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Author Topic: 78 fbird v6 engine swap to chevy 350  (Read 5489 times)

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78 fbird v6 engine swap to chevy 350
« on: May 31, 2008, 10:25:09 PM »

My name is Stephen, I'm a new member! I just recently bought a 1978 Pontiac Firebird with the underpowered 231 V6, with an automatic transmission. The body is in great shape, and I love the look of the car, but it's all show and no go! I've been toying with the idea of swapping to a v8, but I'm not very knowledgeable in this realm. I figured that it's about time I got my hands dirty anyway, and what better opportunity to learn this stuff than on a beauty like this. I plan on having the major work done professionally, but I want to be as involved as possible. I figure if I make most of the decisions up front, I'll save some money, and I'll learn a thing or two in the process.

I've been doing a little research trying to determine what engine would work best in this car. I'm operating under the assumption that a newer fuel injected v8 might get better gas mileage, and might smog easier (i live in California). Am I wrong about that?

I understand that a crate motor will be pricey and require alot of work, since it doesn't include everything needed for the swap. I'll be dealing with a piecemeal situation. I think I want to avoid this. If I buy a donor car, then I should be able to harvest most of the necessary parts from it, thus spending less money on the whole package. I will still need to figure out engine mounts, re-routing cabling, and repositioning the battery to the opposite side. I'm not clear on whether I can use the transmission from the donor car or not.

From what I understand, just about any chevy 350 will fit in this car. I noticed that the 1994-96 Chevy Caprice has the LT-1 engine, which might be a good fit since it's the same engine used in the 93-97 firebird formula.

I'm mostly looking for general advice, since I really don't know what I'm doing here, but I also have some specific questions:

1. Is a newer fuel injected v8 going to get better gas mileage, and lower emissions, or should I not fixate on this?
2. If I do an engine swap from v6 - v8, do I need to register the vehicle differently or update anything with the DMV?
3. Does it matter than the vin #'s won't match?
4. Will I have a problem smogging the car since it was originally a v6? As in, if they smog the new v8 as if it was a v6 will it automatically fail?
5. Am I right in thinking that swapping the engine won't negatively affect the value, since a v6 firebird isn't exactly the most desirable anyway?
6. Since I'll have to swap the transmission, can I switch to manual without a major overhaul?

Thanks for any advice you can spare, and sorry for writing a novel as my first post!


The specs on the car:
2 = pontiac
S = Base firebired
87 = sport coupe
A = 231 c.i.d. 2 bbl v6
8 = 1978
L = Van Nuys, CA
181,047 Production number


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Re: 78 fbird v6 engine swap to chevy 350
« Reply #1 on: June 23, 2008, 09:01:02 PM »
Welcome to the club.  Nice to have new owners in here.  Well, you do have alot of questions here, but some you have already answered for yourself.  Yes, you can do a swap of the motor and depending on what motor you choose, there really isn't any major overhauling that you have to do to the car itself.  Weather you try to stay close to maybe original (meaning maybe a Pontiac 400 or something in that realm) or jump up to a crate motor like a huge 502. Yes, the newer engines do get better gas mileage, but not by a great deal that I would worry about it.  For example, my 1978 with the Pontiac 400 gets about 19-20mpg on the highway and my 1998 Ram Air gets about 25-27 on the highway.  So, it is not a huge difference to where I would fixate too much on what engine.  What you have to ask yourself is "How much do I want to spend?", and "How much horsepower do I want?".  Ask yourself those questions and that will help determine what engine would be better for your needs. You will have to make some changes to the mounts, wiring, fuel lines, etc., but those are all fairly simple things to do and will be about the same no matter what engine you end up with.  The same however is not said about the transmission.  If you swap to a manual, you will have to change the crossmembers, add all of the pedals and route those through the firewal, also change the center hump where it enters the car.  Not all too difficult, just a little bit more involved with cutting and welding and changing.  All States are different with how they register cars, so you will have to check with California as to weather or not you have to register it differently.  I know in my state, they could care less what engine I had in there and never ask.  The look at the VIN number and the Mileage and you are done.  That also makes it nice for Insurance purposes as well because the title says it is a V6 which means your rates will be lower too.  You are also right that the non-original engine won't hurt the value because the Base Firebird is not a highly sought after car.  But, just like I tell everyone else that asks... It is YOUR car and YOUR money, you do what YOU want to do with the car and don't let anyone else tell you any differently.  If you are making the car, then make it to exactly what YOU want it to be.
Brett Campbell
1978 Trans Am, 1989 Trans Am, 1998 Trans Am

National Firebird and Trans Am Club Message Board

Re: 78 fbird v6 engine swap to chevy 350
« Reply #1 on: June 23, 2008, 09:01:02 PM »


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