djwyman

Ok so I am about swap in a 350 into my 91 RS that came with a stock tbi 305. the engine as it is now is a TBI 350 out of a 95 truck and is the same block as the vortec from the casting numbers it is 4 bolt and has the holes tapped for going with roller lifters.

Today I was given a set of zz4 heads with cast number 10088113 would these be good heads to put on this engine or are they junk? should I get something better or would the stock heads on the engine be better?

I am not trying to build some crazy track monster just a nice street car with maybe 300-400hp but as cheaply as possible so if these heads are usable for those kinds of numbers then I would be happy as pie since they were free.

sofakingdom

iTrader: (1)

They're quite a bit better than the 193s or similar "swirlie" crap you have now.

They're capable of HP in that narrow range; whether you'd get that by just plopping them on there, ... ,, .... , .... is a whole other matter.

If memory serves their center 2 intake bolt holes are the early-style angle, not the angle of a L0x intake.

djwyman

well I wasn't expecting to get those kind of numbers by just using those heads with everything else the same but was hoping they would be capable of helping get to those numbers along with carb swap, going upgraded cam and so on. Of everything going into this build if I end up having to buy heads that would be the most expensive part it seams so if these heads are good enough that would save quite a bit of money I can use for other parts of the build.

86LG4Bird

iTrader: (1)

The ZZ4 heads are not junk. They'll easily make 350 hp if you get the other stuff right.

Fast355

iTrader: (2)

With the GM Hotcam they will make a good bit more than that with everything else dialed in well.

djwyman

Awesome to know thanks guys. I was a bit overwhelmed when I was shopping around for heads before getting those given to me because I didn't really want to fork out $800+ for heads when I could just buy a whole engine from a junkyard for less with better heads than the tbi heads. But when I was offered those I was reading random post on different forums that Google brought up when typing in the casting numbers some places praised them others bashed them so when in doubt I thought I would ask my fellow 3rd gen owners what y'all thought.

Fast355

iTrader: (2)

Sallee Chevrolet or Scoggin Dickey Chevrolet, not sure which ran the engine dyno test you see in this link. ZZ4 stock vs ZZ4 with the LT4 Hotcam kit and 1.6 roller rockers.

https://www.eecis.udel.edu/~davis/z28/buildup/cam/

sofakingdom

iTrader: (1)

They came on the ZZ4, which was "rated" (whatever that means) at 345 HP, when equipped with a 208°/221° cam, headers, and a 4-bbl carb. Or, 24x HP when installed in a Vette w/ TPI, manifolds, and the L98 cam.

Not hard to do some well-designed porting (as opposed to BillyBob & Cletus backyard "hog em out til ya hit water" kind of sodomy) and get a 15% or so improvement. A bigger cam also obviously can be used. Their ultimate n/a HP capability on pump gas is probably something in the 460 - 475 HP range but that would require resources and attention to detail not typically available to the casual hobbyist. 360 - 375 crank HP would be a realistic goal for them, given the short block you have and the kinds of things that someone who would have to ask this question would be able to buy/do/ask for.

There's FAR better cams than the LT4 HOT cam for most builds. Not that it's a bad one or anything like that, just, there's better, for most builds. It's optimized for .... wait for it ... the LT4!!!! which is a short-runner EFI system. Being very familiar to everyone, it makes a good "reference" sort of build for generating comparison numbers, but that's something COMPLETELY different from "copy this build because it's the ultimate".

Best cam choice, and similarly a reasonable goal IN YOUR PARTICULAR CASE, will depend on ALOT of factors unique to your situation, such as induction system (carb, TBI, TPI, MiniRam, etc.); gears & converter; willingness to tolerate "race car" characteristics in a street car (A/C, power brakes, gas mileage, etc.); and so forth.

djwyman

Well I am a little on both sides of the fence I am a professional auto technician but in that I don't do performance stuff professionally I can rebuild an engine all day long staying stock anything from a simple SBC to a more complex engine like say a ford echotech 3.5. That being said I am rather new or unexperienced with building performance stuff and what works well with what when getting away from stock but I learn quickly do lots of research before diving into something like this.

I had full intentions of going completely different routes in this build but at things fell into my lap that has brought the price of my project down considerably I am looking at what I can do with in the parts I have. From what I have been reading based on the casting numbers of my block 10243880 and these heads these used to come together as the zz4 crate motor from 96 to like 2000 or something.

my biggest reason for asking about the heads was that I did not want to go with them and they end up being a huge bottle neck in the build.

sofakingdom

iTrader: (1)

That's just it: building a "performance" engine is WAY different from repairing a stock one. Sure, many of the same basic skillz apply; but when you start choosing critical parts on your own rather than looking them up in a catalog and just bolting back on a new one where an otherwise identical one (except that one was defective) was, things change in a hurry.

So yeah, it's a VERY Good Idea to do your research. With luck and listening to the right people, you'll get something you can be proud of the first time, instead of learning the hard way like all of us old geezers did back before Algore invented the interwebz. Ya just gotta learn to ignore the old Friday-night McDonald's parking lot monkey-spank that still exists, the idiots just spew it here instead of keeping it in the parking lot.

So, as said, those are a pretty decent set of heads for a street build, near the top of what's available on stock motors. They're not "the best", though; the 96-2000 truck heads aka Vortec will MURDER anything prior. Those bring challenges of their own along with all that though: they are extremely hostile to high lift, and they require a completely different intake manifold. So they're not quite as easy, in all cases, to make big power with, as what you've got. You could probably sell the 113s and buy a set of Vortecs if you thought that would be better for you, and come out not too far from even $$$.

Most likely your short block has a flat-tappet cam in it, not a roller-tappet. No matter what heads you use, the first thing you should plan for is upgrading to a roller.

Keep in mind by the way, that the block casting number only tells you about the casting itself. It says NOTHING about what the motor that's built out of that casting might be. You can take the block out of a "LT-1" from a 70˝ "Z/28" and turn it into a pitiful 150 HP turd, by using 20cc dish "rebuilder" pistons, a 929 replica cam, and 882 or 624 or similar deeeep smogger heads; or the block out of an equally pitiful 87 TBI truck and turn it into a 600 HP racer. The block itself is almost irrelevant. The only differences over the years and between one block and any other (speaking of 350s, not blocks in general) is the change in dipstick location around 1980 or so, introduction of the 1-pc rear main seal in 86, and introduction of roller cams in 87 which didn't include the truck and Caprice TBI motors although the block is mostly if not completely ready to drop that stuff in. And of course, quality control; 70s blocks are NOTORIOUS for super sloppy OE machine work that's all but unrepairable in the field. Power, as far as what's below the head gasket is concerned, is affected by the pistons, and by general attention to detail. Not the block itself. Everything else is just about durability.

So, bottom line, if you'd be happy with 350ish REAL horsepower - NOT "catalog page" power, where you buy this one thing and it "adds" up to 50 HP!!! and this other that "adds" up to 30 HP!!! and so on and you hallucinate that your 210 HP TBI motor is now putting out 578 HP from all the things that you "added" without ever turning a bolt bigger than ź", 113s will not be the bottleneck. But unwise parts choices can make you fall FAR short of that mark, as well as, inadequately preparing the car - exhaust, transmission, converter, gears, rear suspension, tires - can prevent you from being able to use it.

djwyman

No I don't believe throwing this part that is worth 30hp plus this part that worth 5 hp equal what ever crap. I believe the right combo of parts that compliment each other is the way to build an engine and that is how I am looking at it. Learning that these heads are good enough for my purpose what I plan to do is call around to place like comp cams, summit and such tell them what I am looking to do and they usually are good for guidance in the right direction as far as a cam/valve train package that would work well with what I have and do what I want.

sofakingdom

iTrader: (1)

Yeah that rĄcer "adding up" crap is just that, crap; just the same, it's amazing how many people fall for it.

You could do that; just be sure to ask for verification BEFORE buying, not AFTER.

Comp, Lunati, Crane, and various others, all make good cams. You could even check out a "custom" grinder like Bullet or Straub, but chances are, an off-the-shelf grind will do what you need, since the rest of your combo is not too far off the beaten path.

I'd also suggest, as far as heads in general, put MORE valve spring on them (within reason) than whatever the "bare minimum" recommendation is. Seat pressure, in particular, can always stand to be higher, as long as the pressure "over the nose" is within the recommendations, and the springs are well away from coil bind. Getting the best spring package on there that you can afford will pay off big-time in the long run. Several of us here, myself included, can give you some pointers for spring packages that will maximize whatever else you're doing.

dmccain

iTrader: (2)

I think you will have a nice build before its over with using those heads.

SteveMack

What are the valve sizes in the heads?