armybyrd

iTrader: (4)

Had to make an update as most of my questions have been answered. Using a stock 350 with 1 piece rms and a t5. My 062 vortec heads are at the machine shop with ls6 springs and comp 787 retainers. I've decided to go with a re manufactured quadrajet on an edelbrock performer intake and a comp cams xe274. I've already got the mechanical dizzy as well. With the head gaskets my machinist recommended he said I'd be around 9.4:1. Don't really have anymore questions at the moment but I'm sure I'll come up with a few as I go.

skinny z

Saw your post in the carb section but I see you have a couple of other questions.
I don't know which professional products intake you have but I can say the Edelbrock RPM Air Gap pushes the carb with a typical dropped based open element air filter case right into the hood. I had clearence issues with both my steel IROC hood as well as the early OEM fibreglass hoods. Keep in mind that the RPM Air Gap is about the tallest of the dual plane manifolds out there. The Performer intake doesn't have as much height and if it's anything like your Professional Products intake, there should be enough room provided you select an air filter case that isn't too high.
Changing to a carb from FI will present a variety of wiring issues as well as fueling. Not getting into the fuel pump requirements (which is where some of the wiring may need to be modified), one circuit you'll need is a keyed 12v for the electric choke (provided you go electric). I selected one of the ignition slots in the fuse block for my choke circuit. Plug into that, add an in-line fuse and run it through the firewall to the choke. There are keyed circuits availble under the hood as well, however the fuse block is guaranteed to have what you need.
Plenty of people here are using Quadrajets on their Vortec style engines. The one from the 305 will fit and be functional yes, however, depending on other engine modifications, it will certainly require tuning.
The Vortec heads require the use of self-aligning rockers unless you modify the heads to accept guide plates. Keep in mind that just about any performance application, especially one that includes a cam and valve spring upgrade, will require the heads to modified or upgraded to some degree. The stock springs and pressed-in studs have their limitations.

86LG4Bird

iTrader: (1)

What cam will you be running?
That will determine:
1. what mods, if any, need to be done to the Q-jet
2. whether the pressed-in studs will suffice

Further to what skinny already told you: The car in my sig has an Edelbrock Performer (not RPM) on the Vortec heads and with the Q-jet, the stock LG4 air cleaner assembly barely clears the Formula (power bulge) hood bracing. It touches slightly with engine mount flex under acceleration.

Night rider327

iTrader: (13)

The vortec heads uses the 1987 and up self aligning rocker arms (unless you have screw in studs and guide plates added, then you would use non self aligning rockers)

In stock form the vortec heads are lift limited to about .470" valve lift, some have got buy with .480" but I wouldn't push it myself. I run .484/.512" lift on my vortec heads but I get the "ghetto" grind on the retainers and swapped valve springs out

I can't say about hood clearance as all my third gens have had some type of hood scoop on them.

armybyrd

iTrader: (4)

I don't have an intake manifold yet and haven't decided what cam, intake or carb to use. I don't need anything too crazy but do want some decent power. Ive got the quadrajet so Im considering that for this vortec headed 350 but am open to other carb options depending on ease of install and tuning.

skinny z

My first iteration with the Vortec heads had them in box stock form (brand new). I used them with an old grind flat tappet cam I had (218 @ .050", .454" lift, single pattern), an RPM Air Gap intake and a 600 cfm VS Holley. An aftermarket HEI distributor and Hedman short headers rounded out the package.
With a no stall converter and 3.73 gears with a 700R4, at 3750 lbs I think the best was a low 13 second pass at 102 mph. It was a lot of fun to drive, would burn the street tires off anytime and knocked down some decent mileage.
At the request of a friend's son one day, I did a hard launch, spun somewhere near 7000 rpm and put a valve into a piston. That was obviously well past the limit of the stock springs. Shortly after that, I made the move to Comps 26918 Bee-Hive spring (drop-in, no machining), went for screw-in studs with guide plates and non-aligning Comp Pro Magnum rockers. That went along with an XR276HR roller cam.
Off course, one thing led to another...
By the way, all of that fit under a slightly clearanced stock hood (as I had mentioned) using a typical 3/4" dropped base 3" tall filter case.

cal30_sniper

iTrader: (16)

Vortec heads are perfect for what you're trying to do. I did the swap from TBI to a carb/Vortec setup in a weekend. There are three major things you have to get right:

Ignition
Linkage
Fuel Pressure

Ignition is easy. Use a large-cap HEI distributor with cap in coil. You avoid the garbage 3rd gen coil problems, and retain an easy hookup for your factory tach.

Linkage is also easy. Go to the junkyard and find any 80s Buick, Chevy, Olds, or Caddy (as well as a ton of GM trucks) that are using a quadrajet. Grab the bracket and go. If you're using a TH700r4, make sure you get one with provisions for a TV cable. Also, if you're running a TH700r4, you're going to need a way of locking it up. There are many options, I prefer the B&M kit. I can't speak for the TBI vs carb cable in a 3rd Gen. In the truck, I was able to make the TBI linkage work with the carb, but squarebodies are set up completely different than a 3rdGen in that respect. It's probably easier to find a used 3rdGen carb throttle cable.

Fuel pressure is the hardest issue to deal with. I left the factory pump in the tank and ran an adjustable fuel pressure regulator with a liquid filled gauge under the hood to monitor pressure. Make sure you utilize a return style regulator, and keep pressure below 4.5psi. Quadrajets do not like the 6psi of fuel pressure that most guys run with Holleys. That much pressure unseats the needle valves and causes fuel to get to levels it doesn't belong at inside the carb.

As far as an electric choke setup, I highly recommend it. Use one of the old TBI injector power wires for 12V to your choke. They're already right there, and you won't be reusing them.

The performer intake with a quadrajet clears the hood no problem, even on a Firebird.

I totaled that Suburban a few years back and the motor is now in my roommate's 92 Firebird with a Holley Stealth Ram and production LT4 camshaft. For a street car that gets awesome gas mileage, I highly recommend that cam with Vortec heads. A simple (and cheap) swap to LS6 valve springs and CompCams retainers allows that cam to work well within the limits of factory Vortecs with zero machine work. If you're looking to step up to something a little heftier, I think the Comp XR264 would also make an excellent choice. If you stepped up to 26918 springs, you could run the XFI268 cam, which in my opinion should be about as good as it can get for a fun and very street able Vortec 350.

Hope that helps.

cal30_sniper

iTrader: (16)

Also, I highly encourage your choice of the Quadrajet. In my experience, a properly set-up Q-jet will pass up the early fuel injection systems almost every time in terms of reliability and smooth driveability. Get the choke and jetting right, and it will drive like FI without the hassle of tuning. I knocked down 31mpg with my old 305/T56 combo using a Q-jet, and I still get 14-15mpg out of a 3/4ton 454 Suburban running a rejetted Q-jet. Not to mention, its a very easy system to understand and much cheaper to work on than comparable fuel injection stuff.

armybyrd

iTrader: (4)

I appreciate all the info. I decided to use my quadrajet and ordered 2 books on them to learn all I can. I'll def look into your cam suggestions.

armybyrd

iTrader: (4)

Can anyone confirm the comp cams retainer part numbers for the ls6 springs? I believe theyre the 787-16 but just wanted to double check before I order them. Ive decided to go with the xe268 and will being going with a rebuilt quadrajet. About to order some ls6 springs and then the retainers and finally drop the heads off at a machine shop. Am I missing any other parts? Im trying not to spend too much on this so I planned on reusing the valves and the factory rocker arms. I drive like an old man so Im not too concerned.

armybyrd

iTrader: (4)

Just dropped my heads off at the machine shop. First they're going to magnafluxed and cleaned up. I was quoted $268 to have ls6 springs and comp roller tip rockers installed as well as whatever clearancing is needed. The shop seems reputable although the guy said he's never used ls6 springs on vortecs so hopefully everything works out ok. I was gonna order new ls6 springs ($60) and the comp 787 retainers to go with them. Am I missing anything? I do plan on getting new valve seals as well as pushrods.

MoJoe

iTrader: (5)

I did the same with mine. The LS beehives are spec'd for 1.800" install height, and I measured bind ~ 1.200". My L31 vortec heads with 787's and stock locks measured at 1.725", which increases the seat pressure a little bit (good). But, with 0.500" lift, the spring squeeze to 1.225", which is too close to bind for my comfort. I added these +0.050" locks.

With the offset locks, my springs installed at 1.775", add LT4 HOT cam and 1.52 rockers, full lifts squeezes the springs to around 1.275".

armybyrd

iTrader: (4)

I Just Took My Ls6 Springs And Comp 787 Retainers To the Machine shop And Guy Said the the springs would have to be ground down for these retainers to fit. Also he measured the parts and said the springs were only good for 470 lift. Am I missing something? I thought that's about what the stock vortec springs were limited to?

MoJoe

iTrader: (5)

The 787 retainer have very close tolerance into the LSx beehives. The same for the beehives over the stock vortec valve spring guide. No grinding necessary.

The stock springs were limited by retainer to value guide/seal clearance.

I measured my beehives at 1.200" bind, and installed height of 1.725" with 787 retainers and stock locks. That gives 0.525" lift to bind, but with 0.050" clearance before bind, your are only good for 0.475" lift.
That's why I added +0.050" locks. That increases installed height to 1.775" and gives 0.575" lift before coil bind... Enough safety margin for the 0.500"-ish lift I am running with LT4 HOT cam and 1.52:1 rockers.

armybyrd

iTrader: (4)

So with those locks I'm good?

armybyrd

iTrader: (4)

I planned on using comp cams xe274 (230/236, .490/.490).

MoJoe

iTrader: (5)

Adding the +0.050" locks, $33 at Summit, put me into my comfort zone. Since you are doing the same, it should work the same.

armybyrd

iTrader: (4)

Ok too easy.

2005Impalla

I have a vortec 350 I was going to use the LS6 springs on, I calculated the seat pressure at 127LBS and decided to just get the comp cams springs. I have the Performer EPS intake, it looks like it might be shorter than the RPM. I have not finished my vortec motor so I have not installed it to see if it will clear a Camaro hood yet. If your running a stock cam then the Performer EPS intake with a 625 vacuum road demon or 600 CFM Edelbrock carb would be a great set up. An Edelbrock is the easiest carb to tune if your looking for something simple. If your swapping your heads for more HP I would swap the cam first. Your going to get a little power from the heads but you can get more power from a cam swap.