Amcen1

Hey guys, im new to the boards and i will soon be buying my neighbors 85 trans am. lg4 and 5 speed. I would like to wake up the motor a whole lot. Overall goal is 350 hp at the crank. I would really like to do this on in the 305. How close to this goal will this combo get me?

EngineQuest Hybrid Vortec heads 180cc Intake runners 1.94 valves milled .020
3 inch single exhaust or dual 2.25 dynomax kit?
hooker compitition shorty headers
xe262 or xe268 cam?
edelbrock performer rpm intake
GM vacuum HEI Unit
Holly or Qjet?

These are the main parts im looking at, how close would this combo get me? feel free to "constructivly" criticise me all you need

sofakingdom

iTrader: (1)

Do the exhaust.

Leave all the rest of the motor alone, including above all, the carb and dist. (money down the drain... power doesn't live there)

Get a torque converter and some gears instead.

NagleMac

iTrader: (1)

You'll get probably around 200-220 with that combo.

Amcen1

Thanks for the input guys, but i want to get as much as i can from the engine. I understand the carb wont make a difference, im looking for input on both types of carbs. I was also looking for advice on cam selection, xe262 or 268. Iv read that the bottlenecks for the lg4 are the exhaust, heads, and peanut cam. If i address these issues, how would i only make 200 hp? im looking for crank numbers btw. And its a 5 speed with 3.73 gears already installed from the previouse owner

*edit, do you mean gain 200?

NagleMac

iTrader: (1)

Sorry I was talking wheel hp. Unless you want to put a lot of money into this, you might want to either rethink your goal or theway you want to get to that goal.

Amcen1

I appreciate you taking the time to answer. At this point its all very hypothetical. so what are my real options hear?

InfernalVortex

iTrader: (4)

A rebuildable core 350 roller block will cost you less than the heads youre getting before you pay to have them milled. Think along the lines of a pullout Vortec engine, or maybe an LT1. An LT1 with computer can be had for less than $1k. That's cheaper than what you're talking about and it will make 300fwhp out of the gate.

Just think about it a little more.

An xe268 and Vortecs wont even get you 350 fwhp on a 350. Maybe 315-330ish?

sofakingdom

iTrader: (1)

Sorry, missed the 5-spd part... converter won't help much there, eh?

Carb & dist are a TOTAL WASTE OF MONEY. They are not what's keeping the CAR slow now; therefore changing them out won't speed it up. Leave them alone, other than to make sure the ones you have now are working PERFECTLY.

If you REALLY want 350 HP for some reason, you'd be wise to ditch the 305. 350 HP out of a 305 = ~1.15 HP / cu in. That's basically pie in the sky when you have a low-compression turd of a motor.

Likewise, the heads you have now, aren't what's keeping the car slow. Reducing your compression even further by going from 58cc (more or less) to 64cc, works HEAVILY against increasing the power output.

Best choice for upgrading that engine to that kind of power level is to install a "bore kit" on it.

Amcen1

Haha I will try to fight you guys one more time on this. What if I just copied the hate me build that everyone talks about? http://www.popularhotrodding.com/eng...s/viewall.html

I would like to hear opinions on that, but in all honesty i have a lot of friends who are techs that could "help" me do a motor swap

Orr89RocZ

iTrader: (20)

Vortecs and 268 cam would work great imo. Def a step up from stock. Give it some compression by shaving heads down as much as you can. Will need intake base cut as well to match. Need 55-58cc to get some comp, thats likely .050-.060" off which is a good bit

FRMULA88

hmmm 180 HP engine, bolt on a 150 HP N20 kit = 330 HP Engine "on the gun"
add a cat back 3" exhaust and call it a day.

get it tuned correctly on the nitrous & let it eat , cheap thrills and when you're not on the bottle it's still a "stock car".

Unless you plan on racing it from light to light all the time, this approach is way more economical than any other mod, When you are ready for the 350 / 350 HP engine you can bolt on the N20 kit to that that motor, or sell it.

good luck and have fun.

83Z28/L69

Good luck and have fun with it! I built a 305 myself. I don't have power numbers yet, as I have not picked a cam, but it should be a lot better than stock. I did a stroker crank in my L69 with cleaned up 416 heads that were gasket matched along with the rpm intake. Not really looking for a certain power number, just better than stock.

rusty vango

you want to zero deck the block and run flat top pistons with no dish.BEFORE you start milling the heads.careful selection of parts for your intended goal .is your best bet with a 305.you don't want more than 10-1 compression for pump gas

86LG4Bird

iTrader: (1)

I'll repeat the practical advice you've already been given.
Unless you have free parts lying around and all labor is free, the exhaust is the only cost-effective mod you can do for that motor. Well.....except for a 100 shot
I remember being naively ambitious and wanting to blaze my own trails with this sort of stuff a long time ago, but I'll tell you this story just as an example of how one might approach it if one were through that stage

The car in my sig is my daughter's first car. We bought it from my buddy about 8 years ago with 105k miles and in cherry condition. As much as I've modded engines in my other vehicles, those were COST-EFFECTIVE mods (at least in my past 25 years....lol!), and I made it clear to her from the day we drove it home, that this one was simply not a candidate for any of that.
Lucky for us, my buddy had already installed a junkyard 3.73 Torsen rear and a junkyard factory TPI exhaust, manifolds to tailpipes. HE UNDERSTOOD IT TOO! The platform was there for a power infusion, and the ONLY infusion that made sense was some giggle gas. $100 plus a few leftover parts and it gained an instant 100 hp. I did stick an S-10 converter in it, since it was free, just lying in my garage.
She had a great time with the car for a long time, peppy performance on the street, and respectable on the strip with the gas turned on. I promised her a real engine, in due time, and sure enough, this past summer, the little 305 asked to be pulled by sending little tiny bubbles into the coolant recovery tank
Great! Yanked it, and in went a barely-freshened 350 that I have a total of $400 in, including the $100 core charge that I would have gotten from the dealer when it was pulled for a new GM crate motor in my truck. Timeslips will tell the story, but it appears it has every bit as much as the 305 with the 100 shot.
I know it looks like I'm blowing my own horn here, but really, just imagine what money you'd have to sink into that 305 (other than nitrous ) just to match what can be done with plentiful junk/discarded 350 hardware.

As long as you leave the 305 in there, be smart about it and don't chase any hp goals.

Edit: Oh, BTW, the bubbles were from a crack in the #6 exhaust port ......another possibility to consider before sinking time and money into 305-specific parts.

1gary

Smaller engines require a higher RPM to get to their power curve.It is just a fact of physics.Same costs factor in a serious consideration for a L31 350.If one where to accept the linked magazine article's test results,(and I don't),any steel headed engine with a SCR greater then 9.5 has a very high potential on today's gas to having detonation issues and actually those tests reveal the power curve issue inherent with small engines.So the real street results bring about a question of on a street driven vehicle how many times are you really going to drive the car's engine 4,500 rpm or above??. Make no doubt about it,torque and not hp is king on a street car.As for these comic book articles,never lose sight of the fact those are for promoting the parts used to sell to you and are not removed from being tainted results.The 305's bore size does shroud the flow of the intake valve interfering with the intake flow.Really no fix for that.It is kind of what it is.And no matter what engine your using,a quench target of from .035 to .040 is a anti detonation tool along with a performance asset promoting better flame travel.That is achieved by setting the deck height and milling the block.

It is by no small mistake given the intake shrouding is the reason why 305's turbo use is so popular.It does somewhat help with the intake issue and is there when you want it and doesn't need to be refilled like nitrous so you spend the money once and your done.But still a power curve in the upper regions that you don't normally use driving a street car.As what my signature states,Do-Over's cost double.

Amcen1

Thanks for the advice guys, I have ill definitely think it over a couple of times

OrangeBird

iTrader: (1)

I have condensed your post down to the point I want to address ;

DO NOT , , and I repeat , DO NOT , spend one penny on ANYTHING till this car is really , officially , signed over title , YOURS !!!!

You have no idea how many folks I've seen who had some "verbal agreement" to buy a car that somehow never materialized , and ended up with a whole bunch of performance parts that they ended up selling for pennies on the dollar once the "great deal" on the car never materialized .

Sure , gathering info is free , but buying parts has just gotta wait till after signed over title time .

Remember , a verbal agreement isn't worth the paper it isn't printed on .....

Good Luck

InfernalVortex

iTrader: (4)

If you wanted to learn to build/tune a turbo setup... a stock 305 is perfect for that. Just sayin!

five7kid

iTrader: (14)

Okay, I'll chime in.

Nothing wrong with your build plan. I would only say keep the stock q-jet and distributor (i.e., the entire induction/ignition/computer system). The Vortec heads probably don't have the EGR passage, but that's okay, because the Vortec Performer RPM spreadbore intake doesn't, either. Keep the EGR solenoid connected electrically (vacuum connection is moot), and you won't get error codes set.

The only argument against the q-jet is the T5. You don't want to be power shifting those things, so to eliminate the possibility of the secondary AVs closing between shifts and giving you a lag/bog, a Holley 600 double pumper with vacuum/mechanical advance HEI could be justified. But, if you're just looking for nice street performance, the factory q-jet will be just fine.

FWIW, '85 LG4s had "flat top" pistons with valve reliefs. Also had knock sensor (another argument for keeping the factory q-jet - it'll be defeated if you go with non-computer HEI).

Personally, I wouldn't go with the Hooker shorties, mostly because of the expense of getting a Y-pipe fabricated (the one Hooker offers is a piece of junk). The Hooker 2055HKR shorties come with a great Y-pipe, have an O2 sensor bung. Of course, if you go with the dual exhaust kit (which will kill ground clearance), the Y-pipe is moot - so the Competition shorties would be fine in that case (but if you keep the computer q-jet, you'll need to install an O2 bung).

The only thing "wrong" in general with your plan is the power expectations. With the bigger cam, it might make 300 gross flywheel HP.

And, as we always say when the topic of a 305 build comes up, "If you have to touch the shortblock (grind crank, bore cylinders, etc.), then find a 350 core to build."

Amcen1

No i wont be buying anything untill at least the summer, with the car in my driveway and you guys are really pushin me towards cruisin on craigslist for a 350 shortblock lol

86LG4Bird

iTrader: (1)

five7, Is a Vortec Performer RPM even available with a spreadbore flange? I didn't think so, but didn't look very hard before finding a cheap Performer for mine.
I agree - keep the E-carb/computer/ignition, regardless if swapping blocks or not. No EGR passages in the Vortec heads; it's done with a line from the exhaust manifold to the front of the intake manifold on the L31 (Vortec) engine.

five7kid

iTrader: (14)

I have "built" a 305, so if you'll indulge me, I'll give a brief history of mods, and performance (no dyno numbers, just 1/4 mile data). This is an '82 Berlinetta that had a 2.8 V6 from the factory (didn't run when I got it). At Bandimere Speedway, 5800' elevation (adds about 6% to the ET vs. sea level).

'86 LG4, stock except for L98 exhaust after the cat. 3.08 gears. Best: 16.85 @ 80 mph

Same shortblock, but with self-ported World Products SR305 heads, Crane 2030 flat tappet cam, ZZ4 intake manifold, Hooker 2055HKR headers, 3" cat-back with Flowmaster 80 series muffler, restalled stock converter (to approximately 2200 RPMs). Best: 15.85 @ 85 mph (Transmission wouldn't shift 2-3 at WOT, so that probably slowed it a little)

Same heads, rebuilt ZZ3 shortblock, ZZ4 cam, 3.23 gears (same converter but now stalled at about 2500 with the increased displacement). Same exhaust, but Magnaflow 3" single in/out muffler. Best: 14.07 @ 95 mph (Rebuilt transmission so it now shifted 2-3 at WOT)

LS1/4L60E from 2000 Camaro, LS6 intake and cam, 6.0 liter truck heads shaved to LS1 chamber size (basically an LS6 clone), Hawks long-tube headers, 3600 stall converter, 3.73 gears. Custom Y-pipe to the same 3" cat-back exhaust. Best: 12.62 @ 108 mph.

The LS1 gets the same fuel economy as the stock LG4 did.

Notice the two big jumps in performance: When going to the 350, and when going to the LS1. Admittedly, it isn't all apples-to-apples, since I also changed rear gear ratios. But, I think you can see the point.

86LG4Bird, I believe you are correct. The Vortec spreadbore is only available in the Performer version, not Performer RPM. I got my wires crossed. Again.

bestracing

The statement in bold and having a bad CC Q-jet is the only reason I modded my LG4 in my 86.

I got an RPM air-gap manifold for $25 and I had most of the other stuff just sitting around: SLP Tri-Y exhaust, Crane Cam 456/480 lift, Early HEI dizzy, 1.5 roller rockers, double roller timing chain, Holley 600. I had pulled the motor to clean it all up and paint it while doing all of this as well.

With just that I have ran a best of 14.7 in the quarter but if I had a better stall and gears I'm sure my time would have improved a few tenths more.

Warhark83camaro

Im new to the site dont know Anyone yet.Im on a very tight budget with family of three kids and massive bills to go with it.Im trying to get as much out of tha factory305 lg4 as possible its a 1983 Berlinetta Camaro v8 5speed3.23 posi all factory installed ive ran every numebr on hole car its all original even down to the mechanical clutch instead of hydraulic like my 89 iroc of my previous juvenile life.my goal is to get as much power and economy as possible any one with any words will help ive done work already but enough said for now lets roll on my subject.

86LG4Bird

iTrader: (1)

Since you already have decent gears, there are just two things I would do:


1. Upgrade the exhaust. With the factory peanut cam, headers are a waste (unless you would use them later on a 350 or larger SBC build), so just get some manifolds from a TPI car from a junkyard. If the entire exhaust on that junkyard car still looks serviceable after all this time, get the whole thing. Likely it's not, so your aftermarket exhaust needs to be for an L98/LB9 (TPI) car, NOT the tiny restrictive parts for an LG4 car. Keep in mind that any significant money you put into these parts should be transferable to a better SBC engine at a later date. If that's not part of the plan, then I wouldn't even bother.


2. Fab a fresh air intake to the air cleaner housing to let it breathe a little better than the factory soda-straw neck allows.


DO NOT do anything internal to the engine.

1987thirdgen

Amcen-

I built a 305 too. We decked the heads to 48cc, performance intake, cam, headers, exhaust.
Just a edelbrock 1406 that we really had to lean out. It still runs 8 years later and sounds great, but, for the price I could have more power for the same weight as a 350.

Now, if you are wanting to prove something with the 5.0, it has already been done!

Don't get me wrong- I love my little 305, and am pretty proud of the performance.

Check this article out-
http://www.hotrod.com/how-to/engine/...block-rebuild/

Warhark83camaro

See i put edelbrock performer aluminum intake and 1406 series economy 600cfm carb all used sitting in my neighbors garage floor sweet score free my budy sold me a 1976 corvette vacuum advanced hei with msd 50,000 volt coil and 6.5. 4 pin module i have a single roller timin chain i deleted the stock mechanical cooling fan foor electric daul fans outa dodge intrepid that was abandoned in my old bosses rental propertys garages ive taken the stock lg4 air cleaner an two astro van air cleaners and pop riveted a h.o look alike daul snorkal air cleaner took any thing emissions wise off cat computeturd. Vacuum can added old style valve covers w/breather and removed all and any ac stuff putt up for a numbers match restore i got a sweet deal on distibuter $25 and got a set of scca gta sway bars off of a 1le trans am long with distibuter

Warhark83camaro

Im wondering what cam i could use with stock springs or if i could get 1.6 rockers on it see in my town everyone has big block chevy in tri fives an first gens an5.0s all over im not after them i want ricers and 305 to do it. I need efficiency feul economy hidden power and reliability and somthing to impress my wife who thinks her 01 v6 auto rustang is faster

dmccain

iTrader: (2)

Headers, matching y-pipe. 3in exhaust. You already got a posi and decent gears for LG4 power range. You already have a decent carb and intake from the factory for a 145HP engine. I wouldn't do anything to it other than exhaust really. I changed cams, intake and carb, headers and exhaust on an LG4 once and still only mustered a 14.88 pass out of it. Just enjoy it for what it is til you can get a 350 in there.

Warhark83camaro

But i like the stock part of the car see. have i done any better with wat i have done already. Ima put and envest in it i would like to kick rear end an do it with a 305 just to make the rub in even more harsh

Warhark83camaro

See i have done intake, carb , cat delete , it has a dyno max exhaust when i bought it but its a 2.125 dia" ,ac delete, mech cooling fan delete,daul electric cooling fans, computer& emissions delete fabbed daul snorkel air cleaner , single roller timin chain,i port mtched the intake and heads,indexed spark plugs,put vacuum advanced hei w/high out put coil and module,old school crank case ventilation system, i mean i know there's more to do to improve its performance

1987thirdgen

I have heard good things about gmpp fast burn heads.. If I was not saving for my big block build I would probably slap a set on my 305.

1987thirdgen

BTW by deleting A/c, emissions, computer and getting rid of other factory stuff the car is no longer original. Unless you keep all of those parts, their fasteners (in good shape)and keep the electrical system virgin you will have a long road to bring it back to a point where you can say "numbers matching" and have it mean a damn.

I don't mean to be harsh- just realistic

Warhark83camaro

Amen to that brother. Ive bag tagged an labeled it all and put the wire in the looms and all well hidden but to put back in later time