So in the thought process of trying to decide how to get the GTA rolling again. The "it's certainly a 350" I have seems like the right option if I wanted to spend no money and just wanted to slam it together and then ignore. The basket case L98 I have seems like the right answer if I want to tear it down and send it to a machine shop. So now I'm looking at other options. Like a 90s Vortec 350. I have questions.
Question 1. What exactly has to be done to a Vortec head to make it work with a bigger cam that actually makes power? Everytime I google for that answer I find something different.
Question the other. Does anyone know of a decent and reasonably priced EFI intake manifold that would bolt to those heads and fit under a flat 3rd gen Firebird hood? I'd use the stock truck manifold but I don't want spider injectors. My other dumb idea was a marine manifold that apparently uses normal injectors but I haven't actually tried to find one yet.
IIRC, the Vortec heads are limited to under .500" lift. Any more requires a spring change. Depending on spring, may require some machining. To be safe, swap the press in rocker studs for some screw in.
The easiest button for intake is to use the TPI with a TPI-Vortec base. Edelbrock and GM offered them.
Or, vortec single plane and fitech or something.
I also think pro-comp or someone like that makes a cheap mpfi single plane for vortec heads.
I've seen a bunch of cheap single plane mpfi options but all of them look too tall to fit under the hood.
The Vortec heads need some taken off the top of the guides for big lift.
Marine is certainly a possibility. I'm not sure what they use for a throttle body, but I worked on a couple a few years ago. I want to say the Ramjet crate motor that GM sold a few years back is kinda marine based.
This isn't the answer your looking for.
But since you're still reading. How about a complete LT1 take out from a Camaro or Firebird. You can fine them cheap (guys are pulling out perfectly good ones to LS swap all the things). bonus, Good EFI, low profile, bolt in. Grab one with the harness and go.
https://www.youtube.com/embed/f7mvgf6_p1g
This might steer you in the right direction.
In reply to Indy-Guy:
That's a lot less dumb than a lot of other ideas I've considered.
I remember reading about guys using the lt1 manifols setup and modified for distributor. Dunni if its the vortec pattern though.
I think Scoggins-Dickey makes a manifold that will let you use the factory TPI on Vortec heads.
You could always have the vortec heads redrilled for the l98 intake if i remember correctly.
I think that the outside four intake bolts on both sides are in the same location as the the old original sbc. They are drilled straight down instead of angled. That means you can use any sbc intake, but you have to cut from the edge of the manifold into the bolt hole, giving it slotted holes instead of round. I havent tried it myself, so im not positive, i also dont know what it does for gasket life, but it definitely opens up a whole new world of options.
gearheadmb wrote:
I think that the outside four intake bolts on both sides are in the same location as the the old original sbc. They are drilled straight down instead of angled. That means you can use any sbc intake, but you have to cut from the edge of the manifold into the bolt hole, giving it slotted holes instead of round. I havent tried it myself, so im not positive, i also dont know what it does for gasket life, but it definitely opens up a whole new world of options.
One issue is the ports are a bit higher on Vortecs, so there will be a mismatch. That may affect how the gasket seals. Since Vortecs have been out quite a while, there are plenty of intakes out there for them. Vortecs have LT1 intake ports, so you may be able to adapt the LT1 intake. A Ramjet intake would be better, as it fits Vortec heads, just a bit harder to find.
I loved the Ramjet 350. I wish I'd have the money to snag one and wait until now to install it. But I didn't.Because I'm dumb.
Also, as I understand it, the Fastburn heads from GM are vortec heads cast in aluminum, correct?
SEADave wrote:
I think Scoggins-Dickey makes a manifold that will let you use the factory TPI on Vortec heads.
The do and the TPI is a good match for the Vortec heads if you want to make an excellent torquey street motor. What kind of power do you want to make and what are you going to be using the car for?
My plan for the car was a street car that might occasionally see some autocross. Huge power isn't really a concern but it'd be nice if I still had some power if I wanted to let it rev a bit.
In reply to Chadeux:
trust me, a TPI is a fantastic platform for that. idle to redline the power is always there. The downside... redline is ~4500-5k. The upside is that even at 1500 you'll still be making 300+ftlbs of torque.
Bobzilla wrote:
In reply to Chadeux:
trust me, a TPI is a fantastic platform for that. idle to redline the power is always there. The downside... redline is ~4500-5k. The upside is that even at 1500 you'll still be making 300+ftlbs of torque.
Yup. My TPI Vortec motor makes over 350 ftlbs from 1,500 to 4,500 and it's over 400 from 2,000 to 3,900. That's a bone stock L-31R crate motor with the Scoggins-Dicky lower, GM upper TPI and an AEM ECU. That would be an awesome street/autocross motor.
You've convinced me. I'll be on the lookout for a good Vortec long block and a couple missing TPI parts now.
Pre 87 including TPI, intake bolts all go perpendicular into the head surface (45 degrees to the ground)
TBI years, the outer bolts didn't change but the four in the center are now straight up and down.
96-98 Vortec, all bolts go straight up and down and have raised ports that don't align with old intakes. Exhaust ports are also a bit higher which sometimes causes header collectors to hit floorpans if you don't have quite the right application.
Some guys hog out the holes on the intake to make them work with other heads, but its far from optimal. Stock vortec heads are limited to .470" lift to be safe. Some (if you check) you're OK with .500". Either machine down the guides or use aftermarket retainers to get .550" or a touch more.
96-98 5.7L is the only true Vortec (meaning it has the vortec heads) even though the vortec name was slapped on everything from 4.3L V6 to TBIs. 305 Vortec heads are a whole different critter and don't have the same high-flow port.
Worthless tidbit of information: The vortec's intake port is a direct copy of the LT1 iron head. When the LT1 started being used in B-body cars (late 93), they made an iron head for it and the ports flowed so nicely they copied them for the Vortec. Other tidbit: LT1 heads don't work on Gen1 SBC without welding and machining to get the water passages to line up.
curtis73 wrote:
When the LT1 started being used in B-body cars (late 93), they made an iron head for it and the ports flowed so nicely they copied them for the Vortec.
Does this mean the LT1 is a pretty potent option since the heads flow real well?
All I know about Optispark is a friend of mine had an LT1 in an S10 and tore it out and put a TBI 350 in it because he got tired of dealing with it. The rest of the LT1 seems good though.
Indy-Guy wrote:
curtis73 wrote:
When the LT1 started being used in B-body cars (late 93), they made an iron head for it and the ports flowed so nicely they copied them for the Vortec.
Does this mean the LT1 is a pretty potent option since the heads flow real well?
The heads don't swap. Water passages are in different places. I knew one fellow Impala guy who did the swap with welding, drilling, machining, and a ton of work... but all he had was the same outcome as if he had just put Vortec heads on it.
I will also add that an LT1 block is nearly identical to a 1-piece rear SBC except for things like no fuel pump provision, different front face to handle the optispark, different cam configuration, etc. But the whole rotating assembly from an LT1 will fit in an 88-up 1-piece SBC block.
Consider the LT1 just like a Vortec SBC but with different water passages. A lot swaps over with some careful work, but there really isn't much reason to since they are functionally the same engine when it comes to performance
In reply to Indy-Guy:
The LT1's were an evolutionary step. The main problem with them is the limited numbers built (92-96), the reverse cooling/special waterpump and the front mount distributor that sucked. Modern aluminum heads flow as well/better than the old LT1's and are much cheaper than trying to build one.
But if you have one, and you want to use it they can make power.
