I am considering a drivetrain swap in my 77 Vette. It currently has the base 350, turbo 350 trans and 3.08:1 rear ratio. It has 167,000 miles and is completely stock. I currently also own a 1996 Silverado 4x4 truck. I enjoy driving both, although I am happier with the performance of the truck. In comparison, the Vette seems slugish. I intend to use the Vette as my daily driver late spring through late fall. (basically until the snow flies)

I would like input on the following 2 drivetrain options - preferably experience based.

- swap to a 383 (used)/ 2004r (rebuilt) combo and likely keep stock rear gears

- swap to a Vortec 350/ 4L60e combo from a 1997 silverado (2wd) that was rearended. This would swap would involve the complete engine/ transmission/ computer and necessary wiring harness. I also know that I would need to change transmission mount and run new fuel lines for the fuel injection. Would I need to swap gas tanks or could I keep my tank and make use of the internal components from a 1982 tank since that year was injected? Would I be able to make use of the engine mounted accessories or would I need to change over to everything from the 1977 engine? Would this setup clear my stock hood, or would I need to change hoods?


Kael

 

I'm pretty fuzzy on mechanical stuff, but I'll take a barely educated guess and say what's going to determine whether or not you can use the internal components from an 82 gas tank is going depend on the fuel pump pressure the vortec 350 currently uses.

 

Priya,

Thanks for your input. After a little more checking, I found that you are correct that the fuel pressure requirements are quite different. It also appears that the 82 fuel tank is slightly different than the 77. I now know that I will need to determine if the 82 tank will fit in place of the 77 tank before I give this thought much more consideration. I know that the 77 is 17 gallons while the 82 is 24 gallons. I also did check at the local parts store and verified that the actual electric fuel pump (contained within the in-tank housing) for an 82 Corvette and a 97 Silverado is dimensionally the same size and uses the same connector. Since the fuel pumps are the same dimensions, I could easily swap that with a new one for the truck.

Am I creating a monster with this thought process? I was originally asking because I was interested in a somewhat simple and cost effective swap.

Kael

 

Ask the ls swap guys what they are doing for fuel in the 68-77 cars, as for the vortec engine and trans will fit, you will want to convert to the serpentine blet set up but not sure the brackets from your donor will clear the hood (anyone do this swap?) I know you can use the older brackets from fbody cars,caprice, maybe even trucks, you will use the 96 water pump (id get a new one while its out) the other option id recommend is swapping to a 0411 ecm from a 00-03 (i think) chevy express van with 5.7 you will be able to find more people that can tune the ecm and remove un-needed features.

 

Having spent a lot of time under my bubble back 79 where the gas tank goes, I don't think an 82 tank is going to fit in your 77, but that's just a guess.

I wouldn't be worried about creating a monster (although I may not be the sharpest cookie in the light fixture). I'm going through the same thing with my stock 79 L82 motor. I've collected almost all the 89 Tuned Port Injection parts I need to convert it, I have a set of aftermarket hp vortec heads that are going on with a Scoggin's Dickey manifold. I've been doing a lot of reading about how it works and what it takes but have since stopped since god knows when I'll get to the motor after 3 years on the body and no end in sight. I did learn enough to feel shakily confident I could do the conversion by myself. My husband is some sort of high trained automotive technician so, I have an unfair advantage in that way.

I'm a failure as a mechanic, electrical is voodoo to me, but if I can get to the point of thinking "Maybe I can do it by myself", you can too : )

One thing to keep in mind, with any project there's a lot of budget uncertainty and the more you plan for the project the bigger the potential budget shortfall you risk before completion. If you don't have an ongoing supply of readily disposable cash, you risk getting into the situation I'm in - having spent thousands on motor parts for the TPI/Vortec conversion and now I'm running out of cash to finish the body and paint and certainly can't see anyway to come up with the additional cash to rebuild my factory L82, put the TPI/Vortec stuff on it and get it running.

Don't bite off more than you can chew, I did in pursuit of my dream car.

 

Swap the 350 Vortec and 4L60E in and put an intake manifold, carb and non-computer distributor on it and use a stand alone Trans controller for the 4L60E from TCI. Simple. Trying to interface the truck wiring to the Vette will be a nightmare......the Truck intake is ugly anyway and with the throttle body up top will need a goofy hat to got o an air filter......
Or swap an intake on it and purchase one of the many self learning EFI kits.......may be more than you want to spend....but much easier......
Only thing....on a Vortec block, there is no provision for a fuel pump.....so you will need a fuel system of some sort.

Jebby

 

This is really a simple and cost efficient way to go!!!

 

Thanks, these are the pieces of information that I had not yet considered. And I absolutely do not want to bite off more than I can chew. I want to be able to drive the car not just look at

 

In 97 chevy used the CPI(central port injection) system. Its a kinda odd ball injection system with all the injectors placed in the middle of the intake with small lines that have pressure operated poppet valves at the end of the lines and requires over 60 psi of fuel pressure. Its pretty reliable with the exception of intake gasket leaks and clogged poppet valves. After installation of the updated CPI unit(gets rid of the poppet valve and uses 8 small injectors placed inside each port where the poppets once were) and either the GM updated or aftermarket intake manifold gaskets they are very reliable and good running engines. They come with a nice serpentine set up thats pretty narrow but kinda tall, I'd imagine it'd fit between the fender wells but not so sure itd fit under the hood if you kept the A/C compressor. The aftermarket makes standalone wiring harness for the engine/trans combo that make wiring it up pretty easy and if you can use the 82 tank and get 60 psi of pressure out of it it'd be pretty easy to swap in.

The problem is, they only make about 250 hp. They have relatively low compression and small cams so even though really refined for a SBC and runs well on 87 octane, they just don't make enough power for all the hassle. The only good thing about them is the heads, they flow pretty well for a factory iron head and with a little of work handle decent valve lift. The blocks have a roller cam but no mounting boss for mechanical fuel pumps

If you can get the 97 power train for super cheap, I would buy it, use the 4L60e with a standalone trans computer, and rebuild the original engine using the 97 heads. If you built the engine with pistons that give 9.5-10.0:1 compression and a decent cam you could have a decently powerful engine and overdrive trans for cheap and would avoid all the hassle of electric fuel pumps and EFI wiring.

 

I also agree with Jebbysan . I have a Vortech from a 2000 GMC Savana in my ‘71, with an Edelbrock Performer and a little in-line fuel pump back by the tank. I swapped in a cam from 350 Ram Jet crate engine. Lots of guys replaced the cams in their crate motors before they installed them and sold the take-outs on Ebay, cheap. Runs good, and I didn’t have to change the valve springs. I did have to change the gear on my distributor to work with the steel roller cam, but I was able to keep the tach drive.

 

I have a better suggestion: find out why your car has 'sluggish' performance and correct its 'tuning' problems. I do not know anything about your car or about you. But the probability that your sluggish performance is a function of the carb secondaries not opening fully...or not opening at all...are relatively high (going by past similar threads).

Simple question: Have you removed the air cleaner (engine OFF), held the secondary air valve OPEN, and looked down to see if the secondary throttle plates go to vertical when someone else fully depresses the accelerator pedal? If you have not done this, you do not have proof that you actually have a problem.

Manually exercising the throttle linkage on the carb to see if it fully opens is NOT the same as depressing the accel pedal....as many have found out.

 

And timing. Make sure you have 34° advance at 3000 without vacuum. And around 12 more with vacuum.

 

Do It with a Carb!
but that '97 Silverado's RPO code L31 vin code R Vortec actually does have right at 9.4:1 CR. It has a steel roller cam but it's small and has No fuel pump eccentric on it. The mechanical pump mount pad is probably on block but not finished ... local machine shop can complete for about $100. Then another roller cam & valve springs-retainers and you'll be right at 400 crank hp ... reliably & cheap. Very popular is "Hot Cam" swap or similar.

One caution ... rear-ended vehicles ... might SLAM driveshaft hard forward and internally damage both either/or trans & motor ... happens.

-edit-
here're handy comprehensive specs for that L31 from GM powertrain ... dig deep, 9.4:1 CR is published
http://www.kohlerpower.com/onlinecatalog/pdf/tp6104.pdf

 

FYI ... ALL iron head Vortec 350 motors (L31) came in trucks not cars ... and ALL L31 came with a LONG water pump and associated accessories, belts & brackets.

AFAIK, No C3 came with LONG water pump.

Truck Long wtr pump & brackets don't seem practical for C3 ... would put fan much farther forward than OE C3 ... crank pulley same ... seems that won't clear Xmember

Seems some late 80s - early 90s C4 & Fbody came with a serpentine setup with a SHORT wtr pump. IIRC, seems their A/C ran off a separate Vbelt??

Or, use the OE wtr pump, Vbelts, pulleys, brackets etc from your C3.

 

Thanks for the answers that have been given so far. You have each given me a few things to think about as I move forward with this project. Many of the things mentioned are things I would not have thought about until after i ran into them

Here is a little background information for my original post. I acquired my car in September of 2017. Prior to me obtaining the car, it had not been driven for approximately 8 or 9 years. When I obtained it, I asked a local auto service center to give it a look over to make sure that it was road worthy. Although I knew that the engine was completely stock, I noticed that the idle appeared to have a lopey sounding idle which I thought to be the result of the true dual exhaust. After getting the car back from the service center, I proceeded to drive it daily (about 50-60 miles per day) until the end of October when it was parked for the winter months. During the winter months, I had taken a couple of other vehicles to this same service center and found that their work wasn't as good as I had originally been led to expect. As a result, I made the decision to never return to that facility.

Then, during the spring of 2018, I chose to take the car on a trip out of town because my daughter had a need to use the family vehicle. This trip was just shy of 600 miles roundtrip. While on this trip, I noticed the car seemed to have had a slight shake at certain speeds ( which I attributed to possible flatspots on the tires from sitting. The car was also much slower to get up to speed from a start in comparison to my truck but I assumed that was because of the 3.08 gears instead of the 3.73 that my truck has. On the return portion of the trip, the car developed a severe misfire and would not obtain a speed beyond 50 mph. The previously mentioned shake now was no longer slight. It was now quite significant between 28 mph and 35 mph. After 35 it would become much smoother

A few days later, I took the car to a highly recommended local shop to get the fuel filter, plugs, wires, cap, coil, and rotor replaced. The shop notified me that that misfire was still present after replacing the components. I asked them to look into the misfire more. They removed the valve covers and determined that the rocker arms for cylinder #3 were not moving at all and explained that the cam lobes had likely worn down. When I asked about the cost to replace the cam and lifters, I was told that one of the local engine builders would likely be able to rebuild or replace the complete engine for a lower cost and would eliminate other potential issues from coming up.

The car was then returned home and added to my "when I get around to it" list of things to do. Well, throughout 2018, I didn't get around to it and the car stayed parked. I am now able to get around to it in the very near future and will be able to do much of the work myself instead of hiring it out. So far, I haven't done any personal diagnosis. The only thing I have done is to ask for the input provided in this message thread. Once I know why I have a dead cylinder, I will determine if I really need to swap the engine or if this one can be repaired while in the car. If I do really need to swap the engine, I was considering the truck engine and transmission because it is already a well functioning combo if they could be dropped in as they are and an overdrive transmission is on my wish list. If I have to do a lot of fiddling, that may not be my best option.

Kael

 

Good day Kael,,, sounds like you have a plan in place.
I will say, if you don't want to do too much fiddling, you got the wrong classic car. As you already found out, the issues don't cease. Every one here loves the C3,, hope you can continue to enjoy yours,,,,teddy

 

Teddy,

I wouldn't necessarily say I have a plan in place quite yet. Obviously, my first step is truly figuring out what is going on with my car. I don't want to create a habit of just throwing parts at it. I do however want to figure out a path that will allow me to do more driving than fiddling.

Kael

 

If it were me, I would install a Blueprint Engines 383 and a Bow-Tie Overdrives 2004R overdrive transmission kit.

As you know, it will require other items be rebuilt/refreshed (carb, ignition, exhaust, etc.).

 

So nice to hear of someone buying an old car that's been sitting eight or nine years and then putting it on the road and using it as a long distance daily driver. It just proves that you can use these cars as daily drivers contrary to what people asking hear so much of from Corvette Forum members with much newer cars. I don't buy that, I commutted 100 miles a day for six years and all I drove was the cheapest old beaters I could find that ran well enough to drive. None of them ever got to see a mechanic for a complete go-over before I drove them either.

Were there problems? Of course when you buy cars at the very last stages of their life-cycle you have problems, but it was nothing I couldn't overcome and if you're okay with being late for work a couple of times a year you can do what I did. And yes, I had one, what had been a reliable and solid daily driver for over a year, the engine died in. It still ran when I drove it home, but it was clearly not going to last much longer.

So, some will see your experience and think that's proof you can't use an old C3 as a daily driver, I see it as proof you can, especially if you get it thoroughly checked out by a mechanic before you start using it daily. A rounded cam lobe is not uncommon, but its generally not the sort of thing that's going to sideline you in an old car. What's most likely to break on an old car you just got out of storage is a cooling system failure, brake issues, old contaminated fuel (assuming you do as I did and sometimes pull a car out of field that's been sitting through several Saskatchewan winters and put it on the road. In my experience, if you buy an old, end of life car as I did, if it'll make a few hundred miles without problems, it'll generally go thousands without anything more than annoyances. And with most of the C3's people are wondering if they can use as daily drivers, they're in much better shape and much better kept than the cars I relied on to commute to work 100 miles per day five or six days a week.

 

the long vs short water pump is irrelevant, the 96 truck pump is reverse rotation, stock vette clutch fan will not work/ stock truck fan will hit radiator. This requires electric fans, far as I have seen noone has a serp setup with clutch fan.

Crank pulley from 88-95 clears without issue on my 79, I believe 96 is the same also.

The 96 block doesnt have the coolant bypass like the 55-95 and could cause a leak on ps of pump mount, Also it would be require an external bypass to be added from the intake to the wp without this bypass your engine will overheat and crack the heads.

I personally would sell the 96+ serp brackets and go find some 88-95 brackets to use with that wp. I would also keep your eyes open for a stock lt1/4 cam from fbody or corvette only for cheap or free, this with a new aftermarket timing set, would get you to the stock hp rating for really cheap.