My attempt at following Vortec Pro head porting - Chevelle Tech
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post #1 of 80 (permalink) Old Apr 3rd, 20, 9:31 PM Thread Starter
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My attempt at following Vortec Pro head porting

Mark is a pretty good teacher...I just need to be a better student.

A little more work around the guides, open up the long good port, add the 30 degree back cut on the valves, and one more test and I think I’ll be there. 300+

My numbers are deceiving due to 4.5” bore, but my machinist doesn’t have a 4.310” bore which is notched for the valves. With my chamber deshrouding, a small fixture doesn’t work well.

Anyhow, a few photos.
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1981 Malibu wagon
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post #2 of 80 (permalink) Old Apr 3rd, 20, 9:46 PM
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Rod
 
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Re: My attempt at following Vortec Pro head porting

Nice job. Can you show pics of tools you're using?
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post #3 of 80 (permalink) Old Apr 3rd, 20, 10:54 PM Thread Starter
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Quote:
Originally Posted by Rmchevelle View Post
Nice job. Can you show pics of tools you're using?
Five things really,
Harbor Freight electric die grinder with 6” double cut burr (the burr is not from HF)
Magnetic LED light (very, very important to see)
6” spring inside caliper, also HF, used more for comparing than actually transferring measurements
Straight edge for the chamber mod
iPhone, Mark’ videos, and a Google Sheet and slide instruction I made from his videos.

As well, I’d say half the battle was finding a machinist who would take care of the guides correctly, de shroud the valves in the chamber, and cut the valve angles and widths Mark instructed. 30, 45, 60, 75. The width of the 60 is important, and then only open up to 86-87%. Some open theirs up more, but you can’t put metal back in.

On the exhaust, the width of the 45 is important.

Another video which is very helpful is the one from David Vizzard when he was much younger and talking about mini cylinder head valve angles and porting.
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post #4 of 80 (permalink) Old Apr 4th, 20, 3:55 AM
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Re: My attempt at following Vortec Pro head porting

Nice work..


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post #5 of 80 (permalink) Old Apr 4th, 20, 4:51 AM
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Re: My attempt at following Vortec Pro head porting

very good. For the slow learners among u, what are abbreviations referred to? VTP, MR?

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post #6 of 80 (permalink) Old Apr 4th, 20, 7:50 AM Thread Starter
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Quote:
Originally Posted by Tom Mobley View Post
very good. For the slow learners among u, what are abbreviations referred to? VTP, MR?
VTP - Vortec Pro (Stock and ported) flow from his 620 hp videos
MR - my initials (big valves cut in, no clean up and lastly first attempt, ported) red and yellow

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Best ET w/N2O 11.47 @ 117
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post #7 of 80 (permalink) Old Apr 4th, 20, 8:16 AM
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Re: My attempt at following Vortec Pro head porting

Pretty good there.
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post #8 of 80 (permalink) Old Apr 4th, 20, 9:02 AM Thread Starter
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I should mention, this is without gasket matching whatsoever.

Going to work on the first head a little more today, gasket match, attempt to enlarge the long good port a little more the entire length and open on the sides of the guides further (I didn’t get near 0.075”/0.070” per side on the first attempt).

On the bad port, I’ll gasket match, try to straighten the curve a little more, open up near the guide a little further, and widen and flatten the short turn further.

I’m thinking I left a little too much in the venturi humps in the bowl as well, so I’ll look to take just a bit out of them too.

On the exhaust, round the ledges better and clean up more.

All very minor changes.
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Best ET w/N2O 11.47 @ 117
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post #9 of 80 (permalink) Old Apr 4th, 20, 4:56 PM Thread Starter
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The exhaust
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Best ET w/N2O 11.47 @ 117
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post #10 of 80 (permalink) Old Apr 4th, 20, 11:26 PM Thread Starter
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After roughing in the gasket match for the intake ports, I believe I found the choke points for both ports. Using the 6” spring inside caliper, I started from the intake face and checked the “fit and taper” from the intake port to the valve seat. It becomes readily apparent that the pushrod pinch is a bad choke point, in the good port worse than the bad port.

After reducing this pinch as much as I thought safe, I moved down toward the valve seat. The short port, opens up naturally like a cave, in other words it’s too big already.

The long good port tapers vertically on the way toward the valve seat, but opens up slightly horizontally after the pushrod pinch. In the end, it seemed obvious the verticals needed opened up a little further to move the “pinch” toward valve seat.

I think I’m ready for the next test, hopefully I’ll see more than 300 next time and pickup the low and mid lift flows.

A couple photos of the short turn on the bad hook port.
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1981 Malibu wagon
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Best ET w/N2O 11.47 @ 117
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post #11 of 80 (permalink) Old Apr 5th, 20, 4:55 AM
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Re: My attempt at following Vortec Pro head porting

Quote:
Originally Posted by dragginwagon406 View Post
After roughing in the gasket match for the intake ports, I believe I found the choke points for both ports. Using the 6” spring inside caliper, I started from the intake face and checked the “fit and taper” from the intake port to the valve seat. It becomes readily apparent that the pushrod pinch is a bad choke point, in the good port worse than the bad port.

After reducing this pinch as much as I thought safe, I moved down toward the valve seat. The short port, opens up naturally like a cave, in other words it’s too big already.

The long good port tapers vertically on the way toward the valve seat, but opens up slightly horizontally after the pushrod pinch. In the end, it seemed obvious the verticals needed opened up a little further to move the “pinch” toward valve seat.

I think I’m ready for the next test, hopefully I’ll see more than 300 next time and pickup the low and mid lift flows.

A couple photos of the short turn on the bad hook port.
Thanks for posting this Mike. Very interesting (graphs and photos) and significant improvment with what you've done so far! Do you have access to a flow bench (i.e. "free") or are you paying each time? Curious what typical cost might be for that service.

-Kevin
1965 Chevy Biscayne
<removed> 454cid, "peanut ports", Voodoo 60201
<coming soon> 460cid, Brodix RRO 270, 229/241 Hydraulic Roller
TH400, 3.36 Stock Rearend
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post #12 of 80 (permalink) Old Apr 5th, 20, 6:04 AM Thread Starter
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Quote:
Originally Posted by 65cayne View Post
Quote:
Originally Posted by dragginwagon406 View Post
After roughing in the gasket match for the intake ports, I believe I found the choke points for both ports. Using the 6” spring inside caliper, I started from the intake face and checked the “fit and taper” from the intake port to the valve seat. It becomes readily apparent that the pushrod pinch is a bad choke point, in the good port worse than the bad port.

After reducing this pinch as much as I thought safe, I moved down toward the valve seat. The short port, opens up naturally like a cave, in other words it’s too big already.

The long good port tapers vertically on the way toward the valve seat, but opens up slightly horizontally after the pushrod pinch. In the end, it seemed obvious the verticals needed opened up a little further to move the “pinch” toward valve seat.

I think I’m ready for the next test, hopefully I’ll see more than 300 next time and pickup the low and mid lift flows.

A couple photos of the short turn on the bad hook port.
Thanks for posting this Mike. Very interesting (graphs and photos) and significant improvment with what you've done so far! Do you have access to a flow bench (i.e. "free") or are you paying each time? Curious what typical cost might be for that service.
Kevin,

In general, you’re looking at about 30-45 minutes a session to test three ports; good, bad, and an exhaust.

My machinist is a gear head too, he’s reasonable, and works with me. I’m certainly paying but probably less than you’d expect.

Hopefully I’ll have this engine on his Dyno soon. The progress is exciting. Hoping it’s still reliable. Need to get my cam, lifters, and valve train ordered, but I was waiting to see what pans out of my head testing.
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Best ET NA 12.20 @ 110
Best ET w/N2O 11.47 @ 117
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post #13 of 80 (permalink) Old Apr 5th, 20, 6:10 AM Thread Starter
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By the way, Mark’s videos are great and certainly my go to for this project.

There’s another video I would consider a must watch for my gear head buddies. The entire video is chocked full of good information but the things that catch my interest is about the 30 degree valve seats instead of 45. Full radius in the valve job or 15 degree steps is the best choice, and the goal from a pocket porting.

https://youtu.be/ow5cGV7bXCw
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1981 Malibu wagon
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Best ET NA 12.20 @ 110
Best ET w/N2O 11.47 @ 117
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post #14 of 80 (permalink) Old Apr 5th, 20, 7:40 PM Thread Starter
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The choke point with an explanation. I’m working under the assumption if the middle of the port is bigger than the port entry, the port entry is a choke point and should be corrected. Repeat the process for the upper sides of the port walls.

https://youtu.be/Wz2iCWhi148
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1981 Malibu wagon
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Best ET NA 12.20 @ 110
Best ET w/N2O 11.47 @ 117
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post #15 of 80 (permalink) Old Apr 5th, 20, 8:09 PM Thread Starter
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Choke near port entry eliminated.

https://youtu.be/47uscU68M6E

https://youtu.be/2ZkLVmhTrws
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1981 Malibu wagon
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Best ET w/N2O 11.47 @ 117
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