Advise: engine swap or backdate?

[Nicec2s]

Folks,
I've got a neat, though imperfect 73.5 sunroof Cis car. I drive it daily, for real. It's numbers matching. Been thinking about doing an engine swap (3.2 or 3.6), and saving the cis engine (for when i sell). Alternatively, I'm wondering if it might be more cost effective to buy a good 3.2 and back date it. What do you think?
Sunroof is important to me. Once upon a time I had a 70 911t, with a 3.2. I miss that car.
Please share your advice.
Thanks,
George

[Kris Clewell]

Backdating a car is certainly expensive. You'd have to be building a serious motor to outweigh the cost of doing all that considering the paintwork involved + the cost of another car...assuming you are doing an above average paintjob anyways. Would you be doing the swap yourself or paying a shop? Going from a nice SC to a 72T with an early SC 3.0 swap, I can tell you the weight difference with the added horsepower makes the for a completely different world.

[Xavier PJB]

I backdated, and a fan of it. I decided to "light" backdate my 3.2 by installing 46mm PMO Carbs, cost me 1.5 days of work and the price of the carbs + few things to make it relialable (oil vapor spread fixing and cooler).
Got 264HP and 321Nm of torque with the standard Motronic box.
Would not change it for gold.
Pay attention to the gearbox with the engine torque.
Cheers
Xavier

[Greg D.]

Folks,
I've got a neat, though imperfect 73.5 sunroof Cis car. I drive it daily, for real. It's numbers matching. Been thinking about doing an engine swap (3.2 or 3.6), and saving the cis engine (for when i sell). Alternatively, I'm wondering if it might be more cost effective to buy a good 3.2 and back date it. What do you think

What exactly is imperfect about your 73.5 ? If you look at the cost of buying a 3.2 engine for your car, possibly rebuilding it, dropping it in, and putting your 2.4 back in when selling it...that sounds complicated and expensive... The cost of another carrera + backdate also is a lot of work, it seems to me you are better off fixing whatever is wrong with your car, as is... I've had a 2.4 CIS rebuilt once and it was *the sweetest* engine I've ever had on any P-car I ever owned... That includes flat 4s, 2.0, 2.4 MFI, 3.0, 3.2, 3.6 and later 3.6 and 3.4 watercooled. The CIS 2.4 in good tune was superb, tractable, reliable, great starter, I'm still kicking myself for having sold the car it came with. If I was to nominate the flat 6 that I have enjoyed the most it might be that one.

I once backdated an SC. It wasn't too expensive because we did a lot ourselves, but I would never do it again. The results is a convincing looking car that....still feels like an SC. You *cannot* duplicate the early car feel simply with the backdate weight loss. I can't explain it, but it's not the same. Anyway, I'm not telling you what to do, just giving you data points on stuff I've done among your options. If it was me, I'd buy a beater while my 2.4 is made perfect again, least expenditure, best investment... And if you want to build an early hot rod, I'd suggest buying a clean 912 and dropping an SC or 3.2 engine in it, value wise and feel wise... I know the later cars are galvanized but they are also built stronger or something, and they don't have that light feel early cars have.

[Nicec2s]

Guys,
Thanks for the data/advice.
I do love the "feel" of the 73. I'm not mechanical, so I'd have to have a shop do the engine swap. My car is imperfect in that its due for a repainted and headliner. The typical minor dents and scratches from 39 yrs of service. Mechanically it's just about perfect, as I do drive it everyday (my work is only 5 miles away). The heavier feel of the 3.2 is something I haven't thought of....I've had a couple of 87's and they do feel different. Here's a pic of my 73.5.
Thanks

[raspy2point2]

SC and 3.2 cars--- like driving a Buick. Chris

[Jay Laifman]

If you are already a fan of the car as it is, I'd never change it. But, then I have a 73.5 and love it. Spend all that money on a paint job instead. You'll be that much more proud of your car - but then you might not drive it every day anymore - and what's the point of that?

That said, I sure hope you get more extended drives. As far as I understand it, 5 miles each way is not enough to warm up the engine enough to stop the moisture from causing issues.