Hey all,
I've done a bit of searching and learned quite a bit, but still have some questions. For starters, I'm buying a 383 stroker that Summit made:

3.75" stroke crank, Kieth Black hypereutectic pistons, Crane hydraulic camshaft ( 276/284 duration,.488/.509 lift ) cam already degreed in. Fluidamper harmonic balancer Summit true roller timing chain, clevite main,rod and cam bearings, high volume oil pump and a summit black oilpan. 450 hp @ 5750 rpm 445 ft.lbs. of torque@ 4750 rpm ( those # are generated with trick flow twisted wedge aluminum heads.)

Now, I have to go on record and say this: I'm not familiar with engines! I'm not concerned about high end power, it's not going in a car, and to be honest, I'd be just thrilled to have 300 HP and 400 lb./ft of torque. Now my questions:
1) Is .509 too much lift for Vortec heads? (I'm thinking a milder cam may be in order)
2) What thickness head gasket so I can run on pump gas?
3) What benefit, if any, will I get from the larger valves?
4) I plan on upgrading throttle body and injectors, but to what? (I have a ported upper TPI plenum and will use the SD lower intake.)

Any other information would be really appreciated! This is my first time 'assembling' a setup, so I'm trying to learn as much as possible.

Thanks in advance!
Bryan

 

I'd up in 24 psi injectors. You don't want to go too big because you won't get a good spray pattern. You should be good with a 52 mm throttle body. The cam is fine for those heads, and lastly for the gasket thickness. What is the compression rated at?

 

1. .509" lift is too much for out-of-the-box Vortec heads. The retainers may hit the valve guides. It is also too much for the springs. Always remember when dealing with those heads, they are not performance heads, regardless of the flow numbers; they're replacement truck service parts. Trucks don't come from teh factory with a bunch of hot-rod stuff like big cams and valve springs to match, or undercut valves, or screw-in studs, or any of that sort of thing. You should stay below about .480", unless either you are willing to spend money on machine work (thereby destroying the whole economic basis for the attractiveness of htose heads in the first place), or you are buying the worked over ones from SDPC that cost about as much as Sportsman 2s.

2. That depends on what pistons you've got. If this thing is being built with flat tops, you're already hosed, because the CR will come out at about 10.8:1. With typical dish pistons (12.5cc or thereabouts) you'll still end up at about 10:1 with standard FelPro composition gaskets.

3. If you spend enough money to actually do that kind of machine work, you will exceed the price of buying a set of actual good heads, and you'll still have replacement truck heads, just with big valves in them.

4. If you change injectors, you'll have to do some chip work. 24# ones are probebly going to be all you'll need in any case, with the stock LTRs, you'll never get enough air through there to need more fuel than those will deliver.

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"So many Mustangs, so little time..."
ICON Motorsports

 

To some poeple Vortecs are "replacement truck parts", to others these are performance parts. I added +.050 valve locks for $30 so I could run a .520" cam, and am still way under what a set of aftermarket heads go for. These may be truck heads, and I agree, GM didn't manufacture these for the auto performance market, but does that mean we shouldn't use them in a performance application? GM also didn't mean for the third gen to beat a comparable year vette, but does that mean we can't do it ourselves? My point is, Vortec heads are good for performance to 400hp. People who don't like them, have their reasons, be it that they want more performance, don't like "truck heads" on their car, or it could be that they spent $1k on aftermarket heads to find out later the Vortecs would give the same performance for $600. In my particular case, with the machine work, locks, springs, undercut valves, porting, studs, and even rocker arms, I have $500 in these. And yes, I got a great deal on 2 350's one of which had the Vortecs on them. If you don't like them fine. But maybe the good info should be posted with the bad.



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Joshua Johnston
1991 Z-28
350, T-5, K&N, Ported Vortec heads, Edelbrock RPM, Holley 750 D.P., HEI, 11.07:1 CR, Comp Cams Roller-.510"/.520"-282*/288* dur., Shorty Headers, Dual 2.5 Exhaust, Dynomax Bullet Mufflers, T&R Motorsports custom air intake, Bald tires

 

Thanks for all the tips!

OK, so far I'm thinking I should tone the cam down a bit - such a high duration puts my power at a higher RPM, not good for my purpose. Is a roller cam the only way to get a higher lift with a shorter duration? Say to the .480"s with a 205 degree duration?

I don't want to run out and get lots of work done on the Vortec heads, I agree with that sentiment. I am also not looking to increase air intake volume so much that the velocity suffers.

I'm looking into the pistons, so I guess further questions are moot until that's known. I estimate that it'll be at 10:1 with the 64cc heads, just on what I've read, so I'm thinking the use of a 0.041" head gasket would bring me low enough to be happy.

Is chip work really necessary? Not that I'm against it, but I thought the reason for the higher flow injector upgrade was so the pulse width could stay the same, or at least within the parameters of the TPI. Would that require a fuel pressure regulator change, as well?

Thanks for all the tips, keep them coming!

Bryan

 

one thing is you're gonna spend money on the sdpc vortec base(399.95)the money you are gonna spend on the intake for a mild application use the stock components and have them extrude honed.the accel lpe cam 211/219 is a good street cam and will make a truck load of tourqe.as for the heads the 400 you'll spend on the vortecs you can find used aluminium l98's whch flow better when ported and aren't limited in spring size.

 

Their nature doesn't mean you "shouldn't" use them in a performance application; it does mean, however, that you should understand what they are, and what they aren't, and let the facts guide you accordingly.

What they are, is an excellent flowing casting, with absolutely nothing else "performance" about them. So let's think for a minute about what you might do to a set of heads:

• Machine for screw-in studs - $75
• Machine for valve springs larger than 1.25" - $60
• Machine valve guides down to allow clearance for greater than .480" lift, and to allow the use of Teflon seals - $80
• Quality 1.45" springs - $90
• Quality valves such as Comp, Manley, Lunati, etc. - $220
• Rocker studs themselves, from ARP or similar - $100

So what have we spent so far... $635. Now add that to the price of the heads themselves, you discover you have just put $1035 of heads on your car, and you still have stock cast-iron heads.

Compare that to aftermarket heads.... Edelbrock Perf RPM at $1100, Dart Iron Eagles at $1000, World Prod Sportsman 2s at $800, Trick flow at $975; every one of those already has all the perforance stuff done to themand is in the same basic state as the Vortecs above (ready to port and assemble), and will outflow the Vortecs, for about the same or less money. None of those requires the special Vortec intake, which you might or might not want some one of hte very limited choices available. You have just used your own money as the most potent weapon in your arsenal, to defeat yourself.

The way to get the value out of the Vortecs is to build the motor that they "want" built around them. What seems to "max them out" in terms of their out-of-the-box capabilities is a Comp XE268 cam (.480" lift), 1.5 rockers, flat-top 350 pistons, and a Performer RPM intake. That combination allows you to basically bolt them on as they come, with no machine work beyond whatever port work you choose to do to them (can be free, or at least very cheap). If you try to use them to get more than that motor or its equivalent in other brands out of them, you will lose their biggest single advantage: low cost.

I have no knowledge of the SDPC intake for TPI, that is, whether it's a cost-effective upgrade or not; all I'm speaking to is the guts of the motor itself. By reasonable cost/benefit analysis, the combo that started this post off is a mistake.

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"So many Mustangs, so little time..."
ICON Motorsports

 

RB,
I understand your point. If I were to build another engine, I would use aftermarket heads for the sole reason, that I would be use to the power I have, and would want more. The Vortecs are limited in the amount of power they can produce. But out of the box, with no costly mods at all, you can have 400hp. If you are after more, then yes, I would suggest going with different heads. You did mention something that I didn't think of, the Vortec intake. If you choose Vortecs, then later want different heads, you need a new intake too, unless you use the Fast Burn, or E-Tec heads, both of which, I would not choose. Just for clarification, this is what I paid:
Machine for studs--$80
ARP studs--$33
Elgin Valves--$120
Crane offset locks--$32
H-11 springs (Comp, Crane???)-$79

Because of the offset locks, I didn't need to machine down the guide, even with seals I have .580 clearance.
And like you said, for a 383, the Vortecs are not the best choice by far. They only have a 171cc intake. I believe you would need bigger.



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Joshua Johnston
1991 Z-28
350, T-5, K&N, Ported Vortec heads, Edelbrock RPM, Holley 750 D.P., HEI, 11.07:1 CR, Comp Cams Roller-.510"/.520"-282*/288* dur., Shorty Headers, Dual 2.5 Exhaust, Dynomax Bullet Mufflers, T&R Motorsports custom air intake, Bald tires

 

Umm,The intake port of the LT-4, the ex. of the L-98 alum., the combustion chamber of the super fast burn and these are not performance heads stuck on a truck motor?
Did you ever check the flow specs on a set of Sportsman II's Intake=225cfm the ex. 152cfm and this w/2.02 & 1.60 valves.
I think I'll keep my "truck heads".
Oh, and no flame intended.
Don>>>

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Chronologically challenged. But still kicking!
'92 CAMARO RS
305 TBI 5/spd (now TPI)
B4C Alt.
Cam change:TRW 198/210 ,450/.460 114 LSA
Stock TBI manifolds
'85 IROC Ex.
14.94-92.00 mph
SPDC base and "350" Vortec coming soon!
'69 camaro-BB/Lenco,1050 dominators, /Pump Gas/no drugs 8.97-150+/3200lbs.
SoCal Thirdgen F-Bodies

 

Forgot the quote:
And the link about the springs: https://www.thirdgen.org/messgboard/...ML/004968.html




[This message has been edited by Dyno Don (edited October 27, 2001).]

 

I just called a few local speed shops and so far I'm going to spend about $200 in screw in studs and machine work for larger springs and more lift. Then the LT4 springs from SDPC are like $32!
My friend has a sticker, it says something like "Keer your GM car all GM" suposidly it was a stock sticker from way back when. Vortec heads, LT4 springs and an hot cam will push these GM vortec heads WELL into the 400+hp range and still be all GM. The only problem with vortec heads is I've heard they have thin walls and something about them cracking.
Heck, for the price...I don't see why people don't keep their cars all GM! Take off parts are cheap, new parts are just as cheap and yet everybody looks to an aftermarket company to do all the research for them and then sell the same quality product for hundreds more....go figure
Personally I think teflon seals are crap. No need for them especially if it's a street machine. Some things are overkill and I think if you can afford the aftermarket heads...go ahead and do it, I'll still be just as fast and have spent less
No flames, this is my opinion, not all fact

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, Jon (350 TBI!)
91 Red My website

 

Thanks a lot guys, this is great stuff!

Would a cam like this be suitable for the Vortec heads:

Part #. 12-207-2
RPM Range 1200-5500
Adv. Dur. 255/261
Dur. @ .050 203/212
Lift w/1.5 .421/.451
Lobe Sep. 110

Sounds like I'd keep my TPI and heads happy and still get power lower, where I need it. I know I'm taming the motor down, but...

Edit: Would the LT1 heads let me bolt on my current TPI lower manifold? Will LT1 heads have even smaller combustion chambers?


Bryan



[This message has been edited by Oxjockey2 (edited October 28, 2001).]

 

So it looks like picking the right head will be more important than anything else. I'd like to get a lower duration cam, fine, but I need a higher CC head that will accept my TPI - larger valves would be nice. Where should I start to look for such a head?

To get more than, say, 0.475" lift out of a cam with a short duration (212 duration), would I need a roller cam? I need to keep the computer happy and the EPA, I guess. =)

Thanks a lot guys!
Bryan

 

Well, you seem to want to keep the engine low key. So I think the Vortecs would be okay. Whether it is cost effective for you or not is purely your decision to make. That cam you listed the specs for would work fine.



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Joshua Johnston
1991 Z-28
350, T-5, K&N, Ported Vortec heads, Edelbrock RPM, Holley 750 D.P., HEI, 11.07:1 CR, Comp Cams Roller-.510"/.520"-282*/288* dur., Shorty Headers, Dual 2.5 Exhaust, Dynomax Bullet Mufflers, T&R Motorsports custom air intake, Bald tires