I am currently having a motor put together that I have been compiling parts for, for a few years. I got pushed into it a bit when the cam in my 305 started going down. Here's the scoop:

It's going in an '86 IROC w/ TPI, auto, 3.23 posi. It's bsically going to be an L98 except I'm putting Hyperutectic (sp?) pistons w/ valve reliefs, all the good bearings and rings, and a pull out cam from a zz4 crate engine. It was new the people wanted something bigger. I'm not sure of the casting number on the heads as my builder is setting me up but they are the later center bolt valve cover.

I keep getting mixed info on this setup. I got this cam because I had read that it was a fairly smooth idle under a TPI setup. Are there any concerns that you guys have run into with a setup like this? Anything I need to be paying real close attention to? Any advice would be really appreciated.

 

The cam should be fine; maybe not ideal for a TPI application, but plenty OK. It WILL REQUIRE better than stock valve springs, as its exhaust lift is over .500" with stock ratio rockers.

Yes, this:Make sure they are not truck/Caprice "swirlies", casting # 193; those are garbage. Post what casting # they ACTUALLY ARE, as observed with an eyeball (no assumptions, "iunno", "stock", etc.), and we can tell you what to expect.

 

The springs are going to be upgraded to take care of the cam lift. I will find out the casting numbers today and post those. Thanks for the help.

If you could suggest a better roller cam for a tpi I might have enough in my budget to change cams before I install the motor.

 

Okay, the casting number on the heads is 14102183. if I remember right this is a decent set of heads.

Also, if anyone knows of anyone, or can themselves, program a prom for this car I need one for it. Any suggestions would be great.

 

Never heard of any such number.... neither have these guys....

MorTec, Inc. Chevy Smallblock V-8 Casting Numbers List ....
you sure they're not 14102193? Which would of course be the VERY THING, namely the swirl-port TBI heads, that you should run away from as fast as your feet can carry you.

My suggestion would therefore be to verify the casting #, or look inside the intake bowl and see if you see the giant lump of obstruction the factory calls a "ramp"; and if that's what they are, start looking for some other heads.

Otherwise, all the "programming" in the world won't get you much.

 

Yep, big red-flag there. Could smell 193's a mile away. To most "builders", later centerbolt 350 heads are later centerbolt 350 heads, don't have a clue what heads are really good. OR, they're trying to get rid of the 193 junk they have laying around on the unsuspecting.

Tell him it's 083's or 113's, or nothing. Without one of those, you aren't coming close to building a "ZZ4".

 

193 heads... The factory put a ramp in the intake port to help the incoming charge "get air" before it enters the combustion chamber. lol

On the serious side though, you mentioned that your original cam was "going down"
By that do you mean going flat, as in what flat tappet cams do when they wear out?
The reason for asking is because the ZZ4 cam is a hyd roller and if you try to put that in where there was originally a flat tappet cam, there will be complications.

 

I guess I wasn't specific on the size of the engine. I'm yanking the 305 in favor of a roller 350. That takes care of the roller cam question.

The 183's do exist. If you google the casting number you find all kinds of boards saying they never existed. But PITTSBURGH'S PENNSYLVANIA MOTOR SPEEDWAY 2006 PURE STOCK RULES AND REGULATIONS in rule 13 states that, "The following CHEVY head numbers can also be used: 10065206, 10110810, 14079287, 14085963, 14089119, 14094098, 14096217, 14101083, 14102183, 14102191, 14102193, 376445, 93417369, 93417389." You'll notice 183 are right in the middle. I'll find out from my engine guy what the specs are and post them for you guys. He's probably in the top 3 head guys in this state and said they are a good fuel injection head. But I will get the specs.

So, any suggestions on a different cam and somebody to program a prom for me?

Thanks for all the help so far.

This may actually prompt a move to clear up some missinformation on the head front. I've seen a lot of people on boards junk these heads 'cause thay were told they had to be 193's. It'd be nice to find out if there is another pool of inexpecive heads lying around out there.

 

Okay, I think I have finally gotten to the bottome of the head thing. It turns out my engine guy didn't read the number right. It is 193 and, not really ever working with TPI didn't realize I wouldn't want them. But, I think the 183's are 305 heads. I found one entry that showed them as 305 tbi.

Now, as it has been a number of years since I've looked at all this stuff, what are the draw backs to the 192's on TPI set-ups? I'm not looking for something that is going to tear the rearend out, i just want a solid small block with good torque.

Let me know what you guys think.

 

305 TBI's had 187, 350 TBI's had 193's IIRC. That may have been where the confusion came in, one rule book posts a misprint, doesn't mean they exist

The ramp promotes swirl, but kills flow. They make good torque, they're good in trucks and whatnot, but they run out of flow at 4000-4500 RPM typically. Leave 'em for truck motors, you've got a sports car, treat it like such.

 

Take the 193 bashing with a grain of salt.

The ramp doens't kill flow too badly, the exhaust ports flow better than most castings, and the faster burn helps increase torque, HP, and fuel mileage.

I have put a Summit K1103 cam with 214/224 @ .050, .442/.465, 112 LCA in an otherwise stock TBI truck engine. It has headers, duals, edelbrock 4 bbl intake, and a tweaked Q-Jet carb. It pulls hard all the way to 5,500 rpm with no real drop-off in power until the cam lays over. To NO suprise it pulls right up to where summit advertises it to.

My G20 had 810s (heavy duty 193s with a little bowl work) and a PEANUT roller cam. It would pull strong all the way to 5,000 with the best ET coming from 5,500 rpm WOT shift points. For weighing 5,500 rpm it moves out of its own way pretty good.

YouTube - Chevy Van 350 1

YouTube - Chevy Van 350 2

 

It sounds like we're using similar cams, fast355. The zz4 cam is ~228/221 @ .05, .470/508, 112 LSA (good spec sheet: Gilbert Chevrolet - Performance Parts Catalog. The lift is a bit more on mine.

In my readings on TPI it doesn't flow well over 5,000 rpm anyway and is much better for torque than HP (which I'd prefer anyway on the street). So these heads don't sound like they're the kiss-of-death, at least in my application. Is that reasonable logic?

How's your idle with that cam, fast355?

 

Those 2 cams are not even REMOTELY similar. There's alot more about cams than just the specs might show.

The Summit cam is an old generic grind from the mid-late 60s. It's been copied over and over again by all manner of people who don't do any R&D, and it's available from any of dozens of suppliers. Melling, Sealed Power, A-Motion, Summit of course, all sell copies of it; its little brother the 204/214 one is even packaged as the Edelbrock "Performer" cam. The 204/214 one and the 214/224 one are what people usually mean when they tell you they have a "mild" or "RV" cam. They're OK enough cams for a non-competitive carbed application, not stupidly wrong or anything, if properly selected from the series; but almost any modern cam of similar "paper" specs will beat them in almost any application.

NOTHING WHATSOEVER about it applies to the ZZ4 cam, or vice-versa. They have very little in common, besides that the .050" durations are somewhat similar. Beyond that, they are night-and-day different.

TPI has specific issues beyond merely "flow" and such things. It is an acoustically tuned system, where the high-pressure pulse produced by the air rushing down the runner during the cylinder fill event. This rush of air motion is stopped suddenly by the intake valve, creating a pulse of positive pressure (a sound wave, quite literally), which then travels back up the runner, into the plenum, and down OTHER runners. When this pulse happens to arrive at another intake valve during that cylinder's fill, i.e. while the intake valve is open, it pushes more air into that cyl, and fills the cyl more fully (increases volumetic efficiency and therefore torque output). Because of the length of the runners, this effect occurs at a specific RPM, determined by the speed of sound (i.e. how fast the pulse travels) and the runner length. This acoustic effect, which is exactly the same physics as that used by musical instruments to control the pitch they play at, is why it's calls "Tuned" Port Injection.

When you work out the lengths, you find that the reinforcement occurs within a relatively narrow band around 3600 RPM; about 3-400 either way. The flip side of this, is that there's a corresponding NEGATIVE PRESSURE pulse right behind this poitive one, just like any other sound wave (or any other type of wave, for that matter); and that NEGATIVE pressure has THE EXACT OPPOSITE effect. The pressure wave created and focused by TPI begins to OPPOSE and DECREASE cylinder fill at about 4500 RPM.

The way to build a TPI motor involves understanding these details of how it works. It's alot different from a carb motor, or even a TBI one, where there's relatively little "tuning" of anything; with a non-tuned, or minimally tuned intake system, you just make the runners as short and as large as you can, to allow them to flow as much as possible. TPI isn't like that. You can make it like that, SORT OF; but if you do, you lose its strength (the torque peak at 3600 RPM) and instead begin having to fight everything else about it.

The cam is critical to making it work. A few companies have gone to a great deal of trouble to experiment with TPI SPECIFICALLY, which is a very different situation from taking a 40-year-old generic design and just slapping it off in there. Or, from using the biggest thing you dare to try (a common approach with a carb) based on your tolerance for poor idle, low idle vacuum, low torque at low RPMs, etc. For really OPTIMIZED TPI cams, look at the Lingenfelter ones, the Comp product line, TPiS, and certain Crane cams. Those are the ones that actually work well with TPI; NOT the old generic 60s designs with the lazy lobes.

Also, the ZZ4 cam is a roller cam, and somewhat takes advantage of the faster ramps and all that, that a roller allows. So are practically all the other TPI-specific cams. The "RV" cam is not. However, I can tell you (since I put one into one of my little brothers' cars with a carbed 305 a couple of months ago) that the ZZ4 cam idles just fine; you'd hardly notice that it isn't stock. Although, it's not the best choice, as I stated earlier, because it's NOT a TPI cam. It's OK, that is, not radically wrong like say the Edelbrock "Performer RPM" cam would be, which is the one 2 steps up in the same series as Fast 3xx's cam; but not optimum either. Much better than the old 60s generic grinds though.

For a cheap easliy available FI cam, the ones out of F- and Y-body LT1 motors is decent, and you can pick those up on eBay and elsewhere for $50-75. Just make sure, if you go that route, that you avoid the B-body (Impala and Roadmaster) LT1 cam, it's not near as good. But they still aren't really all that much better than the ZZ4 cam.

Those TBI heads are most definitely the "kiss of death". They're the modern-day equivalent in our hobby of the smogger castings from the 70s. You get A GUY here and there that makes whatever claims about how good they are, and even the occasional magazine article about "look at these surprising flow numbers" and such as that; and yet out here in the real world, when the rest of us take them off and put ANYTHING else on, the car suddenly goes faster. I'd strongly recommend avoiding them. Don't forget, there's a big difference between what ONE GUY claims he can get out of them with whatever porting and so forth he claims to have done (which of course he didn't tell you about.... just slapping a set out of the junkyard on your car, WILL NOT get you the results he claims forhimself), and the COMBINED EXPERIENCE OF THE WHOLE REST OF THE HUMAN RACE.

So don't worry too much about Fast 3xx's combo; it has no relationship AT ALL to yours. And, my advice remains, DON'T USE TBI HEADS, because they make cars SLOW. There's a whole board on this site devoted to that, full of endless tales of woe from people whose cars are so slow that they're emarrassed to drive them; it's called the TBI board. And the reason their cars are slow, is for one reason above all others: THE HEADS. A few of them have broken out of that by spending a little money on better heads, and found that while TBI might not be the hottest thing going out there, it's also not the root cause of their cars being underpowered. THE HEADS were the thing that was holding them back. Don't sentence yourself to enjoying the same struggles that you can read about over there.

 

The only thing I'd change of what sofa said is a detail about the TPI runner pulse effect. Each runner acts individually, the pressure pulse being reflected back down the tube it went up when it reaches the opening of the plenum. When the pulse gets back down to the valve as the valve is opening, the higher pressure of the pulse drives more air/fuel into the cylinder. This effect is optimized over a very narrow RPM range (when the pulse reaches the valve when the valve isn't open, it is reflected back up the tube, and then the valve opens during a low pressure event, reducing the air/fuel getting into the cylinder) and can be "tuned" by changing the runner length - a shorter runner will be optimized at a higher RPM than a longer one.

Just for the sake of technical correctness. . .

 

The 193s won't lay over until after the TPI runners have given up, plain and simple. If you don't like my work on them, look up Dyno Don and Dewey316. Dyno Don was in the mid 13s with very little port work on some 193s.

I have personally used a pair of 187s (stock ports, clearanced for .525" lift only) on a 10:1 305 (,040" over) along with a Crane retrofit hydraulic roller cam (part number 119821). It made 242 RWHP @ 4,900 and 322 RWTQ @ 3,500.

CraneCams

 

Excellent

 

Stock TBI 193 heads, Stock TBI non-roller cam, 8.8:1 compression, Stock cast iron manifolds, and 3.08 gears, 190HP/300TQ stock, 5,600 lbs

https://www.thirdgen.org/forums/tbi/...350-track.html

Drop 2,000 lbs with half the aerodynamic drag and it surely has to be in the 8s.

 

Thanks guys for all the work you're doing on this. My engine guy said if I didn't want those heads he'd swap em out. Just puts me back a bit while he gets it done.

I'll do some looking around over the next few days and see what my budget can handle and then I'll see what you think about what I find.

Nice education on the TPI, sofa. I've read a few books on this system and I don't remember that tidbit.

 

Thats a less than fantastic combo, stock parts, stock results. I see a very high torque rating, compared to HP, the offset being in the neighborhood of diesel territory. Not saying that kinda torque in a street car wouldn't be fun, or it doesn't have it's place in a chev 1500 towing your boat, with a camper on the back, but in a 3rd gen, sports car, with more than stock parts on it, you'd want more than 190HP. You can't argue fast355, that the TBI heads do fall off at higher RPM right? Sports cars, high RPM, and horsepower kinda go together for me, so I think those heads aren't a great choice.

 

Stock 193s, Stock "929" spec cam, stock manifolds it falls over around 4,800 RPM, but will rev to 5,500 without too much trouble under load This is with 100,000 mile stock valve springs as well.