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Third-Gen Firebird LS Swap
Greg Deford; via I was wondering if you could give me some info on the brand of motor mounts Josh Kunkel used on his Camaro? Also, when I was looking for an LS engine, some are listed as manual or automatic, is there a difference or is it that they are just equipped with a flexplate or flywheel? Tom Fogelsong mounted a T56 to a 5.3, I am assuming it was from an automatic since it came out of a Suburban. Would there be an issue with the pilot bearing? I'm planning on putting an LS 6.0 into an '87 Firebird.

Jeff Smith: We've kept in touch with Josh and his father, Russ Kunkle, since they always bring a nice car to the Car Craft Summer Nationals in St. Paul every July. To answer your question on engine difference, there is absolutely no mechanical difference between a manual transmission– and automatic transmission– equipped engine except that the manual comes with the pilot bushing. If you are using a T56, the stock LS pilot bushing is what you want. For your motor mount question, I contacted Russ and this is what he told me:

"The mounts we used on the Camaro were from Spohn and we bought the motor and transmission mounts as a set. The motor mount is actually a new frame mount and uses the fourth-gen motor mount. They make tranny mounts for either the 4L60E or the T56. We used the stock fourth-gen F-body pan; Spohn has it figured out. It's tight, like 1⁄2 inch between the pan sump and the K-member, but it fits. Josh kept the 4L60E with the mount bolted right up to it, and we put a Yank 3,600-rpm-stall converter in front of it. So far, the only folks I know of that make long-tube headers for this particular swap is Stainless Works—Spohn sells those also with a Y-pipe, but it's pretty spendy. We used the stock manifolds and made our own Y-pipe from 21⁄2-inch mandrel bends and merged them into a single 3-inch. I think a guy could use the shorty headers, but he would still have to fab the Y-pipe. The rest is a Flowmaster American Thunder system. The pilot bearing shouldn't be a problem. In our Nova, we put a TKO-600 behind the 6.0L we bought as a kit, removed the flexplate, and popped the bearing in the end of the crank. The clutch, pressure plate, and flywheel are LS7 stuff that bolted right on."

Spohn makes a very cool front K-member (PN 703-LSX, $515.00 Spohn) that uses the stock Camaro steering and is lighter and stronger than the factory piece. The Spohn motor mount kit (PN 971, $85.00 Spohn) adapts an LS engine to either the factory subframe or the new Spohn K-member. Spohn also makes a trans crossmember to adapt the T56 six-speed to these earlier F-bodies (PN LSXT56XM, $105.00 Spohn).

As Russ mentioned in his reply, the conversion to a manual would only require the flywheel, clutch, pressure plate, and factory hydraulic release bearing. You will also need a clutch pedal and actuator rod from a donor car. You have your choice of clutch companies, and there are a bunch to choose from, such as ACT, Centerforce, Hays, McLeod, Ram, Sachs, and a ton more. All these companies will sell a performance replacement of the stock clutch if you choose to go with something better than stock. We are most familiar with the Centerforce line, which includes the Dual Friction system that uses an organic lining on one side of the clutch with a puck-style friction material on the other side. Combined with the Centerforce pressure plate, this system is more than capable of handling the power. A stock pilot bushing should be added, and Centerforce suggests adding a new hydraulic clutch master cylinder as well as a new hydraulic throw­out bearing as part of the swap. These last two components are factory replacement pieces we found for a decent price at Rock Auto. We compared the master cylinder piston diameters (Dorman PN CM39838, $39.78 from Rock Auto) and they are the same as the 2002 master, so that's not an issue. The hydraulic release bearing is also available (Dorman PN CS360058, $68.89 Rock Auto). Be aware there may be compatibility issues between the later-model hydraulic throwout bearing and the early master cylinder with hose connectors.

Also be aware that these late-model, metric-style clutch assemblies use an alignment pin arrangement to align the pressure plate to the flywheel as opposed to shouldered bolts used in older clutch assemblies. If you are reusing a factory flywheel, always use new pins and factory flywheel bolts. Also, since the factory flywheel, clutch, and pressure plate are balanced as an assembly, if you reuse the factory flywheel, the assembly should be checked to ensure it is in fact neutral-balanced with the new clutch assembly.

More Info
Centerforce; Prescott, AZ; 928/771-8422;
Rock Auto; Madison, WI; 866/762-5288;
Spohn Performance; Myersville, PA; 888/365-6064;

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