel for the 427, I have a "67" 435. I see that Corvette Central sells one for a 427, has anybody had any experience with this? I doubt I can find the original part number flywheel, or if it is even necessary. Any help would be appreciated.

Thanks
Randy

 

I would think the reproduction would work fine for you. Numbers won't matter since no one will see it once its installed.

 

Your best bet is to compare weights. A light weight flywheel has less rotational inertia, which absorbs less power during acceleration, but the trade-off is usually a rougher idle and difficulty getting the car launched from a dead stop in normal traffic.

I don't know the weight of the OE L-71 flywheel, but it is probably in the same range as the 30+ pounds of the OE flywheel on my 327. The L-88 flywheel weighs only 18 pounds and is a good, durable racing flywheel, but not a good piece for a street driver.

I suggest that you post your question on the NCRS DB as Joe Lucia can probably give you a complete rundown of big block flywheel part numbers and casting numbers. It's also important to select a flywheel set up for your original clutch diameter (10.5" or 11") and the proper ring gear tooth count - 153 or 168.

Duke

 

Whatever you do be sure to check the flywheel for flatness and TIR [roundness] before you go too far. I bought 2 "Chinese" flywheels last winter that were absolute garbage.

 

You need a flywheel for the 10.5 clutch. 154 tooth. 427 and small block '63-'67 same. There was also a 15# flywheel made.

 

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I beg to differ with you, but the 67 427 used an 11" clutch and the larger 168 tooth flywheel.

Check with your local GM dealer--It might still be available.

 

I ran an 8 pound flywheel in my Chevelle, but that car had a monster cam and idled at 2K RPM.

I did not notice the inertia problem on normal driving, but the car idled so high, that it may have masked any effect. I am not sure if it was the cam or flywheel or a combo of the two, but if you let the tach fall below 1500 RPM in normal driving the car would lounge back and forth violently, then quite.

It revved fast, which was really neat with open headers, but if you missed a gear, it flung in the 7000+ range before you could let of the gas.

I am going to pull the motor on my vette and do a rod inspection, and change if need be and I was tooling with the idea of a lighter flywheel. I don't think an 8 pound would be a great match in my vette, but are there any in the 20 pound range, and if so, would the effects even be worth it. The 8 pound fly wheel and the quick revving is a great sound.
"Whap Whap Whap" The Tach follows your foot down on the pedal.

I could deal with the drivability issue, as I drive my car for all the fun I can have with it. But I don't want to eat clutches up right and left either. And I went through a couple of clutches in my chevelle. Not sure if that was the racing that did them in, or the constant feathering of it.

Mark

 

The L-88 nodular iron flywheel has a 153 tooth ring gear, is drilled for a 10.5" clutch, and will fit with all your existing components, and I think it's still available - 3991406. It weighs 18 pounds versus about 33 for the OE flywheel and with your 4.11 gears will probably work out okay as long as you don't have to slog through a lot of stop and go traffic.

The GM high-perf. nodular iron flywheels are pretty bulletproof. (I believe our OE flywheels are gray iron.) Production prototypes were proof-tested to 10,000 RPM - usually using a fixture driven by a geared up electric motor. The flywheel in my Cosworth Vega is also nodular iron - about 17 pounds - 153 tooth ring gear, but is tapered at the outside circumference to reduce rotational inertia and drilled for a 9 1/8" clutch. It was proof tested by letting a CV engine rev to 10,000 on a dyno!

I considered installing a L-88 flywheel in the SWC, but since I'm pulling a 3.08 axle (76 MPH first gear) I decided to keep the OE boat anchor.

Duke

 

After searching the archives for more intel, I am going to use the L-88 Fly Wheel when I do my motor pull. Can I go to any GM counter to purchase it, or is there a website for such ordering?

Thanks.

I am torn on doing the pull now, or waiting until the after the 1st of the year. It is fairly warm now, and heating the garage can be a pain.

 

Found it on GMPARTS.com

Thanks

 

since youre replacing anyway,,,why not go with the safety of a steel flywheel???

 

Only seen heavy wheels in aftermarket steel. I have the L88 wheel and love it. 327 with 4.11 gears, wide ratio Muncie.

 

You can order ANY GMPD number from ANY GM dealer. Back in the eighties I ordered CV and Corvette parts through a local Buick dealer who gave me a trade discount. The only issue was I had to give them the part numbers, because they did not have Chevrolet catalogs, but I have P&A catalogs for both the CV and Corvette, so that wasn't an issue.

As long as you can give them an OE or replacement part number their computer will tell them if it is active, superceded, or discontinued.

Duke

 

Didn't anyone read the original post ??? The car is a 67, and has a 435/427, which uses the large 168 tooth flywheel and an 11" clutch. If he changes to an L-88 flywheel, he goes DOWN to a 10 1/2" clutch, and his original starter will not match. He might even have to change the bell housing. I don't know if the starter for the 153 tooth flywheel will fit properly in the opening of the larger bell housing.

 

You need a 14" 168-tooth flywheel drilled for the 11" clutch; Tracy should have them.

 

I was addressing my comments to Mark, who has a '65 L-76, and the L-88 flywheel is a bolt-in. You already challenged the previous assertion that the L-88 flywheel will work on a L-71, and John confirmed that it will not - at least not without a number of other changes.

Duke

 

Thanks for the help, I will call Tracy.

Thanks
Randy

 

I bought a Hays 30lb. flywheel brand new for my car and it wasn't anywhere near flat. Bolt it up and check it with a dial indicator before putting everything else back.

 

Actually, the 10.5 will fit in the clutch housing and only the nose casting of the starter needs to be changed - usually $5 at the junk/recycle yard, from the starter core barrel. I assume you will install a new clutch disk and pressure plate while the assembly is out of the car.