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help in choosing a cylinder head

 
royrois
I love my Chevy Chevette!
Posts: 6
Joined: 06/13
Posted: 06/25/13 08:28 PM

I'm new to this engine rebuilding stuff. I'm building a 350 engine that would be on a daily driver. I have no idea what compression ratio should I be looking at. The engine came along with a 14022601 heads. I've done some research and they say that I need to do some work on the 601 heads like replacing it with a 1.94 intake valves and do some porting. Since im only building a street engine is this really necessary?

Or would I be better off with just buying a new low budget head? Anyone can suggest a good after market head that is easy on the budget.  

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68scott385
I mow my lawn and find Chevys
Posts: 1994
Joined: 10/09
Posted: 06/26/13 03:26 AM

Shoot for 9:1 compression ratio, that way it'll run on low octane horse pee.

By the time you spend the money to have those heads ported and larger valves installed, you'll see that for a couple hundred more you could have had better aftermarket heads. Spend the grand for entry level aftermarkets and be way ahead on the return per investment curve.  
68scott385 68scott385 68scott385

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ethelkilledfred-#001
I mow my lawn and find Chevys
Posts: 1371
Joined: 03/10
Posted: 06/26/13 06:31 AM

Icon Quoteroyrois:
I'm new to this engine rebuilding stuff. I'm building a 350 engine that would be on a daily driver. I have no idea what compression ratio should I be looking at. The engine came along with a 14022601 heads. I've done some research and they say that I need to do some work on the 601 heads like replacing it with a 1.94 intake valves and do some porting. Since im only building a street engine is this really necessary?

Or would I be better off with just buying a new low budget head? Anyone can suggest a good after market head that is easy on the budget.


SUM 151124 Ml
http://www.summitracing.com/parts/sum-151124
$309.50 Each-
Cylinder Head, Vortec, Cast Iron, Assembled, 67cc Chamber, 175cc Intake Runner, Chevy, 5.7L

Intake Valves Included: Yes
Intake Valve Diameter (in): 1.940 in.
Exhaust Valves Included: Yes
Exhaust Valve Diameter (in): 1.500 in.
Valve Springs Included: Yes
Maximum Valve Lift (in): 0.520 in.

Notes: Vortec style cylinder heads must be used with Vortec style intake manifolds, no exceptions.

"Are you looking for a good set of heads to up the performance factor of your Vortec engine? Our Summit Performance® Vortec cylinder heads have what it takes to get the job done. Featuring wide-open intake runners, efficient combustion chambers, and a high-performance valve job, these heads deliver all of the power-building airflow you need. Made from superior iron alloy, these heads come ready-to-run for improved performance straight out of the box."  
-

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My Space Brotherhood of Street Racers
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ethelkilledfred-#001ethelkilledfred-#001

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skyeking
I mow my lawn and find Chevys
Posts: 2738
Joined: 08/09
Posted: 06/26/13 04:58 PM

Hi there,
The heads that Agent 001 shows should give you a comp
reading with 25/1000" deck height somewhere about 8.6/1
which is useful for economy..Is my formula right?.
   Come in Spinners...All the best and the standard of
free helpful advice from you regulars is still intact.  
skyeking

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royrois
I love my Chevy Chevette!
Posts: 6
Joined: 06/13
Posted: 06/26/13 05:49 PM

wow thanks i will look into these heads.

the summit vortec head says:
Rocker Arms Included: No
Rocker Arm Nuts Included: No
Guideplates Included: No

Will i be able to reuse my old rocker arms, nuts and guideplates from my old cylinder head? What about pushrods?  

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ethelkilledfred-#001
I mow my lawn and find Chevys
Posts: 1371
Joined: 03/10
Posted: 06/28/13 02:23 AM

Icon Quoteroyrois:
wow thanks i will look into these heads.

the summit vortec head says:
Rocker Arms Included: No
Rocker Arm Nuts Included: No
Guideplates Included: No

Will i be able to reuse my old rocker arms, nuts and guideplates from my old cylinder head? What about pushrods?


"Notes: Vortec style cylinder heads must be used with Vortec style intake manifolds, no exceptions. Click the "Suggested Parts" tab for Vortec style intake manifold options. Machine work must be done to accommodate guide plates."

Vortec heads run self aligning rocker arms an require no guideplates. So the answer is no on reusing the rocker arms and guideplates. You only need to buy new self aligning rocker arms. Push rods should work but check them since the head is new it could sit a little highier, but not enough to cause an issue.

Nal 12495490 W

http://www.summitracing.com/parts/nal-12495490/overview/make/chevrolet

Chevrolet Performance Small Block V8 or V6 Rocker Arm Kits 12495490 $65.97
"These small block V8 or V6 rocker arms are available individually or in sets, and include stamped steel or aluminum rockers with mounting hardware. These self-aligning, high-quality rockers have either a 1.5:1 or 1.6:1 ratio, depending on the application."



Here is some interesting reading to get you familar with vortec heads-

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

"How are Vortec Heads Different from Other GM Cast Iron Heads?

   The intake port is designed with a cast “ski jump” on the port roof which is there to increase port flow velocity.
   Port flow was designed to be high in the .300?-.500? valve lift area to make power with relatively low-lift truck camshafts, whereas the old school Gen I heads liked higher-lift camshafts to make their power.
   The bowl area is wide around the valve guide – much wider than the old GM cast iron ‘camel-hump’ heads.
   The intake and exhaust valves and valve seats have a 3-angle grind from the factory.
   The intake and exhaust valves are back-cut from the factory.
   The combustion chamber has a “heart-shaped” design (‘double-quench’ design), whereas the Gen I cast heads were either open or closed chamber designs.
   Best power is made with 32° total timing, although these heads can make power with timing reduced to 29° when used with short-duration camshafts. Older heads needed 32° and up to ensure a more complete burn.
   Stock out-of-the-box Vortec heads have approx. 480 hp potential naturally-aspirated. Out of the box double hump cast heads produced from 25 to 40 hp less, depending on valve size."

IMG 2895

"Other Vortec Tips and Tricks

   Maximum valve lift on Vortec cylinder heads is .460? to .480?. This range is due to production line machining and casting variance. It is highly recommended to check for clearance on anything over .460? lift.

   Vortec heads require a Vortec style 8 bolt intake. They should not be modified for older 12 bolt style intakes because there is not enough section thickness for proper bolt retention at the location of the center bolts. Besides, most intakes can’t be ported enough to match the raised intake ports on the Vortecs.

   If porting the Vortec heads, a little clean-up on the Vortecs is alright. However, if you dramatically open up the ports you will lose the venturi effect in the intakes that makes them flow and perform as well as they do.

   Use flat top or dished pistons to enhance flame travel and intake swirl.

   Larger valves will increase flow but chamber modification is not needed. The trade off between shrouded vs unshrouded valves not worth the decrease in laminar flow and swirl.

   Bill Hendren of Hendren Motorsports explained how they brought up the compression ratio by milling the head surface down. “The stock Vortec combustion chamber on the 906 heads is about 63cc’s. When we angle milled the heads 45 thousandths, we got the combustion chamber down to 56.8cc. When we angle milled them to 85 thousandths + 15 thousandths flat, we ended up with 51.6 cc combustion chambers.”"  
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My Space Brotherhood of Street Racers
http://www.myspace.com/brotherhoodofstreetracers

BSR-International
http://bsr-international.ning.com/

ethelkilledfred-#001ethelkilledfred-#001

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