by ttweed on Fri Jan 06, 2006 7:19 am
Keeping in mind that any advice you get on the internet is worth exactly what you paid for it, here's my $0.02:
The '77 model year cars are still subject to smog certification in CA. Therefore, any engine work you do will have to include all the pertinent smog equipment if you intend to license and drive the car on the street. I believe the '77 2.7 engines came with the infamous thermal reactors which caused overheating in hot climates when run hard. I'm not sure if there is a CARB-approved replacement for these exhaust systems, but perhaps someone with more experience with the mid-year cars than I can chime in on this. The magnesium cases were also fairly fragile in comparison to the later aluminum cases in the 3.0 and 3.2 engines. When rebuilding them, it is necessary to include a lot of expensive machining steps to insure longevity (line bore, case savers, shuffle pins, etc.) When combined with the usual rebuild parts and labor, this can add up to a very expensive overhaul.
It may be more cost effective to find a used 3.2 engine (complete w/ DME, catalytic converter and all CA smog equipment) and swap it out. You will probably come out ahead, cost-wise, and the difference in performance of the later engine is considerable. It is a bit of a crapshoot finding a used 3.2 in good condition these days, but they are out there if you look hard enough. You need to find one with low enough mileage and/or documented maintenance/rebuild that can be verified to have good compression and leakdown percentages, or you may end up needing to overhaul the used motor sooner than you would like. You will also end up with a used 2.7 engine to part out or sell as a core motor to offset some of the cost of the swap.
There are come folks that contend that putting any non-original engine in a 911 tends to devalue it, but from a collector standpoint, the '74-77 911 is not at the top of the list, so I wouldn't worry about that factor. A 3.2 swap may even be seen as a valuable upgrade for these models on resale, if that is a concern.
Good luck with the project, whatever you do,
TT
Tom Tweed -- #908
SDR Tech Inspection Chair 2005-06
SDR Forum Admin 2010-present
Windblown Witness Assistant Editor 2012-present
Driving Porsches since 1964