Manual trans behind a 400 sbc?

[Transformula]

I have a '78 SBC 400 in my '71 4x4, with a th350 and want to put in a manual trans. I know all that's entailed, but was wondering, since my auto is currently installed, are 400 cranks normally pilot drilled for a pilot bearing or bushing? I've done SBC 350s before and they were. I believe that most 400s came as automatics, (like this one originally did), so I don't know if they were drilled. Also on the block, there is no hole and threads where there would be for a z-bar, only a flat boss, which can be drilled and tapped. Speaking of which, how does the clutch linkage go in one of these trucks? Any pictures out there?

[69 longhorn]

The pilot hole is drilled,& you will need a 400sb specific flywheel(you can go aftermarket cast...aroud 80-100 bones, or opt for a billet wheel...200-300). Dont worry about no holes on the block on your 78. The ball pivot screws into the bellhousing on that truck crazyAl

[tll74]

Putting the manual set up to your 400 in a 72-down truck will require drill and tapping the holes for the clutch pivot ball bracket. I have a new 400 flywheel for 110.00 plus shipping. I could send pics if needed tomorrow. Hope this helps.

[69 longhorn]

Originally Posted by tll74

Putting the manual set up to your 400 in a 72-down truck will require drill and tapping the holes for the clutch pivot ball bracket. I have a new 400 flywheel for 110.00 plus shipping. I could send pics if needed tomorrow. Hope this helps.

OOps, I missed the 71 part, it sounds like 78 was the engine (duh).

[Transformula]

yeah, 71 truck, 78 engine. Thanks for the info! Does anyone have any photos or diagrams of how the linkage goes? I might just make some custom parts with spherical rod ends.

[raycow]

If the clutch linkage is a deal breaker, you could run hydraulic linkage. A search should turn up a bunch of threads on how to do it. Hydraulic is popular with the guys who run headers so they won't have to deal with clearing the Z-bar.

Ray

[Ricks1971]

One thing to remember is that a 400 sbc like a 454 is a external balanced motor so is you put a standard shift transmission to it without balancing the motor it will shake badly. I have built several 400 motors and balanced them for a standard shift motor and the crank,flywheel and dampner need to be balanced.

[raycow]

There is no need to balance anything if you use a 400 SB flywheel. It is made with the correct weight as part of it. You can also get a separate weight that bolts between a "normal" flywheel and the crank. You already have the correct dampener on the front end of the engine.

Ray

[Ricks1971]

Ray, the last two 400's I built and had balanced with the correct center force 400 flywheel were way off and would have shook you out of the cab. GM never used a standard shift behind a 400. To do this correct you must balance these parts together or the engine will shake.

[raycow]

Originally Posted by Ricks1971

GM never used a standard shift behind a 400

Rick, you kind of lost me on this one. I used flywheel p/n 3986394 when I converted an automatic 400 engine to manual and it definitely has the weight on it. Are you saying this is not the correct flywheel for a 400?

Ray

[Ricks1971]

Ray, what I am saying is a 400 motor is a externally balanced motor. Which means the motor needs to be balanced from the dampter to the flywheel. Where as a 350 is internally balanced which means it doesn't. You might have bought the right flywheel but becouse its a 400 when you do a comversion you need to balance the motor or it will shake.

[69 longhorn]

I have seen that swap go either way.... My 383 was built & balanced with an auto flexplate & a 400 sb balancer. I swapped to a stickshift & bolted a Hays billet wheel on . with a centerforce DF clutch. I have seen guys have vibration issues doing this swap, but mine has been running for about 6yrs. If it shakes, it must be in an rpm range that I dont use? crazyAl

[Beuford]

Originally Posted by Ricks1971

Ray, what I am saying is a 400 motor is a externally balanced motor. Which means the motor needs to be balanced from the dampter to the flywheel. Where as a 350 is internally balanced which means it doesn't. You might have bought the right flywheel but becouse its a 400 when you do a comversion you need to balance the motor or it will shake.

I agree with raycow. I have built many 400 sbc engines and put 4 spd and now have a NV3500 behind one in my `70 C20. If you buy a 400 specific flywheel and use the stock harmonic balancer you should have no vibration problem or shake as you call it.
Bob in Pa.

[Captainfab]

I agree that there is no need to have the entire rotating assembly balanced unless a complete engine build is being done. You can either buy a flywheel that is balanced for a SB400 or you can do as I've done and had a neutral balance flywheel 'balanced' at a machine shop to work with a SB400. Never had any issues with engine vibrations, and that engine was spun way higher than it should have been.

[tll74]

GM did use a manual transmission behind a 400 sb. It used in a 1970 Monte Carlo. This was a rare appication but did exist. This was the only year and model that it was used in. I run a balance plate between the flywheel and the crank in my stock car and it has been spinning 6-7 grand for four seasons (approx 60 features not to mention heats, dashes, and qualifing). Stock balancer, crank, 5.7 rods and KB flat tops. Great engine!