I had a 232/244 @ 0.050, 108 LSA cam with .640 lift from the 1.7 rockers on these heads and shortblock at one point with a MPI dual plane and 1200cfm throttle body. Dropped back in cam to make it idle as well as a stock 350 Vortec and put the L31 manifold on it to go through smog. I have a 2,800 stall speed and the 5.13 gears make my cruise RPM 2,850 @ 70. Smaller cam works better with the whole setup for 95% of my driving. The truck intake even modified makes for peak power around 5,500 rpm. Running a smaller cam with less overlap I plan to run EGR again to keep cylinder temps in check. Driveability, MPG, and emissions friendliness trump WOT performance in my case. I checked the result of swapping stock lifters in place of the Rhoads. Cranking PSI dropped to 195 psi with 1/4 turn lash. I have a feeling the idle would be a good bit thumpier as well with a loss of intake vacuum from the increased overlap. I actually ordered a set of 1.6 narrow body non self aligning rockers as well. Going back to stock valve covers and painting the aluminum heads black to hide them. Externally the smog tech will have no reason to believe this is not a cleaned up stock 350 with smog legal headers.

For a good running street 350 I would draw the line around 195-200cc. That is where GM drew the line on what is the strongest 350 they ever built, the 1996 LT4. That engine made peak power near 6,000 rpm and had a nearly flat powerband to 6,400 rpm with a 203 @ 0.050 intake lobe. The 218/228 LT4 Hotcam only pushed the peak power about 400 rpm higher and gave another 30-40 hp at peak and as much as ~50 hp more at the 6,400 redline. Not to say a 180cc or even 170cc head would not be better with the nature of a LTR TPI intake. Most do not seem to stick with the LTR though and will end up with a Stealthram, Ramjet or other intake down the road.

My charge cooling will likely soon be a 75 hp dry shot before the MAF. I have seen a few LT1 and LS1s gain nearly 100 hp from a 75 dry shot due to the charge cooling effect.

 

While there's no chance I spend anymore time or money on a factory TPI type setup, the FIRST is keeping the powerband in the range I'd like to use and provides a better match to any of these heads.
Not that a HSR doesn't sound appetizing, but changing to as such would nearly mandate taller gearing and a power range I'm not looking for in this car. I've got other stuff for lower geared, higher revs.

 

So, where does this leave you regarding an intake? From the responses and suggestions received, the cylinder head choice hinges on that. To take it further, what about the cam? Are you considering a "final" iteration and then calling it a day?
You can obviously creep up on it in stages but the heads are a relatively big ticket item considering all that follows with their purchase. And to do the cam at the same time will have a certain economy built in as many of the build aspects overlap.
So, back to post #1: Is a 195 head too big for a mild 355? Well, yes, no and maybe...

 

that's the funny part and what is common to most builds. Everything hinges on everything else. The more research I do on available heads and intakes makes me like the FIRST for my application. Plus they aren't far away which makes it convenient for purchases and so on. The cam I'll look deeper into after I lock in confidently which heads and intake is going on. My only requirement with cam is that it'll idle calmly and I don't see that as a problem to have and still have very strong overall powerband within the range I'd like to use. My current cam may fill that bill, I don't know yet. If, by that time, typical street driving keeps me too low in the powerband then I'll step up gearing. I have a couple axles in the garage.
And yeah, back to post #1. That's exactly the answer I was figuring I'd get. But that's a great thing, I love everyone's insight. I know and have built my fair share but there so much to gain from everybody's experience. Can't know everything no matter how much you know.

 

The following is from a 2006 Super Chevy Dyno Test of Budget Heads. Granted, this is a 383, with a larger cam than the OP would run, no one knows how well each combination was dialed in unless they were there, this is WOT, starts at 3300 RPM, and are 195 TFS instead of AFR heads, but figured I'd post it anyway - lol

They did test head flow at .050" lift, so maybe that's pertinent. No question the Vortecs flow well down low considering their 1.94 vs the TFS 2.02 valve.

 

On the flow chart it looks like the Vortecs ports stalled as soon as lift exceeded .400".

 

It looks like the exhaust flow on the Trick Flow 195's is stronger at .100, but is outflowed by the Vortec until .500 lift. I find this important for two reasons. 1: The Exhaust/ Intake Ratio is better on the Vortec after .100 lift. 2: The Flow/ Valve Size ratio is in favor of the Vortec on the intake side up to .400 Lift, but the reverse flow somewhere between .400 and .500 is what hurt the Vortec in this case.

(DISCLAMER: I will be comparing the published flow data of the AFR 195cc SBC Street Cylinder head from AFR's website to the flow data of Vortec listed above. Different testing procedures I.E. bore size, Inches of water, and port extension might be different)

On a Small Block Chevy, I prefer the strongest exhaust port that I can get, while paying special attention at .050 - .300 lift. This will aid in blowdown and improve the intake cross flow during valve overlap. at .200 and .300 lift on exhaust, the AFR's outflow the Vortec's by 11.56% and 11.96% respectively. What about lower flow? I do not know, as AFR does not publish them. The AFR's again pull ahead in the Flow/ Valve Size Ratio at .200 and .300 Exhaust Valve lift.

So what does this all mean? it means that the Vortec head are great for what it was designed for, a short duration, low lift cam that gives great low end torque for a pickup truck. I speculate that this is, in part, why the "602" crate engine utilizes the Vortec heads and the "604" crate engine uses the newer design, Fast Burn heads.

Back to the original question. Is a 195cc head to big for a 350 CI Small Block? In my opinion, no. There is a reason why TFS built a 175cc head for the 305, and no one in their right mind would put a 305 head on a 350+ inch motor.

 

Listening to discussions on exhaust ports by Darin morgan and exhaust systems by Calvin Elston, most head exhaust ports are too big to begin with so i am usually not as concerned with the exhaust side as much. The exhaust matters when you can thoroughly use it in proper header and exhaust system design to capture the best scavenging effects from pressure wave tuning. But that has to be tied into proper cam events and induction design. Often times space contraints and other factors limit design so us street guys never fully develop our combos potentials like they can with say a nascar or prostock level lol

i agree the vortec is an awesome factory head and with some mild work can really make power for an iron head. But test above id what I have been saying, superior port design with good chambers and increased flow will take over at typical 3000-6000+ rpm street ranges. Wot under 2500-3000 shouldnt ever occur with proper torque converter. Drivability and part throttle situations usually arent affected too much if the port is good with proper velocity gradients and such as long as cam isnt huge. Efi well tuned combos do better here than carb situations so thats one reason i feel you can get away with larger heads. They arent relying on carb signal. I see this with lsx setups. They have good intakes and heads and a larger cam makes big numbers over stock cam but still retain good drivability and power.

 

Certainly the Vortec's strength.

And this would be their weakness. In stock form anyway. My aftermarket version has a similar characteristic albeit at higher lift and greater CFM.

True enough. I suppose it's the definition of "mild" that comes into play here. The 355 and 236@.050" took full advantage of the 195 Eliminators. And then there are the few that have great drag strip results with Vortecs on 383-406 CID. Admittedly, the 406 "cleaned up" the ports a little. From our discussions here, the cam events play into the effectiveness of the small head in a big way.

For the record, define "larger cam". Is this in terms of overlap? As for carb signal, you need two things. The right carburetor and tuning skills. Most only touch on the surface when it comes to setting the old mixer up effectively. Similarly, a lot of the entry level carbs don't have a great deal of adjustment.

 

Larger cam as in more duration more lift. Naturally overlap increases over stock due to these parameters

efi sequential injection on those late models control each cylinder fuel and timing to levels carbs can not. Theres more potential there for driability. But i am sure a good carb guy can do well

 

I'll certainly give the nod to EFI on that very precise ability. Cylinder to cylinder tuning capability is certainly beyond the reach of my old school setup.
As for the overlap, the one thing I've observed with the LS crew, is the wider LSA that's typically used and the resulting lack of overlap. It's only the super hot variety that trend toward the tighter LSA and use that intake open/exhaust open as a tuning tool. At least from casual observations anyway.

 

Most stock bottom end deals dont have the piston to valve clearance to run tighter but i dont think they neeed overlap. The better the head and higher rpm you run the less overlap you need it seems and wider the lsa becomes.

think prostock. Short duration very high lift for fast valve motion and wide lsa. Ls can do this better than sbc because the cam core is much larger and valvetrain is much lighter plus valve angle makes for a better head that can tolerate higher velocity in the ports since they dont have to turn as sharp

 

Plus their exhaust flow is generally superior to SBC. All in all a much more efficient head design.

 

Unless you are trying to build low-end torque. A 5.7 Vortec puts down more torque than a LY6 6.0L with VVT under about 4,000 rpm. Comparing the dyno chart of two Kodiak marine engines head to head. Then again a set of stock 862 5.3 heads ported and cut for a 2.00" intake valve on a LY6 with VVT would probably exceed the torque of a Vortec 5.7L but require premium fuel to do it.

I studied lots of LS builds and small block builds before deciding to build the 383. At the time I had the heads for the 383 built they were going on a 4.125" bore.

 

what dyno test was that? Seems surprising but the ly6 wasnt as strong as the 6.2 that replaced it with the same heads. The slighly bigger bore and newer truck manifold really helped that setup breathe And made awesome power.

I couldn’t keep mine from downshifting below 4200 but it was already making 368 lbft stock there and had way more below that rpm i could tell. It was stock 6.2 truck with just a tune

 

So I was off a little, looking back. I last looked at this info more than a year ago. 350 was stronger under 3,000 rpm, not to 4,000 but given that it has a shorter stroke and less displacement and lacks VVT that is still impressive. The 350 is also making its grunt with a shorter runner intake, stock Vortec heads and a 196/206 @ 0.050 cam.

I also looked at the direct injected 5.3 and 6.2 as a possible replacement for the 350. In the end I built the 383 because it is capable of more torque than even the DI 6.2L down lower in the RPM curve. The more torque I make in the 2,500-3,000 rpm range the less I have to downshift pulling a trailer. If I had more budget to my build it would have been a 4.125" bore Dart SHP block and 414 cubes. In all honesty that 414 may come later. I like torque. The 383 in the head comparison above is killing a LY6 in power and torque. If the 350 Vortec had been treated to some Etec170s and a set of 1.7 rocker arms or a small cam upgrade, it would probably equal the LY6 in power without hurting the torque production.

 

I am curious how the 11:1 383 with 210 cranking will like being loaded down at 2500 rpm lol. Definitely interesting

 

Me too.
I've discussed this before with Fast and I think it's a matter of timing control. I couldn't quite get it with the old school tech and 10.2-10.4:1 (iron heads) as it would rattle at cruise speeds when just tipping into the throttle. Still high manifold vacuum advance, enough RPM to have the centrifugal timing well advanced and a steep initial setting added up to a lot. Didn't help that I tuned it for lean cruise either. I can't speak for 11:1 but if I had pulled timing out at the appropriate places. which is a pain with vacuum cans, limiting plates, distributor bushings, weights and springs, and maybe fattened up the AFR via the air bleeds (which isn't too bad), I could have pulled it off. Hoping too that I didn't kill WOT from a standing start. It may well be this is what contributed to the engine's current state (and that's unhealthy).

 

Its just that prolonged pulls like towing a trailer will continue to generate heat and pulling timing is only gonna do so much. May also have to richen it up. Its not like a drag pull where you sweeep thru the rpm range quickly.

it likely can be done just might take some more advanced electronics and efi management.

never built a tow rig but i did tune a 454 k3500 once. Its amazing how low the timing is in those things at heavy load areas of the map.

 

That is where modern EFI controllers have an edge. The Catalyst Overheat/Piston protect mode kicks in over time and richens the mixture at a progressive rate. You can set how much it richens the mixture and at what rate. There is also a timing table that can add or subtract timing with the commanded air/fuel ratio that has RPM as a reference. When you are pulling hard you can progressively richen the mixture and pull the timing back.

Tuned my buddies 98 K3500 crew cab dually as well. The 454 Vortec is pretty knock prone and really likes EGR under load.

 

Already been to Durango Colorado and back to Fort Worth, Texas with this cam and the cross ram marine intake pulling the travel trailer. My iron head 9.6:1 350 was more detonation prone. Especially burst knock under load.

 

I think a smog era vacuum advance would have helped you. Those pulled about 20° of vacuum advance but waited until the engine had very high vacuum to advance the timing. They were fully retarded under about 8-10 in/hg. On my test run I had the initial timing set at 4° with 22° of mechanical advance and left the stock springs that do not achieve full advance until about 4,600 rpm. I used the stock 20° vacuum advance unit as well that did not advance the timing until 9 in/hg vacuum. I think that setup would work very well on the street.

 

See, for me, that tiny 7lb/ft deficit is well worth the gains the LY6 had from 3500-5000.

 

I'm using an adjustable vacuum can for the onset point which is set just below my idle vacuum. I idle around 10", it's all in at 8. Also using Crane's adjustable limiting plate. I can get up to 20° IIRC and have it set to 16°. That gives a total idle timing of 28-30°. Centrifugal was a little lazy and had 19° at 3500.
Going off memory, I'm thinking at 75 MPH and 2500 RPM total advance available was 45°. 12-14 initial, 16 vacuum and a portion of the mechanical, maybe another 15°. Rolling into the throttle wouldn't drop the vacuum very much so I was dealing with a lot of spark lead at relatively low engine RPMs and light load. I could hear a faint rattle if I got alongside the guardrail and listened. WOT was excellent though. Never got around to tuning that cruise issue out as the build went in a different direction.
At little off topic but it's good to get some feedback now and again.
Thanks Fired.

 

That was a stock 300 hp 350 compared to a LY6. Basically no gains from having a LY6 in the RPm range I wanted to run in. Now look at the 383 in the head comparison above. Very typical to make 480+ TQ from a 383.

 

Not really off topic, seems pretty pertinent concerning head selection to know what effect compression ratio and head material on your future tuning. It's all good and appreciated.

 

Holdener's tests have been getting a bit of attention lately. Like or dislike aside, the test does point out some interesting aspects to my original question. Might be useful to anyone searching in the future too.

 

I've been reading Holdener's stuff for over twenty years although his videos are something newer to me. I was surprised to see his name on the Hot Rod magazine masthead from copies in the 90's.
In as much as I like the data he collects and shares, some pertinent information is still lacking. As an example, while in the video above he talks about port volume vs torque and power production and how the larger head doesn't hurt the lower engine speed output, what he doesn't include are the flow values at various lifts with respect to each cylinder head. If the 180 head flows less at the target lift points than the 195, then it's going to make more power across the board. Therein lies the rub.
As reflected to an answer to I had on Speed Talk on this very subject, Vizard stated that, as in the example I provided comparing the Vortec to the AFR 195 Eliminator, the smaller head would win the low speed torque contest but ultimately lose out to the superior airflow of the AFR's.
I wish Holdener had a more complete data base to check out. Still enjoy his videos just the same.

 

I was wanting flow numbers for each head as well. I think the tests mostly showed which head was best for each individual combo. None of them didn't have enough or too much so I don't think the spread of port volume comparison is wide enough to show the affects. But what it does show is the most common displacements with the most common head choices available aren't going to sacrifice slow speed power in any significant way. As it's pointed out by comments here with the Fastburns 210cc on 350's or 200cc on 5.3's and tiny stock cams. Reguardless of what I knew before, I learned a lot as well.
Now if the port gets too large and there isn't enough motor for it then yeah, I'd imagine it could get detrimental. I recall an anecdote from long ago of Pontiac making the experimental OHC V8's and one had ports so large that it didn't make power till hitting almost 7000rpm. While completely a story that isn't substantiated, it is a fun one. Also points out that Pontiac was the excitement division, how many others had OHC development at the time?

 

372” sbc
dart 180 as cast
.250”. 149/137
.300” 183/159
.400” 232/180
.500” 255/188
.600” 252/193

dart 215cc cnc
.250” 155/132
.300” 181/149
.400”. 226/178
.500”. 257/192
.600”. 271/198

flow similar til higher lifts. Slight edge to exhaust side on the smaller at low lifts.Not surprised they may similar power across the board til higher rpm. Below 3000 rpm bigger head made more. Also not surprising with as much cam that thing had. 242/250 deg is big imo

low lift flow vs port size can be misleading at times

 

You bet. I wouldn't have guessed (and it would be a guess with the Darts) that the larger port would outflow the smaller version by almost 4% at .250". It goes to show what CNC "porting" can do. Or maybe how weak the as cast 180's are.
I wonder how they stack in the .050"-.200" range. That's where that Vortec/AFR discussion centred around.
And as Holdener mused, what of part throttle performance? Not, it seems, that anybody really cares.

 

Most of that fits the general concensus that we've gotten from the LS world. Bigger heads are what you could buy into. Displacement + Big Head + milder cam = lots of power/streetability.


You won't notice 5-10lb/ft down from 2500-say 4500rpm. You spend almost NO time there once you really want to go. I know that on my car that getting the engine past 4000rpm in 1st, 2nd, and most of 3rd is an afterthought. When I want to go I drop down a gear and am sitting at 4000rpm to start.

Even then, there is plenty of usable/comfortable power available from 2500-3500rpm. Significantly more than I'll ever use in part throttle driving.

All that video does is confirm that what I really wanted was the 383 combo with AFR 227cc heads and pretty much the same cam I have now.

 

That begs the question, how do you test that? Put it in a vehicle and drive it around?
What's the telltale sign of drivability? Vacuum at part throttle?
And by all means, if you only have quarter or half throttle then that's the limiting factor. Does that mean the air volume would stagnate in the head port? More questions to seek myself some answers.

 

Orr, where did you get those numbers from. The 215 numbers look in line with what I've seen for the standard (non-cnc) 215 Pro 1s.

One of the problems I see is that he says they're 210cc CNC ported Dart heads, maybe a snafu with him being a Ford guy, but the smallest Pro1 CNC Dart offers that I know of is the 227cc CNC head - unless he got them from someone else. He also selects "Final CNC 22 12" for bigger head. Another issue, probably related to the question of "what head is it really " is based on the time stamp for the SBC tests, they were done in early 2013, seven years ago. I'm not sure the info he has on the drop downs is enough for him to remember it with all the tests he's done.

 

Larry meaux posted the 215’s on speedtalk but they are old from like 2005 or so. But darts site still claims 276 cfm at .700”. You are right i dont think they are cnc. I figured he said 210 cc cuz the ford heads were 210 cc

the 180’s i got from a member on speedtalk, posted them last yr

 

Can anyone elaborate a little more on this? I'm in the process myself of putting my combo back together and will be running AFR 195 eliminators and have the old 1 3/4" SLP shorties myself...I have been heavily considering just finally giving in and buying Doug's LT's and dealing with the logistical issues.

On the AFR heads part, I would say mine flowed WAY more than what they claim and all I did was a full competition valve job, so there's quite a bit of potential if you decide to go that route. Also on the AFR's, be careful because AFR clearly states to use a Flat/Gasket seat style spark plug. Now, try finding a flat/gasket style spark plug, 5/8" hex end in a 14mm diameter and you truly have found the needle in the haystack as no one makes one (hence again the consideration to try a LT header....)

 

this is the most popular plug spec available. .750” reach. 14mm thread. 5/8 wrench

ngk has a bunch from hot heat range 4 to cold heat 10. Down to 8 with a resistor

i never used slp but did use dyno dons which were suppose to be similar and didnt have any issues with L98 angle plugs

 

I have the Hooker 2210 long tubes on my GTA with the AFR angled plugs setup. Can change all the plugs no issue, nothing fancy.

My Hooker 2055 shorty on the other hand? Holy crap in a hand basket. That was insanely difficult, zero room for any tools back there.

 

*Shorty* plug sir, please see above post. Shorty meaning LESS than a reach of .75"

It's tough cause they're not out there, at least not all the searching, cross referencing & catalog searching I did... maybe you know of one?

 

I searched for a while and came across an answer from somebody who'd be most likely to be correct, Dyno Don.

 

Fired, that is Excellent info! Thanks for sharing as I knew I couldn't be the only one still have those headers kicking around while putting together a top end with angle 1040 AFR's

 

well you didnt say shorty style lol. And shorter doesnt mean the reach changes. Its the length of the plug itself

accell is the only company i seen make them and i dont know what heat range they were

 

That's correct 👍 however searching summit as a one stop shop I didn't see an option for searching for a shorter plug by any criteria other than a reach length shorter than the common .750"

Yeah I'm just not crazy about accell stuff

 

Yeah me either. But what else can u do? Switch heads switch headers?

 

Put a dent or rather dimple in that primary. Engine Masters has proven it makes NO difference in power. In fact they gained 1 hp after bashing the crap out of the headers.

 

I guess it depends on how much a dent is needed if you can do it or not. Idk how the pipes run on slp’s with regular angle plug heads. If it just needs 1/4” or so dent go for it. If it runs right thru the plug and needs like a 1/2”+ idk if you can do that much, thats alot of material to move lol. Do what you gotta do, def not too worried about the hp losses

 

Looks like I'll be upgrading after years of running the SLP 1 3/4". Doug's LT's is most likely the route I'll be going. The spark plug boot clearance issue and the fact that the AFR exhaust ports won't work with the old SLP's makes the decision to finally move to LT's on the 3rd gen a bit easier.

 

This is the potential for the AFR Eliminator's that I personally worked on and saw myself on the flowbench...

Stock (no valve job, no milling, stock CNC'd ports, stock 2.050" intake valve)

.200".....137 cfm
.300.....197
.400.....246
.500.....284
.600.....288
.650.....287

After comp valve job-untouched valves (prob something more to be gained by running them through the valve grinder for sure but these are the numbers regardless)

.200.....177
.300.....236
.400.....285
.500.....313
.550.....323
.600.....332
.650.....338
.700.....342
.750.....343
.800.....338
.850.....334

Somewhere in between .750" and .800" flow peaked @ 346 cfm

My particular combo won't even come close to the full potential these heads have but its good to know that I have that room to grow...problem is that ya gotta have the $$$ for a valvetrain that'll support it

 

Im sorry to say i do not believe those numbers for the 195 heads with just a valve job

 

I also have trouble believing that a valve job could gain that much.

the cnc race port versions don’t come close to that.