best G.M. production SBC street performance heads

grumpyvette

Administrator
Staff member
cy said:
I'm looking for recommended heads for a Street Stock mud truck build. 350 small block. Non-roller. Lower end is a 70's 4-bolt with standard bore and stock parts. I'd like the best heads and cam that I can get. I can use a good Edelbrock intake and whatever 4bbl carb that I want. I just have to stick to production GM heads. I can use any cam as long as it isn't a roller cam and I can still pull better than 15'' of vacuum at 900RPM. I have to be able to run on 91 octane pump gas.
http://garage.grumpysperformance.com/index.php?threads/valve-train-clearances-and-problems.528/

https://www.high-performance-engines.com/cylinder-heads-s/173.htm

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When checking valve spring installed height and valve clearances you can,t guess,.its mandatory you don,t guess and actually measure clearances, valve spring michrometers are not expensive and owning or borrowing one for your engine assembly makes a good deal of sense, you can get close with SNAP GAUGES, and a 2" standard michrometer or a vernier caliper
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http://www.kmotion.biz/instht.htm

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there are PLUS .050, standard and NEG .050 height retainers and valve cups and shims to adjust the installed valve spring height and location in regard to the cylinder head and valve guides
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the answer depends on what you consider production heads
http://www.superchevy.com/how-to/148-05 ... ck-engine/

http://www.strokerengine.com/SBCHeadsFlow.html
Some of the More Popular Gen I Cast Iron GM Cylinder Heads

http://www.onedirt.com/tech-stories/engine/a-guide-to-vortec-vs-oe-small-block-chevy-heads/

#3767754 – Manufactured from 1959-1961 on 283 Cubic Inch engines. Called the “Power Pack” cylinder heads. 1.72˝ intake valves and 1.50˝ exhaust valves. 60cc Combustion Chambers.

#3774692 – Manufactured from 1958-1964 on 283 Cubic Inch engines. Called the “Power Pack” cylinder heads. 1.72˝ intake valves and 1.50˝ exhaust valves. 60cc Combustion Chambers.

#3795896 – Manufactured from 1963-1965 on 283 Cubic Inch engines. Called the “Power Pack” cylinder heads. 1.72˝ intake valves and 1.50˝ exhaust valves. 60cc Combustion Chambers.

#3782461 – Manufactured from 1964-1966 on 327 Cubic Inch engines. 161/62 cc port volumes, 62cc combustion chamber. Identified by Double Camel hump symbol.

#3782461X – Manufactured from 1960-1963 on 283 and 327 Cubic Inch engines. 172/64 cc port volumes, 62cc combustion chamber. Identified by Double Camel hump symbol.

#3890462 – Manufactured from 1966-1967 on 302, 327, and 350 Cubic Inch engines. 64cc combustion chamber. Identified by Camel hump symbol. No accessory mounting holes.

#3917291 – Manufactured from 1967-1968 on 302, 327, and 350 Cubic Inch engines. 64cc combustion chamber. Identified by Camel hump symbol.

#3932441 – Manufactured from 1969-1970 on 350 Cubic Inch engines. 161-165cc intake port. 76cc combustion chamber.

#3932441X – Manufactured from 1969-1970 on 350 and 400 Cubic Inch engines. 161/65cc ports. 80cc combustion chamber. 1.94″ intake/1.5″ exhaust valves.

#333881 – Manufactured from 1974-1975 on 350 Cubic Inch engines. 76cc combustion chamber. 2.02″ intake/1.6″ Exhaust valves.

#3991492 – Manufactured from 1970 on 350 Cubic Inch engines. Available on the LT1 engine and over the counter. 64cc combustion chamber. Either straight or angled plugs.


PART NUMBER OPTION
Intake Manifolds For Vortec Heads

2116 Edelbrock Performer
21161 Edelbrock Performer, Polished 2116
5426 Edelbrock C-26 Dual-Quad
7116 Edelbrock Performer RPM
71161 Edelbrock Performer RPM, Polished 71161
2913 Edelbrock Super Victor, Single-Plane
2912 Edelbrock Victor JR. Sportsman 2V Vortec
7516 Edelbrock Performer RPM Air-Gap Vortec
75161 Edelbrock Performer RPM Air-Gap Vortec, Polished 7516
12496820 With EGR, square and spread bore carb mount
12366573 GM RPM Style, Squarebore Carb.
12496821 GM TBI with EGR
12496822 GM Eliminator Vortec Design (Same as Edelbrock P/N 2913)
------ Holley MPI Commander 950, MPFI Fuel Injection Kits.
3507 Edelbrock Performer RPM Pro-Flo EFI .
2516 Edelbrock Performer RPM (Marine application, but allows to bolt on a Quadrajet without an adapter) .

Note: You can view Edelbrock/Vortec intakes here

PART NUMBER OPTION
Intake Gaskets For Vortec Heads

1255 Fel-Pro Intake Gasket
89017465 GM Intake Gasket(old P/N 12529094)
Rocker Arms for Vortec Heads
12495490 GM Rocker Arms, 1.5 Ratio, Stamped Steel, Self-Aligning
12370838 GM Aluminum Roller Rocker, 1.5 Ratio, Self-Aligning
12370839 GM Aluminum Roller Rocker, 1.6 Ratio, Self-Aligning
1417-16 Comp Cams Magnum Roller Rocker, 1.52, Roller Tip, Self-Aligning
1418-16 Comp Cams Magnum Roller Rocker, 1.6, Roller Tip, Self-Aligning
1317-16 Comp Cams Pro Magnum Roller Rocker, 1.52 Ratio, Self-Aligning
1318-16 Comp Cams Pro Magnum Roller Rocker, 1.6 Ratio, Self-Aligning
10751-16 Crane Gold Roller Rocker, 1.5 Ratio, Self-Aligning
10758-16 Crane Gold Roller Rocker, 1.6 Ratio, Self-Aligning
Camshafts For Vortec Heads
There are hundreds of cams suitable for use with the Vortec head.
Example: 12-235-2 Comp Cam Extreme 4 X 4, flat tappet cam, lift I .447”, E .462”, duration @ .050” 210 degrees Int., 218 degrees Exh.

Strong low end and mid range torque. Excellent cam for RV's and pickups when changing to the Vortec heads.

Note: Valve spring change is required if changing to a performance cam.
PART NUMBER OPTION
Valve Springs For Vortec Heads

10309-1 Crane Cams valve spring and retainer kit. Drop-in springs with no machine work needed.
Valve Covers For Vortec Heads
12355350 GM Chrome With Red Bow Tie In Center
24502540 Valve Cover Adapter, converts center bolt to parameter bolt
10046089 Center Bolt Valve Cover Gaskets
241-75
Holley custom cast aluminum valve covers with ball-milled top. The rigid 1-piece aluminum castings combine strength and light weight in a design that provides a tight gasket seal while also acting to reduce valve train noise.

241-74
Holley custom cast aluminum valve covers with polished flat top. The rigid 1-pc aluminum castings combine strength and light weight in a design that provides a tight gasket seal while also acting to reduce valve train noise.

9415
Mr Gasket, 1987-up SBC, center hold down, baffled. Included: 2 covers, 1 oil fill cap, 2 PCV/breather grommets.

Head Gaskets For Vortec Heads
10105117 GM Composition Head Gasket, 0.028” thick compressed.
12557236 GM Composition Head Gasket, 0.051” thick compressed.
1094 Fel-Pro Head Gasket, 0.015” thick compressed.
PART NUMBER OPTION
Spark Plugs For Vortec Heads

5613611 R44LTS, set of 8
5614210 MR43LTS, set of 8
25164641 #3, Rapidfire style, set of 8
P526S Accel U-Groove “shorty” Double Platinum Header Plugs approximately 3/16" shorter then R44LTS plugs, set of 8
Miscellaneous Parts For Vortec Heads
12495499 GM Head Bolt Kit
12495491 GM Flat Tappet HD Push Rod Kit
12371041 Factory Roller Cam Push Rod Kit
12550027 GM Intake Bolts Set
134-2002 ARP SBC Vortec, Intake Bolt kit. 6-Point Bolts and Washers, Black Oxide, quantity of 8.
434-2002 ARP SBC Vortec, Intake Bolt kit. 6-Point Bolts and Washers, Stainless Steel, quantity of 8.
134-2103 ARP SBC Vortec, Intake Bolt kit. 12-Point Bolts and Washers, Black Oxide, quantity of 8.
434-2102 ARP SBC Vortec, Intake Bolt kit. 12-Point Bolts and Washers, Stainless Steel, quantity of 8.
8032 Edelbrock Universal Throttle Bracket. For SBC Vortec or Edelbrock E-Tec heads.
Bare Vortec Head
12529093 Same as P/N 12558060 except it doesn’t include intake valves, springs, and retainers.
ID go this route if it just needs a G.M. production number and its easily available
25534431 Vortec Bow-Tie Large Port Cylinder Head, Complete

GM Performance Parts' latest and most powerful iron cylinder head with "Large Port" for Street or Racing. This Vortec design Special Performance cast iron cylinder head features revised intake and exhaust ports and includes 2.00" hollow stem intake valve P/N 12555331 and 1.55" sodium filled exhaust valves P/N 12551313. The deck surface is .450" with 65 cc combustion chambers, 215cc intake and 77 cc exhaust ports. All Vortec intake ports are taller and narrower than early model Chevrolet heads. The valve cover mounting holes are for both early model flange and late model center. This head also includes intake manifold mounting holes for both early model 6 bolt main and late model 4 bolt Vortec design. The head has screw in rocker studs P/N 12552126, large valve spring pocket machining, and will accept up to .530" lift camshafts without modifications. Heads are identified with the Bow-Tie logo on the exterior of the head below exhaust flange and Vortec logo on top of intake port area. They also feature GM logo cast into bottom of intake ports. Includes valve spring P/N 12551483, valve seal P/N 10212810, and spring cap P/N 10212808.
Technical Note: You must use a raised runner design intake mainifold P/N 10051103 (6 bolt mounting), or Vortec design 12366573, 12496820, 12496821, 12496822, and 12499371 (4 bolt mounting) with this head. You can use production Vortec intake gaskets P/N 12529094 (torque spec. 11 ft-lb/ 15Nm) for mounting Vortec design heads or use P/N 12497760 (torque spec. 30 ft-lb) with conventional material when using on early model raised runner or Vortec design intake manifolds, this gasket has both 6 bolt and 4 bolt Vortec attaching holes. Head casting P/N 25534371C.
The below posts are from Gary Penn, formerly of GM Performance Parts.
The Gary Penn Vortec discussions:
Part 1: Gary Talks about the Vortec combustion chamber design.
"Here is the short version of the importance of combustion chamber design. First some assumptions, air fuel ratio is right, meaning enough present oxegen to support total combustion of the fuel. Second, forget about the "crevice", the area above the top ring between piston and cylinder wall where the fuel will not burn efficiently. Third, assume flat top piston, best design, promotes most rapid flame travel. Now compare a theoretical combustion chamber with piston at tdc and no air movement. This of coarse would never happen, but bare with me. To burn the fuel would require maybe 60 degrees of timing lead, because you have only the close proximity of the fuel atoms to spread the burn from the plug accross the area of the chamber. This would mean your engine would "fight" against building combustion pressure as piston approached tdc. Very inefficient. "old fashioned" combustion chambers are more desireable than our theoretical case because they induce turbulence. The turbulence speeds the spread of the burn, but in a random and uncontrollable fashion. Requireing maybe 34-38 degrees ignition timing lead. Better, but still not great. This is all heads built prior to the early 90's. And, most aftermarket heads, which are "tweaked" copies of "old fashioned" production heads. Now consider the Vortec head with its predictable and repeatable swirll patterns. Faster burn rate than our previous examples, requireing even less timing lead, about 30-32 degrees, therefore engine has to fight the mounting pressure less than the previous examples. This means more power available to put to the ground, or up in smoke I guess. The theoretical ideal engine would have such a fast burn rate that total combustion would happen at the moment of ignition. Then you could run 0 or 1 degree timing lead. Don't hold your breath waiting for this to be reality, the laws of physics aren't cooperating with us on that one. Make sense to ya?
Regarding port design, "total area under the curve" is most important. Most buy heads based on peak claimed flow at some valve lift (ie. 250 cfm at .600" lift.) But more important than that is flow at all levels and particularly low lift flow. If you chart your flow at all valve lifts from open to close it looks like a bell graph (the line will be shaped like a bell). The fatter the bell the better. A narrow pointy bell is no good. Also, you need efficient flow management, that is laminar flow without turbulence in the ports. Turbulence creates "voids" or low pressure pockets that mean your port will not pass as much air as the same port witout turbulence would. Laminar flow takes the air through the port intact, essentially fills the port with quality air without "voids". Another thing to consider is velocity and momentum. Air and fuel have mass, so they can be accelerated and will have momentum. The Vortec head uses a built built into the port shape to accelerate the air/fuel after it makes the turn toward the valve. This creates low pressure behind it, drawing more air/fuel. And it gives the air fuel high velocity and momentum so that it has a lot of energy when it hits the back side of the open valve, because at this point it has to be redirected and loses energy as it's redirected.
So, bottom line is best high velocity laminar flow at all valve lifts with a controlled high swirll chamber, combined with a flat top piston. Currently, no aftermarket head can begin to compare with the Vortec, even the Fast Burn lags a little behind in the quality of these characteristics."

BTW theres two common vortec intake manifold gaskets, these vortec heads have taller ports than the standard 23 degree first gen SBC heads
The Fel Pro 1255 is .120 thick
The GM 89017465 is .060 thick

if your restricted to heads that came on most cars then mildly reworked standard 170cc port vortec heads are a decent choice
any time you buy new cylinder heads it makes a great deal of sense, to verify they are designed to match the block youll use, the piston dome shape, and to look for several independent reviews, from previous purchasers, that are NOT on the manufactures web site and to read through the fine print on specs on valve size,valve spring load rates , max valve lift, port cross sectional area, combustion chamber volume,suggested head gaskets, intake manifolds, and look for advice on matching cams headers etc.
It certainly won,t hurt to shop for vendors selling at a lower price, but be aware component quality in valves, retainers and machine work do vary wildly as does the care taken in the machine work being done, so you tend to get what you pay for!
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buying out dated fuelie heads with todays increased tech aftermarket heads available if max performance is your goal is a bad joke, as you can easily put $1200 into machine work and porting and not come close to some of the better current aluminum aftermarket head flow levels
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these were great heads back in the 1960s but current design and testing technology has far surpassed that flow and power level nearly 60 years after they were originally used.
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http://sallee-chevrolet.com/Cylinder_Heads/Vortec.html
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Recommended Spark Plugs for Vortec Heads

  • AC Delco Rapid Fire Spark Plugs R44LTS
  • AC Delco Rapid Fire Spark Plugs MR43LTS
  • AC Delco RapidFire No 3 Sparkplug
  • ACCEL P526S U-Groove “SHORTY” Double Platinum (approximately 3/16″ shorter then R44LTS)
  • ACCEL 516
  • Autolite 26
  • Autolite 104
  • Champion RS12YC
  • Bosch HR10B
  • Bosch HR10BX
  • Bosch HR9DC

VORTEC HEADS YOULL FIND IN SALVAGE YARDS HAVE THESE HEAD MARKINGS
The L31 Vortec comes in two different casting numbers, 10239906 (#906) or 12558062 (#062). Originally, the stock #906 casting head was available in two versions. One version had an Inconel exhaust seat with single angle valve grind and was available on 1 ton trucks. The other version was the traditional three angle valve grind. Other than that, the #906 is the same as the #062 head.
GM Performance Parts Bowtie Vortecs are offered in “small port” (#25534351), which has 185cc intake ports/65cc exhaust ports, or the “large port” (#25534445), which features 225cc intake ports/77cc exhaust ports. Both GM factory and GM Performance Parts Vortecs come with 1.94 intake/1.50 exhaust valves. According to the engineers at GM, “Stepping them up to 2.02 valves doesn’t help them any, so it’s not recommended. The port was designed to match the 1.94 valves. With the Vortec flow velocity,vortec heads out flow most of the early fuelie heads most of the older guys used to rave about but they pale in comparison to the better current aftermarket heads available for G.M. engines
http://chevyhiperformance.com/howto/97458/

http://www.2quicknovas.com/vortecheads.html
valve seat and back face angles ,valve diameter and valve lift and duration effect the flow thru the curtain area
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a very common misconception, "that the intake runner size has the most effect on the engines torque curve,is mostly a myth" in reality ,compression ratio, cam timing and engine displacement and proper exhaust scavenging ALL have a larger effect on the engines torque that the intake runner cross sectional area.(yes getting it correct helps but your more likely to cause a problem by selecting an intake port and runner combo thats too small and restrictive than one thats too large in cross sectional area.

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torque curve closely matches the cylinder fill efficiency ,

http://www.rbracing-rsr.com/runnertorquecalc.html

related info

viewtopic.php?f=44&t=529&p=34981&hilit=vortec+heads#p34981

viewtopic.php?f=52&t=266&p=35948&hilit=vortec+heads#p35948

viewtopic.php?f=52&t=401&hilit=vortec+heads

viewtopic.php?f=50&t=10728

http://www.hughesengines.com/TechArticles/1headflowchartscomparisons.php

ID suggest you select from heads from these sources
Jegs; 800/345-4545; Jegs.com

Summit Racing; 800/230-3030; SummitRacing.com

Scoggin-Dickey Parts Center; 800/456-0211; ScogginDickey.com


TRICKFLOW
http://www.trickflow.com/egnsearch.asp? ... 4294867081
http://www.trickflow.com/customerservice
1-330-630-1555 • 1-888-841-6556

BRODIX
http://www.brodix.com/heads/heads.html
479.394.1075

DART
http://www.dartheads.com/products/cylinder-heads
Dart Machinery; 248/362-1188; DartHeads.com


AIR FLOW RESEARCH
http://www.airflowresearch.com/
toll free: 877-892-8844
tel: 661-257-8124

Patriot Performance
Patriot Performance; 888/462-8276; Patriot-Performance.com


RHS
http://www.racingheadservice.com/rhs/cylinder-headshtml
Toll Free: 877-776-4323
Local: 901-259-1134

EDELBROCK
http://www.edelbrock.com/automotive_new ... main.shtml
Edelbrock; 310/781-2222; Edelbrock.com

BMP (world products)
http://www.theengineshop.com/products/cylinder-heads
Tel: 631-737-0372
Fax: 631-737-0467

BUTLER PERFORMANCE
http://www.butlerperformance.com/products/cylinder_heads/cylinder_head_labor.html
866-762-7527

BLUE PRINT ENGINES
http://www.blueprintengines.com/ind...sb-chevy-aluminum-cylinder-heads-cnc-machined
1800-483-4263

PRO-FILER
https://www.profilerperformance.com/
937‐846‐1333
 
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grumpyvette

Administrator
Staff member
Drop in fit, .550" Lift, SBC Iron Vortec
Valve Spring Kit for SB Chevy Vortec
High Performance Hydraulic Flat Tappet Cam, up to .550" Lift

http://www.alexsparts.com/valve-spring- ... at-tappet/

Also mild Hyd Roller w/ up to .550" Lift (see *)

Our Vortec kit is specially engineered for Iron Vortec & 96 iron LT1 Impala heads. That's right, no machine work required to set up a pair of these heads.

We engineered this kit with all the right parts just so Vortec head owners won't have to machine the spring seats or valve guides to run up to .550" lift.

Great for engines with 1.6, high ratio rockers.

Yes, works with self aligning rockers as well as heads w/ screw in studs and guide plates and std, non self aligning rockers.

As some of you know, Vortec heads have a problem w/ retainer to seal clearance. The stock retainers and springs do not allow for more then around .460" lift.

This kit is specially engineered to allow for up to .550" lift, all with parts which fit the heads without additional machine work.

We use a special retainer and spring combination which solves two vortec head problems.



The retainer to seal clearance issue.

Spring base diameter issue (vortec heads will not accept std SBC springs)



The issue with clearance between the retainer and seal was solved by producing a special retainer which offers maximum clearance between the bottom side of retainer and the top of the seal. The bottom of the retainer is pretty much "flush" with the bottom edge of the locks. This design offers maximum clearance without compromising strength or requiring the guides to be shortened.

Our springs are a perfect fit on the stock Vortec spring base.

Both problems solved!

Stock valves have .260" IN/.289" EX Tip lengths which will generally allow for up to .550" lift.

It it durable? Yes! This same kit is running on over one thousand Vortec engines world wide.



Kit Includes:

Sixteen- High Output Drop In Fit Valve Springs
Sixteen- Chrome Moly Retainers, 7 degree
Sixteen- 7 Degree Hardened Valve Locks



For 110 Lb seat pressure, we recommend purchasing a shim kit to facilitate setting up the proper installed height.

Due to the fact vortec heads were made in several countries, (US, Canada and Mexico) it would not be possible to offer a kit which could be installed without making sure the target installed height was correct.

To obtain optimum performance, installed height must be measured and shims added as required. Not only with our kits but with ANY performance valve spring kit.

Recommended seat pressure for High Performance Hydraulic Flat Tappet cams is 110 Lbs however, those running really mild torque or RV cams can use lower seat pressures such as 105, 100 or even 95Lbs.

Please note that each kit comes with a card which shows the target installed height figure.

Specifications:

Outside Diameter- 1.270"
Inside Diameter- .880"
110 Lbs @ 1.780"
310 Lbs @ .550" lift
Coil Bind 1.145"
Kits for High Performance Hydraulic Roller & Mechanical cams can be found by entering VSK600VHR into the search engine.

Recommended Spark Plugs for Vortec Heads

  • AC Delco Rapid Fire Spark Plugs R44LTS
  • AC Delco Rapid Fire Spark Plugs MR43LTS
  • AC Delco RapidFire No 3 Sparkplug
  • ACCEL P526S U-Groove “SHORTY” Double Platinum (approximately 3/16″ shorter then R44LTS)
  • ACCEL 516
  • Autolite 26
  • Autolite 104
  • Champion RS12YC
  • Bosch HR10B
  • Bosch HR10BX
  • Bosch HR9DC

Suitable for most hyd flat tappet cams w/ up to 242 degrees duration @ .050"

Requirements- Valve Seal replacement is highly suggested. It's important for the installer to make 100% sure the seals are fully seated down on the guide. Seals which are not fully seated will reduce maximum lift capacity. We recommend measurements are taken between retainer bottom edge and the seal top to verify there is at least .030" clearance exists.

Vortec heads normally use: 11/32" X .552"-.556" seals.

* This kit is a good choice for stock to mild Hydraulic roller vortec engines. Spring output is 30% higher then stock which increases RPM when used with stock or mild cam grinds. Safe for use with Hyd Roller cams up to 220 degrees duration @ .050" w/ up to .550" lift. Hyd roller cams bigger then this should use our VSK600VHR w/ 130 Lbs seat pressure.

NOTE-1- Spring installed height must be checked and shimmed as necessary.

NOTE-2- Not for Gen III LS series Vortec. Check our other spring kits for late model Gen 3 applications

NOTE-3- We do not recommend the use of "HOWARDS" brand self aligning rockers. Due to their bulky design, clearance between rocker and retainer are either limited or non existent. Most other brands of self aligning rockers work fine. Be sure to verify suitable clearances exist.



There are two versions of shims available; Hardened and Std. (we recommend going with hardened) Our Viton valve seals fit stock vortec guide boss diameters of .552"-.556"(stock)

before you install any cylinder head on any engine clean it carefully , verify there's zero crud in the internal passages, and verify the clearance that you can, and first clean both the block deck and cylinder head mating surfaces with a clean lint free cloth soaked in acetone,
don,t even think of using copper paint its not designed as a true sealant in a similar application, use the correct sealant

DO yourself a huge favor and carefully read the threads and sub links.. below
copperspray1.jpg

http://garage.grumpysperformance.com/index.php?threads/sbc-head-gasket-choice.11070/#post-49251

http://garage.grumpysperformance.co...venting-leaky-head-bolts-studs.50/#post-12527

http://garage.grumpysperformance.com/index.php?threads/head-gasket-related.1859/#post-50617

http://garage.grumpysperformance.com/index.php?threads/sealants-and-threads.805/#post-1171

http://garage.grumpysperformance.co...i-just-picked-up-fuelie-heads-for-cheap.2099/

http://garage.grumpysperformance.com/index.php?threads/which-torque-wrench.342/#post-68488

http://garage.grumpysperformance.co...ping-bolts-and-studs-coolant-free.15/#post-21

http://garage.grumpysperformance.co...trange-oil-leak-at-the-heads.7100/#post-23768

http://garage.grumpysperformance.com/index.php?threads/sealants-and-threads.805/#post-71928

http://garage.grumpysperformance.co...hy-you-should-use-them-at-times.328/#post-402
 
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grumpyvette

Administrator
Staff member
MikeB said:
I've read a lot about max valve lift on stock Vortec heads over the years, and have heard everything from .440" to .480". Well, I just disassembled a pair, and here's what I measured for retainer-to-stem seal distance. (Checked 2 EX and 2 IN valves on each head using a dial indicator.)

Head #1: .506" min / .509" max
Head #2: .535" min / .545" max

Allowing for .050" safety margin, and using the minimum clearance for each head, max safe valve lift on the two heads would be .456" for head #1 , and .485" on head #2.

Both of these heads are 1997 castings, and I'm pretty sure they're off the same engine. So it's true that there's a wide variance from head-to-head.

Conclusion: The guys on web forums who say they have safely run .480" cams are downright lucky, or using up a lot of of that .050" safety margin. I wouldn't run a cam with more than .450" lift w/o measuring first. Mine are going to the shop this week for a valve job and a little more retainer-to seal clearance.

On another note, the springs are very light with an average of 75# @ 1.700" and 180# @ 1.25". But hey, these STOCK 170cc L31 VORTEC CYLINDER HEAD engines were designed to make a torque curve as flat as Kansas from off-idle to 4000 RPM (or less)in a 350 SBC.

MikeB said:
Algoma56 said:
So the beehive springs and different retainer/locks will allow more lift?

Yes, I think it's because of these three things:


  • -- Beehive springs coil bind at lower compressed height
    -- Comp retainers don't protrude as far below top of valve spring
    -- Locks may offset the retainers higher on valve

Here are some notes I made a few months ago:

LS6/LS2 springs
GM 12499224 (blue)
Set of 16: $61
OD: 1.20”
Spring rate: 375
Installed Height: 90# @ 1.800, 126# @ 1.700
Open Pressure: 295# @ 1.250, 314# @ 1.20”
Max Lift: 0.570" (I think this is at 1.800" installed height, like on an LS6)
Top ID: .650”
Top OD: 1.055”

Retainers for LS6 spring ID and Vortec 11/32” valves
Comp 787-16 retainers: $52
Comp 648-16 locks: $24

I think the max lift when used on Vortec heads with the CompCams parts is at least .520". It's certainly more than the .480" out of the box. (And that's with the stock seals fully pressed on the guide bosses.)

If you google "LS6 springs Vortec heads" you'll get a lot of hits. Like I said in a post above, there are other solutions, such as cutting down the guide boss height $ diameter for use with conventional .531" diameter seals, and cutting the spring pocket to accept large diameter springs.

Here's another option. He also has a kit for more aggressive roller cams. But I don't know where his parts come from, so who knows about the quality compared to GM?
http://www.alexsparts.com/valve-spring- ... at-tappet/

380 cu in vortec head build
heres a mild high torque build using a set of mildly reworked vortec heads and a chevy hot cam.

Recently I built a 380 inch small block with 906 Vortec heads for Pat Mcneil. The build: 4.020 X 3.750, 10.1 compression, hyd roller on a steel billet 218/228/112/109/.525, Crane/GM LT 4 1.6 roller rocker arms, very mild, Ferrea 1.940/1.50 stainless valves, GM titanium retainers, GM locators, GM valve springs, the 906 Vortec heads featured honed bronze valve guides, race valve job, spring pockets cut, machined for screw in studs, fully ported, 65 CCs, Performer RPM intake, 850 Holley, 31 degrees total timing, 5 quarts 10/30 Valvoline oil.
IMG_3008.jpg

2972vt.jpg

IMG_3007.jpg

If your going to run vortec heads, you either check you have clearance on current heads, with accurate precision tools and/or if you find you don,t have the required clearance,your going to be forced to modify current heads or you could buy heads with the correct clearance


reading the related info will be helpful
http://www.summitracing.com/parts/sum-151124

http://garage.grumpysperformance.co...train-clearances-and-problems.528/#post-57678

http://garage.grumpysperformance.co...ting-up-the-valve-train.181/page-2#post-54091

http://garage.grumpysperformance.com/index.php?threads/what-springs.11352/#post-51960

http://garage.grumpysperformance.co...-loads-and-installed-height.10709/#post-46627

http://garage.grumpysperformance.com/index.php?threads/removing-valve-seals.4283/#post-44287

https://www.hotrod.com/articles/ccrp-1209-eight-budget-sbc-head-shootout/

https://www.chevydiy.com/ultimate-chevy-big-inch-small-block-cylinder-heads-cheat-sheet/

https://www.chevydiy.com/the-complete-cylinder-head-guide-for-chevy-small-block-engines/

http://www.superchevy.com/how-to/83138-choosing-best-small-block-heads/

http://www.enginebuildermag.com/2014/05/dont-gamble-when-choosing-cylinder-heads/

https://www.hemmings.com/magazine/m...Chevy-Small-Block-Cylinder-Heads/1848889.html

http://www.enginebuildermag.com/2017/03/cylinder-head-design-selection/

https://www.jegs.com/p/ProMaxx-Perf...hevy-Aluminum-Cylinder-Heads/2786544/10002/-1

https://www.flotekheads.com/2016/01/12/best-small-block-chevy-heads/


http://garage.grumpysperformance.com/index.php?threads/the-new-215cc-vortec-heads.266/#post-35948

http://garage.grumpysperformance.co...-vortec-heads-and-other-heads.401/#post-34996

http://garage.grumpysperformance.com/index.php?threads/vortec-info.529/#post-27299

http://garage.grumpysperformance.co...o-the-large-port-vortec-heads.1040/#post-1943

http://garage.grumpysperformance.com/index.php?threads/vortec-related-info.731/#post-1028
 
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