"Would replacing my l-48 heads with set of vortec heads and a performer RPM intake give a worthwhile power boost?"

A couple of things to address.

1. How many miles are on the L48 block?
2. Have you done a compression check on all the cylinders to see if it's a worthy rebuild? Should be at least 100 psi on all cylinders.
3. Burning any oil? Leaks? Oil Pan is common.
4. Automatic or four speed?
5. You're going to have to do a cam change and new lifters regardless of what heads you put on it, to take advantage of the extra air flow.
6. Stock exhaust manifolds or headers? Long tube may cause serious heat problems (ask me how I know) and I'm going with Short Tube, block-hugger style on the build I'm doing right now.
7. the Vortec heads are at least 64cc. They are great heads, But with the dished pistons on the L48, you're better off, going with the aluminum L98 heads off've the 87-91 C4 Corvettes, as they have a small 58cc combustion chamber that will really bump up the compression, more so, than with a 64cc or worse, 76cc heads. That's what I ran on mine You can get a set for $500 and have another $500 into reworking them, $1K total, but they ran, really, really well on my L48, with the stock pistons.

I also ran a Lunati Voodoo cam, a 262 grind, that is optimized for low end torque and will run up to about 5K RPM. It's actually a Marine - RV - 4x4 cam, because this whole combo is all about the hard pull from 1,000 RPM and up, not an all out drag racing setup, where your power comes on later in the RPM band. That cam works for both automatics and manual transmissions.

The L98 heads are the D-Port and nearly the exact same head they use on the ZZ4. These are the 113 castings by the way. My L48 with an old Edelbrock Performer, headers and a rebuilt (by Holley on Ebay) double pumper, with mechanical secondaries, was a really strong runner, that would pull hard, all the way up to the redline. But if you don't have a four speed, I'd stay away from the mech. secondary carb and go with the Holley Street Avenger, vacuum secondaries and about 670 CFM. It's set up, right out of the box (we just put one on a client truck) and it ran really well and the springs are super-easy to change out.

 

In that case I think I will just get the 383HT now. I was thinking maybe just changing heads and intake on the l48 I could save a bunch of time and do the crate swap later on but once it gets into pulling the cam I think I'd rather do it to a new engine outside the car.

I have the corvette central patriot tight-tuck hearders (1 5/8" I think) & true dual 2.5" exhaust. Also, I have a new holley 4150 650cfm carb for which I fashioned fuel lines per Lars' guide. I have a 4spd ST-10. Stock differential, I forget the ratio.

If I got the 383HT and replaced the included intake, which I think is a Performer clone, with a Performer RPM vortec squarebore I understand it should fit under my hood with a drop base filter. I'm currently using a 1" carb adapter to fit the holley and a 2" flat filter that just barely fits under my stock hood.

What would be a good cam choice for the 383? Would I need to replace anything else along with the cam? This is my fairweather daily driver.

Finally, about those dished pistons. It looks like the zz4-era zz383 came with dished pistons and so does the 385HT. Are they really so bad in a 383? It would be nice to be able to use non-premium gas in a 400hp car. I don't see myself pushing it any farther power-wise. I almost wonder if the 383HT would be just fine as it is for the street.

 

That's a truck engine, dude. It's a high torque, low RPM and you'll have a tough time, making it run like a Corvette should. Plus, you'll have to modify the 12558060 heads, just to run a decent cam in it. The mild Lunati 262 cam, I have in my L48, wouldn't even work in that engine.


"Then there's the matter of choosing the proper set of Vortec heads for your application. GM actually offers only one set: PN 12558060 (Scoggin-Dickey Performance Center-SDPC), so you'd think selecting the proper heads would be quite easy, but GM's ready-to-run assemblies will only take a cam up to about .460 lift before you run into trouble. If you want to run a cam with more lift (as we did), you'll have to machine the spring pockets in the heads, cut down the valve guide bosses, and install larger springs. The set of heads we installed from SDPC (PN SD8060A) came with bigger springs and all the required modifications and can safely take cams up to .550 lift"
Read more: http://www.popularhotrodding.com/eng...#ixzz3AyVpiX3a

Also, the cam in it now, only has 196 duration and 0.431 lift. Compare that to the Lunati Voodoo, 262, which has 262 Duration and 0.468 lift, but still has very strong torque, from the get go.

http://www.lunatipower.com/Product.aspx?id=1983

"Hydraulic Flat Tappet. Mid-level performance street cam with excellent drivability. Exceptional replacement for muscle car type cams with automatic transmissions. Works well with stock type exhaust manifolds and dual plane intake with mild 4 bbl carb. This is an Awesome 4X4 and performance marine cam."

That's what I'm running in my L48, with an old Edelbrock Performer (less than $100 just about anywhere on Craigslist) and a rebuilt by Holley, off've Ebay, Holley Double Pumper, with Mechanical Secondaries and it is a strong runner, with the L98 heads. But it's your choice, ultimately... My advice, don't rush into this. Research the crap out of whatever you're going to do, because you don't want to yank the motor twice.

 

Think GMPP sells a 383 with their larger fastburn (vortec style)heads and a little more cam timing complete. Vortecs are awful small for a stroker they can use plenty of air. Its more upfront but well worth it...and all brand new. Cant go wrong
I like building them but for a driver engine complete the GM crates make good sense and probably give more longevity than the typical rebuild.

 

Ah, you're right about the low maximum lift. Back to square one, again.

 

Nope, not anymore. At least not that I've found and I've been looking all week. The zz4 is out, the 385 fastburn is out, the old zz383 is out. The only comparable GM crates I see are the $5600 zz5 and $6500 new-zz383 and their new heads won't even fit my headers.

 

What about a 383 shortblock and a set of afr heads?
tpi421Vette in the C4 section can put you together with a set reasonably..heck he could build the entire motor

 

There you go! I'd certainly look into it.

 

Just sent you a link to a very low mileage ZZ4. If I lived in the US and on the eastern seaboard i would have bought this myself.

 

These are still out there in warehouses. Got to look. If you find one you will likely buy it cheap. Google search for part number 24502609
http://gmpowertrainwarehouse.com/24502609.asp
https://sdparts.com/details/chevrole...mance/24502609
http://www.gmpartscenter.net/oe-gm/24502609
http://www.streetperformance.com/par...-24502609.html

 

I looked! AFR heads are about the same cost as fastburns... ~$2000 assembled. The zz383 short block is $3600 alone, so add $2k heads and you're at $5600 already with no cam, lifters, pushrods, intake, etc.

 

Thanks 63mako. I will contact these guys but my experience so far is that everybody I ask about zz4's says "oops you are right, these are no longer available".

 

Try searching for a CT355. It's basically a ZZ4 modified some for circle track applications. Summit racing has it listed still for $4900, and they are usually pretty good about not have out of date stuff on their website.

There is also a CT350 that had cast iron heads that might be option too.

 

buy the 350HO engine. It's a roller cam block. you just need to swap out the cam and lifters. GM roller lifters are cheap.

You can get 400+ hp out of it with just a cam swap.

 

I hadn't considered this... that is a good point.

The 350HO has the same iron vortec heads as the 383HT so I would ask if you can put a 400hp cam in it then why not in the 383HT? Also the 350HO is cast rotating assembly which I thought wasn't comparable to the forged 383.

The 383HT has a 5000 rpm redline but I'm not sure if this is because of the cam or the longer stroke. 350HO is 5500 redline. ZZ series is 6000.

 

According to this article: http://corvette.wikia.com/wiki/Head_and_Cam_Comparison

a zz4 with iron vortec heads & intake makes 376 hp at 5,600 rpm. Is F22 exaggerating the limits of these heads?

"The Vortec cylinder head is the sleeper in the bunch. It was never a Corvette standard like the L98, nor is it being touted as a small-block head for the next millennium like the Fast Burn. It's been a standard on pickup trucks and SUVs for the last few years, gaining little recognition. As it turns out, the head was designed to flow very well so the truck engines could make good power for pulling heavy loads, trailers, and the like. The intake port was borrowed from the LT1, and the 1.94-inch intake and 1.50-inch exhaust valves allow the head to breathe. Combustion chambers on the Vortec heads are listed at 64 cc, but GM tells us most heads are actually around 61 cc. This bottom-dollar cylinder head ($420 per pair, complete with valves and springs) proved to be a capable performer, producing 376 hp at 5,600 rpm. The rest of the ZZ4 remained as-delivered. We used the same stamped-steel factory rocker arms that were used in the L98 aluminum head test. The only variance between these tests was the intake manif old design. The Vortec cylinder heads feature a simple, eight-bolt intake manifold design that has no access or clearance issues. We fell in love with this feature immediately. The L98 heads had the traditional 16-bolt pattern, so different intake manifolds were a necessity (Vortec cylinder heads that are double-drilled for both traditional and new-style intakes are available, but ours were not). We tested both dual- and single-plane designs on the Vortec heads, and found best power with the single-plane Edelbrock Super Victor for Vortec heads (PN 2913). Suprisingly, the dual-plane intake didn't have a huge torque advantage over the single-plane, although peak torque did occur at a lower rpm level."

 

if the 383HT is forged , then that is the way to go. and yes, you should be able to just swap the cam out.

I was just giving you another less expensive option.

 

Thanks, yeah I'd rather go forged 383, though gdh sent me a link to a used zz4 for sale at a good price.

I'd love to hear more opinions on the vortec heads if anybody has them.

 

No, I'm not exaggerating. Read on.

There are more than one Vortec head and the ones on that truck motor, were the ones discussed in the Popular Hot Rodding issue, that have the limits on cam lift. Also, Scoggy-Dickens sells these heads, but have modified them and they still will only go to 0.475 lift. If you want to run a cam like the Lunati 268, you'll be out of luck, as it has 0.494 lift and that is a cam, that works really well with a four speed car.

http://www.streetperformance.com/part/gm-performance-parts/cylinder-head/687607-12558060.html

"This cast iron Vortec cylinder head will fit 1958 and later small block Chevy engines and offers a 20 to 40 HP increase over earlier cast iron small block heads. Features include 64cc fast burn combustion chambers 170cc intake runners and a high-velocity LT1 port design. It requires the use of a Vortec-style intake and self-aligning rocker arms will accommodate up to a .475 in. lift cam and comes complete with 1.94 in. intake/1.50 in. exhaust valves springs retainers and 3/8 in. pressed-in studs"

http://www.onedirt.com/tech-stories/...k-chevy-heads/

How Many Types of Vortec Heads are Offered?

•GM L-31 Vortec (Cast Iron)
•GMPP ‘small port’ Vortec Bowtie (Cast Iron)
•GMPP ‘large port’ Vortec Bowtie (Cast Iron)
•GMPP ‘Fast Burn’ (Aluminum)
•Edelbrock E-Tec 170 (Aluminum) 170cc intake runner
•Edelbrock E-Tec 200 (Aluminum) 200 cc intake runner
•Dart OE Vortec replacement head 165cc intake runner
•RHS Vortec (available with either 1.940/1.500 or 2.02/1.600 valves)
•EQ “Lightning” Vortec Style Cylinder Heads (Cast Iron)


"The L31 Vortec comes in two different casting numbers, 10239906 (#906) or 12558062 (#062). Originally, the stock #906 casting head was available in two versions. One version had an Inconel exhaust seat with single angle valve grind and was available on 1 ton trucks. The other version was the traditional three angle valve grind. Other than that, the #906 is the same as the #062 head."

Other Vortec Tips and Tricks


•Maximum valve lift on Vortec cylinder heads is .460″ to .480″. This range is due to production line machining and casting variance. It is highly recommended to check for clearance on anything over .460″ lift.

If you think swapping out a cam on a Vortec truck motor is just me, making stuff up, then please feel free to go on and do that. Me? I'm just trying to help out.

 

The used zz4 is no longer for sale.

F22, I'm not trying to discredit you, I really appreciate the your input. I'm just trying to make sense out of what I'm reading. Scoggin Dickey lists these heads for $430 each: https://sdparts.com/details/scoggin-...nter/sd8060ra2
"This RA2 Vortec cylinder head from Scoggin Dickey can handle up to 0.600" lift."

Am I misunderstanding these numbers? Or are these legit and maybe came out after that article was published?

It looks like Scoggin Dickey sells a kit with modified iron vortec heads, plus an edelbroc performer RPM for $1250. I'm not sure if these are the .60 ones. With a $3800 zz383 short block thats $5050. I think choosing a cam and completing the package, plus the normal required accessories, would keep me reasonably close to my original budget. This would be something like $1500 cheaper than a new zz383 long block that still won't fit my headers and may have an inferior intake. And, uh I guess I get to learn how to assemble an engine, for better or worse.

Is this reasonable? Any idea what kind of cam to look for?