Engine rebuild musing, corvair vs 1911 Options

[r3dplanet]

Years ago I was all hot on the idea of dropping a Corvair motor into my 1971 914 when the 1.7 liter eventually pooped out. During that time I've done an enormous amount of work to the rest of the car and overall its in spectacular shape, except the motor which is getting tired. While the current motor is completely clean on the surface I have 90psi in cylinder #3, 140psi on the other three It's starting to leak but it has a fresh D-Jet do over with new parts, wiring, etc. The engine is from 1973 and its an EA code. From what I understand this means that the heads are a newer revision from the early 1.7 heads.

So I'm thinking that maybe over the next winter I'll pull the motor and .. do something.

My goals are good to excellent mileage, reasonable power, low maintenance, high quality. Frankly, I'm happy with the power of the 1.7. It sounds much faster than it is and that's just fine with me. The car is fun to drive and I'm not interested in speed per se.

The reason I got hot over the Corvair motor is because the design is really good in terms of longevity. The early engines had issues with dropping valves and head gasket failure but the later engine (like the 1965 Corsa 140 motor I have sitting on a stand in my garage) did away with that after GM upgraded the engines after 1963. The Corvair engines have hydraulic valves, great power at even the stock rebuild level, and excellent reliability. You can do carbs, Megasquirt, or any of a handful of other fuel systems - only a few of which are really expensive. If you want to go nuts you can throw in six Porsche cylinders/pistons and get a 3.1 liter six. I'm not interested in that, but it's spectacularly cool that one could.

Costs for the Corvair project are a touch murky. I already have the engine, reverse-rotation cam, clutch, flywheel, and adapter plate. Rebuilding the heads to overcome a valve-drop issue costs between $800-$1000, and the engine kit itself is $1100. Fabbing up an engine mount is cheap. What I don't know is the hidden gotchas of this kind of conversion. Figure $500 for a set of carbs or the fuel injection off of Fiero. So $2.5k for the engine and figure some extra for the hidden extras. Perhaps $3000.

On the other hand, I like my 1.7 liter just fine. And from what I understand I can upgrade to a 1911 for not a lot of extra money on top of the rebuild cost - or I could be totally wrong. Scouring this and other websites for engine recipes and costs it looks to me like I'm in for $3000-$4000 just for the parts. Figure in a grand for head work and I'm at $4-5k. While I like the 1.7 and the purist in me (some days I'm a purist) thinks I should keep the car's provenance intact, it's hard for me to justify $5k+ for an 80hp/100k mile motor. So the higher gas prices climb the better of idea this sounds, but the math may say otherwise if the rebuild costs are truly this high. And, perhaps romantically, I'd like the keep the whole car metric.

The mileage argument is certainly in favor of the 1.7 in that I get 30-35 mpg on the two tanks of gas I've ever driven the car through. The Corvair gets maybe 26.

The longevity argument is in favor of the Corvair engine. The engine rebuilder in town says he sees 250k miles on average in between rebuilds vs 100k for the Type-IV.

So I'm undecided. But I figure its better to objectively hash out these ideas in the planning stages rather that get halfway through an engine rebuild and realize that what I'm doing isn't feasible.

Something I'm not at all sure of are the true current facts and figures about each option. The Corvair option has a few mysteries about getting it all configured for the wiring, sheet metal, other unknowns. The 1.7 or 1911 option seems hideously expensive unless my numbers are way off, and they very well could be.

The one argument I'm not interested in is the whole "you have to pay to play" trash. If I want to "play" I'll jump into my fast as hell Barracuda or motorcycle. I do understand the engine rebuilding is not cheap, but I'm not going to be goaded into spending more money than the car is worth on an engine rebuild.

What I AM interested in is your knowledge, experience, and reasoned discussion.

Thanks all. I love this site.

-marcus

[76-914]

1.7 is bullet proof. keep it in it's power range and it's fine. The bottom half is probably good for another 100k miles. Valve jobs run $800+. P&C's $1200 or $49.99 for Chinese (IMG:style_emoticons/default/happy11.gif)

[ape914]

1.7 is bullet proof. keep it in it's power range and it's fine. The bottom half is probably good for another 100k miles. Valve jobs run $800+. P&C's $1200 or $49.99 for Chinese (IMG:style_emoticons/default/happy11.gif)

My JE piston and ring set was about $600 for all four. this was a 96 mm (vs 95 mm stock) piston, the 2 liter "big bore" gives 2056cc. The cylinders are stock, bored out 1 mm (bore them AFTER you have the pistons in hand and measured)( PS I have a set of used 2 liter pistons / cylinders for sale in want ads).
This motor runs fine on the stock D-jet, with the Elgin performance cam, made for D-jet, but more power than stock a bit more radical, but idles nicely, smooth acceleration. You may want to spend about $100-$140 on having your injectors flow tested and cleaned if you got used ones. Go with the lighter stainless heat exchangers and a Bursch muffler for more go power.

Note the early 1.7 motors had a lot of power to start with, if you pick a performance cam, and bump the compression, better exhaust, balance etc...they can rock even more. The 1.7 rocker assembly is prefered over the 2.0 rocker assembly even when building a 2 liter.

I had lots of fun in my old 1.7 early 1970 car stock motor guts, ss heat and Bursch exhaust, stock D jet, Pertronix ignition. Great mpg too, low 30's most of time, mid 30's on long highway trips. The handling is where it is at on these cars anyway, fat sway bar, in front, sticky tires, low profile (50 series) lowered, and stiffer rear springs. Then I handled as if on rails.


I'd stick with the type IV motor over the Corvair. Less work, The D-Jet is really nice verses any carb set up as far as drivability and fuel economy. If that is an important goal then a D-jet based solution would be nice (or spend more $ and go aftermarket FI, what's the budget again???)

Also if it matters to you, these cars specially in stockish clean form are increasing in value, and I suspect will continue to do so for some time. , and if resale value is a factor to you, the car would certainly be more desirable as a tastefully pumped up type IV or as a converted 911 six, than it would be with a comparable Covair six. I guess some potential buyers would be more afraid of this uncommon engine swap.