End of Day 2: Recap and Next Steps
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Lots got done today! Pulled the engine out as I updated earlier but I also got a lot of prep work done for my next steps. Power washed and degreased the engine bay so it’s ready for a fresh coat of paint
I also installed the LS1 flywheel onto the LM7 engine and it fit great, also installed the LS7 pilot bearing which also fit well. If you combine that mix of parts along with a 70s Chevy bell housing and an extended length throw out bearing and you can mate a 70s 4-Speed to a Gen III V8.
Have all these engine RPO codes confused you yet?
The bell housing bolt pattern is almost identical and input shaft diameters are identical. The biggest issue with this combo is the distance between the throw out bearing and pressure plate is 0.4” longer due to how the LS crank is designed, so you either can use an extended throw out bearing like I have or you can swap to a hydraulic setup.
Look how perfectly the super t10 input shaft fits into the LS7 pilot bearing on the LM7 crank.Tomorrow I will be dropping the gas tank and hopefully installing my new tank with an integrated EFI rated fuel pump. I also plan to grind out the welded in motor mounts (was too lazy 8 years ago to use bolts) so I can install mounts in the Chevy/Camaro location on the subframe which when combined with my new motor-side mounts will allow me to locate the LS in the engine bay such it fits like a factory SBC. If that all gets done I’ll weld in new mounts because I’m still lazy, and paint the engine bay with fresh POR-15.
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@bandit "If that all gets done I’ll weld in new mounts because I’m still lazy"
Man, eight years in the future, you're going to hate yourself during the next engine swap.
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Looks like some good progress! I'm equal parts surprised that the 621 (I assume) bellhousing fits onto the newer engine and not surprised because GM. How was the pilot bearing runout?
Taping rags over the ends of the hinges is cheating though, half the fun is maiming yourself on them every few minutes, then just taking them off.
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@cb Oh I’m sure I’ll hate myself in the future, but next time this thing gets an engine swap I want it to be electric.
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@bandit this is going together quick!
Those hydraulic throw out systems are pricey if im remembering right, was that why you went with the extended? -
@mm54 Yep it’s a reproduction 621 bell housing. All the dowels on the block align and all bolts but two fit perfectly. One at the 12 o’clock position is too high by 1/2” on the engine side, and the other at 2 o’clock the LS block is cast for a hole but not drilled. I’m not sure of the runout, I just did a quick mock-up for a visual check. When it comes time to final install the clutch assembly I’ll do my due diligence. Why is runout important in this instance? I’ve not done something fully custom like this before.
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@sony1492 Correct. $14 bearing vs $400-$500 hydraulic setup. I’ll put up with my old style mechanical linkage setup to save that much cash.
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@bandit said in End of Day 2: Recap and Next Steps:
@mm54 Yep it’s a reproduction 621 bell housing. All the dowels on the block align and all bolts but two fit perfectly. One at the 12 o’clock position is too high by 1/2” on the engine side, and the other at 2 o’clock the LS block is cast for a hole but not drilled. I’m not sure of the runout, I just did a quick mock-up for a visual check. When it comes time to final install the clutch assembly I’ll do my due diligence. Why is runout important in this instance? I’ve not done something fully custom like this before.
If the runout is too far beyond spec, it'll put radial loads on the input shaft which can cause hard shifting and transmission (bearing) wear, since the input shaft won't be dead-on straight. The good news is the old 4-speeds have a pretty wide range of tolerance, but I'd be a little skeptical of the repop bell.
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@mm54 thanks for the lesson!
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@bandit That's a lot of progress!
