OOTB Stealth vs Prepped Stealth?

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IQ52

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What airflow difference will you see if you do a valve job and quickly clean up the ports?

Your results may vary, here are the last ones we did. Exhaust was using a 2" tube.

Lift.........OOTB IN/EX.........Prepped IN/EX
.100..............70/57..............75/59
.200............148/114..........152/128
.300............210/159..........216/172
.400............248/193..........263/208
.500............268/218..........288/236
.600............277/234..........299/256
.700............278/244..........305/268

Before the finish milling this set of heads is around 83.5-84cc.
 
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How much $$$. There is a lot to be said for how you say things. I should have stated: "Mr. Laroy, how much do a set of prepped Stealth heads cost?" I many be interested for my 383 build. Or, " how much do you sell a prepped set for? Off to the corner I go.
 
TrailBeast said:
Better flow, duh. :D

Sorry
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Well actually, the better flow is incidental to the purpose of prepping the heads. No head coming off a production line is always ready to go OOTB. So we bring the new heads into the shop, disassemble, flow them and inspect each part. The springs are all measured for pressure (if they are going to be reused), the valves are inspected and checked for roundness (many valves are discarded and new ones procured because we find a lot of the valve stems around the lock groove are marred during the assembly by whoever slaps these heads together), valve guide clearance is checked, the valves are back cut, we use one intake and exhaust valve to do a rough performance valve job to the head and set the valve installed heights to + or - .001". Then the heads are turned over to Cody (my son) and he does the port, bowl and combustion chamber clean up. He returns the heads to me and I do a finish valve job and flow them again. Any big flow discrepancies are noted and corrected by going back to the porting bench and then back to the flowbench to be measured again. That being done we cc the chambers and mill the heads to correct the ever present wavy block surface. The heads and all components are cleaned, valve stems & guides are lubed and the springs are assembled to the correct installed height. The clean heads are bagged, boxed and shipped. And just incidentally.....the flows increase from what we find OOTB.

Reusing all Stealth components, this service is $600. At a dead minimum the stamped 7 degree locks should be replaced with machined locks as they are what tears up the stem and lock groove. I have come to believe that 10 degree locks are not the best solution with the light spring pressures these heads come with. These machined 7 degree locks are a whopping $29 a set. Well worth it when you don't have to file the valve lock groove to prevent it from scoring the bronze guide as you remove the valve. Any other replaced components are of course an additional cost.

440 Source says in their instruction that their springs should be used with lifts of .510" or less.

It's best with new heads to just buy the heads from 440 Source and have them shipped directly to us. It saves shipping one way as 440 Source will ship their heads for free.
 
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fratzog lover said:
Are the valve guides as bad as the early heads? The retainers are supposedly comp units.
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I haven't had any tight guides recently. 440 Source advertises the retainers as Comp units so I have no reason to doubt them. The locks are the cheapest stamped locks. They look just like the cheapos that came with my Indy EZ heads. Replace them with the Comp Cams 7 degree Machined Steel Race Locks 648-16.
 
Hmm... I was thinking about saving up for Trick Flow heads, but for $2000 they will also need checked/prepped. A pair of Stealth heads is $1000 plus $600 for your work, and I think 300 cfm would do great on my 451. (I already have a new set of Comp dual springs for my cam). That's all the flow I'm likely to need in a street/strip car - isn't that enough to make 600 hp?
 
The first 451 we built was 9.5:1 compression with 452 iron heads flowing 290 cfm. With a 950 cfm Quick Fuel, M1 single plane and a Comp Cams XR292R solid street roller it made 588 lb-ft @ 4,600 rpm and 621 hp @ 6,100 rpm. That was 2.14 hp/cfm
 
NICE! I had mine ported local to me (St. Paul MN). Same cost $600 do you do any runner volume measurements? IE a CC of the ports?

My 10.5:1 383 made 460hp/450ftlb on the dyno
.030" over 71 HP block
KB 5cc dome pistons
stock crank/rods
Comp 280H cam
Smith Bros custom pushrods
Crane gold 1.6 rockers
Ported Stealths w/ Comp springs
Unported Ede RPM
1/2" 4 hole spacer
Demon 750 Speed Demon
2" fenderwell headers


1%20head%20work_zpsiwraqbzy.jpg


3%20head%20work_zpsreh1x9w1.jpg


2%20head%20work_zpsjigexpez.jpg


On a side note this is my 1,320th post! LOL 1/4 mile post if you will!
 
zac_F71 said:
NICE! I had mine ported local to me (St. Paul MN). Same cost $600 do you do any runner volume measurements? IE a CC of the ports?

My 10.5:1 383 made 460hp/450ftlb on the dyno
.030" over 71 HP block
KB 5cc dome pistons
stock crank/rods
Comp 280H cam
Smith Bros custom pushrods
Crane gold 1.6 rockers
Ported Stealths w/ Comp springs
Unported Ede RPM
1/2" 4 hole spacer
Demon 750 Speed Demon
2" fenderwell headers








On a side note this is my 1,320th post! LOL 1/4 mile post if you will!
Click to expand...
Any pics of the engine bay? Sounds like a perfect Saturday night hauler.
 
That's a little more than I normally see - but I don't do any hand cleanup of the ports or bowls beyond a gasket match on the intakes. High quality valve job alone is worth measurable gains from low lift to max. The retainers and locks are not Comp unless you request and pay for them. I replace those straight away too.
 
fishmens67 said:
Is the chamber 80cc after cleanup.
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They certainly could have been. The set we just finished shipped at 82.5cc. Which was what they came out to be with minimal clean up. Had we milled them another .016" they should have been 80cc.
 
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Fedex dropped off a set today. I read an old hotrod forum thread from heyoldman in 09 on the stealth head.
I was wondering if flow #'s would be close if I did the cleanup you recommended in that thread.
It seams like a basic procedure I am capable of doing. or is Cody doing a tad more grinding and I should send them your way.

ps, 440 must have seen the state sent , and thought of you. quality looks pretty good. lol
 
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Cody always does a little more than is required of him, and we blueprint the head as described in post #7. But there is nothing wrong with you doing your own head prep if you want to.
 
A chevy guy had nothing nice to say about these heads.
I'm very happy with them on my son's 383.
 
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