WhiteLightnin83

Well in my 83z I already have a 383 stroker that I built very mildy last winter. Now this winter I want more! Last winter I did mainly the shortblock as far as my checkbook would carry me. Now I'm just about to pull the motor and add new heads, carb, and intake and I'm curious as to what I can expect hopefully...Here is a list of what I have for a shortblock...

-1972 LT1 350, punched .030 over, clearanced, and 0 decked.
-Eagle 4340 Steel 3.75" crank
-Eagle 5140 Steel "SIR" lightweight I-beam Rods w/ARP bolts
-KB Flat top -7cc dished hypereutectic pistons and pistons pins
-Clevite 77 rod and main bearings
-Premium plasma moly cast iron rings
-400 balancer and flexplate
-Crane Powermax 234*/244* .488/.510 lift Hydraulic Cam Kit
-New pushrods and timing kit(chain and gears)
-All completely balanced

Now I was looking at this "Head Combo"
Dart Pro 1 Aluminum Heads
64cc chambers(10.9:1 with my shortblock), 2.05/1.6, 215cc intake runner...
Possibley an RPM Air Gap Intake
As for the Carb, I'd like some advice on what you think would be best for my setup... I'm assuming probley something like a Holley 750 Double Pumper but I don't know, thats one place where I'm looking for advice...

I'm very open to any suggestions, maybe I'm going the complete wrong way with this and I could get something much better if better matched, I don't know. The main thing I'm looking to keep is just some type of 64cc aluminum heads because that'll put me right at the limit being at 10.9:1. But when I had a gentleman from the site run this on the Destop Dyno the combo I have listed only put down like 410 hp and 450 ft/lbs and I was definately hoping for more! My goals are pretty much to get as close as possible to 500 hp without needing racing gas and needless to say I'm quite short...

Please feel free to make any comments or give any advice, I need it!
Thanks!

Dustin

Sonix

iTrader: (1)

if you don't want to use racing gas, i'd say that 10.9 CR is a bit high. Try chambers slightly larger, to go for ~10:1, with that cam, that should be ok. Even though they are aluminum, i'd say you're kinda pressing the limits, you don't lose much power dropping CR a bit.


those heads would be purchased assembled? what rockers? I'd recommended 7/16" rocker studs, if it's not already there...

That's all i've got.

WhiteLightnin83

Hmmm damn I always thought aluminum was good to 11:1 on premium. I'm runnin 10:1 on my stock iron 1.94/1.5 LT1 heads.. I'll be running 94 octane, probley with a bottle of 110 octane boost per tank just to help out a bit since this will be mainly a weekend warrior. Probley a tank of gas every 2 or 3 weeks. The heads I'm looking at right now are part number DRT-11521122 at summitracing.com... Any body with suggestions on a carb?
Thanks so far!

Apeiron

Aluminum heads with larger chambers will cost just as much as the small chambers, and you won't have to waste money on octane boost and premium gas. The minimal additional power from the increased compression isn't worth the ongoing extra cost, IMO.

doc

Just a thought about the rotating assembly with a 0 decked block:

1/2 of the stroke plus the rod length plus the piston compression heigth must equal 9.000"

stroke of a 383 is 3.750", and for a rod length of 6.00", the compression heigth must be: 1.125"....

Also, to make 500 Hp, you will need an assembly that will spin up to above 6,000 RPM, maybe as high as 7,000 RPM. So, are you buying a forged crank?

Out of curiosity, at what RPM did the desktop dyno predict 410 Hp?

Damon

With a similar combo I have a buddy running 12.2 @ 112 in his big fat heavy 72 Chevelle (3000 stall, auto trans, 3.73 gears, drag radials). He's also using Dart Pro 1 heads but with the slightly smaller 200cc intake ports and 72cc chambers to keep compression down in the lower 10s. The bigger 72cc chamber version of those heads is the only thing I'd recommend you do different. 11:1 on pump gas might work OK for a while but once you get some miles on the motor and schmutz builds up in the chambers and piston faces you WILL get detonation. I know becuase we started with the 64cc version of those same heads and 11:1 compression originally on this motor. That idea went bust about 9 months later when we split and pushed the head gasket from severe detonation on pump gas (yes, it was running nice and fat and timing was a fairly conservative 32*). Just too damned much compression. Switching to the 72cc heads has since given him almost 3 years of problem-free operation and we lost nothing in terms of power.

The other main difference between your two combos is that I switched him to a solid flat tappet cam (Comp XE282S) from the unknown solid flat tappet that was in it before. I don't know what cam was in it before but it was just wrong for the rest of the combo. When we shoved in the Comp 282 cam it went from running 13.0s @ 103 to 12.4s @ 110 on it's next run. Tuning bought another 2 tenths and 2 MPH later on.

He's got an 800 CFM Holley DP (rebuilt by yours truly- but not tuning- only brought back to factory original Holley calibration specs) on his motor because we had it laying around. A 750 would work just as well.

He's also got a Single plane Weiand Team G (similar to a Vic Jr.) intake on his motor but a modern day Performer RPM would likewise probably work just as well.

Horsepower? Who cares. I guess an HONEST 450. Most people call me conservative. I just say I'm realistic.

WhiteLightnin83

Ok thanks for the imput so far... Now I'm not set on these heads exactly, if you think others would work better then just let me know. Thats just what I caught as appealing to me but I do know that summit has some aluminum heads for sale that are 67 cc chambers and about the same specs otherwise, although I forget the brand name. 67cc heads should have me down to about the mid tens correct? As for the rpms, I'm not sure how much my rotating assembly is good to but I have spun around 7k+ on it and still pulling hard, not often but I have done it a few times. Just as a side note, my rods are 5.7", I dunno if that matters but I know you mentioned something about 6" rods. Just for the sake of simplicity, lets say that I never picked out any heads, intake, or carb and I'm curious to know what you think would be the best to run. Any heads, intake, or carb, just let me know what you think. Also, cams aren't that expensive so if you think my cam is too mild and I would be better off with something else let me know! I'm open for suggestions as I'm not set on what I'm doing with this motor yet, I have all winter to decide! Thanks so far! I REALLY appretiate it!
Dustin

WhiteLightnin83

Ok after doing a little magazine skimming I found something that may be the best alternative for me.... The same Dart Pro 1 Aluminum heads that I was considering before can also be sold as "pre-ported/CNC-machined" for about $1200 more per pair. Now, would this be a better option for me? I'll list the specs.

Non-ported: 215cc Intake Runner, 64cc Chambers, 2.05/1.60 Valves, 1.437 Double Springs.

Ported: 227cc Intake Runner, 66cc chambers, 2.08/1.60 Valves, 1.550 Double Springs

The 66cc chambers would put me down to about 10.6:1 or so I believe but what could I expect from these heads? Will there really be a substantial increase in power or not much of a difference? It doesn't list the max lift that these would be good to though so is there any way to tell? I was considering pairing with a new cam also... I found two cams that I was considering, the first being a Trick-Flow Hydraulic Roller rated to be good from 3200-6800 rpms with the following specs: 246*/254*, .558/.558. The second was a Crane Powermax Hydraulic Roller rated from 3000-6500 with the following specs: 230*/238*, .539/.558.

Just looking for advice in any way possible here esspecially with the cams because to tell you the truth I don't know much about cams, at all. I don't hardly even know the difference between hydraulic and solid or between flat-tappet and roller...

Basically I just need help in lots of ways!
Thanks

SLEEPER 86

$1200 for a cnc job????
seems a bit steep to me.but if you do go the cnc route you might want to start with 200cc intake runners so you end up with about 210cc runners.
on the other hand,bigger intake runners rarely have much effect on final torque output at lower rpms and can only help at higher rpms!
if you're looking to race occasionally and don't care about low rpm throttle "snappiness" go with the larger runners.
if you do get into the 220+ runners you might consider an 800cfm carb.
you are getting into the touchy final details of engine design here,so expect lots of opinions!
just for grins,check the performance section of http//www.camaros.net and ask about the best heads for your combo!very informative,and trustworthy information!
there are some new heads out that are very well designed and won't rape your wallet.
i think the brodix iorn killers look really good for your application.
here's a thread discussing them
http://www.camaros.net/forums/showthread.php?t=67975
Eric B

jbenge

iTrader: (2)

Check my signature for my setup, it runs mid 11's on pump gas shifting at 6000rpm. And it drove pretty well on the street, still using power brakes with a vacuum canister. Next year I'm shooting for high 10's on pump gas with a sold roller cam and some more port work. My new combo will be pretty similar to what IHI was running.
I would recommend the Pro 1's if you are going to get them ported, they respond very well to a little port work. Out of the box with no extra work done its hard to beat the CNC ported AFR or Brodix heads though if you have the money for them.
And I would definately go with a roller cam, hyd/roller if you do a lot of street driving or solid roller if you don't drive it much. Solid cams require more maintenance..valve lash adjustments a few times a year depending on how much driving you do. A cam with similar specs to my old one should get you where you want to be 242/248@.05 .540/.560lift and between 10-10.5:1 compression. I think a 750DP carb would be perfect for your combo. I would get a demon or Proform type carb instead of a holly because you get more adjustability for a lower price....thats been my experience but everyone has their own opinions on carbs.

WhiteLightnin83

Awesome! Thanks so far guys, this is the stuff I was hoping to hear... I'm still very open to what I'm going to purchase but I like the looks of that 11 second slip!

WhiteLightnin83

Just getting a free bump to the top in hopes of more opinions!

F-BIRD'88

You've gotten some good solid advice here.

I'll second Damon's real world advice to avoid trying to run near 11:1 on pump gas. You may get away with it on a dyno for a few seconds on a fresh motor and controlled conditions, but after the motor carbons up a bit and in real world conditions of on street driving (heat soak etc) you'll get detonation problems with anything over about 10.3 or 4 even with good 94 octane.

A motor that pings (even mildy) will loose its ring seal very quickly. And loose its power edge sooner than you'd like. (rebuild time)

A I'd start with 72cc heads on your motor and after carefully measureing and calculating the true CR, maybe have them shaved to 70cc you'd get 10.14:1. 72cc will get you just under 10:1 I'd not exceed 10.4:1.

You will need a better cam than the one you have.
The XS-282 is a great choice with the Dart heads.
You'll be just short of actual 500hp but it will scream.
(usable real world torque and power)
A larger 258/263 on 106LSA cam would get you 500hp peak but won't make you any faster unless you used a race only converter and much more gearing and open exhaust headers to take advantage of the slight power gain upstairs. (You'll need to rev it higher).
The Xs-282 is a nice street cam also.
Wide usuable power band. makes the power you want but is relitively easy to live with

I'd also second starting with a smaller 200cc port and hand porting them some yourself for extra flow. (bowl smoothing,guide contouring and port match( general cleanup) ) You won't need heavy porting on these heads and you'll end up with more overall velocity (think torque) than a out of the box 215+cc port on your 383.

If you'll be buying rocker arms, consider a "split set" (1.6in/1.5ex). The intake ports on Dart heads really like valve lift. Its not so critical on the exhaust side. 1.5 usually works fine.

WhiteLightnin83

Ok cool, that gives me some to think on... Thanks much, I will probley end up just getting the 72 cc chambers and going from there... You do think this should put me pretty close to 500 hp though? What kind of torque would I be looking at with this then? Just a rough estimate... Also what do you think would be the best carb to put on this top end?