I know nothing about vortec heads. I have 11:1 pistons and my heads have 76cc combustion chambers. My compression is around 9.6:1 I have an Elgin cam. It is a copy of the 60's 327/350Hp cam. I have a Motorville Performance intake (looks just like a Performer RPM). I have a 750 Holley, brand new, just putting it on tomorrow actually. Model # Model 4160. It may be a little much for my motor, but my engine guy and i will just jet it down if it is. Can i get a set of Vortec heads that will leave my compression pump gas worthy (91-93 octane)? Will the power and efficiancy increase be worth the money and time? If i get these heads, will i need a new intake? If these heads wouldn't work out, are there any heads that will work with my current setup that help out in the power department? Thanx Rabbitt

I iknow for sure you'll need a new intake. The Vortec ports don't line up on a "standard" SBC intake. That's why all the TPI guys have to go to Scoggins-Dickey for an intake if they switch to Vortec heads. Edlebrock may be making one now, but I'm not sure on that.

I thought Edelbrock made the base plate for SD, but, Vern, you might be right.

Anyway, Vern's right about the SD base plate, although Chevrolet also sells an intake that will work with the Vortec heads. Check out GM's Performance Parts catalog for the p/n.

mmk. I just looked up the intake, Edelbrock Performer RPM Vortec. That answers that question
thanx
Rabbitt

No ones touched on the fact that Vortecs come with 64cc chambers. You're compression, should you choose to keep your pistons, will be to high for pump gas.

"11:1 pistons" - I love it when people say that.

Unless you know the chamber volume, deck height, and gasket volume, you can't say what compression a piston is going to produce. If it's 11:1 with 58cc chambers, zero deck height, and shim head gasket, you might be able to live with 64cc chambers, .015" deck height, and .030" or so gasket with pump gas.

As far as whether or not they are worth it, that depends on what you want to get out of th engine.

But I'm with five7. Compression ratio in itself is the ratio of total volume to compressed volume. The pistons in themselves do not determine the compression ratio. Rather, tell us that you have flat top pistons with x.x'cc valve reliefs, dished, or even domed pistons with -cc's. Then you're on the right track.

Very true. I'm assuming Rabbit has pop-ups. Is that a safe assumption, Rabbit?

I hear ya Five 7...that falls into the same category as "high rise manifold" and "full race cam".

OMG... i spent about 45 minutes typing this long post.. pushed submit and all of a sudden its gone.. i'll summerize

I dont know my exact piston size, i can get it from my engine specialist when i get a chance. They ARE dome pistons. With 64cc heads my compression will be 11:1 - thats what my dad knew. He and my engine specialist built the engine for me.

My engine, as it sits, puts out somewhere between 320-350hp. It wasn't giving me that amount of power since i broke it in but my crappy, barely working carter carb, air cleaner, and exhaust(came with car- 1.5" primary 2.5" collector headers, 2" cat delete pipe, 2.5 in stock exhaust) are terrible. I bought a 14x3" K&N X-Stream air filter set, a new holley 750cfm carb and in gonna buy Hooker 2640 headers from ACS (whenever they get back to me) and a Hooker 3" cat-back exhaust system from Summit this weekend. I hope to be pulling what i am supposed to (by what my engine specialist tells me) with those changes. I want to get up to an honest 400hp and keep it very streetable, if that is possible.

I wasn't planning on changing my pistons, but i would like to get a set of good flowing heads to improve power by a good margin and to improve fuel economy if possible. I get about 20mpg right now, and after changes and a hopeful 400hp, i would like to have around 15mpg if at all possible. Power comes before economy, tho.

Are there a good set of heads and maybe a cam if this one isn't aggressive enough that will work with the rest of my setup and get me more near my 400hp goal? And keep me streetable?

If not and my pistons are not usable for what i want, what should i do?

Thanx for all the help!
Rabbitt

OMG... i spent about 45 minutes typing this long post.. pushed submit and all of a sudden its gone.. i'll summerize

I dont know my exact piston size, i can get it from my engine specialist when i get a chance. They ARE dome pistons. With 64cc heads my compression will be 11:1 - thats what my dad knew. He and my engine specialist built the engine for me.

My engine, as it sits, puts out somewhere between 320-350hp. It wasn't giving me that amount of power since i broke it in but my crappy, barely working carter carb, air cleaner, and exhaust(came with car- 1.5" primary 2.5" collector headers, 2" cat delete pipe, 2.5 in stock exhaust) are terrible. I bought a 14x3" K&N X-Stream air filter set, a new holley 750cfm carb and in gonna buy Hooker 2640 headers from ACS (whenever they get back to me) and a Hooker 3" cat-back exhaust system from Summit this weekend. I hope to be pulling what i am supposed to (by what my engine specialist tells me) with those changes. I want to get up to an honest 400hp and keep it very streetable, it that is possible.

I wasn't planning on changing my pistons, but i would like to get a set of good flowing heads to improve power by a good margin and to improve fuel economy if possible. I get about 20mpg right now, and after changes and a hopeful 400hp, i would like to have around 15mpg if at all possible. Power comes before economy, tho.

Are there a good set of heads and maybe a cam if this one isn't aggressive enough that will work with the rest of my setup and get me more near my 400hp goal? And keep me streetable?

And if not, and my pistons and suitable for what i want, what should i do?

Thanx for all the help!
Rabbitt

with the 327/350 cam and 76cc heads, i would almost be surprised to see 350hp.

What ljnowell is telling you is there is big advancements in cam technology since that 327/350 cam was produced. There are a many people on this site producing 385 to 400 hp with the newer generation Comp Cams Extreme Energy Series, Crane Powermaster, or even the GM Hot Cam combined with Vortec, AFR, Protopline (etc) heads and Edelbrock RPM intakes. Your goal is very realistic. Search the site for other proven combos.

You are talking about flow, right? As in, the 76cc heads wouldn't flow very good, right? Because, compression-wise, what is the the difference between flat-tops and small compression chambers and dome and large compression chambers, as long as the compression equals out to be the same?

With that 151 cam and that awful combo of domed pistons and smogger heads, I'd be surprised to see over 300 HP. People have been building that combo since the mid 70s, and it hasn't worked for anybody yet; I can't count how many people I have seen do that exact thing, part # for part #, and get nothing but disappointment every time. I bet I knew at least 5 people in the late 70s and early 80s that built that exact motor: 882 heads, TRW pistons, 151 cam. They would put a Torker 2 intake on theirs, and a 1850 or 3310 carb. And it would turn out to be a dog.

Vortec heads are reputed to have chambers on the small side of their 64cc rating. People who have measured a few say they're usually around 62cc. If you have the pistons I think you have, i.e. the ones that have about a .125" dome and the half valve reliefs (ends up about 7cc dome volume or so), and a stock deck height (.025") block, and a .039" head gasket, your CR will be a hair under 11:1 with 64cc heads; and just a hair over 11.6:1 with 62cc heads. If on the other hand you had your block decked to your pistons, your actual CR will be just over 12:1 with 64cc heads, and over 12½:1 with 62cc heads. And that's with a normal thick head gasket. Basically, looks to me like, unless this is a strip-only car that you can put race gas in, those pistons need to go away.

The Vortec heads have all this killer intake flow, and typical weenie stock head exhaust flow. As a result, they respond hugely to a cam with a bigger exhaust lobe than intake. You'll pick up alot of power with them, at least 50 HP and probably more, if you change it to a Comp XE268 at the same time as you put more suitable pistons in it.

For pistons, the TRW flat-tops would be fine; L2256F in whatever your overbore is. A block with the stock deck, regular .039" head gaskets, and Vortec heads, will give you between 9½:1 and 9¾:1 CR; that XE cam, or maybe the next bigger one (XE274), a Performer RPM, and a Holley carb, will make a far better motor than what you've got now.

so.. if i got a more advanced crane cam (after research of course) i would be better off? Kinda sux, just paid for the cam, but if it isn't worth it..

Are my pistons useless to me? i really dont want to have to tear the entire engine down and buy new pistons.. but if there aren't good enough heads that will go with dome pistons and leave me within pump gas range....

Problem is, your pistons will give WAY TOO MUCH compression for street use with better heads.

The problem with the dome/smogger combo, is that the combustion chamber ends up being this weird shape, that doesn't burn worth a crap. That's why that combo is always down on power compared to a flat-top/med chamber or a dish/small chamber combo.

That cam has simply got to go, if you want any real power. It's just a total dog. If I had one, I'd throw it in the trash (oh wait... I don't have one, because I already threw the last one I had in the trash) and maybe throw in a quarter behind it just to pay it to stay in there.

Your whole combo is just one of those things that looks good on paper, but doesn't run.

In fact, I'd almost bet money, that if this is in a normal weight street car, it runs high 14s at best.

The combo I gave you, for comparison, is a known proven deep 12s combo. There's several people on these boards running it, getting times from 12.5 to 12.8 out of licensed cars.

Crane, Comp, Lunati, Crower, all have decent cams for the application at hand. The Comp ones I mentioned are the most popular for going with those heads. The XE268 is the one you see in all the magazines being dyno'ed at 400-425 HP.

well just f*cking wonderful. I just spent that ****ing money.. ugh, that's what i get for going to a race specialist for a street motor.

so thats, what, 150-200 for pistons, 150 for the cam, and about 450 for the heads, plus whatever dressup there is?

Is there no way to make dome pistons work for street and get what i want? Cause i know if i want to change the pistons, im gonna be on my own cause my dad and the specialist will just be pissy and not help me... and i have never done such a thing. If i have to, i may just hvae to wait til next summer to do it all.

70+cc aluminum heads.

For instance, http://www.primediapowerpages.com/cg...0216&2D1007262

would i run into the problem that RB83L69 said about the combustion chamber not burning correctly because of the odd shape?

would i run into the problem that RB83L69 said about the combustion chamber not burning correctly because of the odd shape? Or would i be able to put those heads on and change my cam and gain a load of power?

Well, it's kind of hard to reach back into the past and un-spend money; so instead, let's look at what your current combo lacks and what you want to get out of it instead; rather than jumping to "Is it a good idea to put on Vortec heads".

Not to be mean to your dad or whoever built your motor; but they both sound like they were hotrodders 20 years ago that probably built their cars just like that back then, never got them to run right at the time, haven't really done anything of the kind since, and they want to sort of pick up where they left off.

So, what does your current setup do that you don't want, or not do that you want it to? In other words, why, after "spending all that money", are you looking at making major changes to it?

Well, the specialist makes a good living by building race engines.. I've been in cars with motor's that he has built, and they pull 12s or less constantly. Now, my dad and the guy built my motor down for me to get used to the v8 power and then i would upgrade the heads and cam later.


It really doesn't seem to have the low end torque that i would expect, tho it does have a really crappy carb, bad filter, and really restrictive exhaust. After i get past 45mph, it really throws me back into my seat. I also have a 2.73 rearend, open too. I dont know much about rearend, i dont know much of a different throwing 3.55's or 3.73's back there would do with an eaton posi unit (thats the plan this winter).

I want to get around 400Hp (380hp would be fine) I just want to be able to do it with heads(with porting) and a cam change and hope to be able to get near my goal and have the response i want.

Rabbitt

For your combo to run high 14's at best thats implying the car barely makes 200 horse power in a thirdgen. Does that seem realistic, no. Your not driving a 4000lb chevelle, my cars 3000lbs dry.

Stop freaking out and being scared, the tone of your posts make it sound like the engine wont even run with with a dome piston/76cc combo. Yes it will run, yes if you get the right head it will be satisfactory, no it will NOT be optimum. Its a street car, can your wallet handle making it perfect?

Find some 70+ cc heads that flow well, stick with what you have (get the combo working properly!!) and try it. You'll probably be suprised with the results. Especially if you had a bad exhaust and broken carb.

Whats the harm. If your not happy with it then modify it after.

If you change it now youve done the work twice, why not at least get your combo working.

You want 400hp, have you ever driven a 400hp camaro? Thats a lot of power, you can kiss mileage good bye.

btw your gears are killing the car, put 3.55's at least in it. A high hp motor is not going to have low end torque, you need to gear accordingly.

Yah.. thanx for the advice.. i'll just forget about the heads and cam til my carb is in, the filter is on, and the exhaust is done. Then i will decide on whether or not i need more. And if i do, i will put some heads on it and a different cam. If i dont like that either i will just put dish or flattop pistons and small heads and a cam to match.
Thanx for ur help. If my thirdgen friends kick my *** i will just have to grin and bear it and learn from it and build the engine differently.

Thanx
Rabbit

sounds like a plan

do the gears..please..

I like the idea that nsimmons mentioned, of getting a set of aftermarket 70cc heads. They'd be about the same $$ as a set of vortecs that are reworked to go with a high lift cam, and you wouldn't have to buy a special intake to fit them.
It would be killing 2 birds with one stone.
Or you could kill 3 birds with 2 stones and get a better cam while you've got the motor torn down.

When you do get that set of heads, just be sure you don't get stock replacement ones and think that they're supposed to be high performance.

There's alot more than just how much HP the motor makes, to building a fast car. No matter what motor you have, there are other things besides just that alone, that make the car fast, or keep it slow. Gears is one of them. Another is a torque converter. Wouldn't really matter what motor was in there; the car would be a whole lot faster with improvements to those things.

Same for the exhaust and carb and anything else that's broken or inadequate. You could go borrow one of Jeff Gordon's motors, and it still wouldn't run good, if you just hook it up to those things and they aren't right. They'll choke it, or screw it up, or keep it out of its optimum RPM range, or otherwise slow it down, to the point that it would be a complete waste of money.

No matter what motor you have, that sort of thing has to be corrected, for the car to run up to its maximum potential.

Maybe a better strategy than immediately getting all worked up about the motor and whether it's any good or not, would be to work on some of those things that you'll benefit from, no matter what. Especially if the one you've got cranks up every morning and drives off, and doesn't leak or smoke or make loud noises or otherwise show an immediate need for attention.

Remove one of the valve covers and get the head casting numbers.
Some of the 76cc heads are not too bad to work with to get 400 gross hp (with porting and large valves)
The good 76cc heads are the 441,441x 487 487x 920
336 castings Any of these heads with "max porting", 2.02-1.60valves and new camshaft, and some rear gearing
(4.10"s) will get the results you're looking for.
Will need "max porting" and larger valves.
Mill the heads down to get 10:1 compression. (with your pistons)

If you have 882's or 624's, forget it.

The vortecs are nice (with flat top pistons) But you can get the results you're looking for by modifying a good set of 76cc heads.

high 12's are within reach. The 2.73's have to go thou.
think 4.10's

You will need a fairly big cam (and the corrisponding cam kit) to get the power you're looking for 244 to 256@.050" I recommend a solid lifter cam with moderate lift (.500" to .530")
crane, lunati, isky and sig erson have the stuff you're looking for. The crane "saturday night special" kits are nice cause every thing is included.
Harold (Ultradyne Cams) has joined up with Lunati cams.
His (Ultradyne) grinds are right in this ballpark. look in the "New" listings. www.holley.com
You will need a big exhaust system and headers.
use a edelbrock vic JR or a Professional products hurricane single plane.
You will need 4.10's and a 3500+ stall converter.
it won't be great on gas or likely pass emissions but it will run 12's.