Planning an engine rebuild for 79. Here's what I already have: Small Block bored 30 over- 4 bolt, crank and rods. 700r4, water pump, misc block items, pan, timing chain& cover, oil pump...

Here's what I want to do:
Fit under stock hood - L-82.
Will reuse starter, altinator, A/C compressor, steering pump, fan and shroud. Want to reuse the stock exhaust manifolds.
Want to run pump gas, just regular 87 octane, if possible
Want about 350- 375 horses and high 300's in torque
Not necessary to have high RPM engine, would trade higher RPM for lower end torque.
Want it to sound good and have a little lope. Already have flowmasters.
Like Holleys, want to run a spreadbore, mech sec.
Plan on taking block and assoc. parts to local machine shop, clean up have them provide pistons and assemble short block.
Hear the Vortec Heads are good enough for this, so will consider them, but what about bolting to the stock ex. manifolds
This is a fun car, not for racing, just some road trips, local driving. What to put me against the seat when I punch it and not have to work on this everyweekend.
Not to concerned about having to have aluminum heads, but no problem with using them.
Not sure what rear end I have. I go 70mph at 2250RPM with current set up, original 350 L-82 engine and 700r4.
Budget: $3500. I will install the engine, put on heads, intake, carb. Will pay to get lower block work done.
Radiator has already been removed and flushed (when I redid front suspension)

Ok here's your part:
Is there an upper kit (heads-intake-cam) or so that will do this at summit or Scoggin-D?
With the heads you choose, what pistons work best with that set of heads?
If I have to go with individual components, tell me what I need, specifically in heads, cam, intake and Carb.
I am concerned about fitting under hood, so be specific on intake. Hear Edlebrock RPM works, but there are different ones for stock vs vortec.I realize I wlll probably have to get a low profile breather.
I like Mallory ignitions, but anything else come to mind?
Ok, what have I left out.

 

How about this set of heads?

http://www.summitracing.com/parts/EDL-60899/

to get more performance with 87 octane, larger valves are a must. this set of heads have 2.02" intake and 1.6" exhaust valves, can handle .575" lift and take perimeter bolt style valve covers for that "stock" look. With 64 cc combustion chambers, it's the perfect size for middle range compression ratio. Wanting to run 87 octane means that you don't want to exceed about 10.55:1 compression ratio.

To fit under the hood, we need measurements. If your engine currently has the holley carburator you will be using, a couple of measurements will be needed to determine an intake manifold that will work best with the above mentioned heads and fit under your hood. Use the following image to determine these measurements:

 

Port velocity is most important. With ports larger than the maximum flow that the engine can handle, port velocity is reduced resulting in less throttle response and possible black smoking due to the gas not atomizing to its fullest.

With the heads suggested earlier, just because they handle up to .575" valve spring lift, doesn't mean you have buy a cam with that much lift. Especially since the heads have 2.02" valves.

Being that you would prefer lower end torque as opposed to a high rpm powerhouse, there are several cams available from compcams.

Port matching is a cheap, easy way to increase port velocity and increase flow efficiency. A Dremel and a few good grinding wheels to your intake, heads, and especially your stock exhaust manifolds will work wonders. Your stock exhaust manifolds are going to restrict your overall flow and possibly reduce horsepower and torque. But with port matching and smoothing up the insides with allow the engine to breath better.


Oh BTW, I like flattop forged pistons with 2 or four valve reliefs.

Another thing, I have Dyno2003 and can setup a 350 with various components to see the best parts combination for your needs.

A few pieces of info I need to start setting up an engine:
head gasket compressed thickness you will be using
are you leaving the block .030 over or having it bored larger?
are you having the block's deck height shortened?
what size holley carb will you be using?
since you want the setup to fit under your stock hood, I assume you want a short dual plane intake manifold?

 

Sorry if I seem to be spamming the hell out of your thread with my thoughts.

Your stock manifolds seriously reduce your overall performance. I have found a cam that will work very well with what you want.
This camhttp://www.compcams.com/Company/CC/c...x?csid=71&sb=2 with a .030 over 350 setup, 10.36:1 compression, and your stock manifolds:

[IMG][/IMG]

And the same engine with small tube headers (1 5/8" primary tubes):

[IMG][/IMG]

 

Let's back up for a second. At $3,500 you're going to have to be very, very careful to come in at budget. You'll find out pretty quick that money goes up geometrically with any decision that's off-base.

You note the block is .030 over...was it this way from a prior rebuild, or are you noting that you PLAN to bore .030 over? Once we go past .030 over, a sonic test is required to ensure the walls are thick enough for more. .040 I don't really have a problem with and have built engines to that...but anything more is a pass from my perspective.

A Vortec-head 350 is going to make in the range of 330 HP at the flywheel with headers...if your goal is 350-375HP then we need to start looking at other options...and open up your budget a bit. IMHO you can't get to that level without headers and a free-flow dual exhaust.

I have to respectfully disagree with Cviola on some particulars. If you want to run on 87 octane, then you need to be thinking around 9:1 CR. 10.2 is the max with premium fuel for a street engines...and there's no reason to go any higher than that with a GEN I SBC.

Port matching isn't going to show any real benefits on a dual-plane.

CamQuest is *wildly* optimistic on power - especially if any of the models are a little wonky. Be real careful using any DD tool unless you fully understand the models and have verified them with real-world data.

Right now, your focus should be on a good rebuilding reference and finding a local machine shop that will work with a home rebuilder.

This is one of the best books out there - not perfect, but really, really good:

http://www.amazon.com/Rebuild-Small-Block-Chevrolet-Step---Step/dp/1932494219/ref=sr_1_1?ie=UTF8&qid=1316649134&sr=8-1

 

"Billla's" got the information you're looking for, as almost fell over with the earlier mention of 10.5 compression on 87 octane. You should be able to get your desired highway cruising rpm with 0.70 od, running a 3.36 axle.

 

Its up to you , but the mech sec carb AND an automatic tranny are like throwing sand in my eyes - esp when you write that its not for racing, its a fun car, local driving and road trips.

Go on the Holley site or ANY carb site. THEY don't recommend it.

 

Im going to go out on a limb and say "ain't going to happen".
You want 350-375 at low RPM, then a 383 is in order, their HP comes in around 5300RPMs.
Basically what you want with your demands would better be described as "sh** in one hand and wish in the other and see which one fills up first.

 

Well, the first question I have is when you say 350-375 HP are you talking gross HP like the old LT-1's or net HP like engines are rated today and have been since 1972? The L-82 is very capable of making those numbers with VERY few modifications and for considerably less than $3,500 dollars.

Before I make suggestions of which I am also considering after considerable research and comments from many forum members, let me share real a real life example from a fellow forum member who has been documenting HP and 1/4 mile performance from his 100,000 mile ( OEM bottom end and certainly NOT fresh) original 78 L-82 4 Speed (3.73 gears)-just last night ran his car at NE dragway for only the second time ever being on a track (14.9 @94 MPH). His L-82 has a performer manifold, open air cleaner with K&N filter, OEM Q-Jet, Cast iron exhaust manifold with zero pollution control equipment, Stock cast iron 882 Smog heads (no work done to them), just added 2.5 true dual magnaflow system, timing chain replacement, and a cam of unknown orgin:

With everything as stated above with the 2-1-2 exhaust with no cat and OEM type mufflers, the car produced on the dyno last rear 192 RWHP, NOT Net, NOT Gross.

With the additon of the 2.5 true dual magnaflow system, and a carb adjustment, on the STOCK exhaust manifolds, with no other changes, the L-82 produced 248 RWHP with stock 882 Smog heads! or about 250 RWHP which is about 290-300 Net HP and about 330 Gross HP. GM crate engines are rated at GROSS HP unless it is an engine that is currently in a vehicle, then it is NET HP.

These are real numbers, not theoretical guesses!

The L-82 with just a head change, cam, Intake, and exhaust has been documented to produce over 400 Gross HP-easily!

So, without going crazy, I would go for a good set of aluminum/iron heads, a moderate cam like the 268 cam, ported OEM exhaust manifolds/racing cast iron manifold, LTH, or shorties, a holley carb of some sort and you will easily achieve your goal.

The L-82 referenced above (or my totally internally stock L-82) would easily achive 350-375 NET HP with 180 64 CC aluminum/cast iron heads, 268/272 cam, Performer intake, and a proper carb.

Hope that helps!

 

I can't see the referenced configuration providing the referenced results based on my experience, but I still look forward to the dyno data.

 

Billa, I guess I am confused by your comments? Are you saying that a theoretical build with my suggestions would not produce 350-375 HP or that Karols real life dyno numbers and 1/4 mile times on his L-82 are not possible with his combo of parts which of course, would not be possible because the numbers are what they are-no dispute!

My reasoning on the real life L-82 results is that if one can get 250 RWHP with stock 882 heads, a minimum of additional 50 HP is possible with high flow aftermarket heads with everything else being the same, sans a cam to match the heads. 250 RWHP +50 HP (heads/proper cam for the heads)-300 RWHP which is at least 350 Net HP.

Agreed?

 

Let's just leave it at we agree to disagree on the power potential of the configuration you're recommending without rehashing all of it

Again, I look forward to the dyno results

 

Well, until you throw it out there, you wont get to hear what you need to hear. Ok, maybe I am dreaming, but I had to draw a line somewhere and now I can move it to something maybe more realistic. I have a local shop that will work with me on block work. The block is at 30 over now, need to have shop do more detail view of it to make sure it can be use at 30 over. If have to go bigger, no more than 40 over. Ok, got it. I also have a friend who is a mechanic that can help with assembling. So what I am after is stating what I would like and having some input from knowledgeable folks, their considerations, experience and reality. Seems like I got some of that. So from what I hear, If I go with vortec heads, keep CR to low 9's, check out the cam mentioned, probably look into a edlebrock performer intake, Holley carb, Im probably doing all I can do with the budget I have. If I dont like that, them maybe move from stock ex manifold to headers.

 

Absolutely - you did a great job of outlining your goals and constraints!

Yep, I think that general plan is right in there if you're shooting for around 300-325 HP at the crank. The cam referenced (CompCams 12-205-2) is definitely not the cam I'd recommend for the Vortec heads. Vortecs excel at mid-range flow, so you'll want to match that with a near-roller profile like the CompCams Xtreme Energy line or similar...something around .450 lift or so. Now that you've got the overall plan in place, it's a lot easier to hone in on the details.

Also, definitely agree as well with the prior post that mechanical secondaries with automatic transmissions is not a great mix on the street.

 

these days, mechanical secondaries and anytransmission is a red flag. Mechanical secondaries were the hot ticket back in the 70s if you want to have something like bragging rights. They have been bad idea ever since
also, you should carefully think about your horsepower/torque numbers as they are completely and totally unrealistic with a budget Motor

 

Well, mechanical secondaries are fine if zero-to-WOT is your primary concern...sacrificing to some extent low/mid-range throttle response and fuel economy.

 

Would you mind explaining why mec secondaries are not for street? Yes I know and have been to Holleys site and they say dont. I would like to understand why. My only experience with mec sec, was in the mid eighties. I built a SB350, double hump 1.94 intake heads, headers, Holley street dominator intake, cant remember all the details on the cam, but I do rememember 450 lift and 288 duration. It had a turbo350 and a 273 rearend. Idont remember the exact model of Holley but it did have mec sec. I really enjoyed that car, the way it ran and the way it sounded.
Would not the mec sec only open up as much as you push the throttle? Generally, I thought with light throttle, the primaries did most of the work until you reach a certain point the the secondaries start kicking in. If the secondaries can be controlled by the foot pressure, then can you not regulate the overall flow??? Im NOT an educated person on mec sec, but just my understanding which may not be correct. I appreciate most of the feedback here in that I am trying to learn.

 

I thought about writing a bunch of stuff here, but I think in the end the net is that a vacuum-secondary carb is more sensitive to engine load, which the automatic trans applies very differently than a clutch.

Unless zero-to-WOT with a tight, high-stall converter is your gig...a vacuum-secondary carb will give significantly better all-around street performance.

I can give more background if needed, but I'm confident you'll find this is the case in practice.

 

Ok, still learning here. With a Holley vac sec, will there be any of the "lag" you sometimes get when you punch it and would manually shifting the autotrans make any differenece? My past engine, the TH350 could only be shifted manually.

 

There definitely can be a lag, but smart tuning of the secondary opening and correct sizing of the carb virtually eliminates it.

If you're planning to manually shift the TH350, then a mechanical secondary carb will work...but when it's in "drive" you'll get less throttle response and overall poorer fuel economy.

There's no "right" answer here and either carb will work...it's a trade-off, like everything else