HikoriYami

Hey everybody!

I managed to get my hands on a 1992 v6 auto Firebird with a great looking body and relatively rust free. I bought it and expected the engine to die and I could spend plenty of time putting something bigger in. The previous owner was selling it because it sputtered, groaned and had the SES light tripped. Well, that was because the MAP sensor's vacuum tube was broken off. Fixing that, the engine was fine.

Now however, I have a nice looking car with a pitiful engine with 17mpg . I've been working on a build list for next winter and I've run into quite a few questions. I'd be thankful if you could look over my work and tell me how much of my research is good.

I plan on putting in a 383 or 350. From what I've heard, the difference is about 20-40hp. So unless I find some link in the chain that wont work together, it'll just be whatever is more cost effective.

Now this is one of the areas I question. I've read that my v6 and the 305 are mounted on the same mount, just different holes in the mount. This sounds really questionable to me, but I am unable to find something to confirm or deny this. Also, as I understand it, the 4 bolt 383/350/327 will mount to the 305 mount (which could be my mount), correct?

I have the stock auto on my car, so that needs to go. I'm looking at a t56 swap. Not only can they handle the power of the 383/350, but allot of them are bolted to one. There are many 4th gens being parted out in Iowa, so they are also abundant. Will my drive shaft fit here naturally?

Also looking at fuel injection. I think the best bet is to buy a 4th gen with a t56 and a 383 and just transfer over the entire system. But, that's not very cost effective. What are some decent alternatives? Can I take a harness out of another car and make it work? Another idea of mine was to get a carbed engine and install Megasquirt on it. Will that interface with my speedo, Tach, or anything? I obviously need a lot of help on this one, my computer knowledge is probably my weakest point.

Another really questionable area is the rear end. The sticky here says that the v6 is the same as the v8 end. While I think it would be awesome to save some money in this swap, I don't think this is entirely true. What are the limits of my rear end and can it take the new engines power?

I'm planning on getting sub-frame connectors, an engine cross member and v8 springs to hold the 'bird together. I definitely don't want to rip her apart.

I'm definitely just getting started with the plan. Please point out any flaws in my thinking, I'd rather feel stupid now then after I've spent three grand on the wrong things. Thanks for reading and I hope you can help me out here!

sofakingdom

iTrader: (1)

The 6-cyl mounts are not the same as V8 ones. Since the 305 is a V8, that includes the 305. Gotta change em.

But yes, the 305, 327, 350, & 383 (which is just a 350 with a crank with a different stroke) all use the same mounts. As do the 262.5, 265, 267, 283, 302, 307, & 400. They're all small block Chevy motors, and are identical externally in that area. (except for the REALLY EARLY 265 & 283, before about 1958, that didn't have the side mount pads at all) "4-bolt" makes no difference at all. Not to the mounts, or to much of anything else.

As far as "cost effective", that kinda depends on what you're starting out with, what your goals are, and what you consider about "cost". IMO, if you have a 350 and it needs a crank & rods, then it's beyond "cost effective" to buy a 383 setup instead. If you have a 350 and all that stuff is perfect and in running condition absolutely as-is without any further work, it's a different matter. Most people, it's somewhere in between. Get your "core" (the used-up one you want to rebuild) and evaluate it, then you can make a more nearly informed decision.

There are no 4th gens with a 383. Not a good plan to go looking for one. GM never made a 383; it's exclusively an aftermarket deal. By no means exclusive to 4th gens. (or 1st or 2nd or 3rd either, or to F-bodies at all) Maybe even, more rare in 4th gens than the others. Typically, if you want a 383, you get a 350, and then get aftermarket 383 parts to put in it, and go from there.

Yes the 6-cyl rear is identical in every way to the V8 one. It's true that very very few 6-cyl cars got posi, and probably just about as few got disc brakes; but inside the pumpkin, it's all the same. In fact, 6-cyl cars often got better gears than V8s, so who knows, you might already be a bit ahead in that dept. Gotta pull the cover and look.

SFCs are a TERRIFIC idea. Go for it, you won't regret it.

Eric-86sc

iTrader: (18)

The absolute best bang for your buck with your project is to buy a wrecked 4th gen. Use the motor, trans, and rear for your car and part out the rest to make some money back. Another option is to check Craigslist frequently for motors and parts. To add a little more to your questions, a 383 could make more hp than a 350 if it is built with good flowing heads and correct matched carburetor/intake.A 383 is going to make more torque at a lower rpm, which is why they are so popular. For mounts order a set for a v8 thirdgen, rubber is good for comfort while poly or solids would be better if you can tolerate a little vibration. For the rear end, as long as you run street tires a 10 bolt will be ok. I would recommend either 3:23 or a 3:42 ratio which you could possibly already have. A better option for a rear is to get a 9 bolt. They are a little stronger than a 10 bolt which is a better option if you are going to run a t56(a manual trans is harder on rears than am automatic). Remember that a nice motor cannot show its true potential in a car that lacks everywhere else. Along with the motor swap I would recommend tubular lca and any shot bushings on the car to be replaced. Otherwise good luck with your project and keep us updated on how it goes.

HikoriYami

Thanks for the feedback, I had midterms this week and didn't really want to think of something else that's insanely complex, but now I can get back at it.

Buying a wrecked fourth gen seems to be the way to go now. In addition to having mostly everything I need for the engine swap, Ill be able to do a few more mods with it, maybe get some nice leather seats...ect.

So now I'm thinking of getting the fourth gen checking the engine and getting it to work. Then transferring the engine to my bird and making it work. However, I want to at least get that old engine rebuilt, possibly the transmission with it. I don't know if it would be a better idea to swap the engine, tranny and all: and then pull them out and rebuild them.
It definitely would be easier to rebuild the engine before doing the swap, but then if the engine doesn't work, I wouldn't know if I built the engine incorrectly or if I just was missing a wire. (I hope that make sense)

Another question: What are the thoughts on the stock injection on the LT1?

five7kid

iTrader: (14)

The stock injection on the LT1 is fine.

Ross1713

Hello there.... please keep updating, I will be going through the same process v-6 to v-8!
except my project is a 92 Camaro. I have read the post there's a lot of good Info already there, great job. My build is going to be somewhere in the lines of street and touring.

1gary

A L31 roller block should be the foundation either way.1pc rms.

A minimum of 195cc take runner for the 383 along with matched parts to the SCR.

And no those are not GM stock heads.Do not,do not,do not,build solid bottom end and then "try" to save on the heads,cam,kit.

Ross1713

"The good thing about a do-over is you get to really learn what you knew in the first place."....Thanks 1gary!

I really like this.... It speaks the truth!!!

Where can I find a L31 block? what does SCR mean?

five7kid

iTrader: (14)

L31 is the designation for the 350 Vortec block that came in light trucks from '96-'99 (and a few '00). You can also buy it new from the factory/dealer.

SCR = static compression ratio

Ross1713

now this is why I do most of my research here! great info, not only for my Camaro but for my Chevelle as well. the guys at team chevelle think there to good, and always argue never answer question either

bhaas

Just put a Pontiac 455 in that bad boy and get it over with.

Might want to get some sub frame connectors installed to help
stop the massive twisting from all that torque.

Just a thought.

fishkiller

350 with a carb and a turbo 400 pushing both easy to find and build and rebuild when your foot gets heavy

HikoriYami

So, update on my end. I've definitely decided on building a 350 lt1 T56 if at all possible. I just picked up a new job which should allow me to do the swap sooner and with more expensive parts.

The problem I'm running into is finding the donor car, Ive been checking craigslist almost constantly. There are a few 350 autos that have been trashed, but no T56's. Is there a better place to find these cars?

New to the swap: I'm looking at getting the engine machined back to stock specs when I find it. Then I'm thinking of new camshaft, pistons and heads, but I haven't even begun to research any brands to use. I am looking for the middle ground between fuel economy and "POWAR"...with slightly more of the latter.

Also, I will be updating this thread as I move along through the swap process. Ross, I'm looking forward to trading ideas.