Swapping Spica Engine/driveline for Carburetor Engine/driveline

1045 Views 6 Replies 5 Participants Last post by .256346, Nov 21, 2020

.256346

Discussion Starter · Nov 21, 2020

My 74 GTV 2000 w/Spica is a bit unresponsive and the gearbox is cranky - due to the old synchros I'm guessing. Rather than a rebuild of both, I was considering getting a whole new drivetrain that is a bit more "racy". A carbureted 1750 with a gearbox with a lightened first gear and a higher gear for freeway speeds. I can keep the original drivetrain aside in its original condition. Any ideas on pros or cons? Let's face it, either way, it will cost the same. It is either that or sell it and start over.

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Alfar7

· #2 · Nov 21, 2020

Forget the 1750. Convert the 2 liter to carbs, and have the transmission rebuilt.
The 1750 was a stop gap motor based on the 1600 with longer stroke. The head IS a 1600 so if you want a better engine stick with the 2 liter and garbage the Spica.
Rj

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gprocket

· #3 · Nov 21, 2020

I agree with Richard. We just completed a 1750 upgrade for a client (against my better judgement) with overbored pistons, HP pump, headers, high lift cam. After all that expense my seat dyno says it's equivalent to a mildly tuned 2L.

Go with the 2L, rebuilt transmission and if you're looking for highway cruising get a 411 diff from a later model Spider.

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conedriver

· #4 · Nov 21, 2020

Also, keep the limited slip differential from your '74 Alfa since U.S. 1750's did not have limited slip. As already suggested, if you want more relaxed highway cruising, use a 4.10:1 (with LSD) from a later spider.

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.256346

Discussion Starter · #5 · Nov 21, 2020

Alfar7 said:
Forget the 1750. Convert the 2 liter to carbs, and have the transmission rebuilt.
The 1750 was a stop gap motor based on the 1600 with longer stroke. The head IS a 1600 so if you want a better engine stick with the 2 liter and garbage the Spica.
Rj

I Want to keep the original drivetrain original, so I would source another 2.0L and put carbs on that. I could rebuild the existing trans with a lightened first gear, new synchros and a taller 5th gear for occasional highway driving. That sounds the most sensible approach. I thought 1750 would be an alternative because they were equipped with carbs.

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Alfajay

· #6 · Nov 21, 2020 (Edited)

MickeyH said:
I thought 1750 would be an alternative because they were equipped with carbs.

US delivery Alfas with 1750 engines all came with Spica. Canadian and European 1750's may have came with carbs, but good luck finding one. Any 1750 is going to cost you more than a 2L (all else being equal) because 2L's were made for many more years. and as such, are much more common.

Converting a Spica 2L to carbs is pretty simple. Lots threads on the BB about this and you can study the components in this kit that Centerline sells: Weber Conversion Kit | Centerline International

I Want to keep the original drivetrain original,

It's your car, but why? You can convert your 2L engine to carbs and then convert it back to Spica if you decide to sell it down the road as an original car.

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.256346

Discussion Starter · #7 · Nov 21, 2020

Alfajay said:
1750's came with Spica in the US. Canadian and European 1750's may have came with carbs, but good luck finding one. Any 1750 is going to cost you more than a 2L (all else being equal) because 2L's were made for many more years. and as such, are much more common.

Converting a Spica 2L to carbs is pretty simple. Lots threads on the BB about this and you can study the components in this kit that Centerline sells: Weber Conversion Kit | Centerline International

I was advised NOT to source a 1750, and I will follow that advice. Thanks. I want to keep the original engine original so I won't be taking the Spica off.

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