FormerOldsGuy

I have an LG4. Is it worth modifying it or should I just save my money put a 350 in later? I already have a cherry picker, engine stand, tools, etc... so that would be no problem for me. But if I can get some extra power out of a 305, i'd rather just keep my current engine. I'm thinking a better exhaust, an edelbrock intake, and higher-ratio rockers would help. I am totally new to chevy engines,as i have only dealt with olds in the past. Do you have any suggestions for other simple stuff I could do? Do you have to drop the oil pan to remove&replace the timing cover on a chevy? If not, a cam swap wouldn't be too hard. Thanks a lot.

robbob

Your're better off getting a high performance 350.
You could make the lg4 get close up to 400hp,but all the money spent doing this would be a lot,probably more than a crate engine.
If you want to stick with the 305
1-change your cam
2-heads
3-intake manifold
4-headers
There is a build up in the archives somewhere

GMTech

Converting my LG4 to TPI alone put me from a 16 second 1/4 mile, to 15 flat. Headers, catback, and gears shaved another half second off the clock, and I still have the stock heads and cam (wich is even smaller than the notoriously bad Peanut Cam). I'm about to put another cam in just to see how much more I can get out of it.

I'd say if your bored, build it up. If you want a no bullsh!t approach to high HP, ditch the 305.

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'87 Trans Am
S/D TPI retrofit including functional PassKey,
22# injectors,
Whatever chip I feel like burning,
JET AFPR, Ported Plenum,
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Flowmaster Exhaust,
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Summit 1-5/8" headers, 2.5" Dynomax catback.

Best 1/8: 9.519@72.74

'97 Bonneville SSE

RB83L69

Check this one out for some results with a 305....

https://www.thirdgen.org/messgboard/...ML/012689.html

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zippy

since you already have the 305 and they really are a nice engine, i'd stick with it. put all the parts on it that will interchange later with a 350. all parts that you'd also want to put on a 350 is what i'm referring too. playing with the trans and rear end is a good start. maybe a performer rpm intake and a mild cam. if you buy heads for it, buy something that will fit the 305 and 350. this will include certain model 2.02/1.60 heads, but only certain brands. headers will help, but go 1 5/8 or larger so they will be worth it on a 350 later. just some thoughts.

five7kid

iTrader: (14)

The guys above are right. But, that doesn't necessarily mean you shouldn't do something with the 305.

You didn't say what year your LG4 is. In '85, they went up to the same compression as the L69 - which is a good thing. If you have one of those later years, your changes will have more effect.

But, bottom line is GM made that engine for low speed torque and (?) economy. The bore size is small which limits flow past the valves, limiting the size of valves you can put in, limiting the high rpm power you can get out of one. The stock pieces robbob recommends replacing really, really choke the engine off. Etc., etc., etc.

You don't have to drop the oil pan to get the front cover off for the cam change, but future oil leaks are more likely if you don't.


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82 Berlinetta, orig V-6 car, now w/86 LG4/TH700R4. 2.93 limited slip. Cat-back from '91 GTA, ZZ3 intake, Accel HEI SuperCoil. AMSOIL syn lubes bumper-to-bumper. Daily driver, work-in-progress (LG4 w/'87 LB9 block, ZZ3 cam, ported World 305 heads, Hooker headers & y-pipe, 3" Catco cat & 3" cat-back, Spohn SFCs).
57 Bel Air, my 1st car. '66 396, 9.7 CR forged TRWs, Weiand Action+, Edelbrock 1901 Q-Jet (Holley 3310 on the way), GK 270 cam, Magnum rockers, Jacobs Omnipack, 1-3/4" Hedders & 3" Warlocks, TH400 w/TCI Sat Night Special conv & Trans-Scat shift kit, MegaShifter, 3.08 8.2" 10-bolt w/Powertrax, AMSOIL syn lubes bumper-to-bumper. Idles smooth @ 600 RPM in D. Best 15.02/95.06 @ 5800' Bandimere (corrected 13.93/102.4 @ sea level).


P.S.: Some of us still insist on doing it with a 305.

[This message has been edited by five7kid (edited August 19, 2001).]

Sitting Bull

Zippy is wrong about the heads. 2.02 inch intake valve heads will not work with a 305. They will not fit within the cylinder.

Heads are actually the PITA with 305s because of this very factor. But if you want to pull your stock heads and port them, there is a fine tech article on this site explaining how to do it.

Virtually every other high performance part will interchange with the 350 just perfectly. So go for it--but only up to the point where you are not spending more on the 305 than it would cost to put a new stock 350 in.

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1986 Camaro Sports Coupe
T-tops, variable wiper, power hatch, rear defrost, third brake light
LG4 305 V8, Hooker Shorty headers, 3" pipe into Walker Quiet Flow dual exhaust
Edelbrock Performer intake, "Damonized" Q-Jet 4bbl, K&N filter, Crane ignition kit
TH700R4 transmission and Derale cooler
Air conditioning, power windows, power door locks, power brakes, power steering, tilt wheel
Kenwood cassette, Pioneer 6x4 component front speakers
Rockford Fosgate 6x9 Punch rear speakers
Z-28 front and rear sway bars
Aluminum slots and Goodyear 225x60R15 Eagle HP tires
243 horsepower and 326 foot pounds of torque at the flywheel
_ _ _ _ _ __ _ _ _ _ _
Yea verily, and he smote the smog heathens from his small block Chevy, even from the air pump to the converter ...
Todd 1:1

zippy

no, i'm not wrong. trick flow heads will fit the cylinders without contacting. there was a build up in i believe car craft or chevy high performance with this in it. if it's a big deal i can get the exact month/year for reffernce if you'd like.

iroc22

2.02/1.6 heads will fit as long as you don't have more than .450" at .050 on your cam

five7kid

iTrader: (14)

But will be highly shrouded. That's why 1.94's are the largest EFFECTIVE size for intake valves on a 305.

JamesC

iTrader: (5)

The 305 is much maligned, but I'm not entirely sure why. In my estimation for what it is, it's a fine motor. I've had great fun 'awakening' my LG4: Dual snorkel air box and KN filter, AH secondary metering rods and G hanger, tweeked air valve tension, bumped up timing, Summit cam, and Edelbrock intake. While I have a high-flow cat and catback, I'm considering the L69 manifolds, y-pipe, and intermediary pipe, all of which are considerably larger than stock--or my current aftermarket for that matter. The old guy, an 85 IROC, gets down the road pretty well. I haven't considered heads, but apparently the World Products (someone correct me if that's incorrect) S/R heads are quite good.

JamesC

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ATOMonkey

2.02 1.60 valves will fit even if you use old fuelie heads. The block just has to be massaged a little to get them to fit. The extra valve are makes up for the shrouding, plus the machining helps out with that too.

zippy

the trick flows are a bolt on, but with some work any of the 2.02's can be made to fit. i never said they wouldn't be terribly shrouded, but if he's considering adding a 350 later they will work just fine. they put out great numbers on the dyno test from the build up compared to the 305 heads.

R.O.B.

Those heads will not work without being milled down first!

Remember, 305's use 58cc heads, and most aftermarket heads for a 350 are 64cc. He also has an LG4, which is a low compression motor to start with, adding 350 heads (although the shrouding will not allow them to work) will bring the compression down into the 7.xx:1 range!

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Rob
'86 TA 305 TPI
Gutted MAF, Ported Plenum
TB Bypass, Home made Cold Air Intake,
Edelbrock T.E.S.
48psi regulator, (Nickel method)

Sitting Bull

Zippy,

Sorry about that Not a big deal. I always heard that 1.94 valves were the largest and that the centre line had to be moved even to make them work.

My point is that these kind of heads are so expensive that you are better off going for a 350 at that point.