Legacy Stables

Just looking for feedback before I start putting the parts together and void the chance for returning them.

350 block .03 over, 4 bolt main (Have)
lunati voodoo crankshaft. 3.75" stroke (Have)
lunati lhd-1 rods 6" (Have) rods clear block
AFR heads 195 72cc (Have)
JE Pistons Part#: 268830 dome top -5cc (have)
cam hasn't been selected contacting compcams.
rockers hasn't been selected
double roller timing chain (have)
masflow efi system (have)
hooker style sidepipes, 2" muffler (have)

goal is 450hp street car
this will be bolted to a t56, 1st 2nd 3rd 4th 5th 6th Rev
3.73 diff and 26" tires 2.66:1 1.78:1 1.30:1 1.00:1 0.74:1 0.50:1 2.90:1
I can build this and have the tools to do so.

10:1 compression should be pretty close.
4.03 Cylinder Bore Size
3.75 Piston Stroke Length
4.03 Head Gasket Bore Diameter
0.04 Compressed Head Gasket Thickness
72cc Combustion Chamber
-5cc Piston Dome Volume
? 0 Piston Deck Clearance

bluedawg

You should hit 450 with out breaking a sweat. If you plan to buy a off the self cam, go roller and look at the magnum series as the have less split between the intake and exhaust which would work well with Afr heads look at the team g single plain with the lowest rise as you can adjust the plenum deepth with carb spacers.

Ibanez540r

Legacy - I have this kit for sale (not listed yet) that came out of a low mileage 383 (7000 miles)

http://www.summitracing.com/parts/cca-cl12-422-8

It is the Comp Cams Magnum Retrofit Roller 270HR with the Comp Cams Retrofit Roller Lifters.

The one issue is a grooved fuel pump lobe (the actual cam/lobes are perfect), would be a perfect fit for anyone running an electric fuel pump!

Bowerss2

I have a lunati 60104 cam with a similar setup, works very well.

GOSFAST

Go with Comp's XM276HR (12-418-8) and use all your factory pieces, dist gear and f/p pushrod. We use "marine" grinds on numerous builds, they compare with many OEM early perf cams and deliver better vacuum when power brakes are in play.

This is on a 112 LS and will get you extremely close to the 500 HP number! Been there, done it.

Thanks, Gary in N.Y.

P.S. If you go with Comp's lifters do NOT use the "Pro-Magnum's" for a streeter, use the 853's, the 885's (Pro's) are designed to run almost as solids, with .002"/.004" preload. They are more for a specific class of racing with a higher RPM band!

StraubTech

That is a 383 with AFR195 heads and 237/241 on a 108 LSA. If you want it tamer to reach your goal of 450 then around 233/237

jb78L-82

Being that the motor is a 383 which naturally has good bottom end and mid range, a street car with goal of 450HP, along with a T56 tranny, I would certainly go roller cam but less duration to highlight the basic strength of a 383, especially if the motor will spend 99% of the time below 6,000 RPM. My L-82 355 with 10.2:1 compression, Roller Howards cam (.525 lift/duration 219/225, LSA 110, operating range of 1,500-5,600 RPM) with AFR 180's coupled to a 4 speed with 3.70 gears is perfect for street driving. The motor has good bottom end, excellent mid range torque, and pulls strong to 6,000 RPM. I intentionally built the motor to operate from Idle to 6K....not planning to rev to 6,500 RPM on the street. Just my preference...and another approach depending on what you feel is best for your street car

427Hotrod

Just to add to what else is in here...the big red flag to me are those 2" Hooker sidepipes. That's a small muffler to try and stuff 450-550 HP through. The headers are awful long by design but going into a 2" pipe that probably has crimps to make it even smaller will strangle it. Look for some different headers or at least different mufflers.

JIM

gkull

Could you give me your views on Miles Per Gallon VS LSA? My testing looking at BSFC tells me that your 108 would get poor MPG compared to 112 LSA with the same duration.

It also bothers me when shown a graph starting at 3800 rpm. That tells me that the motor could not take wide open throttle below that. Your posted graph shows .499 bsfc at 3800. Not good, then the motor finally gets into it's efficiency range at 4000 through 5800.

Yes, your 108 can make good power. But it is not going to get 20+ mpg going down the highway at 2500 rpm. My C-3 equipped 383 236/242 112 lsa SR ground 4 degrees retarded compared to it's comp cams extreme SR of the shelf equivalent. Can take on wide open throttle at 2500 rpm in 5th gear over drive and accelerate cleanly. Oh and yes it is over 20 mpg avg on 1200 mile trips. Yes, it might be down on HP compared to if I used 110 or 108. But i drive it in excess of 10,000 miles a year. Does yours?

StraubTech

LSA is the distance between peak lift. The size of the compressor, the rpm range, and capabilities of the induction and exhaust system mandate the lobe area and when the valves open and when they close. LSA is a result not a guideline.

I recammed this car 2 years ago. 496 CID with AFR 305's. Previous cam was a solid roller on a 112. Owner had the combo together for 9 years. Made the same trip each year of 140 miles to Grand in Gatlinburg. With cam change and a cam on a 107 LSA customer used a 1/4 tank less gas.

Legacy Stables

thank you for all your suggestions so far

i am looking into the cam suggestions you guys are making. i have to read Vizards book again.

the mufflers will be changed but i got to cut the tack welds.

I am looking for driveability and strong acceleration. i just like passing people on the highway. The car will see long road trips. I will take it up to Wisconsin 3hr trips and out to Colorado, 1-1/2 days 1100 miles. I will probably take it to the track one time just to see what i can do with it. If i get into racing i will build a second vett for that.

cardo0

Those are awesome parts man. Just kinda high dollar. If this your first build I would say save your $$$ and use those Vizard books for a budget build though hard to beat AFR heads. For a seldom raced Street motor a cast crank is good enough and SCAT has full 383" rotating assemblies for less than $1000. When u see all the failed eng build attempts for sale u should realize eng building ain't easy and small errors can lead to failure.

Not to say u can't do this but 2000 bucks is 2000 bucks that can go to your dream build when have some success to help u.

For a cam I would Waite until u can measure your compression ratio (w/liquid) above pistons and head chambers. Also what u have for rear gears and trans.

Good luck and post for help as u need to.

gkull

You again are very good at not answering anything. Oh, your example of some mystery 496 with an unknown cam being replaced by your mystery cam used 1/4 tank less (some unknown amount) Not a real life answer like actual MPG. I gave you a real test where I drive 1200 miles in one day. I will be more specific.

1. Why did the test start at 3800 rpm? That is also very poor to have an efficiency range of 4000 - 5800 often typical of tight LSA numbers.

2. Could you give me your views on Miles Per Gallon VS LSA?

You must know that modern race cars also think about fuel mileage? More laps = less time lost in the pits. Or even think about F1 with no fueling during a race. You get 100 kilos of fuel. Your wonder cams do produce some great numbers on paper without any thought apparently to the idea of broad power curves and efficiency by sacrificing some peak power.

cardo0

He's good at trolling here for cam/parts/crate engine business, making esoteric claims that cant be verified. Where is his corvette?? Hes looking for a buck here not friends. Do u think Hendrick, Childress, Roush motorsports buys any of his .....? Heck, he'd be happy if a Bomber car would drop his name.

gkull

Vizards book is a rough guide and not the gospel.

I imagine that you will be using a H-roller cam. Buy a sleeved dizzy gear billet steel cam. With only 10:1 you can over cam very quickly. my first 383 i under cammed with 232/238 and had detonation problems with flat tops and 64 cc. So I bought a 242/248 and then it was way overboard with a not much of anything till 3500 -7500 rpm range. So i dropped back to a Custom lobe billet cam with what i had learned. I also had 227 cc heads/ single plane/ 830 cfm

GOSFAST

I would pay attention to George here, he's usually on the money for the most part.

Here's another lobe-separation article that may be easier to "decode".

This is from Comp's website!

1.-EFFECTS OF ALTERING CAMSHAFT TIMING
Advancing / Retarding
Begins Intake Event Sooner / Delays Intake Closing Event
Open Intake Valve Sooner / Keeps Intake Valve Open Later
Builds More Low-End Torque / Builds More High-RPM Power (See the note below)
Decrease Intake P/Valve Clearance / Increase Intake P/Valve Clearance
Increase Exhaust P/Valve Clearance / Decrease Exhaust P/Valve Clearance


2.-EFFECTS OF CHANGING LOBE SEPERATION ANGLE (LSA)
Tighten (smaller LSA number) / Widen (larger LSA number)
Moves Torque to Lower RPM / Raise Torque to Higher RPM
Increases Maximum Torque / Reduces Maximum Torque
Narrow Power Band / Broadens Power Band
Builds Higher Cylinder Pressure / Reduce Maximum Cylinder Pressure
Increase Risk of Engine Knock / Decrease Risk of Engine Knock
Increase Cranking Compression / Decrease Cranking Compression
Increase Effective Compression / Decrease Effective Compression
Idle Vacuum is Reduced / Idle Vacuum is Increased (Important in street rides w/power brakes in play)
Idle Quality Suffers / Idle Quality Improves
Open Valve-Overlap Increases / Open Valve-Overlap Decreases
Closed Valve-Overlap Increases / Closed Valve-Overlap Decreases
Natural EGR Effect Increases / Natural EGR Effect is Reduced
Decreases Piston-to-Valve / Increases Piston-to-Valve

After years of building both street AND strip deals we find ourselves using many cam grinds on the "streeters" that would be considered "marine" grinds, by this I mean for boats!

If you go back into G.M.'s records you will see they thought along these lines also for the production-line/street builds.

Here's a few examples, SBC LT-1 (3972178 116* L/S), SBC "Duntov-30/30" (3849346 114* L/S), Z-28 302" (3927140 112* L/S), BBC 396/375, LS-6 (3904362 114* L/S), and the 430 HP 427"/L-88 (3912911 112* L/S). I believe all these numbers here to be accurate!

(Note) Just on a side note here, with respect to the "more power upstairs" theory, I have a customer who had been running a nylon timing gear setup in his 1000 HP unit for very long time (pictured below). Finally went to the "belt-drive".

Thanks, Gary in N.Y.

P.S. I would recommend copying the above info and saving it somewhere on the computer just as a reference for some later reading!

MotorHead

Yeah he's selling $300 cams to members here for $500. $200 for his advice

StraubTech

I've posted many dyno sheets from many customers. I dont' own a dyno so I have no control over numbers...conservative or inflated. I also have no control over where the customer as the shop to start the pull.

99% of my customers want more power and 99% of them get more power. Fuel mileage is not something that is requested by customers and I get few reports back from customers on fuel mileage. This one customer did report back. I apologize if this is not enough info for you.

StraubTech

I don't know if you have ever called here or talked to me in person, but my list of customers that do business with us is just that, our business. I am honored that David Vizard stopped by last week to see our facility and I look forward to working with him on a project for his new book.

I am fortunate that many customers off forums become friends. I have several from this forum. Here is a PM I got over the weekend on a 402 BBC build:

HI Chris, Just wanted to give you an update and a thank you. I finally got this engine running this weekend (it took a year due to some setbacks not car related)

If you recall, this is a 408" BBC with AFR 265 heads and Fast EZ EFI... Your .235/235 Cam.

Engine fired right up, I set the timing total @36 all in. Car runs great! Set the idle at 850 and took a few turns around the block allowing the computer to learn. Works very well with the EFI.

Then I did a test hit- I can absolutely tell it has a bunch more power through the entire RPM band. But what I did not expect was how fast it revs. AMAZING throttle response, Hits REDLINE a lot quicker than previously. It took me by surprise, when I shifted I looked down it was just nosing over north of 6600 but below 7k.


It may be a while till I can get it on a chassis dyno or to the track but will be working on that.

A huge thank you. I will post a video of it idling on the original post.

Andy

No worries on fuel economy from this one, but almost 800HP out of a 496 is not to bad:

https://www.youtube.com/watch?v=FT4H...ature=youtu.be

StraubTech

And the run quite well and pull like freight trains. When your ready for some more power we can get it for you. There is around 40HP left in your mill with the correct camshaft.