67 435 11" clutch,bellhousing

**Joe L.** · December 27, 2003, 12:35 PM

Re: 67 435 11" clutch,bellhousing

Frank-----

ALL big block Corvettes, except L-88 and 1965 L-78, used a 14" flywheel with an 11" clutch. Very early 1967 Corvettes with big block (except L-88) may have used bellhousing GM #3872444. Most 1967 Corvettes with big block (except L-88) used bellhousing GM #3899621. The 3899621 is not difficult to locate; they were used on all manner of Chevrolet cars from 1967 through 1982, or so. The 3872444 is quite difficult to locate. It was used only for 1966 Corvettes, Chevelles, and passenger cars with big block as well as some other 65-66 passenger cars with HD clutch option.

The 3872444 and 3899621 bellhousings are almost identical except for the configuration of one of the reinforcing ribs and, of course, the part number.

**Rob A.** · December 27, 2003, 01:03 PM

Re: 67 435 11" clutch,bellhousing

I think there are currently a couple of the #621 bellhousings on ebay, Check under collector car parts, under bellhousing, but don't select corvette first, since as Joe said, they are used on other vehicles as well.

**Tom P.** · December 27, 2003, 02:49 PM

Re: 67 435 11" clutch,bellhousing

If you buy a 621 housing (3899621) for a Corvette, you will get raped without even getting kissed, for $150-200 (WHICH IS ALWAYS THE CASE WHEN BUYING PARTS FOR A CORVETTE)!!! But, if you shop around, especially the NON-Corvette swap meets, you should be able to pick up one for $25-70. Sometimes, you may find one with a small crack or chip in the lower portion of the housing. Usually, these can be welded, the weld can then be ground down and finished, and you have a perfectly good housing. Not only were these housings used on Vettes, Chevelles, Novas and other Chevy pass cars, but they were also used on 1/2ton pickups with 3spds behind 6cyl and V-8 engines (n 63, the 6cyl engine was TOTALLY redesigned and the bell housing flange became the same as on a V-8).

**Frank H.** · December 27, 2003, 03:18 PM

Re: 67 435 11" clutch,bellhousing

I found the early 444 listed at site for june 66 ,and I have a number for someone with may 621s from $65-up,my car with a Jan 10 67 build date,I ruled out the early 444 as going on a early 942 block.
But really can't seem to narrow down one or two flywheels that would have been used originaly ,date wise it lookes like cast #3973456N could be it,I have found many dated xx6 and xx7 so I'm thinking thats 1966-67 or is it for 76-77 truck maybe?
Anyone have a known 11" flywheel number used on the 67 427
I doubt I'll change the flywheel (its fresh) anytime soon, but would like to Identify the correct one
the tailhouse and bellhousing will get changed,since they show.
Thanks Joe Rob

**William C.** · December 27, 2003, 03:32 PM

Re: 67 435 11" clutch,bellhousing

Keep in mind to go to the large flywheel you will also have to change the starter or at least the nose of the starter.

**Dick W.** · December 27, 2003, 03:42 PM

Re: 67 435 11" clutch,bellhousing

10.4" clutch with nodular iron flywheel used on L/88's as std equipment. Was a popular setup for drag and roundy round racing.

**Joe L.** · December 27, 2003, 04:37 PM

Re: 67 435 11" clutch,bellhousing

Frank-----

I doubt that any '444' bellhousing was used as late as January, 1967.

GM CASTING #3973456 is a much later flywheel casting. It was originally used for 14" flywheel applications beginning in 1970 and is a SERVICE replacement for earlier 14" Corvette applications.

**Tom D.** · December 27, 2003, 04:48 PM

Re: 67 435 11" clutch,bellhousing

Don't know if all this (below) is true. I copied it from e-bay some months back. Don't remember which seller id. I would look at "Chevrolet By the Numbers" by Alan Colvin before buying. /td

Chevy V8 Bellhousing for the large ( 168 tooth ) flywheel. casting # 3899621 . The casting numbers are thicker ( more bold ) than those typically found on later vehicles or service replacements .

This clutch housing was used on 1967 , 1968 , 1969 , 1970 , 1971 , 1972 ( 72 ) , 1973 , ( 73 ) , and 1974 , ( 74 ) Chevrolet 327 , 350 , 396 , 400 , 402 , and 454 engines in Camaro

This part is completely interchangeable with the # 444 housing used in 66 ( 1966 ) cars .

**Tom P.** · December 27, 2003, 09:18 PM

Re: 67 435 11" clutch,bellhousing

If you ARE NOT concerned about have a bell housing with a correct number on it, then the 3899621, 3872444 and 464697 housings are all 100% interchangeable. The differences between them are absolutely VERY minimal. As far as I know, the above 3 casting numbers are the only ones (full enclosure style) that are/were available for the 168 tooth (14in diameter) flywheel. NOT ALL 168 TOOTH FLYWHEELS USED AN 11IN CLUTCH!!!! Some of them were ONLY drilled/tapped for a 10 1/2in clutch.

**Joe L.** · December 27, 2003, 09:55 PM

Re: 67 435 11" clutch,bellhousing

Tom-----

Yes, the 3 bellhousing numbers that you mention are all completely interchangeable and are the only fully enclosed ones EVER used on Corvettes and most other Chevrolet passenger car applications with 14" flywheels. In addition, many GM PART #3899621 bellhousings obtained in SERVICE carried the GM CASTING #464697. There was also a bellhousing finished part number of 464697 so, presumably, there was some slight machining difference between the 3899621 and the 464697. I've examined several examples of these bellhousings side-by-side for a considerable period of time and, subsequent to such study, I can't find a single aspect of difference between them. I suspect that whatever the machining difference is, it's at the "micrometer" level.

In the mid-70s, Chevrolet used 14" flywheels with 10-1/2" clutches. For Corvettes, these included 1978-79 with L-48 and M-20 four speed. Also, 1969 Corvettes with L-71 and MA-6 clutch and 1971 Corvettes with LS-6 used a special 14" flywheel for use with the 10" dual disc clutch.

**Frank H.** · December 27, 2003, 11:37 PM

Re: 67 435 14" flywheel

Well went to look at some bellhousings,but he didn't have any 621 bells,but I did find a perfectly dated locked up 696 42 amp TI alternator for $25.00 that went to a 66 impala that I ended up buying too.
I guess I'll pull the inspection cover on the 67 and see what dia flywheel and
If it has a casting number to ID it,and know if I have to deal with the starter nose too.Probaly the best future flywheel change would be to the lightweight 14" dia. thats drilled for 10.5 and 11" clutchs.
Thanks for all the input
Frank

**Joe L.** · December 28, 2003, 11:47 AM

Re: 67 435 14" flywheel

Frank-----

You don't really need to pull the inspection cover to figure out what flywheel that you have installed. If the bellhousing is a '403' or a '383', then you have to have a 12-3/4" flywheel installed. If it's a '621' or a '697', then you have a 14" flywheel. You can "double check" this by looking at the starter nose. Starter noses for the 12-3/4" flywheel have "straight-across" vertical mounting bolts with one "long" and one "short" bolt. Usually, but not always, the starter nose will be of cast aluminum. Starter noses for the 14" flywheel will have "diagonal" vertical mounting bolts and will use "long" bolts for both positions. Usually, but not always, these starter noses will be of cast iron.

GM does not now nor has it ever offered a 14" flywheel in a "lightweight" design. For "lightweight" flywheels from GM, you need to go with a 12-3/4" design. Of course, "lightweight" flywheels are available in the aftermarket for the 14" style, including aluminum versions. I don't recommend them, though, for street applications.

For 14" flywheels, the casting number will be pretty much irrelevent. Several casting numbers were used over the 66-85 period for 2 piece seal, internally balanced engines. All are completely interchangeable, except those used for the dual disc clutch. I doubt that you have one of those.

**Tom P.** · December 28, 2003, 11:51 AM

Differences between 621-444-697 housings

Joe here are the VISIBLE differences.
I just went and looked at the ones that I have.
On the DRIVER'S side of the 621 the upper diagonal reinforcing rib is WIDE.
This same rib on the 444 is narrow, just like the rest of the ribs. Since the 444 is the earlier housing, then I can only speculate that the rib of the 621 was enlarged as the result of some kind of a need for additional reinforcement.
The 697 housing, on the INSIDE, where the ball stud for the clutch fork attaches, has a bigger boss for the ball stud. Why, I do not have a clue.
Now, here is one more twist to the bell housing issue. THERE WAS A FORTH full enclosure housing (I don't have the number readily available). For the 409 folks, this is a rare and rather valuable housing. It was used on 63-4 409 engines (I'm not sure if it was unique ONLY to the 425hp/409s) and it was quite similar to the 444 housing, BUT, it didn't have all the narrow ribs like a 444. It was smoother on the outside.
Then, of course, we all know about the alum housings of 60-61. They were for the 14in flywheels and looked essentially identical to the 55-62 cast iron housings with an open bottom. The 60-62 housings are probably the most expoensive to buy, with the 60 being the rarest!

**Tom P.** · December 28, 2003, 11:56 AM

Re: Differences between 621-444-697 housings

(---------------about the alum housings of 60-61)--------------Sorry, I meant 60-62.

67 435 11" clutch,bellhousing

67 435 11" clutch,bellhousing

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