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Discussion Starter #1
Hey everyone. I'm looking for some honest recommendations and advice here, and I would like to avoid any pitfalls that would cause me problems as well as gather some advice on things I may have overlooked.

The car is a 3rd gen Firebird. Manual transmission (less than desirable factory T5 for the short term), stock 3.23 10 bolt (soon to be upgraded with 28 spline Eaton, 28 spline Mosers, and girdled cover). Non T top, no power anything weighing in at about 3100-3200 lbs. It currently has a carbed 350 with "8.5:1" CR (Goodwrench with smog 624 heads).

My goal is a 350 that pumps out 300-350 horse. Uses are street/occasional strip driving. I don't launch the car hard, and I don't power shift it. I don't care about gobs of low end torque partially because I know the trans and rear end simply will not take it for long. What I'm aiming for here is a good mid range engine that will pull me hard through my gears one at a time up to 5500-6000 rpm.

These are the parts I'm considering. I would love any suggestions or recommendations regarding the functionality of these parts working together.

ProMaxx (Patriot) Vortec style heads
ProMaxx Performance 2151, Patriot Performance GM Vortec 185cc Cylinder Heads | ProMaxx Performance

.015" Fel Pro Gasket

Edelbrock Performer RPM Intake
Edelbrock 7101, Edelbrock Performer RPM Intake Manifolds & Kits for Chevrolet | Edelbrock - Free Shipping on All Orders @ JEGS

Lunati Voodoo 60103
https://www.lunatipower.com/Product.aspx?id=1984&gid=287

1.5 Roller Rockers with correct length pushrods

3310 Holley (750cfm vac secondary) or 4777 Holley (650cfm DP)
 

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If you can live without a choke, Holley 82750 750 vacuum secondary Street HP. I bought one last summer, eliminated mid throttle stumble, adjusted nothing to get it on the road. I love it. Later changed primary jets two steps leaner just because I thought it needed it. Plugs looked a little lighter after the change but I know that doesn't tell the whole story. This year I'm adding an air/fuel gauge to help me with the tune up. Only drawback is hard to start when the chill sets in and I don't have manifold heat. I have an alternate carb for that kind of weather, do you? I have a similar setup to what you aspire and I have been asking for cam help. I called Lunati and they recommended that same Voodoo as a swap for my XE274H. I'm liking it, maybe.
 

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well prepped heads of choice(250-260 cfm flow)aluminum
If you use a carb, 750 cfm
long tube headers
10:1 cr
I recommend a small (square ) roller cam,ie; 108 on 108 with 220 ish ºs and .520 ish lift
performer rpm intake

If you ask Richard ,he might have a part number for a cam?
the 108 square cam will have a nice smooth power band in this combo
 

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Don't purchase cylinder heads until you get the short block figured out. What are the casting numbers of the block? If it's an older non roller cam block I'd be on the hunt for a complete used "rebuildable core" vortec engine. This will give you a 1 pc rear main seal and be a roller cam block with all the goodies to make it work. Then use your older 2 pc non roller block to sit on while assembling the roller block.

These vortec engine are everywhere. Put an ad on craigslist.org to find one.
 

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Discussion Starter #7
Thanks for all the replies guys. I especially appreciate carb recommendations because that's a spot where I'm leaning towards a 750 vacuum secondary but don't know exactly which carb I want. Choke doesn't matter to me.

In terms of cams there are two recommendations to go hyd roller. I was hoping to stick with a hyd flat tappet (mostly for cost sake) but I wouldn't rule out the rollers. I'll definitely look into the possibility.

Just to humour me, do you think that 10603 cam would give me the mid to upper range performance I'm looking for without having to dish out for roller lifters.
 

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Just to humour me, do you think that 10603 cam would give me the mid to upper range performance I'm looking for without having to dish out for roller lifters.
Yes it would, but it'll want minimum 10.0:1 SCR to work correctly. Using that cam with 8.5:1 would result in what my buddy used to call a "weak-suck operation".

And take it from an old guy who has been there, done that / been there, done that / been there, done that.....You do not want to use a flat tappet camshaft.

Another thing, you do not want to use a shim gasket with aluminum heads. The iron block and aluminum heads, being dissimilar materials, will move around quite a bit and the gasket will "fret" the aluminum heads. See definition #3 here....
http://dictionary.reference.com/browse/fret
To get the squish right, careful measuring and cutting the block decks to "zero", based on the measurement of your stack of parts will be the right thing to do, then using a 0.035" to 0.045" compressed thickness gasket to describe the squish/quench.

.
 

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Discussion Starter #9
Okay, the 10:1 is definitely beyond my compression ratio. After the heads I should be somewhere between a 9.3-9.5:1 SCR from my understanding. From my research my "8.5:1" Goodwrench is closer to 8:1.

Why do you recommend against a flat tappet? It's what I have in my 401 and I haven't had issues.

Thoughts on a Bootlegger instead of a Voodoo? It recommends a 9.1-9.5 SCR
http://www.lunatipower.com/Product.aspx?id=2929&gid=401
 

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Discussion Starter #10
So if I run an iron head that thin gasket should run okay? Or would you recommend the thicker gasket no matter what considering the block won't be decked?
 

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Why would you be looking at using a .015" gasket, do you know that the pistions are .025" in the hole or are you just wanting to use that thin of a gasket to get the compression up. If so this will cause you trouble. Just like Tech1 mentioned you need to strive for around .040" quench/squish. If you are unsure of what this is then google it. In the past I have used Victor Reinz .025 gaskets when I was working with an engine that had the pistons .015-.020 in the hole. I've never had a problem with them.

Many people are recomending a hyd roller cam becaue they will flat out- out perform a flat tappet cam all day long. Example; I had a 87 Z28 that I put mild solid f/t cam in it (383). It made decent power and had me running 11.70's. I changed out the cam to a similar duation hyd roller (rest of the valvetrain as well) but with about .050" more lift and not only did the engine have more power through the whole band, it also go me 3 tenths off the 1/4.
 

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Discussion Starter #12
I was under the impression that these GM motors came with a .025 deck clearance from factory. My thinking is with the .015 gasket putting me right at .040 quench. I suppose I could order a few different gaskets, check the deck clearance when the heads are off, and make my final call at that point. Have you experienced a deck clearance less than .025? That would definitely put me lower than I want.
 

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. OK, the "8.5:1" compression ratio on those engines is actually about a soggy 7.6:1... dished pistons, big chamber heads, pistons prolly at least .025" down in the bores...

. Honestly, if comfortable changing pistons and cams/lifters/springs, some flat top KB #9902 pistons in std. or oversize bore and a flat tappet cam of 214/224 - 227/233 durations @ .050" lift will put you right into or over your stated HP/performance goals for almost no money... using your current stock heads and 4 bbl. carb... and put your shift point up into the 6,000's... for your purposes I'd go the smaller end of that cam durations range for great MPG... even a budget Summit K1103 cam/lifters... and 'Z28 springs'... or the cams you're looking at above to flatten the torque curve slightly and save the tranny... is it a standard or World Class T5? May not even feel a need to change the intake manifold once you see how it runs...
.
 

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OP,
After rereading your original post, are not intending to rebuild this motor? If not, why? If the motor is strong (not worn out), then OK, but if this is a high mile unit, then swapping heads might not work out.

Your 300-350 goal can easily done with just a head, cam and header swap. I'll bet though, that you'll want more after you get 300. I recommend getting the heads off and seeing how the bores look and checking the deck height. Then you should be able to come up with a solid plan.

You also mentioned that you were concerned about the T5. If you keep the torque under 350-400, then the T5 will live if it is prepped properly and you stick to 'normal' driving. Prepping a WC T5 'properly' is relatively inpexensive.
 

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Discussion Starter #15
Unfortunately, this is one of those "8.5:1" that's actually closer to 7:8:1. So recalculating, slapping on a set of standard Vortecs, for example, could bump me up to 9:1. This changes my cam options. Any suggestions?

The T-5 is a NWC and is a ticking time bomb as far as I'm concerned. My plans were to continue to drive it normally until it blows a gear or blows completely and do a T56 swap.
 

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Discussion Starter #16
I forgot to mention the motor is strong. It only has about 20k or so on it.

I don't really want to pull the thing and do bottom end work, and I mostly want to give it some top end goodies for some better power. Is that an unwise desire?
 

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Standard SBC deck hgt can range from .025 to .030.As suggested above,take a measurement after pulling the heads & inspecting everything else.Vortecs on a stock short block using a .015 gasket will generally put you in the 9.5:1 range.Advertised chamber volume is 64cc.In reality,they tend to run a litlle smaller in the 62 cc range.
 

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Discussion Starter #18
Standard SBC deck hgt can range from .025 to .030.As suggested above,take a measurement after pulling the heads & inspecting everything else.Vortecs on a stock short block using a .015 gasket will generally put you in the 9.5:1 range.Advertised chamber volume is 64cc.In reality,they tend to run a litlle smaller in the 62 cc range.
That's good news for me. Thanks for that info :thumbup:
 

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If your short block is good,Vortecs setup with proper springs,a Comp or Lunati 262 or268 cam,.015 gasket,4 bbl carb of your choice & free flowing exhaust will hit your power goal with good drivability.A proven recipe for a 350.
 

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Here's the problem:

If you have not owned the motor ever since it was produced on the Chevrolet assembly line, then you have no idea what has been done to it by its previous owners. The decks could have been cut already or the last builder could have used those fosdick rebuilder pistons with a 1.540" compression height that puts the piston crown down in the bore by another 0.020", wrecking any chance of getting a good squish/quench.

In the first place, these motors are mass produced and although they have a set of standards, plus and minus, the block deck height could be anywhere from (for instance) ~9.015" to ~9.035". All it takes is a small chip in the register of the mill that the operator failed to clean out from the previous block that was cut in the mill to make a heck of a difference. The other thing about milling the block at the factory is that you have no idea if both banks were machined the same from the centerline of the main bearing bore. Matter of fact, is you find a block that has the same centerline to deck dimensions on all four corners, you should run right out and buy a lottery ticket. If the block is milled askew, then you would have 8 different static compression ratios, a different one for each cylinder.

That's the whole idea of building a motor. You use blueprint dimensions from the factory or other sources to equalize everything, so that A works with B and B works with C and D. First, you inspect the main bearing bore for all holes being round and parallel with each other. If they are not, you correct them by the align honing or align boring process. Once the mains are valid, you measure the block deck height at all four corners with a 12" dial caliper. If the decks are all the same and the block deck height falls into place for the stack of parts you will be using, fine, build it. But is the decks are off, like I said, you will have 8 different static compression ratios, the heads will sit askew on the block and the intake manifold doesn't have a chance of sealing up properly on the heads.

The least a fellow can do is to pull the heads and measure the piston deck height. That will tell you what gasket you should use, or if the piston deck height is excessive, or the measurements are off from the front to the rear of the block, it will tell you that the motor should come apart to cut the decks so that you can engineer a proper squish into the motor and to have the same static compression ratio on all 8 holes.
 
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