I took my LG4 firebird to the track..all i have done to it is flowmaster exhaust. I ran a 16.6??? i had really bad wheel spin(14"rims with not much tire left)but i still dont think the car should be running like that. It is auto and if someone could give me some advice on how to make it a little quicker. i want to run 14's before i put nitrous on it. If im outta my mind tell me now. Thanks. Jesse

 

My "stock" time was in the 17.25 range, at 5800 feet elevation (translates to about a 16 flat at sea level). That was with a 2-1/2" cat-back system, though (I never ran the stock 2" system - it was crushed in the donor car). My baseline run was 17.65 with a weak fuel pump (kinda like the "My Generation Camaro").

With an open element air cleaner, timing advanced 6 degrees, Accel coil, synthetic lubes front to back, 3.08 gears (open), 160 degree thermostat, 1/2 tank gas, A/C compressor removed (seized), cleaning out the trunk (about 3450 pounds going down the track), and wider tires, my best was 16.85 @ 81. Typical was hovering around 17.0. That translates to about 15.8 at sea level.

Your first problem is the single-snorkel air cleaner (by the way, "LG4" and "HO" do not compute). It's restrictive even with a stock LG4. The open element isn't the best for everyday driving, but will work fine at the track if you cool the engine down. Dual snorkel is better, though, either a factory piece (getting harder & harder to find), or a home-made one like described in the tech articles.

Next is exhaust. The stock LG4 is extremely restrictive. L69 is much better, but headers, 3" y-pipe at cat, 3" cat and all the way back will open it up.

You could probably gain a second by those two things alone. After that, you're looking at getting inside the engine. The good news is that '85-later LG4's got the flat-top pistons for the "good" compression. You'll want to do cam for sure, heads would really help. Addressing your other post about the Vortec heads, you could use them if you shave them down to 58cc chambers, but you'll have to plumb exhaust up to the intake for the EGR valve because the Vortecs don't have cross-over passages like the 305 heads do. You also need to keep the cam lift down unless you upgrade the valve springs. (I'd recommend you get the World S/R Torquer 305 heads - good valve springs, screw-in rocker studs, redesigned chamber, exhaust cross-over passages - but people are getting tired of me saying that, so...)

You'll probably take a couple of seconds off with those mods. That's respectable. Even better with gears and traction improvements. If you want any more than that and still keep it a daily driver, you should get a 350.

 

Thanks for all the help man. what would you recommend for a cam? ive heard a lot about not going to "big" for a 305? Thanks again. Jesse

 

Comp Cams XE256.

 

Comp makes good stuff. The lobe center is a little tight, but should do what they say it will.

I picked my cam because I found out at the last minute that I couldn't use the roller block I was planning to put a ZZ4 cam in. It was the closest thing I saw to the ZZ4. I was truly impressed with the way it turned out, and would recommend the PowerMax 2030-2050 compucams (just don't wimp out like CHP did choosing theirs).

 

World Products S/R Torquer 305
.400 = I 198 E 156
.500 = I 213 E 166

Summit Racing: $622, no guide plates & not machined for


Vortec
.400 = I 227 E 151
.500 = I 239 E 160

From Scoggin-Dickey Parts Center:
L31 Vortec Cast Iron Heads
Stock Assemblies -> $440
Spring Upgrade - .525 Max Lift, Lite Wt Retainers -> $580
H/P, Machined for Studs & G/Plates - .525 Max Lift -> $597


In regards to the emissions plumbing; From all of us car guys in non smogged states, I would like to send my deepest apologies and condolances to the rest of you suckers... er... guys. Us northerners may only get 3 months of decent weather, but we spend it in emissions-free bliss.

-5finger

 

Yeah, yeah.

You conviently forgot the $175 Vortec-specific manifold. And that you need to shave them for a 305 to get the chamber size down, which means shave the manifold, too.

A few hours with a die grinder on the Worlds and the intake flow numbers are right there with the Vortecs. Exhaust already there w/o porting, even better after (and we all know SBC's need exhaust flow help). No need for guide plates or self-aligning rockers. Higher quality castings. Improved chamber (over factory 305, anyway).

People are tired of hearing about it, perhaps, but you kept it up with the Vortec praises, I gotta defend the honor to the contrary...

 

"all i have done to it is flowmaster exhaust"
Maybe its just me, but if I were swapping to some high flow heads, I wouldn't stick with a stock LG4 manifold. And that 170 vortec manifold is only 50 bucks more expensive then the standard bolt pattern RPM.

There is only a 6 cc difference between the two heads. A slight shave and a thin head gasket should make up the difference. I highly doubt a 6 cc change would be enough to require work on the manifold.

Sure, you could do some work to get the world heads up there, flow wise. But then you can also port the vortec heads and go further still. He can bolt these on and go, and save some time and money in the process.

"No need for guide plates or self-aligning rockers."
What? You're saying that you can run a small block chevy with no guide plates AND no self aligning rockers? Please dont tell me you're serious.

There are plenty of people bolting up those vortec heads to healthy 350's and making great power. How many people do you know that are bolting those World 305 heads onto a 350?

 

Okay, at the risk of making this a "Vortec against the World" shooting war, let's put some facts on the table here.

That "slight 6cc shave" is a bit over .040". Anything over .020" - .030", you'd better shave the manifold. The Vortec decks aren't all that thick to start with, either, so shaving only reduces their already somewhat weaker point.

Who said anything about a Performer RPM? I know you don't worry about emissions, but about 30% or more of us don't have that luxury. It's an issue (don't know if it is for Resistance), so don't assume it isn't a factor in a "general" sense.

SBCs didn't need self-aligning rockers until 1988. In the 30 years since my first SBC, I've had exactly one with guide plates, and it probably didn't need them (the guy I got the engine from always put them on his engines). They were left to the sky-high rev'rs in days gone by, and except for the '88-up factory heads and some aftermarket, have not been required for the typical build-up. World uses a slotted push-rod hole, just like Chevy did from 1955-1987, so they don't need those things. In fact, if you do use self-aligning rockers or guide plates, you should open up the pushrod holes in Worlds or older factory heads.

Bolting Vortecs up to a healthy 350 makes more sense than bolting them to a 305. I wouldn't hesitate to bolt my 305 heads up to a 350, but if I was starting from scratch building up a 350, I wouldn't get S/R Torquer 305 heads. But, I was building a healthier 305, and that's what Resistance is doing, so what's your point?

I stand by every one of my original recommendations, based on the original question posed in this topic. If you want to continue the Vortec discussion, I'd recommend you post a new topic (as if it hasn't been discussed before). Besides, this is way beyond a carb board discussion.

 

ok enough with the war "vortech vs world" not a big deal anyway. Im in cali so yeah i do have to worry bout smog laws big pain in the ***. i didnt know that question would start everything up. but i do know one thing...i dont want to have weak heads or intake...and if you gotta grind on the vortech manifold any...i dont think it would be a good idea...so ill stick with the world idea. Thanks guys. remember we all drive 3rd gens be nice lol

 

Thanks for the additional emissions information (it is important to know that), and for getting things back on topic. There is a very similar post on the Tech forum, too, by the way.

All of my suggestions will keep you emissions legal - in the practical sense. The 350 isn't technically legal unless you go with the GM HO 350 Conversion kit (and that's expensive). But, no inspector in the lower 48 is going to know it isn't a 305 if you don't say anything, so in the practical sense, you'll pass emissions with it if it sniffs clean enough and if you keep all the visual pieces intact.

 

Thanks Five7kid, youve been a lot of help. Ill let you know when i get everything done, i think im gunna go with the world heads and an edlebrock intake man. Now what about the jets on the carb..i still dont know much about that. Thanks again

 

No "jets" to fiddle with, in the common use of the term. Q-jets only had replaceable jets in the primaries, and then only in the non-CC versions. In the CC q-jets, the primary mixture is controlled by a solenoid via commands from the computer, and there really isn't anything more you need to do to it except make sure it is getting the info it needs to work. Like I said in that other post, the only things I adjusted after all my mods were idle speeds and choke opening.

The secondaries have fixed, drilled "jets" in the body, and you tune them by replacing the rods that go into them, and the hanger that pulls the rods up as the secondary air valve opens. This is explained in more detail in the tech article on this board. It is the secondaries that you work on to get better performance out of the carb.

A valuable book to have is Doug Roe's "Rochester Carburetors" (I recently got one from amazon.com), or the Haynes manual "Rochester Quadrajets" (had it for awhile). Both go through q-jets, how they work, how to tune, fix, and rebuild them, but the Roe book is probably a little better (and costs less to boot).