[BuzzLOL]

.. I get 10.24:1 static using 6cc pistons, .015 gasket, .026 deck, 4.030 bore, 3.48 stroke, 64cc heads, 8 cylinders(for cubic inches/L.) using Summit's compression ratio calculator. Lower C.R. if pistons have sizable champfer on top outer edge...

.. I would definitely use the thinner gasket for better quench effects/benefits and power... despite slightly higher compression ratio...

Compression Calculator - SummitRacing.com

[Camaro_Nut2001]

Originally Posted by BuzzLOL

.. I get 10.24:1 static using 6cc pistons, .015 gasket, .026 deck, 4.030 bore, 3.48 stroke, 64cc heads, 8 cylinders(for cubic inches/L.) using Summit's compression ratio calculator. Lower C.R. if pistons have sizable champfer on top outer edge...

.. I would definitely use the thinner gasket for better quench effects/benefits and power... despite slightly higher compression ratio...

Compression Calculator - SummitRacing.com

This is a stock 4.00 bore motor and I just ordered the gaskets, lol.

[cdminter59]

I used this website's calculator. United Engine & Machine Co. Incorporated Cylinder Head Volume: 64cc Piston Head Volume: 6 Gasket Thickness: .015 Gasket Bore: 4.100 Cylinder Bore: 4.030 Deck Clearance: .026 Stroke: 3.4800 Rod Length: 5.7 Intake Valve Closing: 63 (DO NOT ADD 15) (Use valve timing @ 6*) Here is an easy formula to get intake valve closing point. Advertised intake duration / 2 = ?, ? + LSA = sum, Sum - (LSA - ICL) = ?, ? - 180* = Intake closing point 272 / 2 = 136, 136 + 112 = 248, 248 - (112 - 107) = 243, 243 - 180* = 63

[1Gary]

Remember.To smooth port the runners in Vortec heads destroys the "Vortec effect" which is there as part of their design which suspends the A/F mixture.The exhaust side on the other hand will benefit from porting.

[ap72]

Originally Posted by 1Gary

Remember.To smooth port the runners in Vortec heads destroys the "Vortec effect" which is there as part of their design which suspends the A/F mixture.The exhaust side on the other hand will benefit from porting.

Who sold you that line of crap? The vortec heads perform as well as they do thanks to a tall runner, better short turn, and better chamber- it doesn't have a damn thing to do with surface finish.

[Camaro_Nut2001]

Originally Posted by cdminter59

I used this website's calculator. United Engine & Machine Co. Incorporated Cylinder Head Volume: 64cc Piston Head Volume: 6 Gasket Thickness: .015 Gasket Bore: 4.100 Cylinder Bore: 4.030 Deck Clearance: .026 Stroke: 3.4800 Rod Length: 5.7 Intake Valve Closing: 63 (DO NOT ADD 15) (Use valve timing @ 6*) Here is an easy formula to get intake valve closing point. Advertised intake duration / 2 = ?, ? + LSA = sum, Sum - (LSA - ICL) = ?, ? - 180* = Intake closing point 272 / 2 = 136, 136 + 112 = 248, 248 - (112 - 107) = 243, 243 - 180* = 63

Thank you!!!

[ap72]

Originally Posted by cdminter59

valve timing at 6*

Just a small technicality- .006" NOT 6º.

And be careful with this number as advertised duration may or may not be at 6º even for a given cam grinder they're adv duration specs can be measured at different points .004", .005", .006" are all common for hydraulic cams. For solids the lash value is sometimes used, sometimes its .004" and sometimes its .020".

[1Gary]

Originally Posted by ap72

Who sold you that line of crap? The vortec heads perform as well as they do thanks to a tall runner, better short turn, and better chamber- it doesn't have a damn thing to do with surface finish.

While I look for the ref to your question,I found this info that might be useful to the O/P:

Porting For Performance The Science of Horsepower: Engine Builder

Off hand I think it was Larry Carley or Joe Mondello,but I got to find it.You see at the bottom of this ref,Joe talking about a different finish on the intake side.But Joe has been dead I think for two yrs now,so I might not find the ref I want.I used to talk to him often too yrs ago.

[Camaro_Nut2001]

Originally Posted by 1Gary

While I look for the ref to your question,I found this info that might be useful to the O/P:

Porting For Performance The Science of Horsepower: Engine Builder

Off hand I think it was Larry Carley or Joe Mondello,but I got to find it.You see at the bottom of this ref,Joe talking about a different finish on the intake side.But Joe has been dead I think for two yrs now,so I might not find the ref I want.I used to talk to him often too yrs ago.

Thank you for the usefull link as i'm gettin ready to start porting my other head the same as the first one but i'm hopefully gonna build a pretty stout, 475-525 pounds of torque, 400 block i've got for my next build and plan on really working the heads for it. I have a pair of Patriots for it but not sure yet if i'm gonna use them or not.

[1Gary]

Patriot went out of business,so if you have a good set,you might want to baby them.I was told they where bought out and was going to reopen in acouple of months under another name,but I didn't get who bought them or what the new name was.

[ap72]

Originally Posted by 1Gary

While I look for the ref to your question,I found this info that might be useful to the O/P:

Porting For Performance The Science of Horsepower: Engine Builder

Off hand I think it was Larry Carley or Joe Mondello,but I got to find it.You see at the bottom of this ref,Joe talking about a different finish on the intake side.But Joe has been dead I think for two yrs now,so I might not find the ref I want.I used to talk to him often too yrs ago.

a different finish being a 80grit cartridge roll. even the finish a carbide bit leaves is must smoother than a rough casting, especially a GM casting. going over it with 80grit helps smooth the high and low spots, its not needed but sometimes it helps. I like to spray the port with dye right before I'm done and then take a used 80grit roll to it, the low spots show up immediately.

[1Gary]

I am very sure by a reliable source the Vortec heads rough surface plays a role in the performance of the heads by suspending the A/F mixture.That you can benefit from porting the exhaust side,but not to alter the intake runner.That if you smooth port the intake runner,what your left with is just another set of OEM castings.
It is one of those deals that is a summary in your knowledge base you have learned along the way.

[techinspector1]

Originally Posted by 1Gary

While I look for the ref to your question,I found this info that might be useful to the O/P:

Porting For Performance The Science of Horsepower: Engine Builder

Off hand I think it was Larry Carley or Joe Mondello,but I got to find it.You see at the bottom of this ref,Joe talking about a different finish on the intake side.But Joe has been dead I think for two yrs now,so I might not find the ref I want.I used to talk to him often too yrs ago.

Great article Gary, should be required reading for all of us....Joe explains the proper grit to use in the last paragraph of the article.

[BuzzLOL]

.. Obviously there is benefit in altering the intake port... that's why heads have gone from the older 157cc intake ports to 175cc and 185cc Vortec intake ports and 195cc AFR's and 235cc MoTowns, etc...

[ap72]

Originally Posted by 1Gary

I am very sure by a reliable source the Vortec heads rough surface plays a role in the performance of the heads by suspending the A/F mixture.That you can benefit from porting the exhaust side,but not to alter the intake runner.That if you smooth port the intake runner,what your left with is just another set of OEM castings.
It is one of those deals that is a summary in your knowledge base you have learned along the way.

To say any port is optimized as cast is a bunch of stinky BS. Just as any other head they can be improved upon by porting the intake and exhaust, in the case of the oem production vortec heads they can be improved a great deal.