I have a 1981 that is in great condition but the motor appears to have a burned valve, original engine with 79,000 miles. I could pull the motor and have it professionally rebuilt but a local shop has a beautiful motor sitting on an engine stand, complete with manifolds and carb, roller rockers, roller cam, holly dominator, etc. Great motor that would really sound great. But the numbers will not match the car. Is this an important consideration on this year model?

 

here's my take:

There is a crowd that will pay more for a numbers matching origional car, so keep everything so you can put it back in case someone cares.

There is also another crowd who could care less about the next owner, so they make the car as they like it. If they have to sell it, they've got bigger problems.

There are people who just are looking for performance, so origional isn't getting it done.

 

if your planning on keeping that car forever, the who cares? man, the original L-81 is nothing to get all excited about. the originality factor is probably no big deal. i could be wrong but i think all passenger car engine blocks came from the same plant (truck blocks might have still been cast elsewhere) so if it becomes an issue, '81 engines are relatively plentiful.
best suggestion if it worries you so much is buy the rebuilt engine and stick the original in a deep, dark corner of your garage. that way you don't sink a bunch of money into rebuilding a mediocre engine and then continue to worry about resale if you blow it up a couple years down the line.
i don't think the '81 will ever be a particularly valuable year. gonna end up like the '75-'79 and '84s, just kind of the red-headed step children of the snobby nose crowd.

 

As already mentioned, it's your preference...there are the 2 different schools of thought. I'd go with the replacement motor and hang on to the original (maybe rebuild it on your own) and keep it on a stand in your garage in case you do sell and the new owner wnats it. :thumbs:

 

:iagree:

Just put the original away and save it.

 

:iagree:

Comes down to personal prefrence. I don't think they are pulling a premium with original engine anyway. I know my 1980 won't be worth much of anything in the future (compaired to other c3s) so I'm not worried about keeping it stock.

 

Thanks guys, thats about what I was thinking. If you watch the adds the cars that seem have a premium on matching numbers are..well...they are not late 70's early 80s C3's. The motor at the local shop is exactly what I was about to build, small block with a fresh bore job/new pistons, mild cam, roller rockers, roller lifters, alum intake, holly carb, polished alum valve covers, its a work of art. The motor was built for the guys 78 Camaro but a small disagreement with his wife on who would hold the family assets kept him from putting it in the car, its been for sale for a while but now that his wife has decided to take up residence elsewhere and the court wants him to pay a rather large amount of money in the proceeding he has lowere the price to about what a carburator would cost. Can't hardly pass it up even if it does not go into the Vette. I'm heading over now with my trusty leakdown testor and if it checks out I will bring it home. The old motor shouldn't take up too much room in the back of the shop, its in fairly good condition so it might be something to play with later. Hmmmm, 400 crank, flat top pistons....

 

Ummm...if you live in Dallas don't you have to face smog testing? That replacement engine will have a hard time passing visual or tailpipe checks.

Or is your car somehow exempt? (5000 mi./yr. or other)

 

I'd rebuild the matching numbers engine. You'd be surprised how much power you could get out of a streetable 350. And a 383 is even better. I wouldn't put a race engine in that car. I know it's beautiful, Dominator and all, but do you want any torque without revving the heck out of the thing? It would be a mismatch.

Chuck the crossfire. They're limited to a maximum of about 330 hp, and simply do not flow well. If you want the "look", get yourself a vintage cross-ram manifold and put twin carbs on it. They make wonderful power, and you could probably reuse your stock air filter box and cowl induction system. Pop the hood and at first glance, it wouldn't look much different, except for the lack of the "spagetti factory" under the hood.

If you can't find a cross ram (I'd look on e-bay for starters, and check out the swap meet scene), then a straight carburetor on a modern dual plane would work fantastic. But so would a tuned port. No kidding. With minor modifications, a TPI provides INCREDIBLE torque through the midrange, right smack where all your street driving is. You'll get up to about 5000 rpm, so match it with a super torquey cam and go kill C5's all day long!!!!!!!!!!!!!!!!!

Also chuck the iron manifolds. They do not make power at all. The big problem is that the manifold is always pressurized, so when an exhaust valve opens, inevitably some of the exhaust gas gets pushed back into the cylinder. They do not scavenge well at all. I'd suggest a tri-Y header to maximize torque. There's a company making them again, it's in Summit's catalogue. They don't have one for a C3, but I'll almost guarantee that if you get one for a 67-69 Camaro/Firebird, it'll fit the Corvette with minor mods if any. The F-body has its crossmember under the engine, so the headers are made to clear that. The Vette's crossmember is in FRONT of the engine, so that's not an issue.

When you get heads, I suggest 1.94/1.60 valves if you're building a 355 (overbored 350). If you stroke to a 383, then get the 2.02/1.60 valves. Avoid the temptation to get mega-flowing heads with huge valves, because unless you're spinning 7 grand plus, you simply don't need them.

If you can afford a hydraulic roller cam, I'd get that. They make power like a solid flat tappet cam without the constant need to keep adjusting valves. If not, there are several hot hydraulic flat tappet cams out there, and if you're keeping your rpm's in the streetable torque range (below 6500 rpm) you'll make great power and you'll save gobs of money. Isky makes a VERY torquey cam, but because it's symmetric grind, it likes a good exhaust system. I'm talking DUAL exhaust. Don't worry, it's the same basic car as the early C3's, so it can convert to dual exhaust very easily. I'd go undercar 2.5" exhaust (no bigger because of that torque issue), with a crossover near the collectors and twin Flowmasters in back. You'll quickly fall in love with the howling sound of the Flowmasters!

And if anybody cares, or if you ever sell, you'll still have the numbers matching motor and can always bolt the "Misfire Injection" back on for selling purposes. If that ever happens, the new owner will appreciate the higher compression, better torque cam, and dual exhaust system. You'd lose 100 hp but you'll still make a lot of torque, even with the stock TBI system.

And definitely don't waste your money on forged this and forged that. Cast iron will handle all the torque you want in a street engine. Remember, you're not building a top fuel dragster. This has to be satisfying between traffic lights, and on the street, torque is definitely king!
Anyone who disagrees should drive my IROC just once.

:D

 

No offense to crossfire fans. "Misfire" is just tongue-in-cheek, and not intended to **** people off. Fact is, no matter what you do to the crossfire, you just can't get it to flow as well as other systems. It was a good first attempt at electronic fuel injection, but they are simply very limited in air flow ability.

 

:confused: what cross-fire?

 

:seeya Have fun and enjoy your Vette! Let someone else worry about the numbers game. :yesnod: :cheers: :steering: :party: :party:


[Modified by Intimidator454, 10:43 PM 4/5/2003]

 

easy for you to say with that 'off the showroom floor' pacecar ya got there. :jester

 

I don't think they can take offense as the 1981 Corvette does not have crossfire injection. It has the CCC that does some processing, but it still has a carb (albeit a computer controlled one).