acole88

Hello everyone. I'm looking for some input as to what my best option would be for an engine swap in my car.

First, the car is a 1984 Trans Am with the 305 LG4 engine. nothing special, but it is a non CCC car so that might help a bit with my options I'm thinking. 4 barrel q-jet....all stock.

Ive spun a rod bearing in the 305 so now I am thinking of swapping rather than rebuilding. The car is all original and I would like to keep it that way as close as possible. By this, i mean I would like to try to reuse my intake, ignition, exhaust manifolds, and all driven accessories. I don't want people to be able to tell it has had anything done with the engine.

So I'm asking you guys...what is my best option for more power while keeping all the stock parts? I have no problem putting a cam in it as obviously that is an internal thing. Not looking for massive power...just something a little more potent than the 150hp 305. Thanks in advance.

Air_Adam

A basic 350 would give you a noticeable increase in power and torque, and still use all the same parts. Lots of guys (myself included) have even used the heads from the 305 like you have on that 350 with pretty good results. The only real problem is that if you use an '80 or older 350, then the oil dipstick is on the other side, and it WILL interfere with the exhaust manifold. Your options for this are to either pinch the dipstick tube between the head/exhaust maniflold, or change to a set of headers.

torque_is_good

a 305 and 350 are the same size as is a 383 because they are all small blocks.

Just curious, why would you go through the hassle of swapping an engine just to put restrictive exh manifolds onto it? If you're in Cal. and can't do anything then I understand.

As for which engine would fit, any small block. Search this section and you'll find tons of info because the path you are about to travel has been taken many times over the 27 years that your car has been around.

But, it's up to you if you want to gamble and buy someones junker they are trying to dump but will tell you how wonderful it is, you could get a Goodwrench crate engine or look for a rebuilt engine.

acole88

I understand what you are saying about putting the stock exhaust manifolds on the 350. I don't live in Cali, but my reason for wanting to put the stock manifolds on is just for the sleeper aspect of it. I'd like to get a little more power out of the car but without anyone knowing it. I'd be perfectly happy just rebuilding the 305, but I'm under the impression that I'm not going to get much more out of the 305 without dressing it up with a shiny new intake and headers...correct me if I'm wrong here.

camaronewbie

You state that it's a non computer carb, so do you have a new carb shiny on there? If so, then why not add other new shiny parts? BTW - no one's headers remain shiny for long! Neither do intakes (unless you get $600 headers and $400 Endurashine intake.

If it is a factory carb, then it IS computer controlled - all 3rd gens with carbs from factory were computer controlled.

acole88

I thought the Canadian ones had no CCC. My car doesn't even have any evidence of wire harnesses or a computer....

acole88

Well, I've done some reading and it's really starting to look like someone's already been into this car before me. Is it common for someone to remove the CCC system?

camaronewbie

Canadian cars might not have computerized systems, heck I don't know. But I do know that the computerized carbs started in mid year 1981 cars which were still 2nd gen cars - but that might just be American cars.

acole88

I did some more reading and I came across another thread regarding their car not having the CCC system. Turns out it was also a Canadian car. The tread stated that exported cars had the option to exclude the CCC system. This makes sense in my case.

Anyways...back to my original problem. Knowing that I would like to keep the car as stock looking as possible and retaining all original functions (ie. cowl induction etc.) what would my best option be to get a little bit more power? Is my best option to just rebuild the 305 with a cam or should I be looking for a 350 to build? Is putting the 305 exhaust manifolds on the 350 going to be restrictive to the point that I wouldn't notice much of a gain?

Someone mentioned putting 305 heads on a 350. Is there any benefit to this?

I would really like to just rebuild my current motor, but like I said earlier, I am under the impression that just putting a cam in a 305 really isn't going to gain me much.

five7kid

iTrader: (14)

Keeping the stock exhaust manifolds would be the absolute worst thing to do. They will restrict power no matter what else you do.

If you want to keep manifolds, at least get L69, LB9 ('86-'90, or dual-cat version only), or L98 pieces. They are larger for better flow. You will need to do the rest of the exhaust as well.

You can get more power out of the 305 than it had, but since it already needs a lower end rebuild, you might as well go get a 350 and do the work to it.

No matter what you do, don't keep ANY of the stock exhaust.

tylercamaro

iTrader: (1)

if you want to pass it off as a 305 or 350, you could use swap in a 400 sbs with 2 freeze plugs, say its a 350 but have tons more power. and for sure ditch the stock manifolds, they rob more power than hitler when he was alive(sorry bad joke)

tylercamaro

iTrader: (1)

you can stroke/bore/port/polish/and build a 305 alot but it still wont have as great of power as a simple cammed 350. putting 305 heads on a 350 would boost the compression up a significant amount.

Air_Adam

Lots of early Canadian LG4 cars came without the computer control system. Lots even had an iron intake manfold too, not aluminum like their american counterparts.

Five7 is right about the exhaust system... to really get much out of any performance improvements, you really do need to replace all of it. But if you really are dead-set on using iron manifolds then a set of L69 or L98 manifolds would be a better choice, as they have a bit more volume in the 'log' and the outlets are about 1/4" larger diameter or so, so they do breathe slightly better.

A factory aluminum Qjet intake, like what the american LG4 and all L69 cars came with, would work just fine for what you want. They are actually a fairly good intake and will support 300hp or so without any work to them. A stock Qjet tuned up to L69 specifications would be a good setup for a warmed up 305 or a mild 350 like what you want to do. Edelbrock still sells the parts to recalibrate a Qjet (rods, hangers, etc) so it pretty easy thing to do.

A set of 305 heads on a 350 would be a pretty good idea, as long as the 350 has dished pistons (and most do). The good 305 heads are casting #416, 081, and 601. I had a set of 601 heads on my 350 and they worked very well. There are a few benefits to using the 305 heads on a 350:
- Better chamber design, and lower volume (meaning higher compression ratio)
- Heavier/thicker head castings (late '70s/80s 350 heads were 'light' castings that crack and warp easily)
- You already have them on your 305, so they are essentially free.

The only drawback is that the 305 heads have a smaller intake valve than the 350 heads (1.84" vs 1.94") though for what your goals are, this won't be a big deal.

Ozz1967

iTrader: (4)

Get one of those replacement 350 motors, the 290hp ones summit sells, then put on all of your original equipment and you're 100hp ahead to start. Then swap a set of Hooker 2055 headers on it (everyone does headers, it just makes sense) and you'll pull another 10-15hp out of the motor over your factory iron manifolds. I'd say do the headers because "EVERYONE" does headers, it's so basic it almost hurts. Everything else can be reused. Your dipstic can even be on the passenger side. Oh, and as has already been posted, 305 and 350 are physically the same size, so no one could tell the difference, till you smoke them.

acole88

Thanks a lot for all the input guys. I wasn't really sure how much power the stock cast manifolds would rob the engine of. My primary reason for wanting to keep these is simply so people would not see headers on it. The way i look at it is as soon as someone sees a set of headers, they know you've done some work. I just don't want anyone to know the motor has been worked on. I'd like people to still think it only has 150horse. I would like to get close to 275 horse out of a swap, but I'm not really sure if this is realistic using the stock intake/exhaust parts. I'm assuming that I'm being a little too optimistic with this...any thoughts?

Ozz1967

iTrader: (4)

Well, 99% of the first thing people do, is put headers on. Yes, it looksl ike you've done something, but it's the same thing everyone else does. If you're hell bent on keeping the stock manifolds, it's possible to get 275 Hp out of a 350. You won't get that out of a 305 without lots of help.

The stock factory manifold, I'd go with one from an L69 car. Those were pretty decent aluminum intakes for their time and still hold their own today. Port and polish the heads, bore/stroke the motor, all fine, but what's going to really restrict you is the exhaust.

In the end, your car, do what you want. We can only suggest mods to make it "Better". lol

tylercamaro

iTrader: (1)

i was making around 300 with my 305. my dad had i built by my neighbor so i honestly dont know specs. all ported and polished, lightwieght and top of the line everything. costed alot, and now the engine has just been throught way too much and is getting tired

Ozz1967

iTrader: (4)

You can do 300hp from a 305, but it takes alot of work, and you'll need the headers. Chevy Hi performance did a build. You can do a google search for "300hp 305" and you'll get 5-6 hits on it. Some tough builds but doable. If youwant to stick with the 305. Now, remember, same build with a 350 will net you more than 400hp. Not that you should do that, but I'm just saying...

ex-x-fire

Try to find a low mileage vortec 350 at a junkyard.

tylercamaro

iTrader: (1)

like i said it was my dads doing. he actually left the exhaust stock but ported it and everything...i told him that was a waste of money but parents can be stubborn.

paul_huryk

You have a few options:

L98 long block (use a carb) out of an F-Body or Vette (Vette is preferable due to the easily ported alunumum heads)

350/383 replacement motor from one of a million vendors

ZZ4 or ZZ3 motors (very similar to the L98 motors)

As an LG4 owner myself, with all those hoses and pipes under the hood, no one notices a set of rusty headers when you have the hood open. I have a nitrous kit hidden in plain sight that absolutely no one has even noticed in over 15 years!

The sleeper quality is really due to the exhaust - a super loud exhaust gives away the impression of being fast - so go with headers and a not so loud 3" cat back exhaust. A decent stock 350 tuned with a good exhaust can put out 300hp, add another 150hp if you want to use nitrous - enough to run in the 11's with traction easy.