What to do with my 305?

[Phoenyx]

OK, here's the situation:

I just bought a Malibu with a 305/350 combo.

Normally I would just yank the 305 out and go for a 350 or 383. But...
- I want to just concentrate on getting good fuel mileage for now
- and the car only has 43,000 original old lady miles on it (yes, it's true :-0), so the way I see it the 305 should stll be in pretty good shape.

Here are my basic plans:

-use stock bottom end and heads
-duels with glass packs and stock manifolds
-new cam, lifters, springs and stock replacement rockers
-new oil pump (maybe)
-performer intake (big maybe, will probably just use stock one for now)
-gear drive (yeah... I know lol)
-new plugs
-new wires
-new HEI module
-curve kit (maybe)
-remove all emissions
-shift kit (hard one)
-3.73s from old car.


So my question, is what cam should I use? I was just gonna go with the performer one. What do you guys think?

 

[Coveted]

305s arent that bad, i threw a stock bottom end on a h/o 305
cam headers
intake carb
had no problems shifting it at 7200

 

[Blake442]

Why would you throw a bunch of speed parts onto a car you want to get good gas mileage? I wouldn't expect more than 12 mpg out of that combo, and the same stuff on a different motor would have more power.
If you want good gas mileage, do your exhaust, do a tune up, and put a 2 bbl carb on it. Leave the rest of it alone.
My '79 Malibu has a 267 v8, 2 bbl carb, and a th350, and gets a consistant 20 mpg. That's pretty impressive for an all original car with 224,000 miles on it...

 

[megaladon6]

first i'd ditch the heads. newer tech heads will increase efficiency, giving you power and economy. seeing as there aren't a lot of choices, and i'm sure you don't want to spend too much money, i'd try to find a pair of 305/5.0l vortech heads. for a cam i think you'll want (i'm assuming it's a roller block) something like the comp cams xr252. 200/[email protected] and 472/480 lift. you would also want to mill the heads some to increase the anemic stock compression. i'd go for 9.0:1, there it'll run on anything.
with vortec heads you will have to buy the more expensive intake, but it's not that much more--$30-40.
i'd also swap in a 200r4 trans with a shift kit. overdrive will really help with MPG, especially with a 3.23 or larger rear gear. with a th350 and 3.73's in back the engine would be screaming on the highway.

 

[Phoenyx]

OK maybe I should explain myself more. I just want to get a little more performance and economy out this motor for now. I plan on going with a 350 or a 383 next year. I didn't really say anything about speed parts, just a cam, and maybe an intake. It's already got a quadrajet from the factory. And if I do get an intake, I'm just gonna get a spread bore one so I can keep my original carb. And as much as heads will help, I know. I dont wanna shell out money for heads when I'm gonna be building a better motor next year that will need different heads.

I'm mainly looking for a good cam that will work with stock heads, manifolds, duals, and my stock carb. I will only be getting the intake if I have enought cash left.

 

[Blake442]

I hear certain phrases like cam swap, performer intake, gear drive and shift kit and think speed parts. Call them what you will.
Wanting more performance as well as better economy doesn't really work that well as one usually comes at the expence of the other.
I think you're better off enjoying a low mileage motor while you save your money for that 350 or 383...

 

[megaladon6]

i understand you're not going for power. but to get MPG you need efficiency. to get efficiency you need to fully mix the incoming air charge and stuff air into the cylinder. 305/5.0L vortec heads are cheap from the junkyard and won't require any mods with most cams. and they can add quite a bit of torque. stock compression is about 8:1, which may be good for emissions, but not power.
unfortunately there is no easy way to gain significant MPG from the engine. you're best bet is probably the trans/gears and a really good carb calibration.

 

[Phoenyx]

How cheap is cheap on a set of those heads? Oh, and it's a non roller engine.

 

[midwestls]

I would say just drop in a fuel injected, twin turbo, 502. Might just idle at like 60 Otherwise, maybe a decent exhaust system to let it breath a little better (and sound nice) and any kind of aftermarket open air cleaner to give it fresh air. You'll never make 4 cylinder gas mileage with it, no matter what you do. But I've seen many, well tuned mostly stock small block Chevy's turn mid 20's on the highway. Stay off it and it shouldn't do too bad.

 

[85 Cutlass Brougham]

For a cam, use a Comp XE252 as it will add torque and have good vacuum. I second the Vortec's, but would also consider some World 305 SR Torquer heads too as they will allow you to run a stock intake, which is fine for this application. I would use a set of TPI 350 exhaust manifolds as they should be cheap and they have a 2.25 in outlet vs 1 7/8 stock. But by the time you spend all this money, you won't offset it in savings as compared with leaving the engine as-is, and putting a TH200 4R and 3.23 gears in it. The gears will make as big an improvement as the engine mods will, and it is far less work to change the trans and rear axle than tear the engine apart. The drivetrain stuff could be done for under $200, but the engine work I would budget at least $700-1,000. I spent over $500 on changing my cam, lifters, rockers, timing chain and head gaskets last year. Internal stuff is never very cheap because of the hidden costs that you never anticipate. Broken parts that worked before, gaskets, etc. all add up.