[hcompton]

Originally Posted by ap72

it's actually 100% wrong... a 5cfm gain on the intake is worth more than a 5cfm gain on the exhaust, even though the % difference is smaller.

Also, the Vortec intake tract is better than previous sbc heads, but the exhaust is NOT worse, its actaully a hair better too, just not as much as the intake. People get caught up in the intake/exhaust ratio and fail to see what they're really looking at on the exhaust side. Also, there's NO crossover, which is a pretty big deal compared to most other stock sbc heads.

Can you please explain why you think vinnie is wrong since i know he is right and explained it clearly. Can you do the same for your side.

How does this 5cfm reference actually make a difference in the disscussion. Its just jibberish. It doesnt even relate to the real world since the ports cfm rating come from a flow bench that does not scavenge the exhuast or flow at the speed that is even close to the actual exhuast speed at redline. Flow benches push air thru the ports around 25-50 mph the exhuast will come out of the exhust port well past 300 mph.

If the ratio is not correct the engine will not be effecient the VE will drop and will never hit its true power potential.

During overlap the exhuast scavaging will actually pull the a/f mix from the intake port while both valves are open and even let it run out the exhuast port then the pressure wave kicks back at the collector and pushes the a/f mix back into the cylinder and possibly over 100 percent ve with proper cam and tuning.

Again...

Amazon.com: Four-Stroke Performance Tuning: Fourth edition (9780857331250): A Graham Bell: Books

Amazon.com: Four-Stroke Performance Tuning: Fourth edition (9780857331250): A Graham Bell: Books

[ap72]

Originally Posted by vinniekq2

A really good example is porting on F E heads. want to wake up a 390,port the exhaust uncork the exhaust system.Old dodge sb...port exhaust side.
want to make power with vortec heads,open the exhaust.
best after market heads have a high exhaust ratio.
dont want to use a split duration cam or thumper cam,port the exhaust
how many high powered cars have small exhaust?

porting the exhaust does help, so you'd be a fool not to do it if you're searching for max power, but it doesn't help as much as the intake.

You're making sweeping presumptions that really have no basis. And there's not a damn thing wrong with a split pattern cam or even a reverse split pattern cam- the cam should match the application and that means almost NEVER using the same lobes on the intake and exhaust.

If you have to pick a side to spend your time on spend it on the intake. And a very well ported set of Vortecs with a stock valve will pick up 30-40cfm on the intake at about .550" lift. Properly built that can mean about 60hp.

And I am NOT saying porting the exhaust won't help too, if you can they should both be done. It is just not as significant as the intake.

[Camaro_Nut2001]

WOW, I really appreciate everyones input and opinions. I got the exhaust ports done where they all match, to my eyes anyway, lol. I just came in to eat and am going back out to pull the studs and tap the bosses. I have a doctors app. Monday but plan on starting on the intake porting when I get home but, I have a question. I bought these studs, Mr. Gasket Screw-In Rocker Arm Studs 1076 - SummitRacing.com. How do I go about torqueing them? I plan on using Loctite on the threads and the only thing I can think of is to triple lock nut them and torque them that way. What do ya'll think?

[hcompton]

Originally Posted by Camaro_Nut2001

WOW, I really appreciate everyones input and opinions. I got the exhaust ports done where they all match, to my eyes anyway, lol. I just came in to eat and am going back out to pull the studs and tap the bosses. I have a doctors app. Monday but plan on starting on the intake porting when I get home but, I have a question. I bought these studs, Mr. Gasket Screw-In Rocker Arm Studs 1076 - SummitRacing.com. How do I go about torqueing them? I plan on using Loctite on the threads and the only thing I can think of is to triple lock nut them and torque them that way. What do ya'll think?

Not sure about that one. You can use two nuts tighten together but not great for tq specs.

Also if you lock tight them down they may be hard to remove. For guide plates later on.

I agree lock tight is a good idea. Just maybe not red unless they call for red locktight. Be sure its high temp. That part of the head gets very hot.

I got to recommend studs with the nuts on them. But i know you have what you have and dont want to send them back. Just feel like i should say it.

http://www.store.procompelectronics....oduct_id=36923

[F-BIRD'88]

Leave the stock studs alone. They do not pull out like the stock studs on the old heads do.
They are fine as is for most hi perf street applcations. even with high perf springs.
Just use a self guided style rocker arm ( stock or aftermarket)

The risk of breaking the the stud boss by trying to pull them out exceeds the
preceived benefit of a screw in stud.
Again, these stock pressed in studs do not cause the issues that the old heads did.

LEAVE THE STUDS ALONE
What cam and rockers are you using. You are probabily getting all carried away for a bunch of nothing.

[Camaro_Nut2001]

Originally Posted by F-BIRD'88

Leave the stock studs alone. They do not pull out like the stock studs on the old heads do.
They are fine as is for most hi perf street applcations. even with high perf springs.
Just use a self guided style rocker arm ( stock or aftermarket)

The risk of breaking the the stud boss by trying to pull them out exceeds the
preceived benefit of a screw in stud.
Again, these stock pressed in studs do not cause the issues that the old heads did.

LEAVE THE STUDS ALONE
What cam and rockers are you using. You are probabily getting all carried away for a bunch of nothing.

Man, I sure am glad I got a phone call and didn't make it back out to the garage and you caught me before I started. Thanks FBird. I hadn't read, seen anywhere or heard anything about the studs on Vortecs and just assumed they were like any other sbc head. I was going to put screw studs in just in case I ever wanted to go with a bigger cam one day. I'm running the Summit K1103, 272/282-.442/.465 on a 112 lsa and running the stock rockers that came with these heads unless I change my mind and then i'll run these COMP Cams Magnum Steel Roller Tip Rocker Arms 1417-16 - SummitRacing.com.

[Camaro_Nut2001]

Originally Posted by F-BIRD'88

You are probabily getting all carried away for a bunch of nothing.

No, I don't think I am. For one, i'm trying to learn head porting, second if I ever want to upgrade this motor, whether bore and stroke it to a 383 or whatever, I will have the Vortec heads already done, third I want this little stock bore and stroke 350 to run lika a scalled cat for what it is and what its going to be used for, fourth I love wrenchin and playin with my Hot Rods in my garage and doing all I am able to do due to my disability. So, I disagree with you on that perspective BUT, I do Thank you for trying to help me and giving me tips, just like you did on the studs.

[F-BIRD'88]

That cam runs just fine with all stock vortec head parts.

With small cams like that you do not need to get carried away with porting stock vortec heads.
Most of the flow gain from porting is found at higher .450++ valve lift.
You can clean up the ports to good effect but do not attempt to make race ports. its not nessessary and will not help.

That cam works very well with vortec heads on a 350 and 10:1cr, performer rpm intake and 750 holley/edelbrock carb.
375hp 400+ ftlbs torque.

[F-BIRD'88]

Concentrate on getting the compression ratio correct.
a clean up on the as cast vortec ports is fine for this cam.

See the funnel in the intake port just under the valve. Leave it alone when using that cam.
It has a purpose.

[Camaro_Nut2001]

Originally Posted by F-BIRD'88

That cam runs just fine with all stock vortec head parts.

With small cams like that you do not need to get carried away with porting stock vortec heads.
Most of the flow gain from porting is found at higher .450++ valve lift.
You can clean up the ports to good effect but do not attempt to make race ports. its not nessessary and will not help.

That cam works very well with vortec heads on a 350 and 10:1cr, performer rpm intake and 750 holley/edelbrock carb.
375hp 400+ ftlbs torque.

Thank you for the info on my combo, I actually picked this cam when I was gonna run self ported 305 heads, lol. Like I said at the first of this thread, this motor is goin in my '88 S10 with a th350 or th400, haven't decided yet, which will be used as my daily driver/sleeper truck.

[Camaro_Nut2001]

Originally Posted by F-BIRD'88

Concentrate on getting the compression ratio correct.
a clean up on the as cast vortec ports is fine for this cam.

See the funnel in the intake port just under the valve. Leave it alone when using that cam.
It has a purpose.

Yes, I have yet to measure my quench so I can order my head gaskets. I'm going to go with long tube headers, 2 1/2" exhaust with these mufflers Dynomax Super Turbo Mufflers 17733 - SummitRacing.com and this converter Hughes Performance XTM Heavy-Duty Towing Series Torque Converters GM11XTM - SummitRacing.com.

[F-BIRD'88]

Get some 4.10's and a 10" 3000 stall and some sticky tires. It will go like hell.
Do no use a stock GM differential in th stock GM rear end. Get a Eaton or a Auburn posi
and install it correctly. Get some traction bars. Easy 12sec performance from this simple build.
Get the compression ratio correct. You want a true measured 10:1.

[F-BIRD'88]

If you want more performance than this. Drop the compression ratio by installing -15cc to -22cc dished pistons
and install a Weiand 142 blower complete kit for vortec heads.
Easy 11's. 7psi boost. use the cam you got or swap to a comp 12-404-4 cam CS268AH-14
Replace the stock springs with Lunati 73943 springs minus the inner damper.
Bolt on all stock rockers etc.

[F-BIRD'88]

That is a "towing converter" not a high perf converter.

use the B&M holeshot 3000 converter or the Hughs -30 converter. 10" 3000 stall rated.
These are very street friendly high stall converters.

The towing converter is a very tight low stall for a very heavy truck and dedicated low rpm hiweay towing.
Its the wrong torque converter for a mild perf S-10 / 350 vortec combo.

[Camaro_Nut2001]

Originally Posted by F-BIRD'88

Get some 4.10's and a 10" 3000 stall and some sticky tires. It will go like hell.
Do no use a stock GM differential in th stock GM rear end. Get a Eaton or a Auburn posi
and install it correctly. Get some traction bars. Easy 12sec performance from this simple build.
Get the compression ratio correct. You want a true measured 10:1.

Thats exactly the gear i'm gonna run with an Eaton limited slip unit, i'm running one in my '69 Chevy truck and love it, already have the bars but was thinkin about fabbing a 4-link instead, don't know yet. I have my eyes on the tires I wanna run but haven't decided on them yet either completely. Do you think a 3000 stall will be ok for a long term daily driver? I wasn't plannin on turnin this motor over 5K rpms, and not alot of them.