im wanting to get a little more out of my LG4 until i can afford a full on replacement of the powerplant... after reading and reading and reading posts here and a phone call to summit racing i have come up with a partial plan....

how about vortec 305 heads(with valve springs to support .488") $240
gmpp1266572(gms zz style vortec manifold) $220
a hydrualic roller cam with 450/470ish lift 250$
edelbrock headers into a 3" high flow cat,3" flowmaster exhaust (already have)
some sort of dual snorkel intake like the L69s

in the near future i will be replacing the rear with something around 3.23-3.73(hopefully ill find a cheap 4th gen rear with disc brakes)
and i will be rebuilding the trans with a transgo shift kit and adding an aluminum driveshaft

anyone have any idea what kind of power i could expect or wanna make a specific cam recomendation for this combo??
im keeping the AC the egr and air pump

 

If a 350 or larger is in the plan for the future, get 350 Vortecs now. Yes, you'll drop a little compression, but the engine will still run fine, and you won't have to repeat an expense later.

The Edelbrock Performer is $170, RPM $180. Guess who makes the GMPP intakes?

The Edelbrock headers will choke the engine - ask Chevy High Performance magazine and their "My Generation Camaro" '87 project LG4. Go with the Hooker 2055HKR's, get everything for the '86-'90 TPI single-cat application - that's the "good" stuff.

You'll be at least in the 280 gross flywheel HP range. Figure on needing a higher stalling torque converter.

 

hey thanks for the quick reply... and what is involved with the 350 vortec heads, ive heard there was some severe machine work needed for the 305 to except the valve size on those???

and with the intakes... would the rpm be better??? and will all my emissions equipment and stock carb bolt right up to the edelbrock intake??

also any advice on a specific cam??? those numbers are just what im looking for 230-250 at the wheel should be good especially if shes still gettin near 20 mpg... thanks so much for your help

 

i just read the whole "my generation camaro" series... they stated in there that due to some lack of a heat passage that vortec heads are "illegal"
is there any way to get around this so i can keep the stock egr equipment and still go with the vortecs??

 

You can run a tube from the headers to the crossover passage on the intake manifold.

Are you trying to pass visual inspection, or sniffer?
----------
If you're willing to modify the heads for more lift (a very good idea, in my mind), a ZZ4 take-out cam. Plentiful on eBay.

 

so the zz4 cam wouldnt kill my low end too bad or gas mileage??? i dont need it to get 30mpg obviously but i do want it to be near 20... also, as long as she passes the sniffer, i doubt very much that most of the mechanics here in the poconos would know exactly what the egr looks like on my vehicle lol so u think i could get away with just blocking the passage off from the intake or just run the tube, im gonna take a look at the engine and see if i can tell where the "passage is coming from on the intake cause if its not easily seen ill prolly just block it off as long as its not gonna effect driveabillity too bad or my emmisisons
----------
o and for the summer this is my daily driver if that helps... u need 4wd around here in the winter so ill be driving a(gulp) ford explorer lol

 

The no-longer-available emissions-certified Camaro HO 350 Conversion Kit, which used the ZZ4 crate as its base, didn't use EGR at all - just left the whole thing blocked off. This was possible due to the cam overlap.

If they just do a tailpipe probe type sniffer test, it doesn't check for NOx, anyway, so shouldn't be a problem.

A simple approach would be to get the Vortec spreadbore manifold, which has a place to mount the EGR valve, put the EGR valve there to block off the opening, hook up the vacuum lines, and leave it at that. When the valve opens, nothing will happen.

The ZZ4 cam will lower your low-RPM torque. Any performance cam will. Higher stall torque converter is all it takes to compensate for that. I get around 18 mpg commuting, about 23-24 highway (don't do much highway with it). Last 500 miles (included some non-fill-up gas-ups), which had about 100 miles highway, 8 quarter mile passes, the rest commuting, it averaged 17.9 mpg.

 

awesome... i should know that cause one of my best freinds has a street legal zz3 in his 83 z28 and i helped him drop it in there... that was in 99 though and he lives in VA now so i dont get to look at it anymore unfortunately (im a little rusty)lol thanks tho, i was just concerned about the cam because it seemed like alot of lift for the 305, but ill take your advice... i found one on ebay for 90$ shipped to my door, also are the zz4 rocker arms roller tipped and how would i tell if they were authentic, someone has a set for 35$... oh yeah a new valve spring kit, would be all id need to install for the heads to work with the .5" lift of the cam correct>?

 

ZZ4 aren't rollers. Not really any different from stock, other than having a slightly longer slot to handle the extra lift. $35 shipped would be a decent deal.

The valve guides typically need to be cut down so you have sufficient travel between the retainer and the top of the guide. Vortec guides are also larger ID, so not any old spring will fit over them. The typical approach is to prepare the guides for positive-type valve stem seals. Kills 3 birds with one stone - better seals, sufficient travel for the higher lift, and can install typical performance springs. Put the new springs on at the same time. New retainers that eliminate the stock exhaust valve rotators is also a good idea.

 

I'm not saying your wrong, but isn't 280hp kind of high for those modifications? Those are basically 4th gen 350 LT1 numbers.

 

280 gross flywheel horsepower. Comparable to the way a 330 horse 350 HO or 355 horse ZZ4 crate engine would be rated.

4th gens are rated net flywheel horsepower (as are all vehicles since the early-mid 70's). 280 gross would be about 220-240 net (depending upon the details of the installation).

 

ok new question... and thanks 5-7 you are the greatest... my father has a 96 chevy truck 95k miles, with a vortec 350 hes going to give it to me since he just bought a 2007 silverado... i was thinking id swap the 305 for the 350... slide a zz4 cam and rockers, with the valve guide mods you suggested and new valve springs with a edl2116 (summit lists this as square bore and i cannot find the "spreadbore" one u suggested)top it off with the stock carb... my question is, if i drop my 305 in the truck with vortec 305 heads and reinstall the stock F.I. will it run properly? i think my cam is a lil smaller then the vortec 305 cam (although it is a roller so thats a plus) and the compression may be a lil lower, i dont really care about the power of the truck as it would be a 3rd vehicle for me and it would really only be for occasssional use to the dump etc... i just want the truck to run right and pass inspection. sorry to bombard u with so many questions. will the stock fuel system in the firebird be enough for the 350 until i can get a better fuel pump or should i get the pump before i do the swap, also the stock ignition... should these be upgraded immediately or can it wait??? i just want the firebird to run for now it doesnt have to be at max performance until i can afford those upgrades if i can get away with it... i just dont wanna be too lean and possibly hurt somethin ya know... thanks so much in advance i know youll be of great help as you already have been

 

I am not that familiar with the factory Vortec EFI system. I would imagine you would need a 305 chip, but I don't have any idea about specifics.

The 2116 will mount either a spreadbore or squarebore. The Vortec spreadbore w/EGR is GM p/n 12496820 - $252.95 from sdpc2000.com (will also mount either a spreadbore or squarebore - slightly less from them than from Summit).

Stock replacement fuel pump parts will do the job. Remember you have an in-tank electric pusher pump as well - it is usually the first to cause problems.

I can't say that I am certain about the weakness of the stock small-cap HEI. I know the large cap falls on its face about 4500 RPMs.

 

thanks sooo much your the best help ive had ever!

 

update... shes inthere but its all stock and runs fine... im still workin on changing the metering rods but as far as i know shes not lean... i havent even gotten on her yet tho just commuting
----------
oh.. i was thinking about gettin a summit ignition box(cause they are cheap) any idea if they are any good... and would that help the fuel economy any?

 

I don't know personally if the Summit ignition boxes are any good. I haven't heard any complaints. I'm sure they're just a major brand in plain brown wrapper. It isn't likely to help fuel economy significantly over a stock system in good running order. It might be better than the stock module at higher RPMs. Stock coils aren't renowned for their high RPM performance, either.

 

hello,

if you are going to build a 305 here are some proven methods for making power..
http://www.goingfaster.com/spo/325_h...chevrolet.html
http://www.hioutput.com/tech/400hp/400hp.html

later
and

GB

rk

 

i got in here a little today on the highway... and uphill shes fallin on her face... same thing if i try to accellerate from a stop... and mind you im not floorin it just rollin into the throttle hard... any idea why this would happen... seems to me like a definate carb problem... could that be the metering rods... or maybe the stock exhaust too restrictive?? it felt like the tranny was sliipin real bad, but im pretty sure its not cause it shifts fine the exhaust does sound bery restrictive lot of vibration, and it feels like it doesnt want to rev freely any thoughts??

 

Hello
I take it you put the 350 in your car? check your timming and total timming to see if the vacume advance is working properly.. Also check for vacume leaks on the intake, carb and distributor. If it is not these things then start on the carb, you might be fat on the secondaires.. How is the fuel supply and floats doing? What are the readings of your plugs like? What type of Carb are you useing, and did it sit for a long time after being used? ALSO VERY CRITICAL DOUBLE CHECK YOUR IGNITION SET UP!! IF IT IS WRONG YOU COULD FRY THE BOX...The stock exaust should be fine for a stock 350-----just my 2 cents

GB

rk