LT4 into 57

[Rocketman]

This will be my second post. I have a 57 210 that I hope to start the rebuild on next year. I am looking at a 1996 Corvette LT4. I know it is a pretty easy fit by using side mounts which I planned to do anyway. My question is about what flywheel to use with the Muncie 4-speed I have. I have a billet flywheel I planned on using (I bought it years ago). From what I gather, the stock bellhousing will bolt up to the LT-4 which would allow me to use the stock clutch linkage. I know there are lots of other considerations such as gas tank with the internal fuel pump and radiator. I have not committed to this engine yet but will if I can make the Muncie work. Thanks

[Rick_L]

It's not a problem at all. You can use the stock bellhousing or any SBC bellhousing. The 96 LT4 will require a flywheel for an 85 up one piece main seal SBC. The stock bellhousing requires a stock style starter and 168 tooth flywheel. The only OEM setups with the 168 tooth flywheel were 85-99 pickups. They used an 11" clutch, which you'll need. Or you can get an aftermarket flywheel which can take either an 11" or 10.4" clutch, depending on how you order it (or some will have bolt patterns for both). The flywheel you need will have a small weight on it, all one piece main seal flywheels for an SBC do.

[chevynut]

Curious why you prefer the muncie over an overdrive transmission? Is it just because you already have it? If you want to cruise the car on the highway much, the muncie is going to drive you nuts, especially if you want good street performance. What's your intended use for the car? The stock clutch linkage works okay, but there are alternatives that you can consider if you want to. Is your car pretty stock and complete now?

[Rocketman]

Thanks guys. I have had the Muncie for several years. It is not a rock crusher so it will not have the wine. The car will be mostly local and cruises of less that 300 miles. I already have an 11 inch clutch so that will work well with the truck flywheel. The car is fairly complete with an old dead 235 6-cylinder in it and has been in storage for years. Rick, thanks for clearing up what I need on a flywheel. At this time that was my biggest question.

[chevynut]

The stock 6 cylinder bellhousing will not bolt up to the LT4 or any other SBC. You'll have to either get a stock tri5 V8 bellhousing or some other Chevy bellhousing, or an aftermarket scattershield. Lakewood makes one that will accept the stock clutch linkage, if you plan to use that. I'm not sure if all the 6-cylinder linkage is the same as that for a V8 but it might be. What transmission is in the car now? If it's an OD 3-speed manual you will probably have 4:11 rear gears unless they've been changed.

[Rocketman]

I understand about the 6 cylinder bellhousing. I have a trifive V8 bellhousing. The car was originally a powerglide but I converted it to a 3 speed on the column a long time ago. So I think it would have 3:36 gears in it. I know the full history of the car since I am actually the third owner of it. I plan on using the rear motor mounts on the bellhousing and then side mounts. I have collected the disk brakes setup, 605 box, 2" dropped spindles and 1 inch lowering springs for the front. I also have one of the Hurst shifters with the C handle for the trifives. I live in the Dallas area and have a parts car sitting in a pasture over in Louisiana that has been there a long time. This will not be a frame off (I don't have the space) but it is going to be a big project.

[55 Rescue Dog]

Sounds like a pretty good plan, and the Muncie trans is still one of the best ever. Light, small, and shift great. The wide ratio gear set works the best. I ran the close ratio for a season, and switched to the wide ratio gear set, which works better for launching the car while running a good highway gear. 3:36 rear should be fine. Made 3 2000 mile trips back and forth to the west coast back in the day with a Muncie. One car was a 65 small block Vette, and the other a 69 big block Vette getting 18 mpg.

[chevynut]

As long as you don't expect to cruise much on the highway at 70-75 MPH a don't expect real "peppy" street performance the Muncie/3.36 combo should be marginally okay depending on first gear ratio, imo. At 75 MPH the engine would be spinning at around 3000 RPM with a stock-size (28") tire, higher with a smaller diameter tire. The street performance won't be great, especially if you have the 2.20 first gear in the Muncie. That's only an overall ratio of 7.4 which won't win many races. :p Even with the 2.56 first gear it's only 8.6. The stock 3-speed had a 2.94 first gear and the rear gears were 3.55 for an overall ratio of 10.44. To me, that's closer to where it should be for good street performance and will be easier on the clutch. It all depends on your expectations.

My Nomad has a 4.10 rear gear with a 2.66 first gear for an overall ratio of 10.9 which should make for great street performance. It has a .5 sixth gear overdrive so with my 26" rear tires the engine should be turning at just under 2000 RPM at 75 MPH. This is how overdrive can give you the best of both worlds....both street and highway performance.

[markm]

You probably want to ditch the leaky 605 box a CCP500 or Borgeson 670 are much better choices.

[chevynut]

I plan on using the rear motor mounts on the bellhousing and then side mounts.

Not sure how that's going to work out and I don't think I've ever heard of anyone doing that. The side mounts are pretty far back on the side of the engine, and using the bellhousing mounts would put them pretty close together. Most guys use a transmission crossmember and lose the bellhousing mounts for a more modern 3-point mounting system. That's what I recommend.


I have collected the disk brakes setup, 605 box, 2" dropped spindles and 1 inch lowering springs for the front.

If you're going to lower the front of the car that much you really need to understand the offset of your disc brake setup. The "Chevelle" type disc brakes that were popular long ago move the wheels out 7/8" per side and can cause problems with tire rubbing on a lowered car, depending on wheel offset. If you're going with a more positive offset wheel you can probably deal with it. However, a common zero offset wheel will likely be a problem. Just a heads up on problems you might run into.

[Rocketman]

That is an outstanding car you are building. Mine is not going to be anywhere close to that. It will be a nice driver with pretty much stock suspension. I will take a look at the Muncie the next time I am up in the attic to see what the ratios are. You are pretty close on the 3,000 rpms at 70-75 mph. I think the ratio in my Olds is 3.42 and at 70 mph it is tacking about 3 grand.

[Rocketman]

I can see plans changing as I move along. That is the advantage of a forum like this where that is lots of knowledge. I crossmember will be an easy installation and I can see that possibly happening. I had not thought about the wheels rubbing with the front being lowered 3 inches. I am going to use a regular set of 15" Chevy Rally wheels that I will probably have powder coated. Thanks for the headsup.

[chevynut]

One more point of reference....the manual tranny 1996 Corvettes that your LT4 is out of had a ZF 6-speed with a first gear ratio of 2.68 and a rearend with a 3.45 gear ratio for an overall ratio of 9.25. Rear tire size was 285/40-17 which is just under 26" in diameter. The car is just a little lighter than a tri5 at about 3300 pounds curb weight.

[markm]

If you're going to lower the front of the car that much you really need to understand the offset of your disc brake setup. The "Chevelle" type disc brakes that were popular long ago move the wheels out 7/8" per side and can cause problems with tire rubbing on a lowered car, depending on wheel offset. If you're going with a more positive offset wheel you can probably deal with it. However, a common zero offset wheel will likely be a problem. Just a heads up on problems you might run into.

Sorry to bust your bubble you love to bash the Chevelle brakes so much, but Rocketman say he has 2 inch dropped spindles and I don't believe any o0f those use Chevelle rotors. The Chevelle rotor kits use stock spindles.

[markm]

That is an outstanding car you are building. Mine is not going to be anywhere close to that. It will be a nice driver with pretty much stock suspension. I will take a look at the Muncie the next time I am up in the attic to see what the ratios are. You are pretty close on the 3,000 rpms at 70-75 mph. I think the ratio in my Olds is 3.42 and at 70 mph it is tacking about 3 grand.

MY 56 has a 3.42 57 Olds rear and when it was a Th350 it was all over 3000 at 70 mph and so is my 3.42 geared Super T10 equipped 74 Z28.

[chevynut]

Sorry to bust your bubble you love to bash the Chevelle brakes so much, but Rocketman say he has 2 inch dropped spindles and I don't believe any o0f those use Chevelle rotors. The Chevelle rotor kits use stock spindles.

Then if he doesn't use the large offset Chevelle rotors he shouldn't have a problem if he's careful with the setup.

With a 3" drop he still needs to be careful with wheel offset and tire width, or they will rub. If the tires are much wider than about 67.75" outside they will rub the fender on turns, especially with the suspension compressed.

Apparently you like to ignore these facts because the Chevelle rotors kinda work on a stock height car, as long as you don't use a wide tire and compress the suspension on hard turns. Sorry you get butt-hurt every time I post the truth.

[Rocketman]

Well I didn't win the bid on the LT4. However that is the engine I think I will eventually use. I am a long way from being ready for it so that is probably okay. I do have an engine I put together from spare parts on a budget several years ago. It is a 307 (go ahead and laugh for a while). My son took it out of a 70 Nova years ago. I had a set of double hump heads I had redone (just resurfaced and a valve job). I put a 350 horse cam in it with new lifters and a double roller timing chain. It has a used Edelbrock Performer manifold on it and I will probably use a 650 cfm Holley I still have in the box. I mostly put this engine together to have something in the car to be able to move it around while I work on the rest of the car. If anybody wants to give their idea as to how it will run, feel free to. My feelings will not be hurt. It is in effect a stroked 283.

[markm]

307s are tough as nails I know several guys who punched them .125 and installed std bore 327 pistons in them. I still know a big time demo derby guy who runs them for their thick cyl walls.

[Rocketman]

Thanks markm. I can remember guys back in the day punching 265s .125 over and installing 283 standard bore pistons. If I remember correctly they tended to run hot. Do the guys punching the 307s have any overheating problems?

[Rick_L]

Most 307s won't go .125" over with success. .060" over is max for most.

Overheating is not a problem with over bored Chevy engines. That is a pre-internet myth. Flathead Fords had that problem (actually they all tended to overheat because of problematic water pumps), and somehow that belief got extended to all engines back in the old days.

[markm]

Never heard reports of heat issues, but in todays world I would not waste my time building one when 350 4 bolt blocks are so cheap and available. Watch it Rick you don't want to sound like our good buddy CNC Blocks.

[Rocketman]

Markm, I agree with you 100%. I just put this old 307 together years ago since it was in the corner of the garage. I had the crank turned since it can be used in a 327. The block had little wear in it so I had it tanked, the cylinders honed and new cam bearings installed. I put new main and rod bearings in it and a set of cast iron rings. I had the double hump heads redone and they can be used on another motor. I did it to have something to put in the car to move it around and drive while I get the body in shape. I the block would have required reboring and new pistons it would have gone in the junk pile. I think I will still wind up with Gen II LT4 in the car. If not that then it will be a crate engine.