SBC Heads to look for when junkyard diving...

hrdlydangerous wrote: I remember reading an article in HotRod years ago where they put a set of Camaro 305" heads on a 350". The idea was to increase the compression ratio and get better velocity into the cylinder. It seems to me they made more power and torque down low with only a slight tradeoff in the higher RPMs. I'm sure you can get a set of those heads for free or close to it. It may be worth experimenting if you have the time.

I have a set of those camaro heads sitting in the shop that I'd planned to swap onto my Impala 350 years back. New valve springs, or so I was told. I've tried to sell them , no one even called me about them.

ultraclyde wrote:

hrdlydangerous wrote: I remember reading an article in HotRod years ago where they put a set of Camaro 305" heads on a 350". The idea was to increase the compression ratio and get better velocity into the cylinder. It seems to me they made more power and torque down low with only a slight tradeoff in the higher RPMs. I'm sure you can get a set of those heads for free or close to it. It may be worth experimenting if you have the time.

I have a set of those camaro heads sitting in the shop that I'd planned to swap onto my Impala 350 years back. New valve springs, or so I was told. I've tried to sell them , no one even called me about them.

what are the casting numbers of the 305 heads you have? if they aren't 601's they aren't really worth trying to sell..

Here is the condensed version of what I know.

Vortec heads are almost as wonderful as everyone says they are. The Vortec ports were actually carbon-copies of the 94-96 LT1 iron head. Unfortunately the LT1s won't work on a traditional SBC because the water passages are different.

There are three basic intake/head bolt patterns on SBC. 1) the traditional 12-bolt, 2) the TBI 12-bolt in which the two center bolt holes on each side are at a 72 degree angle instead of 90 degrees, and 3) the Vortec 8-bolt which has all 8 bolts straight up and down. Adapting TBI intakes to old heads (and vice versa) is very easy. You can just wallow out those center 4 holes and tighten it down. Adapting non-vortec pieces to vortec pieces isn't so easy. Not only do you have to make some massive adaptations for bolts, but the vortec head ports are considerably taller and most intakes will leave a massive vacuum leak gap.

Old school heads like 882s do flow a satisfactory amount for decent street power, but comparing their chamber shape to a Vortec is like comparing a flathead to a hemi. The vortec chambers will allow for significantly more compression on the same fuel, they flow considerably more, and their ports aren't much larger. Its a win-win. Tons more flow for HP potential, small ports for TQ potential, higher compression on pump gas for a nice bump across the board.

As far as intakes are concerned, look to the ebays. There were gazillions of ZZ4 crate engines sold and a fair number of buyers upgraded from there. The ZZ4 has vortec heads and a carbed intake. Many folks took the intake off and replaced it with a more performance oriented piece - not knowing that the factory ZZ4 intake was an impressive piece. For that reason there tends to be an ample supply of those ZZ4 intakes on the market for cheap. I bought mine for $51 on ebay and its on a 350 in my boat. Vortec heads, Holley 650, cam specs at 214/218 with a 112 LSA, 9.5:1 compression, and it sips 87 octane and idles at 500 RPM... and makes a dyno-proven (corrected) 321 hp. You won't get that with 882s unless you run more octane and more cam.

The big benefit to the vortecs is that they flow more without the penalty of big ports. You get the benefit of increased low-end torque and throttle response with the flow to support more HP.

Vortec heads can be had for $150 a pair if you shop carefully. Add a $75 intake and an adapter to run your TBI and you're in business.

TBI heads (swirl ports) are the lowest-flowing head chevy ever put on a small block. They are not "bad" heads, but they run out of breath at 4500 rpm TOPS on a 350. They can be ported to flow just fine, but the cost is usually far greater than just buying a pair of good heads.

Of all the SBC factory heads, Vortec wins hands-down for power and torque, as well as detonation tolerance and combustion efficiency. If the challenge budget allows, its the way to go.

By the way... when I talk about "vortec" heads, I am referring to ONLY the casting numbers of 906 and 062. 305 vortec heads are not the same, nor are later LS-based engines with the "vortec" name.

In the SBC world, when someone speaks of vortec heads, they are referring to those two casting numbers only.

Also, if you are using stock vortec heads, keep the gross valve lift to under .470". Any more and you risk the keepers hitting the guides. There are two solutions - either machine the guides down to accept more lift, or use one of the common aftermarket spring/retainer kits that allow up to .550" lift.

the ZZ4 never did and does not now come with Vortec heads- every ZZZ series 350 crate engine has had the aluminum L98 Vette heads, with the ZZ4 getting the LT4 valve springs. the ZZZ-ZZ3 crate engines had an intake that only accepts a Holley carb, and the ZZ4 got an intake that accepts either square bore Holley or spread bore quadrajets and has egr provisions, which they did so they could make it emissions legal to swap into some 3rd gen F bodies as a part of a complete package that came with way more parts and pieces for every aspect of the car than they had any right to give you for the price they were charging.. the result was a 50 state emissions legal swap that put something like 310hp to the wheels..so, yeah, the ZZ4 intake manifold is an impressive piece, but it's only for 86 and older iron and 87-91 aluminum heads.

GM does sell a 330hp 350 with vortec heads, and the ZZ383 also has vortecs.

the vortec ports and chambers are based on what they learned with the iron LT1 heads, but they are different.. the intake ports are about 1/4" taller on the vortecs than on the LT1 heads, and the chambers are shaped differently.

Well, we pulled the engine from the truck yesterday and pulled off the valve cover and confirmed that it is indeed the 191 TBI heads that are on it. Granted, they look all but brand new- but they're still horrible heads. So, it's off to got head-hunting in the salvage yard between church this morning and a Weird Al concert this evening.

Well, I'd have to say that it seems the trip to the salvage yard today was an unqualified success- I netted a pair of 062 Vortec heads off a '99 Yukon and even managed to find a throttle body housing just sitting on a TBI engine (interesting that the injectors from them seem to be a very popular item to snag as very few vehicles seemed to still have theirs...). The only way it could have gone better would have been to have found a 1" carb spacer and a TBI-to-carb adapter sitting around too.

Now I need to find a good intake, an appropriate cam (as the TBI engine one is apparently quite a dog), find or fab a TBI-to-carb adapter, and figure out whether I really want to use the TBI or just use the 650cfm Edelbrock the original engine came with.

use the carb.. you already have it and the time not spent wiring up a TBI and getting it to work in a non-stock engine can be used to do other stuff on the car.

novaderrik wrote: the ZZ4 never did and does not now come with Vortec heads- GM does sell a 330hp 350 with vortec heads, and the ZZ383 also has vortecs.

You're right... I was thinking of the 350/330, not the ZZ4. My bad.

Ashyukun wrote: Now I need to find a good intake, an appropriate cam (as the TBI engine one is apparently quite a dog), find or fab a TBI-to-carb adapter, and figure out whether I really want to use the TBI or just use the 650cfm Edelbrock the original engine came with.

The early TBI cams were something horrific like 161 degrees intake duration. I can help you pick a cam.

IMO, the TBI is a waste. First of all, the computer won't like even small changes. You're looking at burning a custom chip which can be hit or miss, and the MAP maps are a bit dodgy when it comes to adaptation. The 2-bbl TBI that was installed on small blocks looks OK on paper; flows around 500 cfm. But, install those big nozzles on it (which are not injectors since they squirt all liquid fuel) and wet flow is more like 390 cfm.

I would take a carb any day over the TBI.

Ironically, I fish in the summer with an old guy who was one of the designers of the TBI at Rochester/Delphi. When asked about it he just says, "on behalf of GM, I would like to personally apologize."

The TBI engine was very well matched; port flow, TBI flow, compression, cam... it was all perfectly matched for a 180-hp engine that wimps out at 4500 rpm. Keeping any of those TBI induction parts is a bit of a poor choice IMO. You've now purchased heads that can easily support twice the HP of what the factory TBI setup could.

The 454 TBI is a better choice. It is basically a spreadbore pattern TB that flows considerably more. You will still run into the programming issues, but once dialed in it will be better suited. But, again... for my money I'd rather change a few $1 jets and springs than burn a custom chip.

curtis73 wrote: The 454 TBI is a better choice. It is basically a spreadbore pattern TB that flows considerably more. You will still run into the programming issues, but once dialed in it will be better suited. But, again... for my money I'd rather change a few $1 jets and springs than burn a custom chip.

"spreadbore TB"? they used a 2 barrel throttle body with a little bigger injectors on the 454- it is a common thing to swap them onto TBI 350's for more airflow- but there is nothing "spreadbore" about them.. they didn't make a specific TBI intake for the early TBI 454's in the late 80's and early 90's, but they did make a nifty adapter to put it on the same intake that the 454 had since the early 80's that had water passages in it to keep the throttle body and intake nice and warm for power and emissions. sadly, that adapter plate has long since been discontinued by GM and a used one is worth a pretty penny..

Thinking about it a bit and after doing some more reading, I think I've come to a conclusion about what I'm going to do regarding at least the fuel delivery:

The initial build of the car will use the carb (I was wrong, it's only 600CFM- an Edelbrock 1405) up until and during the Challenge, so I'll build the engine up to support that.

I will however hold on to all of the TBI hardware (except the heads... if I can't unload those on CL for a few bucks they'll get stripped down and add 100lbs or so to my next scrap run. Or get strapped to the back of the Elky as ballast ) and see about converting the engine over to run it afterward- I plan to use this car as a part/car hauler and general-use vehicle after the Challenge, and it would give me a chance to play with MegaSquirt- which I don't really think I have the room in my budget for. I'll be doing a fair bit of work on it anyway (for the Challenge it will almost certainly use the THM350 it came with, afterward I'll put in the 5-speed I snagged for it- I much prefer stick, the suspension will need to be adjusted for towing, etc).

I'll probably keep my eyes open for a 454 unit as well- just because I want it to be a bit more efficient and won't be using it for racing doesn't mean I don't want it to still make power and be fun to drive!

One last thing on the heads issue- with the Vortecs I now have to sets of heads I have no use for beyond ballast/scrap, so I'm planning to put them up on Craigslist.

Is it worth stripping them down and keeping the springs, valves, and rocker arms, or are the ones on the stock heads not worth bothering with? The ones on the TBI head look nearly new (the engine was rebuilt about 400 miles ago, and the heads look like they were either completely new or cleaned REALLY well).

stock replacement springs are like $30 for those heads, and rocker arms are about the same. you could probably squeeze the springs a fair distance just by squeezing them in your hand... probably not worth pulling off just to have them taking up space on your shelf for the next decade.

In reply to novaderrik:

Excellent. Less work for me before putting them up on Craaaaaaaigslist (sorry, saw Weird Al in concert over the weekend :-P) for a few bucks. Thanks!