66 427 Fly Wheel

[Anthony P.]

I just read a thread from 1/31/17 concerning machining of the flywheel, my question is this, does GM still offer a flywheel for a 66 427? I would like to have this information before I call the local dealer and get frustrated! Thanks in advance

[Joe L.]

Re: 66 427 Fly Wheel

I just read a thread from 1/31/17 concerning machining of the flywheel, my question is this, does GM still offer a flywheel for a 66 427? I would like to have this information before I call the local dealer and get frustrated! Thanks in advance

Anthony------


Yes, GM does offer such a flywheel. It's GM #3991469.

[Jim D.]

Re: 66 427 Fly Wheel

LUK offers the same flywheel (they are the supplier to GM) at a fraction of the GM price.

[Anthony P.]

Re: 66 427 Fly Wheel

Great, Thanks guys for the quick reply! I will get one coming in the morning.

[Joe L.]

Re: 66 427 Fly Wheel

LUK offers the same flywheel (they are the supplier to GM) at a fraction of the GM price.

Jim------

LUK is a supplier to GM for clutches and related parts. However, I don't know if they supply GM with the 3991469 flywheel. The last one of these that I examined had a GM casting number on it and I believe it was cast and machined by a GM manufacturing operation. That's been awhile, though, and the manufacturing source for this flywheel could have changed by now.

The GM #3991469 flywheel is a 14", 168 tooth ring gear flywheel and designed for use with an 11" clutch. The 3991469 flywheel is cast of nodular iron. Many aftermarket flywheels are cast of gray iron.

[Gary B.]

Re: 66 427 Fly Wheel

Guys,

Can some answer the same question for a '66 L79 small block?

Gary

[Joe L.]

Re: 66 427 Fly Wheel

Guys,

Can some answer the same question for a '66 L79 small block?

Gary

Gary------


That flywheel is no longer available from GM and has not been available for quite some time.It was last available under GM #366860 and was always a standard weight flywheel. GM does offer a lightweight flywheel that will work for all 1963-68 small blocks under GM #14085720. This is the descendant of the same flywheel that was used for 1965 L-78 and 67-69 L-88 but it will work for small blocks. However, I don't recommend it because small blocks don't have the torque of big blocks.

Otherwise, aftermarket replacements are available for a standard weight flywheel. The LUK version is their number LFW 131. This is a 12-3/4", 153 tooth ring gear flywheel.

[Gary B.]

Re: 66 427 Fly Wheel

Gary------


That flywheel is no longer available from GM and has not been available for quite some time.It was last available under GM #366860 and was always a standard weight flywheel. GM does offer a lightweight flywheel that will work for all 1963-68 small blocks under GM #14085720. This is the descendant of the same flywheel that was used for 1965 L-78 and 67-69 L-88 but it will work for small blocks. However, I don't recommend it because small blocks don't have the torque of big blocks.

Otherwise, aftermarket replacements are available for a standard weight flywheel. The LUK version is their number LFW 131. This is a 12-3/4", 153 tooth ring gear flywheel.

joe,

Is it at all likely the LFW 131 is made from nodular iron? If not, might any other aftermarket company make a SB flywheel that is nodular iron? You've taught me too much not to ask.

Gary

[Joe L.]

Re: 66 427 Fly Wheel

joe,

Is it at all likely the LFW 131 is made from nodular iron? If not, might any other aftermarket company make a SB flywheel that is nodular iron? You've taught me too much not to ask.

Gary

Gary-----


Unfortunately, I don't know what material that the LUK flywheels are cast from. All that I've ever found that LUK says about the subject is that the flywheels are made from "premium grade cast iron". That really does not tell me much.

[Anthony P.]

Re: 66 427 Fly Wheel

FYI update, Just ordered the 3991469 flywheel from GM dealer, free shipping to my door, $217.00 once i get it I will compare to my original for casting #s and report back.. Thanks to all for the information. and to the original thread that alerted me to the consequences of removing too much material from the original specs!!

one more question for Joe, will that part # be correct for a 69 396/375?

[Gary J.]

Re: 66 427 Fly Wheel

My question would be where it is manufactured? In the US or offshore?

[Jim D.]

Re: 66 427 Fly Wheel

My question would be where it is manufactured? In the US or offshore?

My bet is south of the border.

[Gary J.]

Re: 66 427 Fly Wheel

If that be the case I would have my original faced.

[Anthony P.]

Re: 66 427 Fly Wheel

If that be the case I would have my original faced.

I might have to reface my original! lets wait and see what up with the unit I get from the General.

[Joe L.]

Re: 66 427 Fly Wheel

FYI update, Just ordered the 3991469 flywheel from GM dealer, free shipping to my door, $217.00 once i get it I will compare to my original for casting #s and report back.. Thanks to all for the information. and to the original thread that alerted me to the consequences of removing too much material from the original specs!!

one more question for Joe, will that part # be correct for a 69 396/375?

Tony------


The GM #3991469 is also applicable to 1969 L-78.

I wouldn't be too concerned about the source of the 3991469 you receive. If it's a genuine GM part (which it will be), it will be OEM quality no matter where it comes from. I'd prefer it over a re-surfaced original. By the way, GM has a nodular iron foundry in Mexico as well as several engine plants.